Search Results (2)

To explore the potential of Koenigia mollis as a pioneer plant in acid tin mine wasteland, Koenigia mollis plants and the corresponding rhizosphere soils in different areas in Lianghe County, Yunnan Province were collected, and their chemical properties and heavy metals contents were determined., the adaptability of the plant to the barren tailing environment and its acid resistance and tolerance to heavy metal such as Cu (Cu, CAS. No. 7144-37-8), Cd (Cd, CAS. No. 7440-43-9) and Pb (Pb, CAS. No. 10099-74-8) pollution were analyzed. Results showed that Koenigia mollis growth was normal. The pH value in rhizosphere soils was 3.74–4.30, which was strongly acidic. The organic matter (OM), total nitrogen (TN) (N, CAS. No. 7727-37-9), available potassium (AK) (K, CAS. No. 7440-09-7), and available phosphorus (AP) (P, CAS. No. 7723-14-0) contents in soils of the research area were in low levels. The total contents of Cu, Cd, and Pb in the soil of the research area exceeded the pollution risk screening value for the national risk control standard of soil environmental quality, indicating that Koenigia mollis has a certain resistance to acid and heavy metal pollution. In addition, Koenigia mollis has strong transport and enrichment capacity for Cu, Cd, and Pb and therefore has potential as a pioneer phytoremediation plant for acid tin mine wastelands and a remediated plant for agricultural land around metal mining areas. Full article

To explore the distribution characteristics and degree of pollution of heavy metals in the farmland soil around the Dachang tin polymetallic mining area in Guangxi, a total of 140 soil samples were collected around the mining area in this study. The total amount and various forms of seven heavy metals (Cu, Pb, Cd, Cr, Zn, As, and Ni) were analyzed by inductively coupled plasma mass spectrometry, and the improved continuous extraction method of heavy metal speciation analysis in the soil, the potential ecological risk index (RI), the and Nemerow evaluation index (P_N) were used to evaluate pollution characteristics of the soil and the bioavailability of heavy metals. Corresponding remediation suggestions were given according to the pollution degree. The results show that the whole soil in the study area is acidic, reducing, and the content of organic matter is low. The average content of heavy metal elements is higher than the background value of Guangxi, among which Cd, Pb, and As exceed the control value and are the main elements of pollution. The speciation analysis of heavy metals in soil shows that Cd is dominated by the ion exchange form; Cu is mainly residual and in a humic acid combined form; and the rest of the elements are mainly in residual form. Among the seven heavy metals, Cd has the strongest mobility, biological toxicity, and ecological risk, followed by As, Ni, and Zn. The overall pollution level of the soil in the study area is heavily polluted (P_N = 39.6), which is a very strong ecological risk level (RI = 2196.9), and the main pollutants are Pb, As, and Cd; Cd pollution is the most serious. Correlation (CA) and principal component analysis (PCA) indicate that the pollution sources of Pb, Cu, Zn, Cd, and As among the seven elements were mainly controlled by tailings accumulation, mining, and transportation, and the sources of Cr and Ni were controlled by soil-forming parent materials. Furthermore, according to the actual situation of the farmland around the mining area, two remediation suggestions are put forward: (1) use stabilization remediation technology to clean up the pollution source, such as calcium dihydrogen phosphate to reduce the bioavailability of the most polluted elements, Cd and Pb, in the soil; (2) under the concept of green environmental protection, use Typha orientalis Presl to repair the industrial and mining wasteland and some unused land. Full article