A method for evaluating health of rivers and lakes based on biofilm ecological niche monitoring function

Abstract

This invention provides a method for assessing river and lake health based on biofilm niche monitoring, belonging to the field of river and lake water environment monitoring technology. The method includes: deploying biofilm attachment carriers with different substrate affinity characteristics to induce the formation of natural biofilms with niche functional differentiation; collecting samples from the aerobic surface layer and the anoxic inner layer according to the redox gradient; quantitatively analyzing key functional microbial communities covering carbon, nitrogen, sulfur, and phosphorus cycles; calculating the niche overlap index and exploitative competition intensity coefficient in the limiting substrate microenvironment; and establishing a weighted evaluation model based on multi-element niche functional differentiation-competition response, outputting three levels: healthy, sub-healthy / element cycle decoupling, and degraded / endogenous load runaway. This invention utilizes biofilms as in-situ sensors, enabling early warning from the perspective of community functional reorganization before physicochemical indicators deteriorate, providing a highly sensitive and mechanistic technical means for assessing river and lake ecological health.

Description

Technical Field

[0001] This invention relates to the field of river and lake water environment monitoring technology, and in particular to a method for evaluating the health of rivers and lakes based on biofilm niche monitoring. Background Technology

[0002] River and lake health assessment is a core component of water environment management. Traditional assessment methods mainly rely on two types of means: first, monitoring of physicochemical indicators, such as measuring the concentrations of total nitrogen, total phosphorus, chemical oxygen demand, and dissolved oxygen in water bodies. These methods only reflect the instantaneous water quality status and cannot characterize the health status at the level of ecosystem function, and they are also lagging in responding to early stresses; second, biological monitoring, such as benthic animal integrity index and phytoplankton diversity index. Although these methods can reflect the response at the level of biological communities, the sampling cycle is long, the identification workload is large, and it is difficult to reveal whether the microbial-driven biogeochemical cycle function is in a healthy coupled state.

[0003] Biofilms are a common lifestyle for prokaryotes in natural aquatic environments, widely distributed at sediment-water interfaces, on the surfaces of aquatic plants, and on artificial substrates. Studies have shown that biofilms contain highly differentiated niche structures, with different functional bacterial communities occupying specific spaces based on redox gradients and substrate availability, and driving the cycling of biogenic elements such as carbon, nitrogen, sulfur, and phosphorus through metabolic synergy (1). Biofilms are sensitive to environmental changes and have stable feedback capabilities (2), possessing the potential to serve as indicators of ecosystem health.

[0004] However, there is currently a lack of a method to systematically utilize information on niche differentiation and competition within biofilms to quantitatively assess the health status of rivers and lakes. Existing technologies for biofilm monitoring largely focus on biomass measurement or single-function gene abundance detection, failing to translate mechanisms such as substrate affinity-driven niche differentiation, electron acceptor-induced redox specialization, phenotypic plasticity-conferred functional activity differences, and exploitative competition-driven community recombination into operational evaluation techniques. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a river and lake health assessment method based on biofilm niche monitoring. This invention solves the technical problems of existing river and lake health assessment methods being insensitive to stress responses at the ecosystem function level and unable to provide early warning from the perspective of multi-element biogeochemical cycle coupling.

[0006] To achieve the above objectives, the present invention provides the following solution: A method for assessing river and lake health based on biofilm niche monitoring includes: At least two sets of biofilm attachment carriers with different substrate affinity characteristics were set up in the river and lake water bodies to be evaluated in order to obtain natural biofilms. The vertical gradient curves of dissolved oxygen and redox potential on the surface of the natural biofilm are obtained, and the natural biofilm is sampled in layers according to the redox gradient reflected by the vertical gradient curves to obtain aerobic surface samples and anoxic / anaerobic inner samples. Micropore water at different depths from the surface of the biofilm attachment carrier was collected to determine the concentration of limiting substrate in the micropore water; Total DNA was extracted from the aerobic surface samples and the anoxic / anaerobic inner samples, and the abundance data of the key functional bacteria that indicate the carbon, nitrogen, sulfur and phosphorus cycles of rivers and lakes were obtained by quantitative analysis. The content or electrochemical characteristic signals of extracellular electron transport-related active substances in the aerobic surface sample and the anoxic / anaerobic inner sample were detected, and the niche overlap index and exploitative competition intensity coefficient in the microenvironment of the key limiting substrate were calculated based on the abundance data of the key functional bacterial community and the concentration of the limiting substrate. The exploitative competition intensity coefficient, the niche overlap index, and the abundance data of the key functional microbial communities are input into a health assessment model based on multi-element niche functional differentiation-competition response to calculate the sub-item scores for carbon, nitrogen, sulfur, and phosphorus cycle dimensions, respectively. The scores of each item are weighted to obtain a comprehensive score, and the comprehensive score and the judgment result of the red line veto mechanism are compared with the preset benchmark threshold to obtain the health level or early warning signal of the river and lake ecosystem to be evaluated.

[0007] A river and lake health assessment system based on biofilm niche monitoring includes: The carrier induction and deployment module is used to set up at least two sets of biofilm attachment carriers with different substrate affinity characteristics in the river and lake water bodies to be evaluated, so as to obtain natural biofilms. The profile acquisition and stratified sampling module is used to acquire the vertical gradient curves of dissolved oxygen and redox potential on the surface of the natural biofilm, and to perform stratified sampling of the natural biofilm based on the redox gradient reflected by the vertical gradient curves to obtain aerobic surface samples and anoxic / anaerobic inner samples. The micro-region limiting substrate determination module is used to absorb micropore water at different depths from the surface of the biofilm attachment carrier in order to determine the concentration of limiting substrate in the micropore water; The functional microbial community abundance detection module is used to extract total DNA from the aerobic surface sample and the anoxic / anaerobic inner sample, and to quantitatively analyze the key functional microbial communities that indicate the carbon, nitrogen, sulfur and phosphorus cycles of rivers and lakes, so as to obtain the abundance data of the key functional microbial communities. The niche competition evaluation module is used to detect the content or electrochemical characteristic signals of extracellular electron transport-related active substances in the aerobic surface sample and the anoxic / anaerobic inner sample, and to calculate the niche overlap index and exploitative competition intensity coefficient in the microenvironment of the key limiting substrate based on the abundance data of the key functional bacterial community and the concentration of the limiting substrate. The multidimensional sub-item scoring module is used to input the exploitative competition intensity coefficient, the niche overlap index and the abundance data of the key functional microbial communities into the health assessment model based on multi-element niche functional differentiation-competition response, so as to calculate the sub-item scores of carbon, nitrogen, sulfur and phosphorus cycle dimensions respectively. The health level determination and early warning module is used to perform weighted calculation on the scores of each sub-item to obtain a comprehensive score, and compare the comprehensive score and the determination result of the red line veto mechanism with the preset benchmark threshold to obtain the health level or early warning signal of the river and lake ecosystem to be evaluated.

