A method for identifying pollution sources in lake water

Abstract

This invention discloses a method for identifying pollution sources in lake water bodies, belonging to the field of water pollution prevention and control technology. The method includes the following steps: sampling rocks containing pollutant elements in strata near the lake basin, groundwater flowing into the lake, surface water flowing into the lake, surface water sediments, and bottom sediment and overlying water at the lake inlet; measuring the collected samples; and comparing the analytical results of various pollutants with those obtained from a watershed non-point source pollution survey to identify the pollution sources in the lake water body. This invention, through investigation, sampling, and analysis, summarizes the occurrence state, weathering migration and transport patterns, and distribution characteristics of potential pollutants in the lake watershed under regional geological processes. It then determines the impact of potential pollutants, particularly major pollutants such as nitrogen and phosphorus, on lake water quality under different geological backgrounds, thereby accurately identifying the pollution sources in the lake water body.

Description

Technical Field

[0001] This invention relates to the field of water pollution prevention and control technology, and in particular to a method for determining the pollution sources of lake water pollution. Background Technology

[0002] Lakes serve as connecting points for the interactions between various spheres of the Earth's surface system, forming an important component of the terrestrial hydrosphere and closely related to the biosphere, atmosphere, and lithosphere. Lakes not only function as flood control, irrigation, drinking water sources, transportation hubs, power generators, aquaculture facilities, and tourist attractions, but also possess unique functions such as regulating regional climate, recording regional environmental changes, maintaining regional ecosystem balance, and preserving biodiversity. Therefore, protecting the aquatic environment of lakes is of paramount importance.

[0003] Currently, with global environmental degradation and increasingly severe pollution of lakes, protecting lake water environments is imperative. The primary task is to first identify the sources of pollution and then provide targeted prevention and control measures. However, there is currently a lack of specific and effective methods in this field for identifying the sources of lake water pollution. Summary of the Invention

[0004] To address the above problems, this invention provides a method for determining the pollution sources of lake water pollution.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for identifying pollution sources in lake water bodies includes the following steps: sampling rocks containing pollutant elements in the strata near the lake basin, groundwater flowing into the lake, surface water flowing into the lake and sediments in the river system, bottom sediment at the lake inlet, and water overlying the bottom sediment; measuring the collected samples; and identifying the pollution sources in the lake water body by comparing the analysis results of each pollutant and combining them with a survey of non-point source pollution in the watershed.

[0007] Preferably, the rocks in the polluting strata near the lake basin are rocks in strata whose background values ​​of polluting elements exceed Clark values, as determined by a comprehensive study of regional geological reports, regional mineral geological reports, regional rock geochemical anomalies, and research results from various domestic and international research institutions.

[0008] Preferably, the sampling method for rocks in the polluting strata near the lake basin is as follows: sampling is conducted within 1 / 10 of the distance between the sampling points, and three sampling points are combined into one sample to collect fine-grained material from the soil leaching layer-parent material layer at a depth of 10cm-50cm from the surface.

[0009] Preferably, the groundwater flowing into the lake is groundwater determined by a comprehensive study based on regional geological reports, regional hydrogeological reports, regional tectonic distribution, and research results from various domestic and international research institutions, which determines whether pollutants brought from the depths of the earth by tectonic activity will ultimately be discharged into the lake.

[0010] Preferably, the inflow of groundwater into the lake requires understanding the topography, geological structure, lithology and distribution of the lake basin and its surroundings, and the distribution of aquifers and relatively impermeable layers; it also requires identifying the groundwater type, burial conditions, chemical characteristics, recharge, runoff and discharge conditions, and exploitation status of the groundwater in the hydrogeological unit; and the formation type, outcrop location, formation conditions, flow rate, and water quality of springs in the hydrogeological unit.

[0011] Preferably, the sampling method for the groundwater flowing into the lake is as follows: collect instantaneous water samples according to the monitoring points, and make sampling records and unique identification of the samples.

[0012] Preferably, the lake inflow surface water and river sediments are determined based on the distribution characteristics of the lake basin and the known distribution of tributaries; the basic principle is to control the anomaly range by sampling points in the region, delineate the anomaly location, and identify the anomaly distribution and combination characteristics.

