CN108911148A - A kind of basin agricultural non-point source pollution control method - Google Patents

Abstract

The solution of the present invention discloses a method for controlling agricultural non-point source pollution in a watershed, comprising the following steps: A. Establishing an ecological ditch: constructing an ecological ditch in the area to be treated according to the situation of the water system to be treated, and the ecological ditch includes a water retaining ridge and/or Water intake; B. Afforestation and return to wetness and construction of biological ponds: For the cultivated land that still cannot be diverted after step A, adopt the combination of hole-shaped land preparation and mixed planting mode; Wet with the whole planting mode, and build it into a biological pond for the wet area; C. Ecological restoration along the river: use a mixed mode to build a plant buffer zone along the river road in the treatment area, and increase the side water barrier of the paddy fields along the river road Depth; wherein, the order of operations between step C and A or B can be interchanged arbitrarily. Compared with the prior art, the scheme of the invention saves a lot of cost, can reduce the concentration of pollutants to the greatest extent, and has strong applicability and development prospect.

Description

A method for controlling watershed agricultural non-point source pollution

technical field

The invention relates to the field of environmental engineering, in particular to a method for controlling watershed agricultural non-point source pollution.

Background technique

With the development of our country's economy, environmental protection problems are becoming more and more serious. In the past, people dealt with point source pollution. However, with the deepening of people's understanding of environmental problems, the problem of non-point source pollution has gradually attracted people's attention. Agricultural non-point source pollution refers to the non-point source pollution formed when pollutants in farmland enter water bodies through farmland surface runoff, soil inflow, farmland drainage and underground seepage during precipitation or irrigation during agricultural production activities. In recent years, the excessive use of chemical fertilizers and pesticides in China, and the domestic sewage in rural scattered residential areas have been discharged into rivers without treatment or after simple treatment. These will have a great impact on local rivers and lakes.

Although the "Evaluation Report on China's Fertilizer Utilization Efficiency (Fertilizer Consumption) (2000-2015)" edited by the Rural Economic Research Center of the Ministry of Agriculture, Renmin University of China and China Agricultural Sciences, and officially published in 2017 shows that in 2015 The growth rate of the total amount of chemical fertilizer application in the country has dropped to 0.4%, and the annual target of less than 1% has been achieved. Relevant professionals said that through this report, it can be judged that the goal of zero growth in chemical fertilizer application is expected. However, even if the amount of fertilizer application can be controlled to a certain extent, the treatment and control of existing non-point source pollution is still an urgent task in the process of completely changing the ecological environment of river basins and promoting sustainable social and economic development.

Based on this, it is urgent to find out a practical and feasible agricultural non-point source control method in the watershed, effectively intercept, absorb and degrade agricultural non-point source pollution, and improve the living environment of surrounding residents.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for controlling agricultural non-point source pollution in watersheds with low cost and good effect.

In order to solve the above technical problems, the technical solution adopted in the present invention is: a method for controlling watershed agricultural non-point source pollution, comprising the following steps:

A, build ecological ditches: build ecological ditches in the area to be treated according to the water system situation to be treated, and described ecological ditches include retaining ridges and/or water intakes;

B. Afforestation and dehumidification and biological pond construction: For the cultivated land that still cannot divert water after step A, adopt the combination of cave-like land preparation and mixed mode for afforestation; This mode is also wetted, and the wetted area is constructed into a biological pond;

C. Ecological restoration along the river: The roads along the river in the area to be treated shall adopt a mixed mode to build a plant buffer zone, and increase the water retention depth of the paddy field side of the road along the river;

Wherein, the operation sequence between step C and A or B can be interchanged arbitrarily.

Preferably, slope protection plants are planted on the water retaining sill and/or the water intake.

Further, the bottom of the water retaining sill and/or water intake is covered with zeolite, coal ash, activated carbon, biochar, diatomaceous earth or kaolin.

Preferably, a nitrogen adsorption material layer is laid on the bottom of the water retaining sill and/or water intake, and a phosphorus adsorption material layer is laid on the nitrogen adsorption material layer.

Further, the step A also includes heightening and thickening the paddy field stalks and pond embankments.

Further, the step B also includes adding an overflow on the field ridge in the wet area and building a water control gate, a drainage culvert, or controlling the water level of each biological pond by a water control PVC aqueduct.

