Prediction of soil cadmium distribution across a typical area of Chengdu Plain, China

Abstract

A suitable method and appropriate environmental variables are important for accurately predicting heavy metal distribution in soils. However, the classical methods (e.g., ordinary kriging (OK)) have a smoothing effect that results in a tendency to neglect local variability, and the commonly used environmental variables (e.g., terrain factors) are ineffective for improving predictions across plains. Here, variables were derived from the obvious factors affecting soil cadmium (Cd), such as road traffic, and were used as auxiliary variables for a combined method (HASM_RBFNN) that was developed using high accuracy surface modelling (HASM) and radial basis function neural network (RBFNN) model. This combined method was then used to predict soil Cd distribution in a typical area of Chengdu Plain in China, considering the spatial non-stationarity of the relationships between soil Cd and the derived variables based on 339 surface soil samples. The results showed that HASM_RBFNN had lower prediction errors than OK, regression kriging (RK) and HASM_RBFNNs, which didn’t consider the spatial non-stationarity of the soil Cd-derived variables relationships. Furthermore, HASM_RBFNN provided improved detail on local variations. The better performance suggested that the derived environmental variables were effective and HASM_RBFNN was appropriate for improving the prediction of soil Cd distribution across plains.

Inhibition of Cd accumulation in grains of wheat and rice under rotation mode using composite silicate amendment

“…However, in this area, soil Cd has become a serious pollutant due to its geological origin and historical phosphate mining. 21 Furthermore, it was reported that the Cd concentrations in the grains of wheat and rice in some areas of the Chengdu Plain exceeded the national limitation. 22,23 Thus, to reduce the environmental risk of Cd in soil and ensure the food safety of crops in water/upland rotation in the Chengdu Plain, remediation of Cd-contaminated soils under wheat/rice rotation is urgently needed.…”

Adsorption and pH values determine the distribution of cadmium in terrestrial and marine soils in the Nansha area, Pearl River Delta

“…Cadmium (Cd) is a carcinogen that can be accumulated in the body by entering the food chain and seriously endanger human health (Godt et al 2006, Peng et al 2016. Excessive importation of this heavy metal into the soil has attracted worldwide attention because of its high toxicity, persistence and bioenrichment capacity (Dong et al 2018, Li et al 2017. Survey results show that 13.86% of China's grain production is affected by inorganic pollutants present in soils, among which cadmium ranks as the most polluting metal, accounting for 7.75% (Zhang et al 2015).…”

Distribution, Ecological Risk Assessment, and Bioavailability of Cadmium in Soil from Nansha, Pearl River Delta, China

“…Industrialization/urbanization (e.g., industry, agriculture, and transportation) and natural geological processes can lead to the heavy metal pollution of some farmland soils [2,3]. Heavy metals in soils pose a threat to human health through the food chain [4,5], and cadmium (Cd) is an important pollutant among various heavy metal elements, due to its high migration rate from soil to plants and strong biological toxicity [6]. There is increasing evidence that environmental exposure to Cd is associated with increased cancer incidence [7].…”

“…In recent years, researchers have paid more attention to the spatial distribution of heavy metals in soils in order to assess the potential risks to humans and the environment [6,12,13,14]. The spatial distribution of pollutants has been used to quantify the level of pollution in an area, and the identification of influencing factors can be used to measure the effectiveness of pollution abatement measures [15].…”