Normalizing dredging judgment method based on exogenous particle input influence

Abstract

The present application relates to a kind of based on normal dredging judgment method of exogenous particle input influence, based on the establishment of different depth dredging simulation and the control group of un-dredging of target area sediment;After simulating dredging, the environmental and target pollutant release condition of new sludge-water interface under different dredging depths are observed, and the content of each target pollutant in sediment is obtained;While detecting the content of each pollutant in control group;Target area water is observed, and the particle in target area water is captured, and the content of each pollutant in particle and the monthly sediment flux of particle are obtained;The content of pollutant under different conditions is compared, and the influence of exogenous pollution input on the new sludge-water interface is observed by simulation, to judge the influence degree of exogenous pollution input on environmental dredging effect, and whether it needs to carry out normal multiple dredging, to provide more accurate technical guidance for the continuous control of endogenous after environmental dredging implementation, improve the economic and environmental benefits of environmental dredging.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, specifically to a routine dredging judgment method based on the influence of external particulate matter input. Background Technology

[0002] Environmental dredging technology is a primary means of controlling endogenous pollution in the sediment of surface water bodies such as rivers, lakes, and reservoirs. The main objectives of environmental dredging include controlling eutrophication, treating black and odorous water bodies, improving water quality, and enhancing the health of aquatic ecosystems. Ultimately, the goal of all these objectives is to improve and enhance the quality of the aquatic ecological environment. However, since its large-scale application, this technology has been subject to considerable controversy, primarily focusing on its effectiveness in improving the water environment. Improving the environment at the newly formed sediment-water interface and controlling the pollutant release flux are crucial to the effectiveness of environmental dredging, especially under continuous external pollution input. The continuous accumulation of large amounts of external pollutants at the newly formed sediment-water interface significantly impacts the effectiveness of environmental dredging, and may even necessitate routine, multi-round dredging operations due to the large influx of external pollution. However, current research on the changes in the newly formed sediment-water interface under the influence of external pollution input, and the resulting potential for routine dredging, still has several shortcomings:

[0003] First, there is insufficient understanding of the newly formed mud-water interface, which affects the effectiveness of environmental dredging. The mud-water interface is the main site for the release of various pollutants from the sediment. However, current environmental dredging technologies mainly focus on the content of certain pollutants in the sediment, and in particular, rarely pay attention to the pollutant exchange process and mechanism at the newly formed mud-water interface during practical application. In some areas, pollutants continue to be released after sediment dredging, and even the release flux increases, affecting the improvement of the water environment.

[0004] Secondly, there is insufficient mastery of methods for observing the newly formed mud-water interface in environmentally friendly dredging. Currently, the application of environmentally friendly dredging technology still suffers from a simplistic and crude approach to the dredging process. Construction units typically focus primarily on engineering parameters such as the dredging area and volume, lacking a systematic methodology for precisely observing changes in the mud-water interface at different stages of dredging.

[0005] Third, research on the changes in the newly formed mud-water interface at different stages of environmental dredging is insufficient. Before, during, and after dredging, the mud-water interface environment and pollutant transformation processes undergo fundamental changes depending on the underwater environment and the form of pollutants in the sediment. In particular, when external sources continue to input pollutants, the content and flux of pollutants at the newly formed mud-water interface will be continuously aggravated. However, current research on these changes in environmental dredging applications is still insufficient, affecting dredging efficiency. Therefore, a routine dredging assessment method based on the impact of external particulate matter input is urgently needed to address the influence of continuous external pollution input on the newly formed mud-water interface environment and pollutant migration and transformation processes in environmental dredging, thereby providing more precise guidance for the application of environmental dredging technologies. Summary of the Invention

[0006] In view of the impact of external pollution input on the pollution control effect of environmental dredging, and the current shortcomings in the observation and research methods of the newly formed slurry-water interface in environmental dredging, the purpose of this invention is to provide a routine dredging judgment method based on the influence of external particulate matter input. By simulating the newly formed slurry-water interface at different stages of environmental dredging under the influence of external input, the method studies the changes in the interface environment and pollutant migration flux, judges the degree of influence of external pollution input on the environmental dredging effect, and determines whether routine multi-round dredging is necessary. This provides more accurate technical guidance for the continuous control of endogenous release after the implementation of environmental dredging, and improves the economic and environmental benefits of environmental dredging.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a normalized dredging judgment method based on the influence of exogenous particulate matter input, comprising the following steps:

[0008] Based on the bottom sediment of the target area, establish dredging simulations at different depths and a control group without dredging;

