According to the “People's Republic of China environmental protection law "and other laws and regulations and the State Council issued the ”soil pollution prevention action plan ", in order to strengthen the supervision and management of pollution land environmental protection, pollution prevention and control plots of environmental risk, engaged in non-ferrous metal smelting, petroleum processing, coking, chemical, electroplating, leather and other industries engaged in production and business activities, as well as hazardous waste storage, utilization, land disposal activities. To recover the land use rights, land use rights have been recovered, and intends to change the use of residential land and commercial, schools, medical care, pension institutions and other public facilities with suspected polluted land and pollution plots. Needs to carry out the investigation of contaminated sites including the work. To carry out the investigation of soil environmental pollution plots, risk assessment, risk management, governance and repair and its evaluation activities.
       According to the type of main pollutants, China's contaminated sites can be broadly divided into the following categories:
       (1) heavy metal contaminated sites. Mainly from the iron and steel smelting enterprises, tailings, and chemical industry solid waste storage field, the representative pollutants including arsenic, lead, cadmium, chromium and so on.
       (2) persistent organic pollutants (Persistent organic, pollutants, POPs) POPs Chinese pesticide contaminated site. Once produced and widely used mainly has six chlorobenzene, DDT, chlordane and Mirex, although some of the pesticides has been banned for many years, but there is still residual in the soil. Chinese pesticides POPs site in addition more. POPs, there are other contaminated sites, such as polychlorinated biphenyl (PCBs) power equipment storage and dismantling the venue.
       (3) polluting sites such as petroleum, chemical industry, coking and so on, which are mainly organic pollution. The pollutants are represented by organic solvents, such as benzene series and halogenated hydrocarbons. They are also often found in line with other pollutants, such as heavy metals
       (4) electronic waste pollution site. Extensive e-waste disposal poses a threat to human health. This kind of pollutants from heavy metals and POPs (mainly brominated flame retardants and dioxin toxic substances) is the main pollution characteristics.

       The first stage of site environmental investigation
 
       The first stage is to site environmental investigation data collection, pollution identification stage site survey and personnel interview, in principle, on-site sampling and analysis. If the first stage investigation confirmed the site and the surrounding area and the history of the current non pollution sources and environmental conditions of the field is considered acceptable, the investigation activities can end.
 
       The second stage of site environmental investigation
       The second stage is to site environmental investigation and sample analysis mainly confirmed pollution stage, if the first stage environment survey showed that within the site or the area around the existing sources of pollution, such as chemical factory, pesticide factory, smelter, gas station, chemical storage tanks, solid waste treatment facilities or activities that may produce toxic or harmful substances owing to the lack of data; and the cause of the inside and outside space cannot be ruled out the existence of pollution, as potential contaminated sites for the second phase of site environmental investigation, determine the types of pollutants, concentration (degree) and spatial distribution.
       The second stage of site environmental investigation can usually be divided into preliminary sampling analysis and detailed sampling analysis was carried out in two steps, each step includes the formulation of the work plan, field sampling, data evaluation and analysis steps. The preliminary sampling analysis and detailed sample analysis can according to the actual situation in batches implemented, gradually reduce the uncertainty of the investigation.
       According to the preliminary analysis of the sampling results, if the pollutant concentration did not exceed the national and local standards and clean control point (concentration of inorganic soil environmental background), and through the uncertainty analysis confirm that it does not need further investigation, site environmental investigation stage second may end, or that the possible environmental risks, to be detailed not related to the investigation. Pollutant standards, according to professional knowledge and experience of comprehensive judgment. Detailed sampling analysis is based on preliminary sampling analysis, further sampling and analysis, determine the pollution degree and scope.
 
       The third stage of site environmental investigation
       If the need for risk assessment or remediation, to third environmental site. Third stage site environmental investigation to supplement the sampling and testing, obtain the parameters meet the risk assessment and remediation of contaminated soil and groundwater required. The investigation of this stage alone, can also be carried out in second stages in the investigation