[0013] Preferably, the sampling method for the sediments in the lake inflow to the surface water is as follows: take 30cm of undisturbed water system sediment, and take one sample every 10cm from top to bottom, for a total of 3 samples from one point.

[0014] Preferably, the sampling method for the bottom sediment and overlying water at the lake inlet is as follows: undisturbed samples are taken, a tubular sampler is inserted into the sampling point, and the overlying water sample is 20-30cm above the bottom sediment. The water is then drawn out by siphoning, and the sediment is removed sequentially from the sampler. The sediment is divided into layers of 10cm each, and bottom sediment samples of 0-10cm, 10-20cm, and 20-30cm are taken respectively.

[0015] Preferably, the pollutants include: total phosphorus, ammonia nitrogen, total nitrogen, organic matter, and heavy metals.

[0016] Potential factors contributing to lake pollution include: mineralized elements migrating through the soil due to concentration differences, and then being transported into the lake via surface water and groundwater; polluted water flowing into the lake through surface runoff, groundwater, geochemical migration, and geological structures, leading to excessive levels of pollutants; and the risk of leaks due to aging, damage, and blockages in some pipelines, causing secondary pollution in the surrounding soil and subsequently seeping into the lake as groundwater. A migration diagram of each pollutant is shown below. Figure 1Therefore, the factors contributing to lake pollution are complex and not limited to human pollution. Factors other than human pollution are often difficult to determine accurately.

[0017] The beneficial technical effects of the present invention are as follows:

[0018] This invention summarizes the occurrence, weathering, migration and transportation patterns and distribution characteristics of potential pollutants in lake basins under regional geological processes through field investigations and sampling analysis of rocks, tectonic zones, groundwater, surface water, river sediments, and bottom sediments. It then determines the impact of potential pollutants, especially major pollutants such as nitrogen and phosphorus, on lake water quality under different geological backgrounds, thereby accurately identifying the pollution sources of lake water bodies. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of pollutant migration as described in this invention.

[0020] Figure 2 This is a map showing the distribution of strata in various regions of the Erhai Lake basin in Example 1.

[0021] Figure 3 This is a map showing the locations of rock sample collection points near Changyu Village, Wase Village, and Shangxin Village in Example 1.

[0022] Figure 4 This is a map showing the sampling points of rock samples near Haixi Reservoir in Example 1.

[0023] Figure 5 This is a map showing the sampling points of rock samples from the Cangshan Group in Example 1.

[0024] Figure 6 This is a diagram showing the total nitrogen and total phosphorus content of the eastern section of Erhai Lake in Example 1.

[0025] Figure 7 This is a map showing the sampling points for groundwater samples in Example 1.

[0026] Figure 8 This is a flowchart of the groundwater sampling process in Example 1.

[0027] Figure 9 This is a map showing the sampling points for surface water samples in Example 1.

[0028] Figure 10 This is a map showing the sampling points for bottom sediment and water overlying the bottom sediment in Example 1.

[0029] Figure 11 This is a comparison chart of manganese, total phosphorus, and nitrogen content in the water sample covering the sediment in Example 1.

[0030] Figure 12 This is a comparison chart of manganese, total phosphorus, and nitrogen content in the sediment sample from Example 1. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0032] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0034] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0035] The detection and analysis in the embodiments of this invention are all carried out in accordance with relevant standards and specifications, and the specific standards are shown in Tables 1-3.

[0036] Table 1. Detection methods, detection limits, and evaluation criteria for groundwater monitoring factors

[0037]

[0038]

[0039] Table 2. Detection methods, detection limits, and evaluation criteria for sediment reference soil monitoring factors.

[0040]

[0041]

[0042]

[0043] Table 3. Detection methods, detection limits, and evaluation criteria for surface water monitoring factors

[0044]

[0045]

[0046] Example 1

[0047] This embodiment uses Erhai Lake as an example to identify the pollution sources of Erhai Lake:

[0048] (1) Rock sampling near Erhai Lake basin

[0049] The strata around Erhai Lake are relatively complete, with outcrops ranging from the Precambrian to the Quaternary periods. The Precambrian Cangshan Group (high in phosphorus and copper) is distributed in the Diancang Mountain area; the Lower Paleozoic strata are only found in the Ordovician strata, while the Upper Paleozoic Devonian (high in manganese and phosphorus), Carboniferous (high in manganese, phosphorus, and carbon), and Permian (basalt and tuff with extremely high copper, titanium, and niobium) strata are all outcropped in the eastern and northeastern parts of Erhai Lake; the Mesozoic Triassic, Jurassic, and Cretaceous strata (with relatively high background levels of manganese, aluminum, arsenic, gold, and copper) are mainly distributed in the northeastern and northwestern parts of Erhai Lake (see...). Figure 2 ).

