Recently, the Ministry of Ecology and Environment issued the Technical Guide for Statistical Characterization of Groundwater Environmental Background Values (Trial).(hereinafter referred to as the Guide). The person in charge of the Department of Soil Ecology and Environment of the Ministry of Ecology and Environment answered reporters' questions on the "Guide.
Q: What is the background of the Guide?
Answer:The "14th Five-Year Plan for Soil, Groundwater and Rural Ecological Environment Protection" clearly requires that for groundwater-type drinking water sources with excessive water quality, the reasons for exceeding the standard should be analyzed, and remediation measures should be taken according to local conditions; for non-geological backgrounds that cause the national groundwater environmental quality assessment If the points fail to meet the water quality target requirements, a compliance or maintenance plan should be formulated according to local conditions, and the prevention measures and completion time limit should be clarified. It is necessary to identify and judge whether the groundwater quality exceeds the standard due to human activities or geological background.
In order to standardize and guide the statistical characterization of groundwater environmental background values, achieve accurate pollution control, scientific pollution control, and pollution control according to law, support the protection of groundwater drinking water sources and national groundwater environmental quality assessment, and strengthen the supervision and management of groundwater pollution prevention and control After in-depth investigation, extensive solicitation of opinions, and case verification, our department has clarified the application scenarios, work processes and technical methods of the statistical characterization of groundwater environmental background values, and formed the "Guide" and issued.
Q: What are the main elements of the Guide?What?
Answer:The Guide consists of six parts and appendices, including general principles, work content and process, data acquisition, sample collection and testing, data processing and analysis, statistics and characterization.
One is the general. Including the purpose of preparation, scope of application, normative references, terms and definitions, and guidelines. The Guide is applicable to situations where statistical characterization of groundwater environmental background values is required, such as the determination of the cause of groundwater exceeding the standard and the reasonable determination of restoration target values.
The second is the work content and process. According to the needs of statistical characterization of groundwater environmental background value, the work content and process of groundwater environmental background value data acquisition, sample collection and testing, data processing and analysis, as well as statistics and characterization are proposed.
The third is data acquisition. The investigation scope and the method of determining the target aquifer are clarified, the requirements for data collection and collation are put forward, the principles and methods of historical hydrochemical data screening, background value index selection, hydrogeological zoning division, and preliminary division of statistical units are refined, and the distribution density and minimum sample size requirements of a single statistical unit are specified.
Four is the sample collection and testing. The technical requirements for sampling point layout, well construction sampling and testing are clarified. The Guide stipulates that when the sample density or sample size of a single statistical unit does not meet the statistical characterization requirements of groundwater background values, additional sampling points should be set up to collect and test groundwater samples.
Fifth, data processing and analysis. The method of normality test and conversion of groundwater environmental background value data is clarified, and the principles and methods of identifying and eliminating abnormal values of various indicators such as macro components and comprehensive indicators, trace and trace components, and the requirements of abnormal data verification are specified.
Six is statistics and characterization. The principle of statistical unit adjustment is stipulated, the technical requirements for the statistics and characterization of the background value of groundwater environment and the analysis of the causes of the background value are clarified, and the application scenarios and methods of the background value of groundwater environment are put forward.
7 is the appendix. It provides the necessary informative appendices such as the information collection table of the statistical characterization of the background value of the groundwater environment, the list of test indicators, the method of drawing the background value statistical chart, and the normative appendices such as the outline of the report preparation.
Q: What are the application scenarios of the Guide and how are they applied?
Answer:Groundwater environmental background values are mainly used in the following two scenarios:
The first is the analysis and determination of the causes of groundwater-type drinking water sources, national groundwater environmental quality assessment points or groundwater pollution sources in the area where the natural chemical components of groundwater exceed the standard. When there are no pollution sources such as historical contaminated plots or enterprises in production within the scope of investigation, or when there is evidence that human factors cause groundwater to exceed the standard, there is no need to carry out statistical characterization of groundwater environmental background values. Second, the target value of groundwater pollution remediation involving natural chemical components in areas with high background value is reasonably determined.
When it is used to analyze and determine the cause of exceeding the standard, if the value of groundwater exceeding standard index in a statistical unit is not higher than the upper limit of its background value, it can be determined that the exceeding standard is mainly affected by geological background; otherwise, it can be determined that it is mainly affected by human factors, and further work such as pollution source investigation, pollution traceability and source interruption should be carried out.
When the target value for groundwater pollution remediation is determined, if the remediation target value determined through risk assessment is lower than the upper limit of the regional groundwater environment background value, the upper limit of the background value can be used as the remediation target value..
Q: How to ensure the objectivity of the statistical characterization results of groundwater environmental background values?
Answer:The Guide reduces the interference of subjective factors in the process of statistical characterization of background values as much as possible through strict technical requirements of five key links, so as to ensure the scientific and reasonable results of statistical characterization of background values.
The first is to strictly screen the historical water chemistry test data and eliminate the water quality data contaminated by man-made.
The second is to specify the sample density and minimum sample size requirements for each statistical unit to avoid excessive background value errors due to too little data.
The third is to strictly control the quality of the well construction, sampling and analysis and testing process, and eliminate the data that does not meet the quality control requirements.
Fourth, with the help of statistical methods, in the data processing and analysis of the link to further identify and eliminate abnormal data.
Fifth, through the review and adjustment of the boundary data of the statistical unit, the inclusion of high background data that does not belong to the statistical unit is avoided, thus raising the upper limit of the background value..
Q: How to promote the implementation of the Guide?
Answer:At present, some provinces have carried out the statistical characterization of groundwater environmental background values, and the experience and suggestions of local trials have been fully absorbed in the process of compiling the Guide. In the next step, we will do a good job in the publicity and implementation of the Guide. The first is to strengthen publicity and training, and adopt various forms such as policy interpretation and training meetings to carry out training for local ecological and environmental departments, third-party practitioners, and related experts. The second is to strengthen the technical guidance for the statistical characterization of background values being carried out and planned to be carried out in various places, and to promote the standardized implementation of the Guide. The third is to develop supporting calculation software, which is provided free of charge to relevant parties to realize the automation of background value data processing, improve the accuracy of calculation, and support the audit of data quality and result accuracy.
Feed |Department of Soil Ecology and Environment, Ministry of Ecology and Environment
Source | Ministry of Ecology and Environment
