introduction

Groundwater is an important part of water resources and an indispensable natural resource for human survival, life and production activities. It plays an invaluable role in ensuring residents' living water, social and economic development and ecological environment balance. As a fresh water resource on the earth, it has high ecological and economic value. With the rapid development of the social economy and the improvement of people's living standards, more and more gas, solid and liquid wastes have been generated, which have caused serious pollution to the water environment from different ways. All in all, under the influence of human activities, the phenomenon that groundwater quality changes towards the deterioration of water quality is collectively referred to as groundwater pollution.

Known as “eight hundred miles of Qinchuan”, the Guanzhong area is the center of economic, political and cultural development in Shaanxi Province. It is densely populated, developed with industrial agriculture, rich in tourism resources, and strong in science and technology and education, including Xi’an, Baoji, Xianyang and Weinan. copper River five large, medium and small cities and Yangling Agricultural High-tech industries demonstration zone. However, in recent years, due to excessive exploitation of groundwater, a series of environmental problems such as continuous decline of groundwater level, deterioration of groundwater quality, and land subsidence have been caused. With the rapid development of the economy in Guanzhong and the rapid increase in population, the current per capita water resources are less than 17% of the national total, less than 30% of the province, and it is a region with severe water shortage. Therefore, in order to adapt to the growing demand for economic development and population growth, in today's promotion of sustainable development, how to use groundwater resources reasonably and effectively has become a top priority, as well as the realization of regional groundwater resources protection, regional ecological environment improvement and regional national economic development. The basic premise.

First, the source and route of groundwater pollution

In the natural environment, groundwater will have a certain self-purification ability, and the ion exchange and adsorption of the aquifer will help reduce the concentration of pollutants in the water. Human activities emit a large amount of waste and interaction with the geological environment, causing certain damage to the natural balance, changing the physical, chemical and biological properties of groundwater, so that the concentration of groundwater pollutants exceeds the specified indicators. According to the causes of groundwater pollution, groundwater pollution can be divided into agricultural and livestock pollution, industrial pollution, and domestic pollution.

(1) Pollution from agriculture and animal husbandry

1. Pollution of pesticides and fertilizers In the mid-1940s, humans began to use chemically synthesized pesticides to eliminate pests and diseases. However, only about 12% of these pesticides were absorbed by crops, and some of them were vaporized into the atmosphere, and the rest all entered the soil and the surface. In the appendages, this part of the unabsorbed pesticide is contaminated by surface runoff into the aquifer. The large-scale use of chemical fertilizers has greatly increased the productivity factors of the land, but only about 42% are absorbed and utilized by the crops, and the rest are dissolved in irrigation water and rainwater, so that the elements in the fertilizers penetrate into the ground, and the groundwater is exposed to nitrogen, phosphorus and other elements. Contamination leads to an increase in total hardness, nitrate and ammonia nitrogen in the groundwater.

2. Organic waste pollution from livestock

There are many families raising livestock in rural areas in Guanzhong. The large amount of organic waste produced by these animals will cause certain pollution to groundwater over time.

(2) Pollution from industry

1. Pollution of industrial waste and sewage

Industrial production will produce a large amount of garbage containing various chemical substances. These garbage are generally stacked in the open air or simply landfilled. The harmful substances in the garbage penetrate into the ground through the surface runoff and the rainwater, especially the industrial production. The process discharges a large amount of wastewater containing various toxic and harmful elements, many of which are discharged into sewers, rivers or directly discharged into the ditch without physical and chemical treatment.

The Guanzhong area (Tongchuan and Weinan) is one of the concentrated areas of the mining industry in Shaanxi Province. After the mining, the meteorites accumulated by the rainwater are easily formed into groundwater pollution, and the abandoned roadways and boreholes in the mining area are affected by rainwater or surface water bodies. Underneath, it may just become a channel for groundwater pollution. Meanwhile, mining pit water is discharged (e.g., coal mining drainage) is generally very low pH values, such acidic water seeping into the ground can lead to certain salts into the aqueous layer, the resulting salt effect causes soil calcite, dolomite dissolving, calcium and magnesium ions dissolved in water, groundwater increased total hardness. In addition, the loopholes in the use and management of petroleum and its chemical products make diesel, gasoline, benzene and other benzene-containing carbohydrates easily cause pollution in underground aquifers.