Further, in the step B, the plants planted in the afforestation area are selected from golden willow, magnolia, rhododendron, crape myrtle, weeping willow, metasequoia, pool fir, eucalyptus, red loropetalum, etc., and the plants planted in the humid area are selected from wild rice , calamus, Xianglian, bitter grass, annual caps, quinces, hollow lotus, oriental cattail, chrysanthemum, cereus, water bamboo, water chestnuts, taro, Zailihua, aquatic canna and iris, etc.

Further, the plants in the plant buffer zone include trees and shrubs.

Further, the control method also includes step D, increasing the vegetation coverage of the original pond wetland in the treatment area, increasing biodiversity, and restoring the wetland in the pond water area to be treated, and the sequence of steps D and A or B or C can be exchange.

Further, the step D also includes controlling the water quality by using the method of adjusting the population structure of the biological species to the original pond wetland.

Further, the specific operation of controlling water quality by adjusting the biological population structure is: by adjusting the fish and benthos population structure in the water, controlling the growth rate of aquatic plants to prevent excessive growth, and constructing submerged plant communities.

Further, the control method also includes step E: intercepting and collecting litter and dead organisms in situ, specifically including: artificially clearing woodland litter regularly, regularly salvaging or harvesting wetland plants; Raw herbaceous plants; install a protective filtering device in wet areas, and the operation sequence of step E and step C or D or E can be interchanged arbitrarily.

The beneficial effects of the present invention are: by establishing an ecological ditch to construct a wetland ecological environment with powerful functions, the excess nutrients are recovered and reused through the runoff guiding and drainage path, and the pollution caused by nutrients such as nitrogen and phosphorus lost due to rainfall runoff is avoided; Set up water retaining ridges and/or water diversion ports, scientifically control water volume, increase the meandering of water system ditches, prolong hydraulic retention time, and improve the absorption efficiency of nitrogen and phosphorus nutrients; implement on cultivated land that cannot divert water after the establishment of ecological ditches in the treatment area The afforestation project can effectively control agricultural non-point source pollution in the area to be treated; use hole reclamation to prepare the soil to reduce the area of soil disturbance. Prevent water and soil erosion; When the whole land is still wet, the paddy fields need to be plowed. The soil disturbance area is large, and the field ridges should be used to strengthen protection and control the water volume in the field; after the establishment of ecological ditches, the cultivated land that can be diverted to water should be returned to wet, and the interception of the area to be treated should be improved. , the ability to absorb and degrade agricultural non-point source pollution; increase the height and thickness of the field ridges to increase the water storage capacity of the wet area in the area to be treated, prolong the residence time of sewage, and improve the sewage purification capacity of the wet area in the area to be treated; Configure the aquatic animal purification system to further improve the purification function of the wetland ecosystem, thereby effectively improving the ability of the wetland ecosystem to purify agricultural non-point source pollution.

Description of drawings

Fig. 1 is a schematic cross-sectional view of a water retaining sill in an embodiment of the present invention;

Fig. 2 is a schematic plan view of a water retaining sill and a water diversion port according to an embodiment of the present invention.

Detailed ways

In order to describe the technical content, achieved goals and effects of the present invention in detail, the following description will be made in conjunction with the embodiments and accompanying drawings.

A method for controlling watershed agricultural non-point source pollution, comprising the following steps:

A, build ecological ditches: build ecological ditches in the area to be treated according to the water system situation to be treated, and described ecological ditches include retaining ridges and/or water intakes;

B. Afforestation and dehumidification and biological pond construction: For the cultivated land that still cannot divert water after step A, adopt the combination of cave-like land preparation and mixed mode for afforestation; This mode is also wetted, and the wetted area is constructed into a biological pond;

C. Ecological restoration along the river: The roads along the river in the area to be treated shall adopt a mixed mode to build a plant buffer zone, and increase the water retention depth of the paddy field side of the road along the river;

Wherein, the operation sequence between step C and A or B can be interchanged arbitrarily.