[0050] Based on the aforementioned geological conditions around Erhai Lake, investigations were conducted in the phosphorus-bearing strata (Lower Devonian Lianhuaqu Formation (D1l) and Upper Devonian Shazijing Formation (D1l)) in Changyu Village, Wase Village, and Shangxin Village in the northern and northeastern parts of Erhai Lake. 2+3 One rock geochemical profile was laid out in the area (see...) Figure 3 Phosphorus-bearing strata in Eryuan County, northwest of Erhai Lake (Lower Devonian Lianhuaqu Formation (D1l) and Upper Devonian Shazijing Formation (D1l)). 2+3 One rock geochemical profile was laid out (see...) Figure 4 One geochemical profile was established in the metamorphic rock strata of the Cangshan Group in the western part of Erhai Lake (see...). Figure 5 ), and 26, 11 and 5 rock geochemical samples were collected from these three profiles respectively to verify the possibility that phosphorus and heavy metal elements in the strata entered the groundwater and eventually flowed into Erhai Lake under the influence of chemical, physical and biological processes.

[0051] The sampling method is as follows: Sampling is conducted within 1 / 10 of the distance between the measured sampling points. Three sampling points are combined into one sample. Various forms of contamination should be avoided during sampling. If sampling is impossible due to waste rock piles, swamps, colluvial deposits, riverbed deposits, paddy fields, etc., the point may be abandoned, but this should be noted in the record. Within the same work area, materials of the same properties and from the same stratum should be collected as much as possible. Generally, fine-grained materials from the soil leaching layer-parent material layer at a depth of 10cm-50cm from the surface are collected. The weight of the collected samples should ensure that after sieving (40-60 mesh) and sending to the laboratory, the weight of a single sample is not less than 100g. For samples requiring trace metal element testing, the weight of a single sample after sieving is not less than 200g.

[0052] The location of measurement and sampling points shall be carried out in accordance with the requirements of ZBD / 0002 "Specifications for Geophysical and Geochemical Exploration Measurement".

[0053] The samples were tested and analyzed, and the results were statistically analyzed. The total nitrogen and total phosphorus content profiles of the eastern section of Erhai Lake are shown in the figure below. Figure 6 The average values ​​of various elements in the strata surrounding the Erhai Lake basin are shown in Table 4; samples of manganese-bearing rocks (YH-50) and diabase (YH-51) (sampling locations are shown in Table 4) Figure 9 The results of the element detection are shown in Table 5.

[0054] Table 4. Average values ​​of elements in strata surrounding the Erhai Lake basin

[0055]

[0056] Table 5. Elemental Analysis Results of Manganese-Bearing Rocks and Diabase

[0057]

[0058]

[0059] from Figure 6 The data in Tables 4 and 5 show that the overall trends in arsenic, mercury, cadmium, lead, nickel, copper, total nitrogen, total phosphorus, and available phosphorus in each stratum are positively correlated. Specifically:

[0060] ① Total nitrogen and total phosphorus content: The total nitrogen content of the rocks in the Lower Devonian Lianhuaqu Formation (D1l) (997.17 mg / kg) is about 3.08 to 5.04 times higher than that of other strata; the Permian basalt formation (Pβ) and the Middle and Upper Devonian (D1l) 2+3 The total phosphorus content of the rocks in this formation is approximately 2.04 to 5.41 times higher than that of other formations. Specifically, the average total phosphorus content of the Permian basalt group (Pβ) is 1256.33 mg / kg, while that of the Middle and Upper Devonian (D...) is significantly higher. 2+3 The average total phosphorus content of the strata rocks was 1283.00 mg / kg.

[0061] The aforementioned strata are mainly distributed in the eastern (Changyu Village area) and northern parts of Erhai Lake.

