In the process of building a harmonious society in China, the development of social economy puts forward higher requirements for resource development, environmental protection and quality and safety of agricultural products. Geological work should not only provide economic security, but also pay attention to ecological environment problems; We should not only serve the economic construction healthily, but also serve the development of agriculture and environment, and realize the coordinated development of economy, society, resources and environment. Therefore, on the basis of national pilot, China Geological Survey started multi-objective regional geochemical survey and agricultural geological environment survey in 2002. First of all, Shandong Province started the provincial-ministerial cooperation project "Ecological Geochemical Investigation of the Lower Yellow River Basin in Shandong Province" and achieved a series of results.
Eastern Shandong is the main part of Shandong Peninsula Blue Economic Zone and the most economically developed area in Shandong. Since the reform and opening up, the regional economy has developed rapidly and steadily, and the pace of urbanization has accelerated. The exploitation of resources leads to the environmental pollution caused by heavy metals, the discharge of "industrial three wastes", the extensive use of pesticides and fertilizers, and sewage irrigation, which leads to the increasingly serious ecological environmental pollution problems, which are closely related to human life and human survival. In order to find out the present situation and development trend of ecological environment in this area and provide scientific basis for the sustainable development of social economy in this area, the Shandong Provincial People's Government deployed and carried out the "Investigation and Evaluation of Agricultural Eco-geochemistry in Eastern Shandong" in 2006 (Lu Zi [2006709]). The centralized management department of the project is Shandong Provincial Department of Land and Resources, and the project implementation unit is Shandong Geological Survey Institute. The starting and ending time of work items is from 2007 to 20 1 1 year.
The overall goal of "Biogeochemical Investigation and Evaluation in Eastern Shandong" is to comprehensively carry out multi-objective regional geochemical investigation and eco-geochemical evaluation research, provide scientific basis for social and economic sustainable development planning, and serve ecological management and protection, agricultural planting suitability, agricultural product quality and safety, environmental pollution control and so on.
The overall task is:
First, carry out multi-objective regional geochemical survey, mainly including systematic collection and measurement of element contents in soil and shallow groundwater, and find out their distribution and distribution characteristics; Determine the soil geochemical reference values and background values of the whole working area and its sub-areas; Delineate various geochemical anomalies such as environmental, agricultural and mine-induced anomalies, and verify important anomalies.
Second, according to the survey results and related standard methods, carry out regional evaluation and comprehensive evaluation, including soil geochemical zoning and eco-geochemical environmental zoning, regional soil environmental quality, shallow groundwater environmental quality, bulk agricultural products and human settlements environmental safety evaluation, and fully understand the current situation of agricultural geological environmental quality; Evaluate the suitability of regional agricultural geological environment and put forward planning suggestions.
Third, under the guidance of multidisciplinary theory, using various methods and technologies, the major agricultural geological environment problems are comprehensively studied at multiple levels and angles. Study the composition, existing mode, distribution characteristics and sources of toxic and harmful elements or beneficial elements, accurately grasp the harmful elements that affect the safety of the system, and make geochemical prediction and early warning; Study the migration and transformation law and influence mechanism of elements in rock-soil-plant; Comprehensively study the ecological effect and influence mode of regional geochemical conditions on agricultural environment, and establish regional evaluation index and evaluation model.
Second, technical ideas and implementation
(A) the technical concept
The agricultural eco-geochemical survey in eastern Shandong covers six prefecture-level cities, including Qingdao, Yantai, Weihai, Rizhao, Weifang and Linyi, 46 counties and cities (districts) and 1 198 townships, covering an area of 54 370km2.
Adhering to the earth science as the foundation, taking geological science, agricultural science and environmental science as the theoretical guidance, and developing in the form of multi-sectoral cooperation and multi-disciplinary cooperation are the basic technical ideas. Based on investigation, with evaluation as the core and research as the link, it is the overall technical route.
(2) Main technical indicators
1)1:250,000 surface soil geochemical survey. The system collected surface soil samples (0 ~ 20 cm deep) for laboratory analysis, and found out the distribution and dispersion and enrichment characteristics of 54 elements or indicators in the surface soil. The sampling density is 1 sample /km2, and four samples in the even square grid are combined into 1 sample for analysis.