It can be seen from the above description that the beneficial effects of the present invention are: by establishing an ecological ditch to construct a powerful wetland ecological environment, recycle redundant nutrients through the runoff guiding path, and avoid the loss of nitrogen, phosphorus, etc. due to rainfall runoff Nutrient elements cause pollution; set up water retaining sills and/or water diversion outlets, scientifically control water volume, increase the meandering of water system ditches, prolong hydraulic retention time, and improve the absorption efficiency of nitrogen and phosphorus nutrients; after the establishment of ecological ditches in the treatment area, still Implement afforestation projects on arable land that cannot be diverted to water, effectively control agricultural non-point source pollution in the area to be treated; use hole reclamation to reduce the area of soil disturbance, pile up the soil around the hole when digging holes, and backfill in time when planting seedlings or level it on the spot around the construction area Reduce the amount of excavation to prevent water and soil loss; the paddy fields need to be plowed when the whole land is still wet, and the soil disturbance area is large, and the field ridges should be used to strengthen protection and control the water in the fields; the cultivated land that can be diverted after the establishment of ecological ditches is implemented to return wet, Improve the ability of the area to be treated to intercept, absorb and degrade agricultural non-point source pollution; increase the height and thickness of the ridges to increase the water storage capacity of the wet area in the area to be treated, prolong the residence time of sewage, and improve the sewage purification capacity of the wet area in the area to be treated ; Configure the aquatic animal purification system in the wetland area to further improve the purification function of the wetland ecosystem, thereby effectively improving the ability of the wetland ecosystem to purify agricultural non-point source pollution.

Preferably, slope protection plants are planted on the water retaining sill and/or the water intake.

Further, the bottom of the water retaining sill and/or water intake is covered with zeolite, coal ash, activated carbon, biochar, diatomaceous earth or kaolin.

Preferably, a nitrogen adsorption material layer is laid on the bottom of the water retaining sill and/or water intake, and a phosphorus adsorption material layer is laid on the nitrogen adsorption material layer.

From the above description, it can be known that the beneficial effect of the present invention is that a material capable of adsorbing nitrogen and phosphorus is laid on the bottom of the water retaining sill or water diversion to adsorb elements such as nitrogen and phosphorus in the water body.

Further, the step A also includes heightening and thickening the paddy field stalks and pond embankments.

As can be seen from the above description, the beneficial effects of the present invention are: paddy field stalks and pond embankments are heightened and thickened to increase water storage capacity and prolong sewage residence time.

Further, the step B also includes adding an overflow on the field ridge in the wet area and building a water control gate, a drainage culvert, or controlling the water level of each biological pond by a water control PVC aqueduct.

Further, in the step B, the plants planted in the afforestation area are selected from golden willow, magnolia, rhododendron, crape myrtle, weeping willow, metasequoia, pool fir, eucalyptus, red loropetalum, etc., and the plants planted in the humid area are selected from wild rice , calamus, Xianglian, bitter grass, annual caps, quinces, hollow lotus, oriental cattail, chrysanthemum, cereus, water bamboo, water chestnuts, taro, Zailihua, aquatic canna and iris, etc.

From the above description, it can be known that the beneficial effect of the present invention is that a part of the precipitation will be infiltrated in situ by the measures of afforestation and dehumidification, which can regulate the runoff and reduce sedimentation during the flood season, and reduce the peak flow at the same time, which is conducive to improving the resistance of the area to be treated against flood disasters. , to ensure stable and high agricultural production, and to protect the safety of people’s lives and property. Planting Xianglian, Oriental Cattail, Zailihua, Aquatic Canna, Iris and other plants in the humid area not only has the effect of landscape, water purification, but also Xianglian, Oriental Cattail, etc. Economic crops can bring economic benefits to residents and avoid secondary pollution caused by plant withering; perennial plants such as Zailihua, aquatic canna, iris can avoid the need for multiple planting, reduce the amount of engineering, and save economic costs .

Further, the plants in the plant buffer zone include trees and shrubs.

Further, in the step C, the plants in the plant buffer zone are selected from plants such as Metasequoia, Redwood Ball.

As can be seen from the above description, the beneficial effects of the present invention are: after the plant buffer zone is established, the vegetation coverage in the watershed is greatly improved, and evaporation can be accelerated. With the increase of the vegetation coverage, the rainfall will also increase accordingly. In addition, the farmland under the plant buffer zone can generally reduce the wind speed by 20-30%, and the wind speed reduction can reduce the adverse effects of strong winds on the growth of farmland crops. The increase of vegetation coverage in the area to be treated can absorb harmful gases and dust in the air and achieve the effect of purifying the air. In addition, the forest can also cancel noise.

Further, the control method also includes step D, increasing the vegetation coverage of the original pond wetland in the treatment area, increasing biodiversity, and restoring the wetland in the pond water area to be treated, and the sequence of steps D and A or B or C can be exchange.