[0009] After simulated dredging, the nascent mud-water interface environment and the release of target pollutants at different dredging depths were observed to obtain the content of each target pollutant in the sediment. , where n represents the target pollutant to be reduced through dredging; simultaneously, the content of each pollutant in the control group was measured. ;as well as

[0010] The water body in the target area is observed, and particulate matter in the water body is captured to obtain the content of various pollutants in the particulate matter. And particulate matter monthly sedimentation flux Sr;

[0011] when At the same time less than and At that time, based on the monthly particulate matter settling flux Sr, captured particulate matter was added monthly to the newly formed mud-water interface after simulated dredging; and long-term simulated observations were conducted on the newly formed mud-water interface and the undredged control group. Based on the time when the target pollutant release flux reached or exceeded the corresponding pollutant release flux of the undredged control group, the dredging work of the target area was planned.

[0012] Preferably, the simulated dredging accuracy is ≥5 cm, and the simulated dredging depth Dx satisfies: Dx ≥ the target area's simulated dredging depth ≥10 cm.

[0013] Preferably, the target pollutants in the sediment include at least nitrogen, phosphorus, TOC, harmful heavy metals, and organic pollutants.

[0014] Preferably, the environmental conditions of the nascent sludge-water interface and the release of target pollutants at different dredging depths are observed. The observed indicators include pH, dissolved oxygen penetration depth, the profile distribution of various pollutants in the sediment interstitial water, and the concentration of various pollutants in the sediment. The release flux was measured, and the instantaneous mud-water interface effect after dredging was evaluated through observation indicators to obtain the content of various target pollutants in the sediment. .

[0015] Preferably, the target pollutant release flux calculation model is as follows:

[0016] ;

[0017] In the formula: F is the target pollutant release flux; Porosity of the sediment; The diffusion coefficient of the target pollutant at the mud-water interface; The concentration gradient of the target pollutant at the mud-water interface is obtained by fitting first-order reaction kinetics based on the distribution profile of the target pollutant in the interstitial water.

[0018] Preferably, the depth of the interstitial water is in the range of 3 to 10 cm.

[0019] Preferably, the monthly particulate matter settling flux Sr is the continuously captured particulate matter settling flux, and reaches 10 to 15 times the actual sediment deposition rate in the target area; and the continuous capture observation time of the monthly particulate matter settling flux Sr is greater than 6 months, and the average settling flux during the observation period is taken.

[0020] Preferably, when Greater than When the dredging depth Dx is considered invalid, the dredging depth is increased; when Less than and At that time, it was determined that multiple rounds of routine dredging work were not necessary.

[0021] Preferably, the dredging work for the target area is planned based on the time it takes for the target pollutant release flux to reach or exceed the corresponding pollutant release flux in the undredged control group, specifically as follows:

[0022] If the time for the release flux of the target pollutant to reach or exceed the release flux of the corresponding pollutant in the undredged control group is less than 6 months, the target area shall carry out routine multiple rounds of dredging within 5 years after dredging.

[0023] When the release flux of the target pollutant reaches or exceeds the release flux of the corresponding pollutant in the undredged control group within 6-12 months, the target area will carry out routine multi-round dredging within 5-10 years after dredging.

[0024] If the target pollutant release flux reaches or exceeds the corresponding pollutant release flux of the undredged control group for more than 12 months, the target area does not need to carry out multiple rounds of routine dredging work.

[0025] Preferably, when the content of harmful heavy metals and organic pollutants in particulate matter is lower than the preset risk screening value, the simulation observation of the impact of particulate matter on the content and flux of pollutants at the new interface is no longer carried out.

[0026] Beneficial effects: This invention comprehensively considers the control effect of pollutant release from the newly formed mud-water interface at different stages of environmental dredging, as well as the impact of external pollutant input on the pollutant content of the sediment and the pollutant release flux at the newly formed mud-water interface. On the one hand, by observing the newly formed mud-water interface, a more suitable environmental dredging depth can be selected, significantly improving the control effect on the release of various pollutants from the sediment. On the other hand, by simulating the impact of external input on the newly formed mud-water interface, a normalized dredging judgment method is proposed, which is of great significance for reducing the economic losses caused by blind dredging and improving the water environment improvement effect of environmental dredging. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the sedimentation flux of exogenous particulate matter in the target water area in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram comparing the content of exogenous particulate matter and pollutants in dredged and undredged sediment in the target water area in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram illustrating the effect of exogenous particulate matter input on the total phosphorus content of sediment in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram illustrating the effect of exogenous particulate matter input on the interstitial water phosphate concentration in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram illustrating the effect of exogenous particulate matter input on phosphorus flux at the nascent mud-water interface in an embodiment of the present invention. Detailed Implementation