[0008] The present invention discloses the following technical effects: This invention provides a method for evaluating the health of rivers and lakes based on biofilm niche monitoring. By setting differentiated substrate affinity carriers, this invention artificially enhances the precise occupation of microbial resources by microorganisms, solving the technical problems of the strong randomness of natural biofilm formation and the difficulty in unifying evaluation standards. By using the redox gradient inside the biofilm to guide the stratified occupation of specific functional bacterial communities, the biofilm is used as an in-situ "biosensor," amplifying the sensitive response of functions such as nitrification and phosphorus cycling to environmental changes. By introducing the niche overlap index and the exploitative competition intensity coefficient, early warning can be issued from the perspective of community functional reorganization before the deterioration of the physicochemical indicators of river and lake water quality. The weighted evaluation model covering carbon, nitrogen, sulfur, and phosphorus and the red line veto mechanism realize a comprehensive judgment of the health status of rivers and lakes from the perspective of multi-element cycle coupling. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 A flowchart of a river and lake health assessment method based on biofilm niche monitoring function provided in an embodiment of the present invention; Figure 2 This is a diagram of an ecological niche-induced in-situ river carrier deployment device provided in an embodiment of the present invention; Figure 3Schematic diagram of biofilm attachment carriers with different substrate affinity properties provided in embodiments of the present invention; Figure 4 This is a schematic diagram of the ecological niche differentiation of functional microbial communities in a vertical cross-section of a biofilm provided in an embodiment of the present invention; Figure 5 A flowchart for determining health level provided in an embodiment of the present invention. Detailed Implementation

[0011] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0013] like Figure 1 As shown, this invention provides a method for assessing river and lake health based on biofilm niche monitoring, comprising: Step 100: Set up at least two sets of biofilm attachment carriers with different substrate affinity characteristics in the river or lake body to be evaluated to obtain natural biofilms; Step 200: Obtain the vertical gradient curve of dissolved oxygen and redox potential on the surface of the natural biofilm, and perform stratified sampling of the natural biofilm based on the redox gradient reflected by the vertical gradient curve to obtain aerobic surface samples and anoxic / anaerobic inner samples. Step 300: Aspirate microporous water at different depths from the surface of the biofilm attachment carrier to determine the concentration of limiting substrate in the microporous water; Step 400: Extract total DNA from the aerobic surface sample and the anoxic / anaerobic inner sample, and perform quantitative analysis on the key functional bacteria that indicate the carbon, nitrogen, sulfur and phosphorus cycles of rivers and lakes to obtain the abundance data of the key functional bacteria. Step 500: Detect the content or electrochemical characteristic signals of extracellular electron transport-related active substances in the aerobic surface sample and the anoxic / anaerobic inner sample, and calculate the niche overlap index and exploitative competition intensity coefficient in the microenvironment of the key limiting substrate based on the abundance data of the key functional bacterial community and the concentration of the limiting substrate. Step 600: Input the exploitative competition intensity coefficient, the niche overlap index, and the abundance data of the key functional microbial communities into the health assessment model based on multi-element niche functional differentiation-competition response to calculate the sub-item scores for carbon, nitrogen, sulfur, and phosphorus cycle dimensions respectively. Step 700: Calculate the weighted scores of each item to obtain a comprehensive score, and compare the comprehensive score and the judgment result of the red line veto mechanism with the preset benchmark threshold to obtain the health level or early warning signal of the river and lake ecosystem to be evaluated.

[0014] Furthermore, the biofilm attachment carrier includes: First carrier and second carrier; The first carrier is a polymer carrier with hydrophobic alkyl chains modified on its surface. The second carrier is an inorganic mineral carrier with a positively charged surface or rich in micropores.

[0015] Specifically, the deployment steps for niche-inducing carriers are as follows: At least two sets of biofilm attachment carriers with different substrate affinity characteristics are placed in the river or lake body to be evaluated. Utilizing the differentiated affinity of the carrier materials for microbial substrates, the formation of natural biofilms with niche functional differentiation is induced. The specific deployment method is as follows (see details for specific equipment). Figure 2 The device includes a rigid central support on which at least two sets of biofilm attachment carriers with different substrate affinity properties are fixed in layers. Wherein: like Figure 3 As shown, the first carrier is a high molecular weight polymer carrier (such as a polypropylene hollow fiber membrane) with a surface modified with hydrophobic alkyl chains (such as octadecyltrichlorosilane), and its water contact angle is greater than 110°. It is used to induce heterotrophic bacteria that depend on extracellular polymer adsorption and utilize macromolecular organic matter for preferential colonization.

[0016] The second carrier is an inorganic mineral carrier (such as chitosan-modified zeolite) with a positively charged surface (Zeta potential > +20mV) or rich in micropores (pore size 1-10 μm). It utilizes electrostatic adsorption and capillary action to induce the fixation and enrichment of ammonia-oxidizing bacteria and nitrifying bacteria throughout the process.

[0017] The composite carrier device is suspended and fixed in a designated water layer of the river or lake to be evaluated (usually 0.5 m below the euphotic layer to 1.0 m above the sediment-water interface) using a buoy, and vertically positioned using a weight. Each device is set up with at least three parallel samples, and the deployment period is 15 to 45 days (depending on water temperature and nutrient level; a shorter time is used for warm, eutrophic water bodies) to ensure that the biofilm reaches the "maturity period" (i.e., the biofilm thickness and dehydrogenase activity reach a plateau).

[0018] Furthermore, the step of obtaining the vertical gradient curves of dissolved oxygen and redox potential on the surface of the natural biofilm, and performing stratified sampling of the natural biofilm based on the redox gradient reflected by the vertical gradient curves to obtain aerobic surface samples and anoxic / anaerobic inner layer samples, includes: The dissolved oxygen saturation and redox potential on the surface of the natural biofilm were measured using microelectrode puncture to obtain the vertical gradient curve; Based on the redox gradient reflected by the vertical gradient curve, the aerobic layer in the natural biofilm with dissolved oxygen saturation in the first preset range is defined and peeled off to obtain the aerobic surface sample. Based on the redox gradient reflected by the vertical gradient curve, the anoxic or anaerobic layer in the natural biofilm with a redox potential in the second preset range is defined and peeled off to obtain the anoxic / anaerobic inner layer sample.