[0062] ② Content of heavy metals nickel and copper: Permian basalt formation (Pβ), Middle and Upper Devonian (D 2+3 The nickel and copper contents of the Lower Devonian Lianhuaqu Formation (D1l), Lower Devonian Qingshan Formation (D1q), and Lower Devonian Kanglang Formation (D1k) are higher than those of other strata. Among them, the Permian Basalt Formation (Pβ) has the highest nickel and copper contents, at 70.47 mg / kg and 202.36 mg / kg, respectively.

[0063] The aforementioned strata are mainly distributed in the eastern (Changyu Village area) and northern parts of Erhai Lake.

[0064] ③ Lead content: The highest lead content was found in the metamorphic rocks of the Precambrian Cangshan Group, at 22.88 mg / kg.

[0065] Precambrian Cangshan Group metamorphic rocks It is mainly distributed in the western part of Erhai Lake.

[0066] ④ Upper Devonian System (D 2+3 The manganese content of the siliceous manganese-bearing rocks in the strata is as high as 8729 mg / kg, and they are mainly distributed in the eastern part of Erhai Lake (Changyu Village area).

[0067] (2) Groundwater sampling in Erhai Lake Basin

[0068] According to the monitoring points (see) Figure 7 Instantaneous water samples were collected, and groundwater sampling was conducted strictly in accordance with the "Technical Specification for Groundwater Environmental Monitoring" (HJ / T164-2004). The sampling flowchart is shown below. Figure 8 The collected groundwater samples were tested, and the results are shown in Table 6.

[0069] Table 6 Statistical Table of Groundwater Sample Monitoring Results

[0070]

[0071] Statistical analysis was performed on the detection results of pH, chemical oxygen demand (COD), total phosphorus, carbonate, total nitrogen, ammonia nitrogen (as N), arsenic, copper, zinc, chromium, cadmium, lead, nickel, and mercury in the collected groundwater samples. COD and mercury were not detected (ND). The results showed that:

[0072] ① The total nitrogen content of samples DXS-2, DXS-3, DXS-4 and DXS-5 was relatively high, with the highest being DXS-4 (7748.00 μg / L). These samples were mainly distributed in the eastern part of Erhai Lake.

[0073] The aquifers of DXS-2 and DXS-4 are the Lower Devonian Kanglang Formation (D1k) and the Lower Devonian Qingshan Formation (D1q), while the aquifers of DXS-3 and DXS-5 are the Lower Devonian Qingshan Formation (D1q) and the Lower Devonian Lianhuaqu Formation (D1l). The total nitrogen content of the rocks in the Lower Devonian Lianhuaqu Formation (D1l) is higher than that of the rocks in other formations. The higher total nitrogen content of DXS-3 and DXS-5 is related to their respective aquifers.

[0074] ② Sample DXS-6 had the highest total phosphorus, carbonate, and zinc contents, at 201.69 μg / L and 615.00 μg / L, respectively. The total phosphorus content was 7.73–28.12 times higher than other groundwater samples, and the carbonate content was 8.20–27.95 times higher. The samples were distributed in the eastern part of Erhai Lake. The aquifers they belonged to were mainly Upper Devonian (D...) strata. 2+3Upper Devonian System (D) 2+3 The total phosphorus content of the strata rocks was higher than that of other strata. The total phosphorus content of sample DXS-6 (Changyucun) was higher than that of other groundwater samples, which is related to the strata rocks.

[0075] ③ The ammonia nitrogen (calculated as N) and arsenic content of hot spring samples DXS-7 and DXS-8 are higher than those of other groundwaters. The hot springs are located near the fault zone and are distributed in the northern part of Erhai Lake, which is related to the geochemical behavior of tectonic hot springs.

[0076] (3) Sampling of surface water and sediments entering Erhai Lake.

[0077] Surface water sampling was conducted in conjunction with the distribution of the inflowing water systems of Erhai Lake. A total of 14 surface water samples were collected, and the sampling locations are shown below. Figure 9 .

[0078] The surface water sampling method is as follows: sampling is carried out in accordance with the "Technical Specification for Surface Water and Wastewater Monitoring" (HJ / T91-2002), and instantaneous water samples are collected; for oil sampling, any existing oil film is destroyed before sampling, and a glass container is installed in the support of the water sampler using a vertical water sampler, and it is placed at a depth of 300mm, while water is being collected and raised upwards; the required water sample volume is shown in Table 4-4 of the "Technical Specification for Surface Water and Wastewater Monitoring" (HJ / T91-2002).