[0032] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0033] Example: A routine dredging assessment method based on the influence of exogenous particulate matter input, comprising:

[0034] Before implementing environmentally friendly dredging, dredging simulations at different depths were established based on the bottom sediment of the target area. The simulated dredging accuracy was ≥5cm, and the simulated dredging depth Dx satisfied that: Dx ≥ the target area's planned dredging depth ≥10cm. A control group without dredging was also set up. After the simulated dredging, the following operations were performed:

[0035] (1) Instantaneous observation of the newly formed mud-water interface: The environment of the newly formed mud-water interface and the release of target pollutants at different dredging depths were observed immediately. The observation indicators included pH, dissolved oxygen penetration depth, distribution of various pollutants in the interstitial water of the sediment, and various pollutants in the sediment. The release flux was measured, and the instantaneous mud-water interface effect after dredging was evaluated through observation indicators to obtain the content of various target pollutants in the sediment. , where n represents the target pollutant to be reduced through dredging; simultaneously, the content of each pollutant in the control group was measured. .

[0036] Among them, the pH and dissolved oxygen penetration depth at the interface of the newly formed sediment must be observed using a high-precision microelectrode system, with a vertical observation accuracy of ≥100μm; the detection of target pollutants in the sediment should at least include nitrogen, phosphorus, TOC, harmful heavy metals (cadmium, mercury, arsenic, lead, chromium, copper, nickel, zinc) and organic pollutants (HCH, DDT and benzo[a]pyrene); the detection of target pollutant concentration and release flux in the interstitial water should at least include nitrogen, phosphorus, TOC and harmful heavy metals (cadmium, mercury, arsenic, lead, chromium, copper, nickel, zinc).

[0037] In one embodiment, the profile distribution of the target pollutant in the interstitial water of the sediment is obtained using an existing balanced interstitial water sampling device, wherein the filter membrane pore size of the device is <0.45μm and the vertical acquisition accuracy of the interstitial water is >4 mm; the target pollutant release flux calculation model is as follows:

[0038] ;

[0039] Where: F is the target pollutant release flux (mg / (m³)). 2 d)); Porosity of the sediment; The diffusion coefficient of the target pollutant at the mud-water interface (10) -6 / (cm 2 s)); The concentration gradient of the target pollutant at the mud-water interface was obtained by fitting first-order reaction kinetics based on the distribution profile of the target pollutant in the interstitial water; the obtained interstitial water depth ranged from 3 to 10 cm.

[0040] (2) Long-term observation of the new sediment interface: The sediment columnar samples after dredging at different depths were cultured and observed at different time scales in an indoor simulated environment. At the same time, an undredged control group was set up. The culture time was ≥12 months. During the culture process, the pH of the new sediment-water interface, dissolved oxygen penetration depth, distribution of various pollutants in the sediment interstitial water profile, and release flux of various target pollutants in the sediment were observed at different times.

[0041] The water body in the target area is observed, and particulate matter is captured using a particulate matter trap. In this embodiment, the height-to-diameter ratio of the trap's collection tube is 5-10, which allows for continuous capture of settled particulate matter in the target area, and the content of various pollutants in the particulate matter can be detected. The monthly particulate matter deposition flux Sr is defined as the continuously captured particulate matter deposition flux, which must be 10–15 times the actual sediment deposition rate in the target area. The continuous capture observation period for the monthly particulate matter deposition flux Sr should be >6 months, and the average deposition flux during the observation period should be used. The content of each pollutant in the particulate matter is compared. The content of various pollutants in the newly formed surface sediment after dredging The content of various pollutants in the control sediment (undredged) :

[0042] when > If the dredging depth Dx is not considered valid, the dredging depth needs to be increased.

[0043] when < < If the dredging depth Dx is considered effective and the external input has little impact on the endogenous pollution of the sediment at the new interface, then multiple rounds of routine dredging are not required.

[0044] when < < If the dredging depth Dx is considered effective, further assessment of the impact of external inputs on the endogenous pollution load of the newly formed interface is required.

[0045] when < < If the dredging depth Dx is considered effective, then external input has a significant impact on the endogenous pollution of the sediment at the new interface, and multiple rounds of routine dredging may be required.

