Abstract
Study of changes in agrochemical residues on the Qinghai–Tibet Plateau is necessary for the agricultural green development of the fragile plateau and its downstream regions. The total agrochemical residue (TR) caused by main agrochemical inputs was estimated in the study area of Qinghai province and the Tibet Autonomous Region over 1995–2017 by using the emergy synthesis method. The total agrochemical residue was decomposed into the intensity factor, the structure factor, the productivity factor, and the labour factor by using the Logarithmic Mean Divisia Index (LMDI) decomposition method. The change in TR could be divided into four time periods, i.e., a rapidly increasing period during 1995–1998, a stable period during 1999–2004, a slowly increasing period during 2005–2011, and a fluctuant period during 2012–2017. The study area had a mean TR intensity in area (TRA) of 3.31 × 1014 sej/ha, which was only 38.21% of that in China; however, the annual growth rate of TRA in the study area was 2.93%, higher than the rate of 1.91% in China over 1995–2017. The study area had a mean TR intensity in production (TRP) of 4.06 × 1010 sej/CNY (Chinese Yuan), which was 71.05% of that in China; however, the annual decreasing rate of TRP in the study area was 0.95%, lower than the rate of 1.98% in China over 1995–2017. All the LMDI decomposed factors contributed to the TR increase during 1995–1998; the intensity factor, the structure factor, and the labour factor contributed to the TR decrease during 1999–2004; the structure factor and the productivity factor contributed to the TR increase during 2005–2011; and only the productivity factor contributed to the TR increase during 2012–2017. Compared with the whole country, the study area has more potential to reduce TR by improving agrochemical use efficiency, strengthening the recovery of plastic film residue, increasing organic agricultural materials, raising the efficiency of agricultural production, and accelerating the transfer of rural labours to secondary and tertiary industries.
Highlights
Nonpoint source pollution is one of the rising environmental problems that may directly and indirectly threaten public health and the ecological conditions [1,2,3,4], which commonly includes an urban nonpoint source and an agricultural nonpoint source
The TR intensity in area (TRA) growth rate was slightly lower than the total agrochemical residue (TR) growth rate, as the cropland growth rate was lower than the TR growth rate over 1995–2017; the TRA growth rate was higher than the TR growth rate during 1999–2004, as the cropland rapidly decreased in the initial implementation period of Grain for Green Policy (GFGP)
The total agrochemical residue (TR) caused by main agrochemical inputs was estimated in the study area of Qinghai Province and the Tibet Autonomous Region over 1995–2017 by using the emergy synthesis method
Summary
Nonpoint source pollution is one of the rising environmental problems that may directly and indirectly threaten public health and the ecological conditions [1,2,3,4], which commonly includes an urban nonpoint source and an agricultural nonpoint source. Agricultural nonpoint source pollution has become a major reason for eutrophication, water and food quality degradation, and soil pollution in many regions of the world [2,5,6,7]. Resulted from the development of intensive agriculture based on excessive applications of agrochemicals, agricultural nonpoint source is difficult to quantify [8,9] because it is concealed, dispersed, and difficult to detect [10]. Rational assessment of the economic benefits and environmental problems of agricultural chemical inputs is crucial to regional sustainable development. Quantitative assessments of agricultural nonpoint source pollution affecting environmental quality, food safety, and human health were mainly carried out in the intensive agricultural development countries or regions. There is no method to evaluate the comprehensive status of agrochemical residues from different agrochemical inputs
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