Distribution and ecological assessment of heavy metals in irrigation channel sediments in a typical rural area of south China
- Authors: Gu, Chiming , Liu, Yi , Li, Zhiguo , Mohamed, Ibrahim , Zhang, Ronghua , Brooks, Margot , Chen, Fang
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66924 , vital:29000 , ISSN 0925-8574 , https://doi.org/10.1016/j.ecoleng.2016.01.054
- Description: Publisher version , Elevated levels of heavy metals in sediments of irrigation channels can pose risks for crops and livestock, as well as for human health. In this study sediment samples were collected from the irrigation channel in a typical rural area of south China, and digested, in order to analyze their contents for the presence of heavy metals Cu, Zn, Pb, Cr, Cd, and Ni, as well as the non-metal As, to assess total concentrations and pollution levels. The pollution load index and potential ecological risk index of these elements were utilized to assess contamination levels and ecotoxicity. Our results showed that the concentrations of the 7 elements were in the order of Zn > Ni > Cr > Cu > As > Pb > Cd. With the exception of Cr and Pb, concentrations of elements were higher than their background in soil, especially for Cd (1.79 mg kg−1), As (99.61 mg kg−1) and Ni (142.62 mg kg−1), which were 18.49, 8.89 and 5.30 times their background concentrations, respectively. The whole sampled zone was characterized by medium pollution and had a very high potential ecological risk. The area of arable land presented a medium pollution risk, while areas near to the path or road showed high risk of pollution. The predominant contributors to elevated ecological risk for the whole zone were Cd and As.
- Full Text: false
- Date Issued: 2016
Dynamic changes of soil surface organic carbon under different mulching practices in citrus orchards on sloping land
- Authors: Gu, Chiming , Liu, Yi , Mohamed, Ibrahim , Zhang, Runhua , Wang, Xiao , Nie, Xinxin , Jiang, Min , Brooks, Margot , Chen, Fang , Li, Zhiguo
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:28997 , ISSN 0168384 , https://doi.org/10.1371/journal.pone.0168384
- Description: Publisher version , Mulching management has been used in many places all over the world to improve agricultural sustainability. However, the cycling of carbon in the soil under applications of mulch on sloping arable land is not yet fully understood. A four-year field experiment was carried out in Xiaofuling watershed of Danjiangkou reservoir in China. The object was to evaluate the effects of the application of straw mulch (ST) and grass mulch (GT) on dynamic changes in soil organic carbon and its fractions. Results showed that mulch applied on the soil surface increased the contents of SOC and its active fractions in the soil. Compared to the control without cover (CK), ST and GT treatments increased the contents of SOC, LOC, DOC, POC and EOC by 14.73%, 16.5%, 22.5%, 41.5% and 21%, respectively, in the 0–40 cm soil layer, and by 17%, 14%, 19%, and 30%, respectively, in the 0–100 cm soil layer. The contents of organic carbon and its active fractions decreased with increasing soil depth in all of the treatments. SOC was accumulated in the period of December to the following March. The contents of soil DOC and LOC were high in January to March, while the contents of soil POC and EOC were high in June to September. The relative contents of soil organic carbon fractions were POC > EOC > LOC > DOC over the four years. Straw mulching had no significant effect on the changes in soil organic carbon active fractions during the different periods. Based on this long-term field experiment in Danjiangkou reservoir, we found that straw mulching had a significant effect on soil, increasing SOC content and stock in slopping arable land, and that live grass mulching was more effective than rice straw mulching. We discuss possible optimal periods for the implementation of mulching practices on sloping land.
- Full Text:
- Date Issued: 2016