Further, the control method also includes step D, improving the ecological function of the original pond wetland, and performing wetland restoration on the pond water area to be treated, and the operation sequence among steps B, C and D can be arranged arbitrarily.

Further, said step D also includes controlling water quality by adjusting the biological population structure to the original pond wetland.

Further, the specific operation of controlling water quality by adjusting the biological population structure is: by adjusting the fish and benthos population structure in the water, controlling the growth rate of aquatic plants to prevent excessive growth, and constructing submerged plant communities.

It can be seen from the above description that the beneficial effects of the present invention are: the method of adjusting the biological population structure is used to control the water quality, which enhances the productivity and self-sustaining ability of the original ecosystem; It absorbs water pollutants by itself, and then accumulates in the body, and on the other hand, it is removed through the enrichment of the food chain. Eliminate algae and promote the decomposition of organic debris in the water body by stocking filter-feeding aquatic animals, which can not only improve the transparency of the water body, but also indirectly inhibit the eutrophication of the water body, thereby improving water quality; use submerged plants to grow and cover the bottom Function, reduce the release of source pollution in the water body, absorb and reduce the nutrient content in the water body, provide a habitat for benthic animals, and provide a shelter for fish, and at the same time prevent fish from being injured when chasing.

Further, the control method also includes step E: intercepting and collecting litter and dead organisms in situ, specifically including: artificially clearing woodland litter regularly, regularly salvaging or harvesting wetland plants; Raw herbaceous plants; install a protective filtering device in wet areas, and the operation sequence of step E and step C or D or E can be interchanged arbitrarily.

As can be seen from the above description, the beneficial effects of the present invention are: in order to prevent restoration plants or litter, dead organisms, etc. from returning to the soil after rot, or causing secondary pollution with water loss, artificially regularly remove woodland litter, wetlands, etc. Plants are regularly salvaged or harvested and protective filtering devices are installed; in the afforestation mode, wet herbs can be planted to intercept litter.

An embodiment of the present invention is: a method for controlling agricultural non-point source pollution in a watershed, where a certain village in a certain watershed is the research area of the watershed, and the topography of the research area is mainly river valley plains with flat topography. The overall topography of the study area is high in the north and low in the south, high in the east and west and low in the middle.

According to the third-party water quality testing report, the water quality in the study area is surface water. As shown in Table 1 below, the ammonia nitrogen, total phosphorus, and total nitrogen in the surface water in the study area exceeded the Class III standard for surface water, and none of the other detection factors exceeded the Class III standard for surface water.

Table 1: Water quality test report Unit: mg/L, pH value is dimensionless

Note: 0.04 in "0.04L" in the table refers to the detected condition, and L refers to not detected.

According to the field survey, the main reason for ammonia nitrogen, total phosphorus, and total nitrogen exceeding the standard is the excessive application of fertilizers rich in N and P in agricultural production within the catchment area.

Comprehensively consider the status quo of land use and water pollution in the study area, and rationally arrange various control measures in combination with social and economic conditions, including the following operations:

Build water retaining ridges and water diversion outlets in the research area, and heighten and thicken paddy field ridges and pond embankments to increase water storage capacity and prolong sewage retention time; return wet to the cultivated land that can be diverted after the establishment of ecological ditches in the research area, and plant Xianglian , oriental cattail, Zailihua, aquatic canna, iris, etc.; implement afforestation in the cultivated land that still cannot divert water after the establishment of ecological ditches in the study area, plant golden willow and metasequoia, etc.; restore wetlands in the pond water area of the study area, plant weeping willow, cattail, Phragmites and foxtail algae, etc.; configure aquatic animal purification systems in the pond waters and return wet areas of the research area to build biological ponds to further improve the purification function of the wetland ecosystem; plant weeping willows, phoenix bamboos, and maple poplars along the river; On both sides of the road along the road in the study area, plant metasequoia and red wood balls; increase the water retention depth of the paddy fields along the road along the river.

Through the construction of ecological ditches and wetland restoration, each treatment unit has a wetland area of 34.1309hm ² , and the load capacity of agricultural non-point source sewage can reach 24.9155 million m ³ /year, which is larger than the agricultural area of each drainage unit in the research area. The amount of source sewage is 20,370,800 m ³ /year. The treatment units can fully purify the agricultural non-point source sewage in the research area before being discharged into the river, and the load capacity of the purified agricultural non-point source sewage can meet the requirements.