[0019] Specifically, the biofilm sample stratification and pretreatment steps are as follows: During the biofilm maturation period, the biofilm is sampled in strata based on the redox gradient on the carrier surface, obtaining aerobic surface samples and anoxic / anaerobic inner layer samples respectively. The specific detection steps are as follows: Microelectrode profiling: Before recovery, dissolved oxygen and redox potential microelectrodes with a tip diameter of 10-50 μm were used to puncture the biofilm on the carrier surface with a step precision of 50-100 μm to record DO, H2S, and NO3 in real time. - The vertical gradient curve; Limiting substrate concentration acquisition: Using micro-sampling technology, micropore water (approximately 5-20 μL in volume) was collected at different depths from the carrier surface, and NO2 was determined using ultra-high performance liquid chromatography or ion chromatography. - CH4, SO4 2- PO4 3- Concentration distribution of limiting substrates.

[0020] More specifically, such as Figure 4 As shown, the stratified sampling was performed based on the measured dissolved oxygen microelectrode profile data of the carrier surface: when the dissolved oxygen saturation within 1 mm depth of the carrier surface was greater than 60%, it was defined as an aerobic surface sample; when the dissolved oxygen saturation within 1 mm depth of the carrier surface was less than 2 mm depth and the redox potential was less than -100 mV, it was defined as an anoxic / anaerobic inner sample.

[0021] Furthermore, the step of aspirating microporous water at different depths from the surface of the biofilm attachment carrier to determine the limiting substrate concentration in the microporous water includes: Micro-area sampling technology was used to extract micropore water from the aerobic surface layer and the anoxic / anaerobic inner layer depths of the biofilm attachment carrier. The concentration distribution of substrates related to carbon, nitrogen, sulfur, and phosphorus metabolism in the microporous water was determined by chromatographic analysis to obtain the concentration of the limiting substrate.

[0022] Furthermore, the limiting substrate is any one of nitrite, methane, sulfate, or phosphate.

[0023] Furthermore, the total DNA is extracted from the aerobic surface sample and the anoxic / anaerobic inner sample, and the key functional bacterial communities indicating the carbon, nitrogen, sulfur, and phosphorus cycles of rivers and lakes are quantitatively analyzed to obtain the abundance data of the key functional bacterial communities, including: Total DNA was extracted from the microorganisms contained in the aerobic surface sample and the anoxic / anaerobic inner sample; Using the total DNA as a template, the target functional genes of key functional bacterial communities indicating the carbon, nitrogen, sulfur, and phosphorus cycles in rivers and lakes were quantitatively amplified; wherein, the key functional bacterial communities include: methanogenic archaea, methanogenic bacteria, nitrifying bacteria, ammonia-oxidizing bacteria, sulfate-reducing bacteria, sulfur-oxidizing bacteria, polyphosphate-accumulating bacteria, and phosphate-solubilizing bacteria. The gene copy number of each functional group in the key functional bacterial community is calculated based on the quantitative amplification results to obtain the abundance data of the key functional bacterial community.

[0024] Specifically, the microbial community includes methanogenic archaea and methanotrophic bacteria. The methanogenic archaea are selected from the genera *Methanosaeta* or *Methanosarcina*, and the methanotrophic bacteria are selected from the genera *Methylomonas* or *Methylococcus*. The nitrogen cycle indicator bacteria are selected from nitrifying bacteria, ammonia-oxidizing bacteria, ammonia-oxidizing archaea, and denitrifying bacteria. The nitrifying bacteria are selected from the lineage of *Nitrospira* carrying the *comammox amoA* gene. The ammonia-oxidizing bacteria are selected from the genera *Nitrosomonas* or *Nitrosospira*. The ammonia-oxidizing archaea are selected from the genera *Nitrosopumilus*, *Nitrososphaera*, or *Candidatus Nitrosotalea*. The denitrifying bacteria are selected from the genera *Pseudomonas*, *Paracoccus*, or *Bradyrhizobium* carrying the *nirS* or *nirK* gene. The sulfur cycle indicator bacteria include sulfate-reducing bacteria and sulfur-oxidizing bacteria. The sulfate-reducing bacteria are selected from the genera *Desulfovibrio* or *Desulfobacter*, and the sulfur-oxidizing bacteria are selected from the genera *Thiobacillus* or *Sulfurimonas*. The phosphorus cycle indicator bacteria include polyphosphate-accumulating bacteria and phosphate-solubilizing bacteria. The polyphosphate-accumulating bacteria belong to the genus *Candidatus Accumulibacter*, and the phosphate-solubilizing bacteria are groups of bacteria carrying phosphorus-solubilizing genes from the genera *Pseudomonas* or *Bacillus*.

[0025] The key functional microbial communities that indicate the health of nitrogen cycling in rivers and lakes also include bacteria of the genera *Geobacter* or *Shewanella*, which have the ability to transfer extracellular electrons over long distances.

[0026] Furthermore, the detection of the content or electrochemical characteristic signals of extracellular electron transport-related active substances in the aerobic surface sample and the anoxic / anaerobic inner sample, and the calculation of the niche overlap index and exploitative competition intensity coefficient in the microenvironment of the key limiting substrate based on the abundance data of the key functional bacterial community and the concentration of the limiting substrate, includes: The protein to polysaccharide ratio of extracellular polymers in the aerobic surface sample and the anoxic / anaerobic inner sample is detected as the content of extracellular electron transport-related active substances, or the sulfide oxidation and sulfate reduction currents are detected as the electrochemical characteristic signals. Based on the abundance data of the key functional bacterial communities and the concentration of the limiting substrate, the overlap of the utilization of the key limiting substrate microenvironment resources by different functional bacterial communities is calculated to obtain the niche overlap index. The competition intensity of the limiting electron acceptor is obtained by combining the abundance data of the key functional bacterial community and the concentration of the limiting substrate. The competition intensity of the limiting electron acceptor is then weighted by combining the stress response coefficient characterized by the content of the extracellular electron transport-related active substances and the niche overlap index to calculate the exploitative competition intensity coefficient.

