Pollution characteristics and ecological risk assessment of heavy metals in paddy fields of Fujian province, China

Abstract

to analyze the concentration, spatial distribution patterns, and ecological risks of heavy metals (Cd, Cr, Pb, As, Cu, Ni and Co), 272 topsoil samples (0-20 cm) were collected from paddy fields in Fujian province in July 2017. The results revealed that the mean concentration of all heavy metals exceeded the background values in Fujian province, with the mean concentration of Cd being 5.20 times higher than its background. However, these concentrations of heavy metals were lower than their corresponding national standards (GB 15618-1995). Spatially, for Cd, the high concentration areas were located mainly in southeast of Sanming city and northeast of Quanzhou city. For Pb and As, the places of highest concentration were mainly in southeast of Quanzhou city and Zhangzhou city, and the main areas of high Ni concentration were distributed southeast of Nanping city. The geo-accumulation index (I geo) of Cd and As were indicative of moderate contaminations, and the index of Co, Cu and Cr suggested that these were practically uncontaminated. The nemerow integrated pollution index (P n) showed that the entire study area was prone to a low level of pollution, but at the county level, Yongcun county and Zhaoan county are in an warning line area of pollution. According to the potential ecological risk (RI), the ecological risk belongs to the low risk of paddy fields in Fujian province. However, Cd should be given attention (E r = 25.09), as it contributed to the majority of potential ecological risks in Fujian province. The large number of industrial waste, mining byproducts, chemical fertilizers, pesticides and other synthetic chemical substances in the agroecological ecosystem has seriously threatened food security, food safety and human health around the world 1-6. Thus, soil pollution treatment is urgently needed to solve the current problems in agricultural production. At the same time, the accumulation of heavy metals in agricultural soil is a serious problem for human health and safe food production 7-9. Heavy metal contaminants are commonly introduced to soils through anthropogenic activities, such as mineral resources development, agrochemical use, fossil fuel consumption, poultry manure, waste disposal, and sewage irrigation 10-12. Soil heavy metal contamination has become serious and widespread in China. According to the national communiqué of the soil pollution survey by the ministry of environmental protection of China and the ministry of land and resources in 2014 13 , some regions of soil have become heavily contaminated, and the quality of cultivated soil is particularly concerning. The total over-standard rate of soil (environmental quality standard for soils in China, GB15618-1995) in China was 16.1%. Further, the over-standard rates of Cd, Cu, Hg, As, Pb, Ni and Cr were 7.0%, 2.1%, 2.7%, 1.5%, 4.8% and 1.1%, respectively 13. A soil pollution control plan has been developed in China to improve soil quality, ensure the quality and safety of agricultural products and protect the health of humans, such as a n...

Distribution of Natural and Anthropogenic Sources, and Mapping of As, Co, and Hg by Three Ecological Risk Indices in the Mid-continent of the USA

“…Compared to EF of Co in IA, KS, an NE (0.10, 0.90, 1.03) respectively, it was lower than EF of Co (5.33) demonstrated by Odat, 2015 [44]. As values in the current study showed in Table 3 had lower concentrations compared with the investigated levels in soils in paddy fields of Fujian province in China presented a mean value of 22.60 [28]. However, Co mean values were the same in the current study in IA as reported by [28], but lower than estimated in KS and NE (Table 3).…”

“…The factor 1.5 is the background matrix correction factor for minimizing the impact of possible variations in the background values (it is used because of the possible variations in background values for a given metal in the environment as well as exceedingly small anthropogenic impacts) that may be attributed to lithologic variations or impacts in the soils [29]. Muller (1969) categorized I geo index into seven class indicators that are used to define the degree of metal contamination according to the criteria and these classifications are shown in Table 1.…”

Potential Ecological and Human Health Risks of Heavy Metals in Soils in Selected Copper Mining Areas—A Case Study: The Bor Area

“…The GB values were calculated as means of data compiled from the specialty literature (see Table 1). This index consists of seven classes: uncontaminated (I geo ≤ 0); uncontaminated to moderately contaminated (0 < I geo ≤ 1); moderately contaminated (1 < I geo ≤ 2); moderately to heavily contaminated (2 < I geo ≤ 3); heavily contaminated (3 < I geo ≤ 4); heavily to extremely contaminated (4 < I geo ≤ 5); and extremely contaminated (I geo ≥ 5) [18].…”

5-day flooding followed by 3-day drainage wet-dry alternation cycle is highly effective in reducing Cd and As content in rice

“…Because its effects on animals are cumulative, it is toxic to livestock and humans at lower concentrations than to plants. Compare with other heavy metals, Cd was found to be the main components contributing to the potential health and ecological risks in China by the latest studies 1,2 . The Joint Expert Committee on Food Additives (JECFA) has established a health-based guidance value for Cd (25 µg kg − 1 bodyweight per month) 3 , and the Codex Alimentarius Commission has adopted a maximum concentration of 0.4 mg kg − 1 for Cd in white rice grain 4 .…”