[0079] The collected groundwater samples were tested (if the water samples contained settling solids, they should be separated and removed), and the test results are shown in Table 7.

[0080] Table 7 Statistical Table of Surface Water Sample Test Results

[0081]

[0082] By analyzing and statistically processing surface water samples flowing into Erhai Lake for pH, arsenic, mercury, lead, cadmium, chromium, copper, zinc, nickel, manganese, total nitrogen, ammonia nitrogen, total phosphorus, and chemical oxygen demand, the following findings were obtained:

[0083] ①Sample DB-14 is a stream near the sewage treatment plant on the west side of Erhai Lake. Its levels of copper, zinc, total nitrogen, total phosphorus and other indicators are higher than those of other surface water systems.

[0084] ② The total nitrogen content of samples DB-9 and DB-8 was higher than that of other surface water samples flowing into Erhai Lake. The total nitrogen content of sample DB-9 was 7.15 mg / L, and that of sample DB-8 was 5.09 mg / L. Both samples were collected in the eastern part of Erhai Lake, with DB-9 collected from the Changyu Village area.

[0085] When collecting surface water samples, sediment samples were also collected from the aquatic system. The method was as follows: using specialized sampling equipment, undisturbed sediment samples were collected at a designated location, with a depth of 30 cm. Samples were taken every 10 cm from top to bottom, for a total of 3 samples per point. The pretreatment method for the sediment samples was as follows: original sample → drying → crushing → passing through a 60-mesh sieve → reducing to 20g for analysis → the remaining portion was kept as a secondary sample. Thirteen sediment samples were collected, including DB-11 and DB-12, which were hot spring sediment samples. The test results are shown in Table 8.

[0086] Table 8. Statistical Table of Sediment Sample Detection Results for Surface Water System Entering Erhai Lake

[0087]

[0088] By analyzing the pH, arsenic, mercury, lead, cadmium, chromium, copper, zinc, nickel, manganese, total nitrogen (as N), ammonia nitrogen (as N), and total phosphorus in sediments flowing into Erhai Lake, and statistically analyzing the data (Table 6.3-1), it was found that the total nitrogen and total phosphorus contents in the surface water sediments flowing into Erhai Lake were relatively high. The sample with the highest total nitrogen was DB-10 at 22273 mg / kg, while the samples with relatively high total phosphorus were DB-8 (1801 mg / kg), DB-4 (1692 mg / kg), DB-3 (1526 mg / kg), and DB-9 (1487 mg / kg). DB-10, DB-8, DB-4, and DB-3 are surrounded by farmland and towns, which have a certain impact on the total phosphorus and total nitrogen in the surface water. The high total nitrogen content of DB-9 is related to the surrounding phosphorus-containing strata.

[0089] (4) Samples were taken from the seabed mud and the water covering the mud.

[0090] Sediment samples were collected from the Erhai Lake area corresponding to the surface water sampling river. Sampling locations are detailed below. Figure 10 .

[0091] Stainless steel columnar sediment samplers were used for sampling. Undisturbed samples were collected. Water samples were taken from the sediment overlying water at a depth of 20-30 cm, which was then siphoned out. The sediment was then removed sequentially from the plexiglass tube, segmenting the columnar sediment into 10 cm layers. Sediment samples of 0-10 cm, 10-20 cm, and 20-30 cm were collected, placed in PVC resealable bags, and stored in a refrigerator. The collected Erhai Lake seabed sediment and overlying water were analyzed, and the results are shown in Tables 9-11.

[0092] Table 9. Test Results of Seabed Mud Samples from Erhai Lake

[0093]

[0094] Table 10. Test Results of Seabed Mud Samples from Erhai Lake

[0095]

[0096] Table 11. Detection results of water samples overlying the seabed mud (20-30cm) of Erhai Lake.

[0097]

[0098] The contents of arsenic, mercury, cadmium, nickel, lead, copper, chromium, zinc, manganese, hexavalent chromium, organic matter, total phosphorus, and total nitrogen were detected in sediment samples and overlying water samples. Statistical analysis of the test results yielded the following results:

[0099] Among the test results of the water sample on the sediment, sediment (0-10cm), sediment (10-20cm), and sediment (20-30cm), the elements with higher content and greater variation were manganese, total nitrogen, and total phosphorus.