[0027] Specifically, the key limiting substrate includes NO2. - CH4, SO4 2- and PO4 3- The exploitative competition intensity coefficient is obtained by measuring the rate of consumption of the limiting electron acceptor and calculating the total nitrifying bacteria. amoA Genes and denitrifying bacteria nirS The gene copy number ratio is used as a whole to determine the result, in conjunction with changes in the protein / polysaccharide ratio in extracellular polymers.

[0028] More specifically, stratified samples ensure that the abundance of functional microbial communities has precise spatial attributes. This spatial attribute is key to this invention because only by comparing the abundance of different microbial communities within the same microenvironment (redox layer) can the degree of overlap in their natural ecological niches be accurately reflected. Without stratification, the mixed sample data will lose its ecological significance and cannot be used for subsequent competition analysis.

[0029] The abundance of comammox nitrospira and denitrifying bacteria may be numerically independent and parallel, but the location of the anoxic microregion and the limiting substrate (such as NO2) may influence each other. -The concentration of each electron acceptor was used to calculate the exploitative competition intensity coefficient for the same electron acceptor. This transformation allows the invention to move from an evaluation dimension of "quantity" to "functional conflict".

[0030] When calculations show that the intensity of exploitative competition exceeds the historical baseline threshold, it means that the originally differentiated ecological niches have undergone decoupling and reorganization. Even if the total nitrogen and total phosphorus in the overlying water have not yet exceeded the standard, it can still issue an early warning signal of river and lake health degradation.

[0031] Furthermore, the step of inputting the exploitative competition intensity coefficient, the niche overlap index, and the abundance data of the key functional microbial communities into a health assessment model based on multi-element niche functional differentiation-competition response to calculate the sub-scores for the carbon, nitrogen, sulfur, and phosphorus cycle dimensions, respectively, includes: Substitute the abundance data and the limiting substrate concentration into the health assessment model to calculate the carbon cycle coupling coefficient, sulfate reduction-sulfur oxidation coupling coefficient, and polyphosphate-solubilization niche overlap, so as to obtain the sub-item scores of the carbon, sulfur, and phosphorus cycle dimensions respectively. Based on the health assessment model, the nitrification niche occupancy rate and denitrification functional interface separation degree are calculated according to the abundance data to obtain the basic score of the nitrogen cycle dimension. The exploitative competition intensity coefficient and the niche overlap index are input as correction terms into the health assessment model to correct the base score and output the sub-scores of the nitrogen cycle dimension.

[0032] Furthermore, the specific calculation method for the exploitative competition intensity coefficient is as follows: The "exploitative competition intensity coefficient" is not a single value, but a comprehensive index (denoted as IEC) composed of the following three sub-indices with weights. This index is used to quantify the degree of niche overlap and competitive exclusion caused by functional microbial communities sharing limited resources.

[0033] Sub-indicator A: Competition intensity of restricted electron acceptors (IA); Calculation principle: Reflects the rate of competition for the same electron acceptor among different bacterial communities. In anoxic microregions, both nitrifying and denitrifying bacteria can utilize NO2. - As electron acceptors, the difference in their consumption rate characterizes the competitive situation.

[0034] ; Among them, V nitrite NO2 measured in biofilm microregions - Consumption rate (μmol·g) -1 ·h -1 NO2 was measured using microelectrodes. - The slope of the concentration change over time is obtained; Vbaseline NO2 measured in unstressed natural water bodies - Basic consumption rate (μmol·g) -1 ·h -1 This value is pre-determined and stored in a database as a baseline threshold; R amoA / nirS This represents the ratio of the total copy number of the amoA gene in nitrifying bacteria to the copy number of the nirS gene in denitrifying bacteria. The subscript "inner layer" indicates the ratio in the anoxic inner layer sample, and the subscript "baseline" indicates the historical baseline ratio in unstressed water bodies. Decision logic: If I A >1.2 indicates NO2 - An abnormally rapid consumption rate or an imbalance in the proportion of comamox indicates intensified competition for electron acceptors.

[0035] Sub-index B: Extracellular polymeric stress response coefficient (I B ); When microorganisms face exploitative competitive stress, they secrete more extracellular proteins to enhance their adhesion and enzymatic predation capabilities, resulting in an increase in the protein / polysaccharide ratio in EPS.

[0036] ; Among them, (P / PS) 实测 The ratio of protein content (μg / g) to polysaccharide content (μg / g) of the extracellular polymeric substances (EPS) extracted from the sample was determined by the Coomassie Brilliant Blue method and the phenol-sulfuric acid method; (P / PS) 基线 The baseline protein / polysaccharide ratio (typically 0.5-0.8) is used for biofilms in unstressed natural aquatic bodies. Decision logic: If I B >1.5 indicates that the microbial community is responding to resource scarcity stress through phenotypic plasticity.

[0037] Sub-index C: Niche overlap index (I C ); The degree of overlap in the utilization of multidimensional restricted substrates by two functional groups is directly quantified.

[0038] Calculation formula: ; Among them, P ik and P jk These represent the pairs of bacterial groups i and j with the k-th limiting substrate (NO2). - CH4, SO4 2- PO4 3- The relative utilization coefficient of the microbial community is obtained by normalizing the product of the abundance of each microbial community and the concentration of each substrate.

[0039] Exploitative competition intensity coefficient (I) ECThe comprehensive judgment formula is as follows: This invention weights and fuses the above three sub-indicators to output the final exploitative competition intensity coefficient: ; The recommended values ​​for the weighting coefficients are: (Electron acceptor has the highest competitive weight). , .

[0040] The calculated exploitative competition intensity coefficient (I) EC This will serve as the core correction parameter for the nitrogen cycle dimension score, as well as an independent criterion for triggering the red line veto mechanism.

[0041] Furthermore, the weighted calculation of each of the sub-item scores to obtain a comprehensive score, and the comprehensive score and the judgment result of the red line veto mechanism are compared with a preset benchmark threshold to obtain the health level or early warning signal of the river and lake ecosystem to be evaluated, including: The scores of the carbon, nitrogen, sulfur, and phosphorus cycle dimensions are weighted and summed according to preset weights to obtain the comprehensive score. Determine whether the sub-item score or the related endogenous release risk coefficient meets the preset red line triggering conditions to obtain the determination result of the red line veto mechanism; The judgment result of the red line veto mechanism and the comprehensive score are compared with the benchmark threshold. If the red line is triggered, the early warning signal of the deterioration state is directly output. If the red line is not triggered, the health level is determined according to the interval of the comprehensive score.

