黄土高原磷湿沉降特征及其对坝系流域磷输出影响-以羊圈沟为例

对黄土高原坝系流域磷(P)的湿沉降过程进行动态监测,分析了降雨-径流过程中各形态磷的输出变化,探讨了黄土高原坝系流域磷湿输出分异特征及其对水体的影响.结果表明:2015年湿季(7、8月)共11场降雨,产生的磷湿沉降负荷为30.8 kg,磷湿沉降通量为0.16kg·hm~(-2),干季(9月)共3场降雨,产生的磷湿沉降负荷为20.51 kg,磷湿沉降通量为0.11 kg·hm~(-2),干湿季磷湿沉降负荷呈现出明显差异性;选取3场降雨过程(降雨量从小到大)进行动态分析发现,流域磷湿沉降负荷分别为3.33、7.51和6.35 kg,相应的本地区磷湿沉降通量依次为0.02、0.04、0.03 kg·hm~(-2),3场降雨总磷(TP)的输出负荷为1.5×10-3kg,溶解性总磷(DTP)的输出负荷为1.24×10~(-3)kg,PO_4~(3-)-P的输出负荷为7×10-4kg,表明该地区磷湿沉降以可溶性磷为主.根据单因子评价方法中的标准指数法,发现流域水质不能满足Ⅴ类水质标准,应对流域水体加强管理.

Characteristics of phosphorus wet deposition in the loess plateau and its effect on the phosphorus export in the dam watershed: A case study of Yangjuangou watershed

In this study, through dynamically monitor on the P wet deposition process, we analysis the different forms of P export changes during runoff process under rainfall events, and then study the variability of P wet deposition export and its impact on water quality in dam watershed, Loess Plateau. The results show that there were 11 times of rainfall events in the wet season, wherein P wet deposition load reached 30.8 kg and P wet deposition flux was 0.16 kg·hm^-2, but there were only 3 times of rainfall events in the dry season, in which P wet deposition load reached 20.51 kg and P wet deposition flux was 0.11 kg·hm^-2. In addition, we selected three rainfall events to make dynamic analysis. We found that the P wet deposition load in the watershed were 3.33, 7.51 and 6.35 kg, respectively, and the associated P wet deposition flux would reach 0.02, 0.04 and 0.03 kg·hm^-2, respectively. the three rainfall events led to TP, DTP and PO₄^3--P output load at 1.5×10^-3, 1.24×10^-3 kg and 7×10^-4 kg,respectively, indicating that the soluble phosphorus dominates the phosphorus wet deposition in this area. According to the single factor evaluation of standard index method, we found that the river water quality can not meet the class V water quality standards. Thus, the water protection and management for the watershed should be strengthened.