Through the solution of the invention, 20.3708 million ^m3 of agricultural non-point source polluted water can be purified every year. Using the engineering substitution method, the pollution control cost of a small sewage treatment plant is calculated at 1.1 yuan/t, and the annual pollution control benefit can reach 22.41 million yuan. The method of the present invention can also realize water conservation. Calculated as 600m ³ of water conservation per hectare of forest wetland, 33.17hm ² of returning farmland to forest will increase water storage by 23,300 m ³ per year. The solution of the invention can reduce the amount of soil erosion from moderate to slight, that is, reduce 200 tons per hectare per year, and reduce soil erosion by 7,800 tons per year in the research area. In addition, the forest plays a significant role in releasing oxygen and fixing carbon dioxide, and can secrete fungicides, which can kill tuberculosis, typhoid, diphtheria, dysentery and other germs; it can also reduce noise and beautify the environment.

The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent transformations made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in related technical fields, are all included in the same principle. Within the scope of patent protection of the present invention.

Claims (10)

1. A method for controlling watershed agricultural non-point source pollution, characterized in that: comprises the following steps: A. Establish ecological ditches: build ecological ditches in the area to be treated according to the water system situation to be treated, and the ecological ditches include water retaining ridges and/or water intakes; B. Afforestation and dehumidification and biological pond construction: For the cultivated land that still cannot divert water after step A, adopt the combination of cave-like land preparation and mixed mode for afforestation; This mode is also wetted, and the wetted area is constructed into a biological pond; C. Ecological restoration along the river: use the mixed mode to construct the plant buffer zone along the river road in the treatment area, and increase the water retention depth of the paddy field side of the road along the river; Wherein, the operation sequence between step C and A or B can be interchanged arbitrarily. 2. The method for controlling watershed agricultural non-point source pollution according to claim 1, characterized in that: the bottom of the water retaining sill and/or water intake is covered with zeolite, coal ash, activated carbon, biochar, diatomaceous earth or kaolin . 3. The method for controlling watershed agricultural non-point source pollution according to claim 2, characterized in that: a nitrogen adsorption material layer is laid on the bottom of the water retaining sill and/or water intake, and a phosphorus adsorption material layer is laid on the nitrogen adsorption material layer . 4. The method for controlling watershed agricultural non-point source pollution according to claim 1, characterized in that: the step A also includes heightening and thickening the paddy field stalks and pond embankments. 5. The method for controlling watershed agricultural non-point source pollution according to claim 1, characterized in that: said step B also includes adding an overflow on the field ridge in the wet area and building a water control sluice, a drainage culvert or a water control PVC guide Water pipes control the water level of each biological pond. 6. The method for controlling watershed agricultural non-point source pollution according to claim 1, characterized in that: in the step B, the plants planted in the afforestation area are selected from the group consisting of golden willow, magnolia, rhododendron, crape myrtle, weeping willow, metasequoia, and pool fir , eucalyptus, and red loropetalum, and plants grown in humid areas are selected from wild rice, calamus, Xianglian, bitter grass, annenia, celery, hollow lotus, oriental cattail, chrysanthemum, celery, wild water chestnut, and water chestnut , Taro, Zaili, Aquatic Canna and Iris. 7. The method for controlling watershed agricultural non-point source pollution according to claim 1, characterized in that: the control method also includes step D, improving the vegetation coverage of the original pond wetland in the treatment area, improving biodiversity, and treating the treatment area For wetland restoration in pond waters, the order of step D and A or B or C can be interchanged. 8. The method for controlling watershed agricultural non-point source pollution according to claim 7, characterized in that: said step D also includes controlling water quality by adjusting the population structure of biological species in the original pond wetland. 9. The method for controlling watershed agricultural non-point source pollution according to claim 8, characterized in that: the specific operation of controlling water quality by the method of adjusting the biological population structure is: by adjusting the fish shoal and benthos population structure in the water, Control the growth rate of aquatic plants to prevent excessive growth and build submerged plant communities. 10. The method for controlling watershed agricultural non-point source pollution according to any one of claims 7-9, characterized in that: the control method also includes step E: intercepting and collecting litter and dead organisms in situ, specifically including : artificially regularly remove litter in woodland, regularly salvage or harvest wetland plants; plant wet herbaceous plants in deforestation areas; install protective filter devices in wet areas, and the operation sequence of steps E and steps C or D or E can be Any exchange.