[0042] Specifically, as a correction term (data fusion) for the nitrogen cycle dimension score: The baseline score of the nitrogen cycle dimension (S) 氮 ) is through R comammox and S denit Obtained by looking up a table. The calculated I... EC As a multiplier correction factor applied to the base score: ; Wherein, the correction function f(I) EC The definition is as follows: If I EC ≤1.0, f(I EC =1.0 (No competitive coercion, no score deduction); If 1.0 EC ≤2.0, f(I EC =0.8 (Mild coercion, score downgraded); If I EC >2.0, f(I EC ​=0.5 (Severe coercion, score significantly reduced).

[0043] As a multi-dimensional coupled stress indicator (threshold trigger): When the calculated I EC >2.0, and simultaneously satisfying the endogenous phosphorus release risk coefficient R in the phosphorus cycle dimension. P-释放 When the score is >5.0, regardless of whether the overall score initially calculated by S5 is in the sub-healthy range, the system will forcibly downgrade the output level from "sub-healthy" to "deterioration / endogenous load out of control".

[0044] In the actual evaluation process, step 500 outputs a data structure containing: the exploitative competition intensity coefficient (I... EC ); each sub-item indicator (I A I B I C ); Niche overlap index matrix.

[0045] The computer program reads the data body and first checks I. EC Has the downgrade red line been triggered? If not, then I... EC The overall score is calculated by substituting the values ​​into the nitrogen cycle scoring formula. This design ensures that ecological mechanism analysis can quantitatively and reproducibly influence management decision outputs.

[0046] The comprehensive assessment of river and lake health levels is based on specific comprehensive evaluation rules, which include a four-dimensional weighted scoring formula and a red-line veto mechanism. The four-dimensional weighted scoring formula is: S 综合 =W N ×S 氮 +W P ×S 磷 +W C ×S 碳 +W S ×S 硫 ; The weight coefficients for each dimension are preset based on the sensitivity of the element cycle to eutrophication stress and the ecological irreversibility. The specific weight values ​​are as follows: Nitrogen cycle dimension weight W N The phosphorus cycle dimension weight W is 0.30-0.40. P The weight W for the carbon cycle dimension is 0.25-0.35. C The weight W for the sulfur cycle dimension is 0.15-0.25. S It is 0.10-0.20; The red line veto mechanism means that when the score of the sulfur cycle dimension is lower than the preset red line threshold (40 points) or the endogenous release risk coefficient of the phosphorus cycle dimension exceeds the preset critical value (5.0), the health level of the river and lake will be directly and forcibly judged as degraded / endogenous load out of control, regardless of the calculation result of the weighted scoring formula.

[0047] Furthermore, the method also includes using microelectrodes to record O2 and NO3 inside the biomembrane in real time. - The gradient change curve is used as the rate of change of the slope of the curve as a dynamic evaluation index of the buffer capacity of the river and lake system against external input loads.

[0048] This embodiment also provides the following specific methods: This invention uses a 100-point scale to independently score each dimension, with each dimension having a maximum score of 100 points. The specific scoring criteria for each dimension are as follows: Carbon cycle dimension scoring criteria (maximum score 100 points, weight 0.20): The carbon cycle dimension uses the coupling coefficient between methane production and oxidation pathways as the core evaluation indicator, which is defined as: ; Among them, AOB pmo - Abundance of aerobic methanogenic bacteria; N pmo -Methane oxidation functional gene pmoA Copy number; AOG mcr -Abundance of methanogenic archaea; N mcr - Methanogenic functional genes mcrA Copy number; C 表层 - Methane concentration at the surface of the biofilm, μM; C 内层 - Methane concentration in the inner layer of the biofilm, μM.

[0049] Table 1 shows the scoring criteria for the carbon cycle dimension. Table 1 is as follows: Table 1

[0050] Nitrogen cycle dimension scoring criteria (maximum score 100, weight 0.35): The nitrogen cycle dimension uses the nitrification niche occupancy rate and the separation degree of the denitrification functional interface as dual core indicators.

[0051] Indicator A: Nitrification niche occupancy rate (R) comammox ) ; Where, N 内层 Inner layer of biomembrane comammox Nitrospira amoA基因拷贝数 N 总 For biomembranes 总AOB+AOA+comammox amoA基因拷贝数 ; Index B is the separation degree of the denitrification functional interface (S). denit ); ; Where, N d表层 aerobic surface nirs / nirK基因拷贝数 N d内层 hypoxic surface nirs / nirK基因拷贝数 .

[0052] Table 2 is the scoring criteria for the nitrogen cycle dimension, as shown below: Table 2

[0053] Sulfur cycle dimension scoring criteria (maximum score 100 points, weight 0.15): The sulfur cycle dimension uses sulfate reduction-sulfur oxidation coupling efficiency and electron flow balance index as core indicators.

[0054] Index C: Sulfate reduction-sulfur oxidation coupling coefficient (E) S-耦合 ); ; Among them, A 硫氧化 Abundance of sulfur-oxidizing bacteria; A 硫还原 Abundance of sulfate-reducing bacteria; C 界面 For [SO4] 2 ] 界面 Concentration; C 上覆水 For [SO4] 2 ] 上覆水 concentration; I 硫氧化 To measure the sulfide (HS) at the aerobic-anoxic interface of biofilms using a gold / mercury amalgamated microelectrode (tip diameter 10-25 μm) within a potential window of -0.6 V to +0.2 V (vs. Ag / AgCl), sulfide (HS) was observed at approximately -0.1 V. - The oxidation peak current value is expressed in nanoamperes (nA). This current value is directly proportional to the concentration of reduced sulfides at the interface.

[0055] I 硫还原 The current value, expressed in nanoamperes (nA), represents the peak current related to sulfate reduction activity observed at approximately -0.4 V when LSV measurements were performed using the same microelectrode within the anoxic inner layer of the biofilm under the same potential window. This current value reflects the intensity of the active electron flow generated by sulfate-reducing bacteria metabolism.

[0056] Note: The ratio of the two (I) 硫氧化 / I 硫还原The ratio (I) characterizes the coupling efficiency between the oxidation and reduction half-reactions during sulfur disproportionation. A ratio close to 1.0 indicates that sulfides are oxidized promptly after formation, indicating good coupling of the sulfur cycle pathway; a ratio significantly deviating from 1.0 indicates that sulfur oxidation lags behind sulfur reduction, and free sulfides begin to accumulate. 硫氧化 and I 硫还原 The sulfur cycle-related electrochemical signals were characterized using microelectrodes. Table 3 shows the scoring criteria for the sulfur cycle dimension, as shown below: Table 3

[0057] Phosphorus cycle dimension scoring criteria (maximum score 100, weight 0.30): The phosphorus cycle dimension uses the overlap of the ecological niches of polyphosphate-solubilization functional groups and the risk coefficient of endogenous phosphorus release as core indicators.