(3) Pollution caused by human life to groundwater

As the population increases, a large amount of domestic garbage and sewage will be generated. Many of these garbage are directly treated by the buried method, and the sewage is directly discharged into the sewer. The wastes that are buried in the surrounding areas of the city will slowly infiltrate into the ground and pollute the aquifers. In addition, the septic tanks in the residential areas are also the main way to cause organic pollution.

Second, measures to prevent groundwater pollution

(1) Increase publicity and raise public awareness of the environment

China's "Water Law" and "Water Pollution Prevention Law" should be strictly implemented. The government and relevant departments should increase the intensity of governance. All levels of departments should attach great importance to it, strictly enforce the law, do not tolerate it, and do not slack off. Enterprises or individuals of groundwater resources are severely punished. Secondly, all units should also carry out extensive publicity work, through television, radio, newspapers and other information media, to raise awareness of the harm of groundwater pollution in the whole society, enhance the environmental awareness of the whole people, start from their own, save water, save energy, and pass Various effective ways, such as recycling and repairing old materials, to reduce waste discharge, and to protect limited groundwater from the point of view.

(2) Control the discharge of pollution sources and classify the living and production wastes

In the industrial system, we should adopt the principle of “prevention first, combining prevention and control”, starting from the source of control, increasing the human, material and financial input of prevention work, actively advocating enterprises to carry out technological reform and clean production, and deadlines for heavily polluting enterprises. Rectification, the need to shut down after the rectification is still not up to standard discharge. In the agricultural system, efficient irrigation techniques and scientific methods of farming crops should be used to minimize the application of pesticides and less fertilizers, especially the use of synthetic pesticides. The traditional flood irrigation method is not only water-saving but also reduced. Groundwater pollution from irrigation water. In addition, the domestic production of garbage should be classified, properly recycled and reused, and the advanced technology should be used for the treatment of non-recyclable garbage. The anti-seepage technology of landfill leachate should be actively developed to minimize the groundwater pollution caused by bad methods such as landfill. .

(3) Strengthening the basic work of hydrology and rationally developing and utilizing water resources

Hydrology (surface water, groundwater monitoring) business and research work is the prerequisite for scientific development and utilization of water resources. It is necessary to increase investment in this area. It is necessary to carry out in-depth experimental research such as groundwater artificial recharge, water pollution control, water resources modernization management, Research on the impact of water resources development and utilization on the ecological environment provides a scientific basis for decision-making at all levels of government. In Europe, North America and Australia, an important measure taken in the prevention and control of groundwater pollution is to conduct groundwater environmental vulnerability assessment and to compile an evaluation atlas. This method is worth learning from. In addition, it is necessary to strengthen the research on groundwater monitoring network construction and pollution prevention technology, monitor groundwater quality and predict its future development trend, carry out groundwater dynamic monitoring and analysis, and use advanced technological achievements to develop and utilize water resources.

Third, the conclusion

The three major problems of “population, resources and environment” are closely related to groundwater. How to integrate the sustainable use of groundwater resources into the coordinated development of resources, economy and environment is a hot issue in the society, facing the increasingly severe groundwater pollution in China. The situation, groundwater pollution prevention is imminent. Therefore, it is necessary to further strengthen the system construction of groundwater pollution prevention and control, increase investment in groundwater pollution prevention and control, and coordinate the development and utilization of groundwater with protection. Groundwater pollution is a problem that affects the vital interests of everyone. The prevention and control of groundwater pollution needs to start from everyone. It requires the cooperation and cooperation of all sectors of society to play an effective role in prevention and control.

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