Enrichments of Cadmium and Arsenic and Their Effects on the Karst Forest Area

Abstract

An understanding of the enrichment mechanisms of cadmium (Cd) and arsenic (As) in the process of rock weathering and soil formation is essential to develop agriculture according to local conditions. However, the enrichments of soil Cd and As under natural background conditions in karst areas are still uncertain. The enrichment factor, geo-accumulation index, redundancy analysis, and other methods were used to analyze the enrichment degree and the influencing factors of Cd and As on 5 rock–soil profiles and 15 topsoil samples, which were collected from a karst forest area in Libo County, Guizhou Province. The results showed that the enrichment process was divided into three stages. In the first stage, Cd and As were enriched in carbonate rocks, and their mean concentrations were 1.65 and 3.9 times those of the corresponding abundance of the crust. In the second stage, the enrichment of the parent rock into the soil, the enrichment factors of Cd and As in the parent material horizon relative to the bedrock horizon were 9.2 and 2.82, respectively. The third stage refers to the enrichments of Cd and As in the topsoil, where Cd enrichment was more obvious than that of As. Soil organic matter (SOM) and phosphorus (P) are important factors that influenced the enrichments of Cd and As in the topsoil. The functional groups of SOM were complexed with Cd and As; P easily formed precipitates with Cd, and the tree litter was fed back to the topsoil, which may be the reason for the surface enrichment of Cd and As. This study will help the scientific community understand the enrichment mechanisms of soil Cd and As in karst areas.

Environmental impact assessment of Egyptian Damietta governorate soils contamination with cadmium

“…The high values in Damietta and Kafr Saad regions may be attributed to the high rates of phosphorus fertilization application and irrigation with sewage effluent or mixed water. These findings are agreed with several research work 48,49 and they reported that sewage sludge, soil organic matter and phosphorus fertilizers are important factors that influenced the enrichments of Cd in the topsoil. Frequency distribution of total Cd in the studied soils shows that 26% of the studied soils contained values of total Cd less than 500µg kg -1 (Figure 5).…”

“…Under such conditions the solubility of Cd in the surface soil layers and its downward movement to the soil subsurface layers increases. This agree with Wang et al 48 which reported that soil organic matter important is factors that influenced the enrichments of Cd in the soil.…”

The Pedosphere as a Sink, Source, and Record of Anthropogenic and Natural Arsenic Atmospheric Deposition

“…A study on the remote Northern Sakhalin region of Russia found arsenic concentrations built up to 9.2 mg/kg in the surface organic horizons of peats and podzols of forest settings, with an average of 2.8 mg/kg . Wang et al found high concentrations of arsenic in the humic horizon of a forest soil in southeast China of 27 mg/kg. They concluded that this enrichment originated from a limestone bedrock concentration of 8.6 mg/kg, stating that internal biogeochemical cycling was responsible, i.e., plant assimilation and bioconcentration of soil arsenic, without providing evidence.…”

Study on Spatiotemporal Characteristic and Mechanism of Forest Loss in Urban Agglomeration in the Middle Reaches of the Yangtze River

“…Additionally, while planned logging (e.g., transforming natural forests into oil palm forests or timber forests) may stop significant net forest loss, it diminishes the forest's ecological value and degrades many of its ecosystem services [17][18][19][20]. Among regions with extensive and highly developed heavy industries and mining activities, environmental pollution (e.g., soil and water pollution) can lead to significant permanent forest loss [21,22]. For many developing countries, urban construction is the main cause of forest loss.…”