[0058] Indicator A: Niche overlap between polyphosphate and phosphorus solubilization (O p-重叠 ); Calculated using the Schoener overlap index: ; Where, p 聚磷,z p represents the relative abundance of polyphosphate-accumulating bacteria at biofilm depth z. 解磷,z denoted as ρ_z, representing the relative abundance of phosphate-solubilizing bacteria at biofilm depth z; m represents the number of stratified sampling layers.

[0059] Indicator B: Endogenous phosphorus release risk coefficient (R) p-释放 ); ; Among them, A 解磷 Abundance of phosphate-solubilizing bacteria; APA represents alkaline phosphatase activity; A 聚磷 For polyphosphate abundance; C 孔隙水 For [PO4] 3- ] 孔隙水 Concentration; C 上覆水 For [PO4] 3- ] 上覆水 concentration.

[0060] Table 4 is the scoring criteria for the phosphorus cycle dimension. Table 4 is as follows: Table 4

[0061] Formula for calculating the overall score: S 综合 =0.20×S 碳 +0.35×S 氮 +0.15×S 硫 +0.30×S 磷 ; Among them, S 综合 —Comprehensive score for river and lake health (0-100 points); S 碳 —Score for the carbon cycle dimension; S 氮 — Nitrogen cycle dimension score; S 硫 —Sulphur cycle dimension score; S 磷 —Score for the phosphorus cycle dimension; Standards for classifying the health levels of rivers and lakes: Based on the comprehensive score S 综合 (For specific evaluation methods, please refer to...) Figure 5 The health status of rivers and lakes is divided into three levels: Level 1: Healthy Status; Table 5 is the standard table for classifying the health status of rivers and lakes, as shown below: Table 5

[0062] Level Two: Sub-healthy State / Element Cycle Decoupling; Table 6 is the classification standard for sub-healthy state of rivers and lakes, as shown below: Table 6

[0063] Level 3: Degraded State / Uncontrolled Internal Load; Table 7 is the classification standard for river and lake degradation levels, as shown below: Table 7

[0064] The present invention also provides the following embodiments: Using a eutrophic shallow lake as the evaluation object, the implementation process and evaluation results of this invention are presented.

[0065] Sampling Sites and Carrier Deployment: A lake area of ​​a eutrophic shallow lake (historical TP concentration 0.12-0.28 mg / L, TN concentration 1.8-3.5 mg / L) was selected as the evaluation object. An ecological niche induction device was deployed on May 10, 2024, containing two types of carriers: Three parallel sets of each type of carrier were installed and fixed in nylon mesh bags 0.5 m below the lake bottom to prevent direct sediment cover. The carrier density was 0.05 m per cubic meter of water. 2 Carrier surface area.

[0066] Biofilm samples were collected in stratified layers: The samples were recovered 30 days after carrier deployment. Micro-profiles of the carrier surface were measured using a Unisense OX-50 dissolved oxygen microelectrode and a Unisense RD-50 redox potential microelectrode. The results are shown in Table 8, which presents the basic data for biofilm carrier measurements. Table 8 is as follows: Table 8

[0067] The 0-1 mm layer was defined as the aerobic surface layer, and the 2-3 mm layer as the anoxic inner layer. Each biofilm layer was scraped using a sterile scalpel and collected in sterile centrifuge tubes, with each sample weighing approximately 0.5 g wet. Absolute quantification of each functional gene was performed using SYBR Green qPCR. The qPCR results are shown in Table 9 below. Table 9 shows the abundance distribution of each functional bacterial community in the vertical profile of the biofilm. Table 9

[0068] Dissolved oxygen, methane, and hydrogen sulfide concentrations at various depths of the support were determined using a microelectrode system. SO4 was determined using ion chromatography (Dionex ICS-2100). 2- The concentration of PO4 was determined using the phosphomolybdic blue colorimetric method. 3- Concentration. The results are shown in Table 10, which is the table of chemical parameter determination results for the microregion of the biofilm. Table 10 is as follows: Table 10

[0069] Alkaline phosphatase activity was determined using the disodium p-nitrophenyl phosphate method. The alkaline phosphatase activity of the hypoxic inner layer sample was 3.2 μmol·g. -1 ·h -1 .

[0070] Scoring calculation for each dimension: C 耦合 =(5.6×10 6 ×5.6×10 6 ) / (8.7×10 6 ×8.7×10 6 )×(2.1 / 185)=0.414×0.0114=0.0047; C 耦合 =0.0047<0.3, and the CH4 concentration in the inner layer of the biofilm (185 μM) was much higher than that in the surface layer (2.1 μM), with a measured methane bubbling flux of 32 mL·m -2 ·d -1 According to the carbon cycle scoring criteria, it was rated "poor" with a score of 42 points.

[0071] Nitrification niche occupancy rate throughout the process: R comammox =3.8×10 5 / 2.93×10 6 ×100%=13.0%; N 总 =3.8×10 5 +2.5×10 6 +4.8×10 4 =2.93×10 6 copies / g; Denitrification interface separation degree: S denit =1-(8.7×10 4 / 4.2×10 6 ) = 1 - 0.021 = 0.98; R comammox =13.0%, within the 10%-25% range (favorable conditions); S denit =0.98≥0.7 (favorable condition).

[0072] Because of R comammox It did not meet the excellent standard and was judged as "good" to the lower end, with a score of 72 points.

[0073] E S-耦合 =(7.8×10 5 / 9.2×10 6 )×(0.08 / 0.45)×0.65=0.0848×0.178×0.65=0.0098<0.3; The H2S concentration in the hypoxic inner layer was 62 μM, which was judged as "poor" and scored 38 points.

[0074] The number of stratified sampling layers m=2 (surface layer and inner layer), and the relative abundance proportion of each layer is shown in Table 11. Table 11 is the calculation table of polyphosphate-solubilized niche overlap, as shown below: Table 11

[0075] O P-重叠 =1 - 1 / 2 × (|0.98 - 0.03| + |0.02 - 0.97|) = 1 - 0.5 × (0.95 + 0.95) = 1 - 0.95 = 0.05; R P-释放 =(6.7×10 6 ×3.2) / (4.5×10 6 )×(28.5 / 2.1)=4.76×13.57=64.6; O P-重叠 =0.05≤0.3 (favorable condition); RP-释放 =64.6>5.0 (Poor condition). According to the scoring rules, R... P-释放 The threshold for the "poor" rating was triggered, and the overall assessment was "poor," with a score of 45 points.

