流域空间结构指标与药物污染水平的关系研究

Quantifying relationships between watershed characteristics and pharmaceutical pollution in aquatic environment

流域地表特征与土地利用结构同流域水环境质量关系密切。流域空间结构指标能够表征流域空间结构特征和生态功能,主要包括流域特征指标和景观格局指数等。为探讨海湾流域生态系统结构与药物污染特征之间的关系,以浙江象山湾为研究区域,采用固相萃取、超高效液相色谱质谱联用等分析手段,研究流域水环境中药物的污染水平、分析其分布特征与流域特征指标和景观结构的关系。结果表明,象山湾22个流域共有22种药物检出,总检出浓度范围为n.d.—220.2 ng/L,主要包括林可霉素、大环内酯类、喹诺酮类、抗癫痫药物、β受体阻滞剂、抗抑郁药物,其中林可霉素、大环内酯类和抗癫痫药物的检出率高达100%,检出浓度分别为2.36—29.1 ng/L、n.d.—35.8 ng/L和n.d.—37.5 ng/L。流域地貌结构指标与水环境药物污染关系密切,其中平均坡度(MS)与药物总浓度、面积高程曲线斜率(SAEC)与β受体阻滞剂都呈显著负相关关系(P<0.01);流域景观结构也与水环境药物污染紧密相关,其中景观蔓延度指数(CONTAG)、城镇用地面积加权平均形状因子(IsSHAPE-AM)、林地最大斑块景观面积比(fLPI)与药物总浓度呈显著负相关关系(P<0.05),Shannon均匀度指数(SHEI)与药物总浓度呈显著正相关关系(P<0.05)。通过明确药物与流域空间结构指标的关系,可为应用景观生态措施进行流域管理提供科学依据。

Watershed characteristics play a significant role in improving water pollution at watershed scale. Understanding the relationships between watershed characteristics and water quality is of great significance for watershed management. Pharmaceuticals are of increasing concern for their ubiquitous detection and potential threat to aquatic environment. However, little is known about the relationships between watershed characteristics and pharmaceutical pollution in the aquatic environment. To study the relationships between watershed characteristics and pharmaceutical pollution in the aquatic environment, we investigated the occurrence of 29 pharmaceuticals and their quantifying relationships with watershed characteristics in Xiangshan Bay, Eastern China. Pharmaceuticals were extracted by using solid-phase extraction(SPE) and analyzed by ultra-high performance liquid chromatography tandem mass spectrometry(UHPLC-MS/MS). The redundancy analysis and regression modeling were used to explore the correlation between watershed characteristics and pharmaceutical concentrations. The results showed that 22 target pharmaceuticals were detected in the surface water samples, with the detected concentrations ranged from not detected(n.d.) to 220.20 ng/L. Lincomycin(100% of samples), macrolides(100% of samples), antiepileptic drugs(100% of samples), beta-blockers(95% of samples), antidepressant drugs(77% of samples) were the predominant compounds with concentration of 2.36—29.1 ng/L, n.d. —35.8 ng/L, n.d. —37.5 ng/L, n.d.—15.0 ng/L, and n.d.—3.49 ng/L, respectively. Redundancy analysis revealed that the concentrations of pharmaceuticals in the watersheds were positively correlated to topographical features of watersheds. Correlation analysis also showed that the total pharmaceutical concentrations had a significantly negative correlation with mean slope(MS)(P<0.01), and beta-blockers had a significantly negative correlation with slope of area elevation curve(SAEC)(P<0.01). The landscape pattern is also a crucial factor for determining pharmaceutical pollution in the aquatic environment. We have also found that the total pharmaceutical concentrations were negatively correlated with contagion(CONTAG)(P<0.05) and positively correlated with Shannon′s evenness index(SHEI)(P<0.05). Furthermore, the area-weighted mean shape index of urban land(IsSHAPE-AM) and the largest patch index of forest(fLPI) had significantly negative correlation with total pharmaceutical concentrations(P<0.05). Overall, the watershed characteristics had significant influences on the pharmaceutical pollution. According to pharmaceutical pollution in the watersheds, the study of the watershed characteristics′ correlation to water pollution will help better understanding the influences of the surrounding characteristics on the water quality of surface water at watershed scale. These findings can provide scientific support for improving the water pollution control in surface water at watershed scale from the perspective of sustainable landscape management.