[0100] ① Manganese:

[0101] The sediment sample with the highest average manganese content was DN-4 (1369 mg / kg), while the two samples with the lowest average manganese content were DN-8 (841 mg / kg) and DN-3 (926 mg / kg). The three sediment-overlying water samples with the highest manganese content were DN-8 (937 μg / L), DN-1 (989 μg / L), and DN-3 (1182 μg / L).

[0102] ②Total phosphorus:

[0103] The sediment samples with the highest average total phosphorus content were DN-4 (1150 mg / kg), DN-6 (1099 mg / kg), and DN-7 (1067 mg / kg); the sediment overlying water sample had the highest total phosphorus content of DN-4 (250 μg / L).

[0104] ③ Total nitrogen:

[0105] The sediment samples with the highest average total nitrogen content were DN-1 (3150 mg / kg), DN-2 (1962 mg / kg), DN-4 (1954 mg / kg), and DN-9 (1933 mg / kg); the sediment samples with the highest total nitrogen content in the overlying water were DN-1 (3420 μg / L) and DN-9 (3070 μg / L).

[0106] Figure 11 A comparison chart of manganese, total phosphorus, and nitrogen content in water samples overlying sediment; Figure 12 This is a comparison chart of manganese, total phosphorus, and nitrogen content in sediment samples.

[0107] from Figure 11 and Figure 12It can be seen that the changes in manganese content in sediment samples and overlying water samples are inversely proportional; the changes in total phosphorus in sediment samples and overlying water samples are directly proportional; and the changes in nitrogen in sediment samples and overlying water samples are directly proportional.

[0108] This invention involves sampling rocks in strata containing pollutants near the Erhai Lake basin, as well as groundwater, surface water, surface water sediments, bottom sediment at the inlet, and water overlying the bottom sediment. The collected samples are then analyzed, and the results of the analysis of each pollutant are compared to determine the pollution sources of Erhai Lake.

[0109] Through preliminary data collection and research, and sample collection, phosphorus- and manganese-containing strata were identified in the field in the Changyu Village area in the eastern part of Erhai Lake, the Haixi Reservoir area in the northern part of Erhai Lake, and the Jianhu area. Furthermore, the phosphorus content of Erhai Lake water near these areas is higher than that in other places during the rainy season.

[0110] Analysis of three rock chemical profiles and 88 samples collected around Erhai Lake revealed high background values ​​of phosphorus and nitrogen in the strata surrounding the lake, particularly in the basalt and carbonate rock strata east of Erhai Lake, where the levels were 2-3 times higher than in other strata. Correspondingly, the total phosphorus content in groundwater from phosphorus-bearing strata was 13 times higher than in other strata, and the content in groundwater from carbonate rock strata was 15 times higher. This confirms that the strata have a certain impact on the water quality of Erhai Lake.

[0111] According to the test results of the hot spring samples, the ammonia nitrogen content in the hot spring water was 11 times that of other samples, and the arsenic content was 15 times that of other groundwater samples. This indicates that the hot springs in the Erhai Lake Basin have brought some polluting elements from the depths into the water body of the Erhai Lake Basin, and the active tectonic activity has a significant impact on the water quality pollution of the Erhai Lake Basin.

[0112] Analysis of water and sediment samples from the inlets of the ten main rivers flowing into Erhai Lake, as well as sediment samples from the corresponding lakeside areas, shows a linear relationship between pollutant content in the rivers and pollutant content in the corresponding lakeside areas, indicating that pollutants in the lakeside areas are mainly carried in by rivers. Among them, rivers with higher pollutant content in the west and north are mainly distributed in agricultural non-point source pollution areas and urban areas, while rivers with higher pollutant content in the east are mainly distributed in the area where phosphorus and manganese-containing strata are exposed in Changyu Village.