[0076] Overall score and health level determination: The scores for each dimension are summarized in Table 12. Table 12 is a weighted score table for each element dimension, as shown below: Table 12

[0077] Overall Score S 综合 =52.8 points, which falls within the 45-74 point range, and is judged to be in a sub-healthy state.

[0078] Further subtype diagnosis revealed that the system met the characteristics of subtype B (phosphorus stress-dominated type), while the scores in dimensions C and S were also low, indicating that the system exhibits a multi-element cycle decoupling trend caused by phosphorus stress.

[0079] Sulfur cycle red line: S dimension 38 points < 35 points, not triggered; Phosphorus cycle red line: P dimension 45 points < 40 points, not triggered; Nitrogen cycle red line: N dimension 72 points < 35 points, not triggered. The overall score of 52.8 points is valid and does not trigger a mandatory downgrade.

[0080] This embodiment also provides a river and lake health assessment system based on biofilm niche monitoring, including: The carrier induction and deployment module is used to set up at least two sets of biofilm attachment carriers with different substrate affinity characteristics in the river and lake water bodies to be evaluated, so as to obtain natural biofilms. The profile acquisition and stratified sampling module is used to acquire the vertical gradient curves of dissolved oxygen and redox potential on the surface of the natural biofilm, and to perform stratified sampling of the natural biofilm to obtain aerobic surface samples and anoxic / anaerobic inner samples. The micro-region limiting substrate determination module is used to absorb micropore water at different depths from the surface of the biofilm attachment carrier in order to determine the concentration of limiting substrate in the micropore water; The functional microbial community abundance detection module is used to extract total DNA from the aerobic surface sample and the anoxic / anaerobic inner sample, and to quantitatively analyze the key functional microbial communities that indicate the carbon, nitrogen, sulfur and phosphorus cycles of rivers and lakes, so as to obtain the abundance data of the key functional microbial communities. The niche competition evaluation module is used to detect the content or electrochemical characteristic signals of extracellular electron transport-related active substances in the aerobic surface sample and the anoxic / anaerobic inner sample, and to calculate the niche overlap index and exploitative competition intensity coefficient in the microenvironment of the key limiting substrate based on the abundance data of the key functional bacterial community and the concentration of the limiting substrate. The multidimensional sub-item scoring module is used to input the exploitative competition intensity coefficient, the niche overlap index and the abundance data of the key functional microbial communities to calculate the sub-item scores of the carbon, nitrogen, sulfur and phosphorus cycle dimensions respectively. The health level determination and early warning module is used to perform weighted calculations on each of the sub-items to obtain a comprehensive score, and compare the comprehensive score and the determination result of the red line veto mechanism with a preset benchmark threshold to obtain the health level or early warning signal of the river and lake ecosystem to be evaluated.

[0081] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0082] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for assessing river and lake health based on biofilm niche monitoring, characterized in that, include: At least two sets of biofilm attachment carriers with different substrate affinity characteristics were set up in the river and lake water bodies to be evaluated in order to obtain natural biofilms. The vertical gradient curves of dissolved oxygen and redox potential on the surface of the natural biofilm are obtained, and the natural biofilm is sampled in layers according to the redox gradient reflected by the vertical gradient curves to obtain aerobic surface samples and anoxic / anaerobic inner samples. Micropore water at different depths from the surface of the biofilm attachment carrier was collected to determine the concentration of limiting substrate in the micropore water; Total DNA was extracted from the aerobic surface samples and the anoxic / anaerobic inner samples, and the abundance data of the key functional bacteria that indicate the carbon, nitrogen, sulfur and phosphorus cycles of rivers and lakes were obtained by quantitative analysis. The content or electrochemical characteristic signals of extracellular electron transport-related active substances in the aerobic surface sample and the anoxic / anaerobic inner sample were detected, and the niche overlap index and exploitative competition intensity coefficient in the microenvironment of the key limiting substrate were calculated based on the abundance data of the key functional bacterial community and the concentration of the limiting substrate. The exploitative competition intensity coefficient, the niche overlap index, and the abundance data of the key functional microbial communities are input into a health assessment model based on multi-element niche functional differentiation-competition response to calculate the sub-item scores for carbon, nitrogen, sulfur, and phosphorus cycle dimensions, respectively. The scores of each item are weighted to obtain a comprehensive score, and the comprehensive score and the judgment result of the red line veto mechanism are compared with the preset benchmark threshold to obtain the health level or early warning signal of the river and lake ecosystem to be evaluated.

2. The method for river and lake health assessment based on biofilm niche monitoring function according to claim 1, characterized in that, The biofilm attachment carrier includes: First carrier and second carrier; The first carrier is a polymer carrier with hydrophobic alkyl chains modified on its surface. The second carrier is an inorganic mineral carrier with a positively charged surface or rich in micropores.

3. The method for river and lake health assessment based on biofilm niche monitoring as described in claim 1, characterized in that, The process involves obtaining vertical gradient curves of dissolved oxygen and redox potential on the surface of the natural biofilm, and performing stratified sampling of the natural biofilm based on the redox gradient reflected by the vertical gradient curves to obtain aerobic surface samples and anoxic / anaerobic inner layer samples, including: The dissolved oxygen saturation and redox potential on the surface of the natural biofilm were measured using microelectrode puncture to obtain the vertical gradient curve; Based on the redox gradient reflected by the vertical gradient curve, the aerobic layer in the natural biofilm with dissolved oxygen saturation in the first preset range is defined and peeled off to obtain the aerobic surface sample. Based on the redox gradient reflected by the vertical gradient curve, the anoxic or anaerobic layer in the natural biofilm with a redox potential in the second preset range is defined and peeled off to obtain the anoxic / anaerobic inner layer sample.

4. The method for river and lake health assessment based on biofilm niche monitoring as described in claim 1, characterized in that, The step of aspirating microporous water at different depths from the surface of the biofilm attachment carrier to determine the limiting substrate concentration in the microporous water includes: Micro-area sampling technology was used to extract micropore water from the aerobic surface layer and the anoxic / anaerobic inner layer depths of the biofilm attachment carrier. The concentration distribution of substrates related to carbon, nitrogen, sulfur, and phosphorus metabolism in the microporous water was determined by chromatographic analysis to obtain the concentration of the limiting substrate.

