Abstract
With rapid economic and industrial development, the potentially toxic element (PTE) pollution of farmlands in China has become increasingly serious. Based on the Hakanson potential ecological risk index (RI) and national food pollutant limit standards (GB 2762-2017), the effects of exogenous potentially toxic elements (PTEs), i.e., arsenic (As) and mercury (Hg), on rice growth were studied. Common varieties of hybrid (YY 538, CY 84) and conventional (XS 134, JH 218) rice were grown in pots having representative paddy soil from Zhejiang Province, China. The results showed that As and Hg in soil significantly inhibited growth; however, the plant height of hybrid rice was less affected. Further, there were significant correlations between concentrations of PTEs in soil and rice grains; however, hybrid rice had a stronger ability to absorb and accumulate PTEs. The comprehensive potential ecological RI of soil PTEs was 39.4–89.9, which is below the level of ‘minor ecological hazard’, and the contribution rate of Hg was 79.9%–84.2%; as such, Hg posed the greatest potential ecological risk in the study area. The ecological risk limits of As and Hg in the safe production of different rice varieties decreased in the order XS 134 > JH 218 > YY 538 > CY 84. The ecological risk limits of As and Hg for conventional rice were higher, and the risk limits of As and Hg for hybrid rice were lower, than the limit of the soil environmental quality assessment index in the national “Soil quality control criteria for soil pollution in agricultural land (for trial implementation) (Trial)” (GB15618-2018). The health risk limit of soil As in the typical paddy soil of China decreased in the order XS 134 > JH 218 > CY 84 > YY 538. The health risk limit of Hg decreased in the order XS 134 > JH 218 > YY 538 > CY 84. The health risk limit of As was lower, whereas the risk limit of Hg was higher, than the limit of the soil environmental quality evaluation index in the national “Soil quality control criteria for soil pollution in agricultural land (for trial implementation) (Trial)”(GB15618-2018).
Highlights
Since the beginning of the 21st century, with rapid economic and industrial development, the potentially toxic element (PTE) pollution of farmlands in China has become increasingly serious owing to industrial and mining enterprises, transportation, solid waste discharge, and the widespread use of fertilizers and pesticides
64.8% of farmland in sewage irrigation areas in China is polluted by PTEs, and the annual grain yield loss is more than 12 million tons, with total losses of at least 20 billion yuan [3]
When high concentrations of As and Hg (60 mg/kg and 2 mg/kg, respectively) were added to the soil, the plant heights of conventional rice Xiushui 134 (XS 134) and Jiahe 218 (JH 218) decreased by 27.1% and 19.8%, respectively, compared with those in the control (CK)
Summary
Since the beginning of the 21st century, with rapid economic and industrial development, the potentially toxic element (PTE) pollution of farmlands in China has become increasingly serious owing to industrial and mining enterprises, transportation, solid waste discharge, and the widespread use of fertilizers and pesticides. The 2017 National Soil Pollution Survey Bulletin, published in April 2017 by the Ministry of Environmental Protection and the Ministry of Land and Resources of China, showed that the number of soil samples exceeding the recommended PTE limits accounted for 21.7% of the total samples [1,2]. 64.8% of farmland in sewage irrigation areas in China is polluted by PTEs, and the annual grain yield loss is more than 12 million tons, with total losses of at least 20 billion yuan [3]. The problem of PTE pollution in soil-rice systems has attracted worldwide attention and is a current research hotspot [7]
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