2)1:250,000 deep soil geochemical survey. The natural environment soil samples were collected systematically (the sampling depth was below 1.5m in principle, and the sampling in hilly areas was carried out according to the Notice on Sampling Techniques for Multi-objective Regional Geochemical Survey in Hilly Areas and Loess Plateau in China issued by China Geological Survey in February 2007), and the distribution, dispersion and enrichment characteristics of 54 elements or indicators in deep soil were found out, with the sampling density of 1 piece /4km2.
3) Geochemical investigation of available state of topsoil. The system collects topsoil samples for chemical analysis, and finds out the distribution, dispersion and enrichment characteristics of effective elements in topsoil. The sampling density is 1 piece /36km2, and a single sample is analyzed.
4) Geochemical investigation of shallow groundwater. Shallow groundwater samples were collected systematically to find out the distribution and dispersion and enrichment characteristics of relevant geochemical indicators in shallow groundwater, and the sampling density was 1 sample/16km2.
5) Select Yantai area to carry out geochemical survey of organic pollutants, and evaluate the organic pollution area, with the sampling density of 1 unit /36km2 and single sample analysis. The analysis item is the total amount and composition of DDT and HCH *** 10 index.
6) High-density soil radionuclides (238U, 232Th and 40K) and surface γ were measured in densely populated areas of Qingdao, and their radioactive characteristics and distribution laws were deeply studied to comprehensively evaluate the environmental radioactive quality.
(3) Analysis and testing
Hubei Institute of Geological Experiment undertakes the investigation, analysis and testing of soil total elements, soil heavy metal forms and regional geochemistry of agricultural products. A total of 54 indicators analyzed are1:200,000 Ag, As, Au, b, Ba, Be, Bi, Cd, Co, Cr, Cu, f, Hg, La, Li, Mn, Mo, Nb, Ni, p, Pb, Sb and Sn specified in the national regional geochemical exploration plan. On the basis of 39 elements of Fe, considering the research needs of agriculture and environment, three elements of Br, C, Ce, Cl, Ga, Ge, I, N, Rb, S, Sc, Se, TL 18 and two indicators of organic carbon (OrgC) and pH were added for analysis. Analysis of wheat (root soil, root, stem and leaf) samples As, Cd, Hg, Pb, Cr, Cu, Zn, Ni, Se, F * * *10; Speciation analysis of heavy metals in wheat rhizosphere soil: As, Cd, Cr, Cu, Zn, Ni, Hg, Pb, 8 kinds of heavy metals, including water-soluble state, ion exchange state, carbonate bound state, weak organic (humic acid) bound state, iron-manganese bound state, strong organic bound state and residual state, with a total of 56 indexes.
Shandong Geological Science Experimental Research Institute undertakes the testing of the available amount of shallow groundwater and soil. The analysis items of shallow groundwater include total hardness, total dissolved solids, chloride (Cl-), nitrite (), permanganate index (COD), cyanide (CN-), fluoride (F-), iodide (I-), hexavalent chromium (Cr6++), As, Ba, Be, Ca, Cd and Co. The analysis items of soil available elements are available nitrogen, available phosphorus, available potassium, available boron, available molybdenum, available (active) manganese, available copper, available zinc, available iron, available sulfur and available selenium 1 1. At the same time, the corresponding indexes of total amount and cation exchange capacity (CEC), organic matter and pH value were analyzed.
The Central Laboratory of Shandong Academy of Agricultural Sciences undertakes the analysis and detection of organochlorine pesticide residues in soil (total amount and components of DDT and HCH 10). These high-quality massive data have long-term application value of multi-department, multi-discipline and multi-field.
(4) Comprehensive research
On the basis of systematically collecting the preliminary research results of agriculture, environmental protection, land resources and other departments in Shandong Province, and investigating the present situation and progress of agricultural geology and agricultural environmental protection at home and abroad, comprehensive research work has been carried out in the aspects of land environmental quality evaluation, shallow groundwater pollution evaluation, temporal and spatial evolution of soil elements, soil acid buffering capacity, product safety status, heavy metal migration mechanism of soil plant system, agricultural geological environment evaluation method system, agricultural comprehensive zoning and so on. This book is a comprehensive summary and re-study of these achievements.
