[Evaluation and Source Analysis of Soil Heavy Metal Pollution in a Planting Area in Wanquan District, Zhangjiakou City]

Taking the soil of a vegetable planting area in Wanquan District of Zhangjiakou City as the research object, 132 surface and 80 deep soil samples were collected to test and analyze the contents of eight heavy metals such as As, Cd, Cr, Hg, Cu, Ni, Pb, and Zn and the occurrence forms of Cr and Ni. By applying geostatistical analysis and the PMF receptor model and combining three heavy metal pollution evaluation methods, the spatial distribution characteristics of soil heavy metals in the study area, the degree of heavy metal pollution, and the distribution of Cr and Ni fugitive forms in the vertical layer were clarified, and the sources and contribution rates of soil heavy metal pollution were analyzed. The results showed that the average contents of Cd and Pb in surface soils were higher than the background values of soils in Hebei Province, and the spatial distribution characteristics of Cr, Ni, Cu, Cd, Pb, and Zn in surface soils were similar. The ground accumulation index method showed that the study area was mainly free of pollution, with a small number of lightly polluted sites, and most of them were polluted with Cd. The enrichment factor method showed that the study area was mainly free-weakly polluted, with medium pollution of all elements; the significantly polluted elements in the background area were As, Pb, and Hg, and the significantly polluted element in the key area was Cd. The potential ecological risk index method showed that the study area was mainly lightly polluted, with local distribution. The potential ecological risk index method showed that the study area was mainly lightly polluted, with a local distribution of "medium" and "strong" risk points, with "very strong" risk points for Hg in the background area and "very strong" risk points for Cd in the focus area. These three evaluation results indicated that the background area was dominated by Cd and Hg pollution, whereas the focus area was dominated by Cd pollution. The study on the fugitive morphology of vertical soil showed that Cr was dominated by the residue state (F4) and supplemented by the oxidizable state (F3), and the vertical direction was dominated by the surface aggregation type and supplemented by the weak migration type. Ni was dominated by the residue state (F4) and supplemented by the reducible state (F2), and the vertical direction was dominated by the strong migration type and supplemented by the weak migration type. The sources of heavy metals in the surface soil were divided into three categories; Cr, Cu, and Ni were mainly from natural geological background sources. The contributions of Cr, Cu, and Ni were 66.9%, 66.9%, and 76.1%, respectively. As, Cd, Pb, and Zn were mainly from anthropogenic sources, with contributions of 77.38%, 59.2%, 83.5%, and 59.5%, respectively. Hg was mainly from dry and wet atmospheric deposition, with a contribution of 87.8%.

Planting conditions can enhance the bioactivity of mulberry by affecting its composition

Mulberry (Morus alba L.) has a special significance in the history of agriculture and economic plant cultivation. Mulberry has strong environmental adaptability, a wide planting range, and abundant output. It is not only an important resource for silkworm breeding but also a raw ingredient for various foods and has great potential for the development of biological resources. The bioactivities of mulberry in different planting areas are not the same, which is an obstacle to the development of mulberry. This study collected information on the planting conditions of mulberry branches in 12 planting areas, such as altitude, temperature difference, and precipitation. A comparison of the levels of 12 constituents of mulberry branches from mulberry grown in different planting areas was then made. An in vitro model was used to study the bioactivities of mulberry branches in the 12 planting areas, and mathematical analysis was used to explain the possible reasons for the differences in the composition and bioactivities of mulberry branches in different planting areas. After studying mulberry samples from 12 planting areas in China, it was found that a small temperature difference could affect the antiapoptotic effect of mulberry branch on microvascular endothelial cells by changing the levels and proportions of rutin, hyperoside, and morusin. Adequate irrigation can promote the antioxidation of the mulberry branch on microvascular endothelial cells by changing the levels and proportions of scopoletin and quercitrin. The results of the analysis of planting conditions and the levels of active constituents and their correlation with bioactivities support the improvement of mulberry planting conditions and have great significance in the rational development of mulberry resources. This is the first time that a mathematical analysis method was used to analyze the effects of planting conditions on mulberry biological activity.