Pesticide trace capacity model for planting land and its application in comprehensive risk rating

In order to assess the pesticide trace capacity (PTC) and comprehensive health and environment risk from pesticide usage in planting land, a PTC model for planting land, F_ptc = (T_am+18) × P_am × H_as × F_st × C_som × 10⁻⁹, was constructed by five key factors, including annual mean temperature, annual precipitation, annual sunshine hours, soil texture, and soil organic matter content. Those factors were chosen from many external factors according several principles, including the representativeness of factors, the universality of mechanism, the critical of link, the significance of effect, the standardization of observation methods, the systematicness of existed observation and the convenience of data acquisition. The PTC model for planting land with pre-established pesticide trace model was used to evaluate the pesticide trace capacity and the comprehensive risk of pesticide usage on family farm and regional scale. The results showed that F_ptc (pesticide trace capacity factor) was 2.73-3.50 and I_cpr (comprehensive pesticide risk index) was 0.56-1.77, which posed low-medium risk for the cultivated lands of four family farms in the middle and lower reaches of the Yangtze River in 2016－2017. In addition, F_ptc was 0.6-1.7 and I_cpr was 3.3-7.3, which posed medium-high risk for the planting lands in all branches in Heilongjiang reclamation area in 2017. Furthermore, F_ptc was 1.9-3.8, and I_cpr was 4.7-12.6 for the planting land in Zhejiang Province in 2017, indicating that all cities were medium-high risk while Jiaxing was high risk. This study showed that the PTC model can be widely used to estimate PTC of planting lands with different spatial and temporal scales. Combined with the pesticide trace model, it can also be used to estimate comprehensive risk from pesticide usage.