Three. Major achievements and innovations
Through the implementation of the project, abundant regional geochemical data in eastern Shandong were obtained, the present situation of agricultural geological environment was found out, the influence of heavy metals on agricultural geological environment was deeply studied, and the migration and transformation law and influencing factors of elements from soil to crops were discussed, which improved the research level of environmental geochemistry. According to the investigation results, combined with the actual situation of the investigation area, comprehensive agricultural zoning and environmental prediction and early warning were carried out, and a series of suggestions and countermeasures were put forward for agricultural geological environment protection. The research results obtained have important scientific significance and practical application value in many fields, showing broad application prospects.
(A) the main results
1) has obtained high-precision measured data of multi-media, multi-elements or indicators, compiled a series of basic geochemical maps, and comprehensively updated and enriched regional geochemical data.
2) The reference values and background values of soil geochemistry of 54 elements (indicators) and the average content of available states of 10 elements in eastern Shandong were established, the distribution characteristics and laws of elements were summarized, and the main factors controlling the distribution of soil elements were analyzed.
3) Find out the present situation of agricultural geological environment in eastern Shandong, and achieve the goal of "finding out the family background". ① The present situation of soil environmental quality and soil pollution problems were found out. ② The environmental quality and pollution status of shallow groundwater were found out. ③ The present situation of abundance and deficiency of soil nutrient elements was found out, and the control factors affecting the effectiveness of elements were discussed. ④ Geochemical evaluation of provincial land quality; Delineate green pollution-free food production bases and exploration areas.
4) The distribution of selenium in soil and the controlling factors of its bioavailability were studied, which provided a new idea for developing efficient ecological agriculture and increasing farmers' income.
5) The prediction and early warning of soil pollution, regional ecological security and environmental changes have been carried out, which has deepened the understanding of agricultural geological environment and improved the comprehensive research level.
6) Studying the correlation between surface and deep soil elements and evaluating soil pollution by using enrichment coefficient provides a new idea for identifying soil pollution caused by human activities.
7) Carry out high-density radioactive environmental geological survey in Qingdao. The distribution, sources and influencing factors of environmental γ -radiation absorptiometry in Qingdao were found out. It provides a basis for the future planning, construction and long-term development of the city.
8) The "Ecological Geochemical Survey Database" was established, and the regional geochemical survey data were comprehensively updated.
(2) Main innovation points
This survey fully considered the social demand of exploration geochemical survey data, and realized the combination of total geochemical amount of elements with effective amount and speciation analysis, inorganic elements with organic pollutants, and geochemical environmental investigation with biological effect investigation, which not only enriched the survey content, but also greatly improved the effective utilization rate of data and shortened the understanding process. It is manifested in the following aspects:
1) By studying the speciation of heavy metal elements in soil, it is found that different forms of heavy metal elements have different biological activities and migration abilities for crops, among which the ratio of ion-exchanged state to water-soluble state (active state) of Cd is the highest, which is an important factor to determine the ecological risk of heavy metal pollution in soil. The forms of soil elements in different environments, such as pH, organic matter, CEC and clay, are also very different, indicating that the change of soil environment may lead to the activation of heavy metals in soil and lead to ecological risks.
2) The migration and transformation law of harmful elements such As As, Cr and Cd from soil to crops and its influencing factors were studied, which provided a basis for the evaluation of ecological and environmental effects of elements and had academic significance and application value; The measures to improve the safety of grain production were discussed, which provided scientific basis for ensuring the safety of agricultural products and human health.
3) At the provincial level (1:250,000 scale), the safety of wheat quality in the study area was predicted by using the national food hygiene standards for the first time. The results show that 90. 15% of the study area can grow green and pollution-free wheat, and 3.47% of the study area can grow selenium-enriched wheat.
4) The investigation of organic pollutants (BHC and DDT) in Yantai City has promoted the depth and breadth of comprehensive environmental assessment, and the evaluation results are more in line with reality.
5) By studying the relationship between soil alkaline ions (the sum of K, Ca, Na and Mg) and pH, an early warning model of soil acidification buffering capacity was established for the first time.