Analysis of Heavy Metal Pollution in Cultivated Land of Different Quality Grades in Yangtze River Delta of China

Abstract

The distribution of heavy metal pollution in cultivated land is closely related to the quality of the cultivated land. In this study, 533 soil samples were collected from cultivated land in the Yangtze River delta region in China for Cd, Pb, and Hg analyses. Spatial statistical analysis was used to study the heavy metal pollution in the cultivated land, and the driving forces of heavy metal distribution in different cultivated land quality subdivisions were analyzed with GeogDetector. The conclusions are as follows: (1) Among the three heavy metals in the study area, the coefficient of variation of Cd is the largest, and that of Pb is the smallest. The proportion of Cd and Hg exceeding the standard value (the standard of level two in GB 15618—2018) is relatively large, both of which are 5%; (2) From the perspective of the spatial distribution of soil heavy metal pollution, only four counties (CX, HN, WY, and LH) were free of heavy metal pollution. Soil heavy metal pollution in AJ, SY, QJ, and DS counties is relatively serious, and the pollution may come from agricultural activities, manufacturing, and prevalent coastal shipping industries in these counties; (3) The heavy metal pollution levels of cultivated land with different quality levels are different. The high-quality cultivated land has no high contamination, while the medium and the general cultivated land both have high contamination. High contamination is related to Cd for medium and general cultivated lands, and to Hg in only general cultivated land; (4) The main driving factors of heavy metal concentration in cultivated soil were GDP, followed by soil organic matter, and pH. These results indicate that the spatial distribution of heavy metal concentration in cultivated soil was affected by the level of economic development, followed by the ecological environment, indicating that human activities had a critical impact on the ecological environment of cultivated land.

Impacts of Farming Layer Constructions on Cultivated Land Quality under the Cultivated Land Balance Policy

“…Evaluations of agricultural production capacity, cultivated land potential, sustainability, grading, etc., are commonly used to assess CLQ [55][56][57]. Although different evaluation factors affect the quality of cultivated land at the same time, it does not mean that the CLQ index is acquired by their simple addition because some factors have a limiting effect [44].…”

Research on Fuzzy Comprehensive Evaluation Index System of Mental Health Education for College Students

“…The application of this method makes the mental health education of college students highlight and has strong pertinence. College students' mental health assessment is the guidance and foundation of college students' mental health education, so colleges and universities should put college students' mental health assessment first, improve the subjects of college students' mental health assessment, and establish a set of more scientific assessment standards [ 14 ]. The intervention of school group work emphasizes people's utility in the situation.…”

Adsorption Performance of Cd(II) by Chitosan-Fe3O4-Modified Fish Bone Char

“…To study the adsorption kinetics, Cd(II) solution (25 mL) with an initial pH of 5.40 and an initial concentration of 200 mg•L −1 was added to a 50 mL conical flask, and then adsorbent (0.05 g) was added to the Cd(II) solution, under the conditions of 25 • C, 200 r•min −1 , using a constant temperature culture oscillator (ZHWY-2102C, Shanghai ZHICHENG analytical Instrument Manufacturing Co., Ltd., Shanghai, China) to oscillate for 1, 3,5,10,20,30,40,60,90,120,180,240,300,360,480, 600, 720, and 1440 min. Finally, the resulting solution was passed through a 0.45 µm water filter membrane, and an atomic absorption spectrophotometer (ZEEnit 700P, Jena Analytical Instrument Co., Ltd., Thuringia, Germany) was used to determine the concentration of Cd(II) in the filtrate.…”

“…Cd in the soil is easily absorbed by plants and transported in their tissues [4]. At present, Cd content of many food crops in China has exceeded the corresponding national food safety standard [3,5]. Wastewater irrigation is an important cause of cadmium pollution in agricultural soil.…”