[0046] when < < or < < At that time, based on the monthly particulate matter settling flux Sr, captured particulate matter was added monthly to the newly formed sludge-water interface after simulated dredging to assess the impact of external input on the endogenous pollution load of the sediment at the newly formed interface. Long-term simulated observations were conducted on the newly formed sludge-water interface and the undragged control group. Based on the time it takes for the target pollutant release flux to reach or exceed the corresponding pollutant release flux in the undragged control group, dredging work for the target area was planned, as follows:

[0047] When the simulation observation period is less than 6 months, the target pollutant release flux This means that the pollutant release flux reaches or exceeds that of the undredged control group. This indicates that the impact of external inputs is significant, and the area to be dredged needs to undergo routine, multi-round dredging within 5 years after the dredging.

[0048] When the target pollutant release flux occurs within a simulated observation period of 6 to 12 months... Reaching or exceeding the corresponding pollutant release flux of the undredged control group This indicates that external inputs have a certain impact on dredging results, and the area to be dredged needs to undergo routine, multi-round dredging within 5 to 10 years after the dredging.

[0049] When the simulated observation period exceeds 12 months, the target pollutant release flux Still less than the corresponding pollutant release flux in the undredged control group. This indicates that external input has little impact on dredging effectiveness, and the area to be dredged does not require routine multi-round dredging for the time being.

[0050] In one embodiment, when the content of harmful heavy metals (cadmium, mercury, arsenic, lead, chromium, copper, nickel, zinc) and organic pollutants (hexachlorocyclohexane, DDT and benzo[a]pyrene) in particulate matter is lower than the content listed in Tables 1 and 2 (refer to the "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control (Trial)" (GB15618-2018)), the simulation observation of the impact of particulate matter on the content and flux of pollutants at the new interface is no longer conducted.

[0051] Table 1 Screening values ​​for soil pollution risk in agricultural land (harmful metals, mg / kg)

[0052]

[0053] Table 2 Screening values ​​for soil pollution risk in agricultural land (organic pollutants, mg / kg)

[0054]

[0055] Based on the method for judging routine dredging based on the influence of exogenous particulate matter input in this invention, for polluted water areas such as estuaries, lake and reservoir shorelines, and confluence bays with large exogenous pollutant input fluxes, the method simulates and observes changes in the sludge-water interface environment, pollutant content, and pollutant release flux under the influence of exogenous input. It then proposes routine environmental dredging recommendations for target areas to improve the water environment improvement effect of environmental dredging, as detailed below:

[0056] 1. Analyze the content of various pollutants in the sediment, including nitrogen, phosphorus, TOC, harmful heavy metals (cadmium, mercury, arsenic, lead, chromium, copper, nickel, zinc) and organic pollutants (HCH, DDT and benzo[a]pyrene);

[0057] 2. Conduct dredging simulations at different depths, namely 15, 20, 25, and 30 cm;

[0058] 3. Reference Figure 1 As shown, continuous observation was conducted in the target water area for one year to obtain the monthly exogenous particulate matter deposition flux, and the average deposition flux Sr was calculated, which is approximately 10 times the sediment deposition rate of the target water area.

[0059] 4. The content of various pollutants in particulate matter, including nitrogen, phosphorus, TOC, harmful heavy metals (cadmium, mercury, arsenic, lead, chromium, copper, nickel, zinc) and organic pollutants (HCH, DDT and benzo[a]pyrene);

[0060] 5. At a dredging depth of Dx = 25 cm, the contents of nitrogen, phosphorus, and TOC in particulate matter (average during the observation period) were higher than those in the newly formed surface sediment after dredging and the undredged control sediment. Figure 2 As shown, this indicates that the dredging depth is effective, but the external input has a significant impact on the endogenous pollution of the sediment at the new interface, and multiple rounds of routine dredging may be required.

[0061] 6. According to the average sedimentation flux Sr of particulate matter in the target area, add captured particulate matter to the newly formed mud-water interface after simulated dredging each month, analyze the nitrogen, phosphorus and TOC content in the sediment, the nitrogen, phosphorus and TOC concentration in the interstitial water and the changes in release flux, and assess whether multiple rounds of routine dredging are needed.

[0062] 7. During the one-year simulation observation period, the input of exogenous particulate matter had little impact on the flux of nitrogen and TOC at the newly formed mud-water interface, and was always lower than the flux of nitrogen and TOC at the undredged sediment interface.

[0063] 8. During the one-year simulated observation period, the total phosphorus content of the surface sediment from exogenous particulate matter reached the phosphorus content of undredged sediment after 7 months. Figure 3 As shown, the phosphate concentration in the interstitial water of the surface sediment approached the concentration in the undredged sediment six months after dredging. Figure 4 As shown, the phosphorus flux FP-1 at the nascent sludge-water interface reached the phosphorus flux FP-0 at the undredged sediment interface 8 months after dredging. Figure 5 As shown;

[0064] 9. Based on the above, it is determined that the input of exogenous particulate matter has a significant impact on the phosphorus flux at the newly formed mud-water interface. The proposed dredging area needs to carry out regular multiple rounds of dredging, with an interval of approximately 6 to 8 years.

