基于河流参照状态的季风区域季节性农业灰水足迹核算方法与例证

灰水足迹核算对水资源管理具有重要意义.灰水足迹核算的两个重要参数污染物自然本底浓度和污染物入河系数在季风区域均存在明显的季节性差异，而在之前灰水足迹核算的研究中较少考虑季风区域灰水足迹可能存在的季节性差异.本文以河流总磷的参照状态作为其自然本底浓度核算了承德市农业灰水足迹.结果发现：相较于将总磷自然本底浓度值认为零，将总磷参照状态作为其自然本底浓度值的农业灰水足迹核算结果是其核算结果的1.29倍.农业灰水足迹呈现明显的季节性差异，雨季农业灰水足迹是旱季农业灰水足迹的10.65倍.在2003—2015年承德市农业灰水足迹构成中，种植业灰水足迹占较大比重，并且该比重随时间有增大的趋势.然而，承德市区县粮食产量的增长率与化肥的增长率未表现出显著关系，说明粮食产量的增幅与化肥施用的增幅无关.承德市农业灰水足迹相对较大的区县集中于承德北部区域，主要包括围场县、丰宁县和隆化县；农业灰水足迹相对较小的区县为营子区、双滦区、双桥区和宽城县.本文可阐明季风区域农业灰水足迹核算的季节性差异，以期促进灰水足迹核算方法的发展.

Calculation method and illustration of seasonal agricultural grey water footprint in monsoon region based on river reference conditions

Grey water footprint accounting is of great significance for water resources management. There are obvious seasonal differences in the two important parameters of agricultural gray water footprint accounting:the natural background concentration of pollutants and the pass through rate of pollutants in the monsoon region. However,in previous studies of graywater footprint accounting, the graywater footprint of monsoon regions was rarely considered possible seasonal differences. This paper used the reference condition of river total phosphorus as its natural local concentration to calculate the agricultural gray water footprint in Chengde. It was found that, compared with the natural background concentration of total phosphorus, the agricultural gray water footprint accounting result was 1.29 times. The gray water footprint of agriculture showed obvious seasonal differencesand in the rainy season, the footprint was 10.65 times of that in the dry season. From 2003 to 2015, the gray water footprint of the plantation industry accounted for a large proportion, which increased with time. However, the growth rate of grain output and the growth rate of chemical fertilizers in Chengde did not show a significant corelation, indicating that the increase in food production had nothing to do with the increase in fertilizer application. The districts and counties with relatively large agricultural grey water footprints in Chengde were concentrated in the northern part of Chengde, mainly including Weichang County, Fengning County, and Longhua County. The counties with relatively small agricultural grey water footprints were Yingzi District, Shuangliao District, Shuangqiao District, and Kuancheng County. This article could clarify the seasonal differences in agricultural gray water footprint accounting in the monsoon region.