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| Spatial distribution characteristics and influencing factors of plastic film residue in Zhangye Oasis |
| Received:June 17, 2020 |
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| KeyWord:residual plastic film amount;spatial distribution characteristics;influencing factors;Zhangye Oasis |
| Author Name | Affiliation | E-mail | | DU Ze-yu | Linze Inland River Basin Research Station, Northwest Institute of Eco-Environment and Resource, Chinese Academy of Sciences, Lanzhou 730000, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | SUN Duo-xin | Gansu General Station of Agrotechnology Extension, Lanzhou 730000, China | | | YANG Rong | Linze Inland River Basin Research Station, Northwest Institute of Eco-Environment and Resource, Chinese Academy of Sciences, Lanzhou 730000, China | yangrong@lzb.ac.cn | | SU Yong-zhong | Linze Inland River Basin Research Station, Northwest Institute of Eco-Environment and Resource, Chinese Academy of Sciences, Lanzhou 730000, China | |
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| Abstract: |
| Knowledge of plastic film residue amounts in agricultural soil is still lacking. Spatial distribution characteristics and influencing factors of residual film amounts were investigated to accurately evaluate the situation of regional plastic film pollution and provide a scientific basis to propose regional plastic film reduction measures. To this end, 105 farmland plots were selected in the Zhangye Oasis, Hexi Corridor. The amounts of residual film in farmland soil were monitored and the impact indicators including vegetation category, soil type, and plastic-film use were also investigated. The obtained data above was analyzed through statistical and geostatistical analyses. Results showed that the amount of residual film in the farmland of the Zhangye Oasis ranged from 0.79 kg·hm-2 to 114.72 kg·hm-2, with an average value of 25.63 kg·hm-2, showing a higher distribution trend in the northwest than in the southeast. The spatial heterogeneity of the amount of residual plastic film in the study area was high with a distribution characteristic of a Gaussian model. The average values of residual film by county were of the order Linze County(49.07 kg·hm-2) > Gaotai County(33.72 kg·hm-2) > Ganzhou District(23.33 kg·hm-2) > Shandan County(11.32 kg·hm-2) > Minle County(10.44 kg·hm-2). The amount of residual film was affected by film-covering modes, mulched years, crop types, and other factors. There were significant differences(P<0.05)in the amount of residual film under the three kinds of film-covering modes, namely a whole film mulching mode, artificial film mulching mode, and mechanized film mulching mode, with mean values of 37.35, 27.46 kg·hm-2, and 15.26 kg·hm-2, respectively. The amount of residual film increased significantly after continuous film covering for more than 10 years(P<0.05). Maize fields(35.39 kg·hm-2)had the largest amount of residual film. Generally, the residual film pollution in the study area was at a medium level; Linze and Gaotai counties are heavily polluted, while Shandan and Minle counties are slightly polluted. Geographical analysis indicated that the number of mulched years was the dominating factor, which alone could explain 33.24% of the residual film spatial variability of the region, followed by the vegetation categories(31.73%). To reduce the pollution of plastic film, it is necessary to adjust the structure of agricultural planting, improve the policy of using plastic film according to local conditions, and popularize the mechanical recovery technology for residual film. |
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