[0065] The embodiments of the present invention have been described in detail above with reference to the examples. However, the present invention is not limited to the above embodiments. For those skilled in the art, after learning the contents described in the present invention, several equivalent changes and substitutions can be made without departing from the principle of the present invention. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A routine dredging judgment method based on the influence of exogenous particulate matter input, characterized in that: Includes the following steps: Based on the bottom sediment of the target area, establish dredging simulations at different depths and a control group without dredging; After simulated dredging, the nascent mud-water interface environment and the release of target pollutants at different dredging depths were observed to obtain the content of each target pollutant in the sediment. , where n represents the target pollutant to be reduced through dredging; simultaneously, the content of each pollutant in the control group was measured. ; as well as The water body in the target area is observed, and particulate matter in the water body is captured to obtain the content of various pollutants in the particulate matter. And particulate matter monthly sedimentation flux Sr; when At the same time less than and At that time, based on the monthly particulate matter settling flux Sr, captured particulate matter was added to the newly formed mud-water interface after simulated dredging on a monthly basis; and long-term simulated observations were conducted on the newly formed mud-water interface and the undredged control group. Based on the time when the target pollutant release flux reached or exceeded the corresponding pollutant release flux of the undredged control group, the dredging work of the target area was planned. The simulated dredging accuracy is ≥5 cm, and the simulated dredging depth Dx satisfies: Dx ≥ the target area's simulated dredging depth ≥10 cm. The target pollutants in the sediment include at least nitrogen, phosphorus, TOC, harmful heavy metals, and organic pollutants; The environmental conditions of the nascent sediment-water interface and the release of target pollutants at different dredging depths were observed. The observed indicators included pH, dissolved oxygen penetration depth, distribution of various pollutants in the sediment interstitial water, and the concentration of various pollutants in the sediment. The release flux was measured, and the instantaneous mud-water interface effect after dredging was evaluated through observation indicators to obtain the content of various target pollutants in the sediment. .

2. The method for determining routine dredging based on the influence of exogenous particulate matter input as described in claim 1, characterized in that: The calculation model for the target pollutant release flux is as follows: ； In the formula: F is the target pollutant release flux; Porosity of the sediment; The diffusion coefficient of the target pollutant at the mud-water interface; The concentration gradient of the target pollutant at the mud-water interface is obtained by fitting first-order reaction kinetics based on the distribution profile of the target pollutant in the interstitial water.

3. The method for judging routine dredging based on the influence of exogenous particulate matter input according to claim 2, characterized in that: The interstitial water depth ranges from 3 to 10 cm.

4. The method for determining routine dredging based on the influence of exogenous particulate matter input as described in claim 1, characterized in that: The monthly particulate matter settling flux Sr is the continuously captured particulate matter settling flux, and it reaches 10 to 15 times the actual sediment deposition rate in the target area; and the continuous capture observation period of the monthly particulate matter settling flux Sr is greater than 6 months, and the average settling flux during the observation period is taken.

5. The method for determining routine dredging based on the influence of exogenous particulate matter input as described in claim 1, characterized in that: when Greater than When the dredging depth Dx is considered invalid, the dredging depth is increased; when Less than and At that time, it was determined that multiple rounds of routine dredging work were not necessary.

6. The method for determining routine dredging based on the influence of exogenous particulate matter input according to claim 1, characterized in that: Based on the time it takes for the target pollutant release flux to reach or exceed the corresponding pollutant release flux in the undredged control group, the dredging work for the target area is planned, specifically as follows: If the time for the release flux of the target pollutant to reach or exceed the release flux of the corresponding pollutant in the undredged control group is less than 6 months, the target area shall carry out routine multiple rounds of dredging within 5 years after dredging. When the release flux of the target pollutant reaches or exceeds the release flux of the corresponding pollutant in the undredged control group within 6-12 months, the target area will carry out routine multi-round dredging within 5-10 years after dredging. If the target pollutant release flux reaches or exceeds the corresponding pollutant release flux of the undredged control group for more than 12 months, the target area does not need to carry out multiple rounds of routine dredging work.

7. The method for determining routine dredging based on the influence of exogenous particulate matter input according to claim 6, characterized in that: When the levels of harmful heavy metals and organic pollutants in particulate matter are lower than the preset risk screening values, simulation observations of the impact of particulate matter on the content and flux of pollutants at the new interface will no longer be conducted.

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