5. The method for river and lake health assessment based on biofilm niche monitoring as described in claim 4, characterized in that, The limiting substrate is any one of nitrite, methane, sulfate, or phosphate.

6. The method for river and lake health assessment based on biofilm niche monitoring as described in claim 1, characterized in that, The total DNA was extracted from the aerobic surface samples and the anoxic / anaerobic inner samples, and the abundance data of the key functional bacterial communities indicating the carbon, nitrogen, sulfur, and phosphorus cycles of rivers and lakes were obtained by quantitative analysis, including: Total DNA was extracted from the microorganisms contained in the aerobic surface sample and the anoxic / anaerobic inner sample; Using the total DNA as a template, the target functional genes of key functional bacterial communities indicating the carbon, nitrogen, sulfur, and phosphorus cycles in rivers and lakes were quantitatively amplified; wherein, the key functional bacterial communities include: methanogenic archaea, methanogenic bacteria, nitrifying bacteria, ammonia-oxidizing bacteria, sulfate-reducing bacteria, sulfur-oxidizing bacteria, polyphosphate-accumulating bacteria, and phosphate-solubilizing bacteria. The gene copy number of each functional group in the key functional bacterial community is calculated based on the quantitative amplification results to obtain the abundance data of the key functional bacterial community.

7. The method for river and lake health assessment based on biofilm niche monitoring as described in claim 1, characterized in that, The method involves detecting the content or electrochemical characteristic signals of extracellular electron transport-related active substances in the aerobic surface samples and the anoxic / anaerobic inner samples, and calculating the niche overlap index and exploitative competition intensity coefficient of the key limiting substrate microenvironment based on the abundance data of the key functional bacterial communities and the concentration of the limiting substrate, including: The protein to polysaccharide ratio of extracellular polymers in the aerobic surface sample and the anoxic / anaerobic inner sample is detected as the content of extracellular electron transport-related active substances, or the sulfide oxidation and sulfate reduction currents are detected as the electrochemical characteristic signals. Based on the abundance data of the key functional bacterial communities and the concentration of the limiting substrate, the overlap of the utilization of the key limiting substrate microenvironment resources by different functional bacterial communities is calculated to obtain the niche overlap index. The competition intensity of the limiting electron acceptor is obtained by combining the abundance data of the key functional bacterial community and the concentration of the limiting substrate. The competition intensity of the limiting electron acceptor is then weighted by combining the stress response coefficient characterized by the content of the extracellular electron transport-related active substances and the niche overlap index to calculate the exploitative competition intensity coefficient.

8. The method for river and lake health assessment based on biofilm niche monitoring as described in claim 1, characterized in that, The process involves inputting the exploitative competition intensity coefficient, the niche overlap index, and the abundance data of the key functional microbial communities into a health assessment model based on multi-element niche functional differentiation-competition response to calculate sub-scores for the carbon, nitrogen, sulfur, and phosphorus cycle dimensions, including: Substitute the abundance data and the limiting substrate concentration into the health assessment model to calculate the carbon cycle coupling coefficient, sulfate reduction-sulfur oxidation coupling coefficient, and polyphosphate-solubilization niche overlap, so as to obtain the sub-item scores of the carbon, sulfur, and phosphorus cycle dimensions respectively. Based on the health assessment model, the nitrification niche occupancy rate and denitrification functional interface separation degree are calculated according to the abundance data to obtain the basic score of the nitrogen cycle dimension. The exploitative competition intensity coefficient and the niche overlap index are input as correction terms into the health assessment model to correct the base score and output the sub-scores of the nitrogen cycle dimension.

9. The method for evaluating river and lake health based on biofilm niche monitoring as described in claim 1, characterized in that, The weighted calculation of each sub-item score to obtain a comprehensive score, and the comprehensive score and the judgment result of the red line veto mechanism are compared with a preset benchmark threshold to obtain the health level or early warning signal of the river and lake ecosystem to be evaluated, including: The scores of the carbon, nitrogen, sulfur, and phosphorus cycle dimensions are weighted and summed according to preset weights to obtain the comprehensive score. Determine whether the sub-item score or the related endogenous release risk coefficient meets the preset red line triggering conditions to obtain the determination result of the red line veto mechanism; The judgment result of the red line veto mechanism and the comprehensive score are compared with the benchmark threshold. If the red line is triggered, the early warning signal of the deterioration state is directly output. If the red line is not triggered, the health level is determined according to the interval of the comprehensive score.

10. A river and lake health assessment system based on biofilm niche monitoring, characterized in that, include: The carrier induction and deployment module is used to set up at least two sets of biofilm attachment carriers with different substrate affinity characteristics in the river and lake water bodies to be evaluated, so as to obtain natural biofilms. The profile acquisition and stratified sampling module is used to acquire the vertical gradient curves of dissolved oxygen and redox potential on the surface of the natural biofilm, and to perform stratified sampling of the natural biofilm based on the redox gradient reflected by the vertical gradient curves to obtain aerobic surface samples and anoxic / anaerobic inner samples. The micro-region limiting substrate determination module is used to absorb micropore water at different depths from the surface of the biofilm attachment carrier in order to determine the concentration of limiting substrate in the micropore water; The functional microbial community abundance detection module is used to extract total DNA from the aerobic surface sample and the anoxic / anaerobic inner sample, and to quantitatively analyze the key functional microbial communities that indicate the carbon, nitrogen, sulfur and phosphorus cycles of rivers and lakes, so as to obtain the abundance data of the key functional microbial communities. The niche competition evaluation module is used to detect the content or electrochemical characteristic signals of extracellular electron transport-related active substances in the aerobic surface sample and the anoxic / anaerobic inner sample, and to calculate the niche overlap index and exploitative competition intensity coefficient in the microenvironment of the key limiting substrate based on the abundance data of the key functional bacterial community and the concentration of the limiting substrate. The multidimensional sub-item scoring module is used to input the exploitative competition intensity coefficient, the niche overlap index and the abundance data of the key functional microbial communities into the health assessment model based on multi-element niche functional differentiation-competition response, so as to calculate the sub-item scores of carbon, nitrogen, sulfur and phosphorus cycle dimensions respectively. The health level determination and early warning module is used to perform weighted calculation on the scores of each sub-item to obtain a comprehensive score, and compare the comprehensive score and the determination result of the red line veto mechanism with the preset benchmark threshold to obtain the health level or early warning signal of the river and lake ecosystem to be evaluated.

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