[0113] Analysis of the sediment samples from Erhai Lake revealed the following results: the highest organic matter concentration was 46.9 mg / kg, located at the mouth of the Xi'er River, while the lowest was 23.2 mg / kg, located near the confluence of rivers in the northern part of Erhai Lake; the highest total phosphorus concentration was 1150.3 mg / kg, located near the confluence of the Beicun River, while the lowest was 739.7 mg / kg; and the highest total nitrogen concentration was 3149.7 mg / kg, located near the confluence of the Xi'er River, while the lowest was 1170.0 mg / kg, located near the confluence of rivers in the northern part of Erhai Lake.

[0114] Analysis of water samples from major rivers flowing into Erhai Lake showed that total phosphorus levels ranged from a high of 1801 mg / kg to a low of 1077 mg / kg. The highest total phosphorus level in the phosphorus-bearing strata at Changyu Village was 1487 mg / kg, which is 1.38 times the lowest level of 1077 mg / kg. Ammonia nitrogen levels ranged from a high of 129 mg / kg to a low of 1.46 mg / kg. The highest ammonia nitrogen level in the phosphorus-bearing strata at Changyu Village was 129 mg / kg, which is 88 times the lowest level of 1.46 mg / kg. Total nitrogen levels ranged from a high of 872 mg / kg to a low of 442 mg / kg. The highest total nitrogen level in the phosphorus-bearing strata at Changyu Village was 872 mg / kg, which is 1.97 times the lowest level of 442 mg / kg.

[0115] In summary, the pollutants in the seabed mud of Erhai Lake originate not only from human pollution but also, to a considerable extent, from the geological strata; similarly, a significant portion of the pollutants in Erhai Lake also originate from the geological strata.

[0116] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for determining the pollution source of lake water pollution, characterized in that, Includes the following steps: Sampling was conducted on rocks containing pollutants in the strata near the lake basin, groundwater flowing into the lake, surface water flowing into the lake and sediments in the river system, bottom sediment at the lake inlet, and water overlying the bottom sediment. The collected samples were analyzed, and by comparing the analysis results of each pollutant and combining them with the non-point source pollution survey of the basin, the pollution sources of the lake water body were identified. The rocks in the polluting strata near the lake basin are those in strata whose background values ​​of polluting elements exceed Clark values, as determined by a comprehensive study of regional geological reports, regional mineral geological reports, regional rock geochemical anomalies, and research results from various domestic and international research institutions. The groundwater flowing into the lake is determined by a comprehensive study based on regional geological reports, regional hydrogeological reports, regional tectonic distribution, and research results from various domestic and international research institutions. It is the groundwater that may be discharged into the lake due to pollutants brought from the deep earth by tectonic activity. The lake inflow surface water and river sediments were determined based on the distribution characteristics of the lake basin and the known distribution of tributaries; Its basic principle is to control the range of anomalies by sampling points in the region, delineate the location of anomalies, and identify the distribution and combination characteristics of anomalies.

2. The method for determining the pollution source of lake water pollution according to claim 1, characterized in that, The sampling method for rocks in the polluted strata near the lake basin is as follows: sampling is conducted within 1 / 10 of the distance between the sampling points, and three sampling points are combined into one sample. Fine-grained materials are collected from the soil leaching layer-parent material layer at a depth of 10cm-50cm from the surface.

3. The method for determining the pollution source of lake water pollution according to claim 1, characterized in that, The sampling method for the groundwater flowing into the lake is as follows: collect instantaneous water samples according to the monitoring points, and make sampling records and unique identification of the samples.

4. The method for determining the pollution source of lake water pollution according to claim 1, characterized in that, The sampling method for the sediments flowing into the lake surface water is as follows: take 30cm of undisturbed water system sediment, and take one sample every 10cm from top to bottom, for a total of 3 samples from one point.

5. The method for determining the pollution source of lake water pollution according to claim 1, characterized in that, The sampling method for the bottom sediment and overlying water at the lake inlet is as follows: undisturbed samples are taken, and a tubular sampler is inserted into the sampling point. The overlying water sample is 20-30 cm above the bottom sediment and is extracted by siphon. The sediment is then removed from the sampler in sequence, and the sediment is divided into layers of 10 cm each. Bottom sediment samples of 0-10 cm, 10-20 cm, and 20-30 cm are collected respectively.

6. The method for determining the pollution source of lake water pollution according to claim 1, characterized in that, The pollutants include: total phosphorus, ammonia nitrogen, total nitrogen, organic matter, and heavy metals.

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