选择浙江典型平原河网—温瑞塘河为研究区，联合多种水化学参数和稳定同位素(δ15N/δ18O-NO3-、δ15N-NH4+、δ18O-H2O)，识别了水体溶解无机氮(DIN)污染的时空分布特征和主要来源，在此基础上，构建了一种耦合硝酸盐和氨氮浓度及其同位素和贝叶斯污染源解析模型(SIAR)的DIN定量源解析方法，计算了温瑞塘河各污染源对DIN的贡献率。结果表明:温瑞塘河DIN污染严重，其浓度变化范围为1。43～12。88mg/L，氨氮、硝酸盐和亚硝酸盐分别占DIN的63％、35％和2％;DIN污染呈现明显的时空异质性，时间上DIN浓度呈现丰水期＜平水期＜枯水期的变化趋势，空间上呈现主河道＜支流，城乡结合部河道＜城市河道的特点;研究区DIN转化以硝化过程为主，反硝化过程不明显;模型计算结果显示粪便污水、土壤氮、化肥和大气沉降对丰水期水体 DIN 的贡献率分别为(71。29±14。24)％、(18。96±13。89)％、(6。78±5。91)％和(2。97±2。28)％，对平水期 DIN 的贡献率分别为(57。51±15。53)％、(25。01±16。45)％、(15。24±8。19)％和(2。25±2。28)％，对枯水期 DIN 的贡献率分别为(57。60±16。27)％、(26。75±17。58)％、(13。03±7。95)％和(2。61±2。55)％;不确定性分析结果表明土壤氮和粪便污水贡献率存在较大的不确定性。本研究建立的DIN溯源方法能够有效计算不同污染源对水体DIN的贡献率，弥补了以往研究只单独解析硝酸盐或者氨氮来源的不足。
Tracing dissolved inorganic nitrogen sources in plain river networks using stable isotopes:a case study of the Wen-Rui Tang River
In this study,a representative plain river network in Zhejiang Province,namely Wen-Rui Tang River,was selected as the research area.The spatio-temporal variations and primary pollution sources of riverine dissolved inorganic nitrogen(DIN)were identified by combining multiple hydrochemical parameter with stable isotopes(δ15N/δ18O-NO3,δ15N-NH4+,δ18O-H2O).On basis of these findings,a quantitative source apportionment method of DIN was developed by integrating nitrate and ammonia concentrations,their isotope compositions,and a SIAR model.Finally,the contributions of each pollution source to riverine DIN in Wen-Rui Tang River were calculated.Results revealed that the Wen-Rui Tang River exhibited severe DIN pollution with DIN concentrations ranging from 1.43mg/L to 12.88mg/L.Ammonia,nitrate and nitrite accounted for 63％,35％,and 2％of DIN,respectively.Significant spatio-temporal variations of DIN content were observed in the Wen-Rui Tang River.Temporally,DIN concentrations followed the order:high flow season＜usual flow season＜low flow season.Spatially,DIN concentrations in mainstream were lower than those in tributaries and DIN concentrations in urban-rural segments were lower than those in urban segments.The predominant transformation process of DIN was nitrification rather than denitrification within the study area.The model results revealed that the contributions of manure and sewage,soil nitrogen,nitrogen fertilizer,and atmospheric deposition to DIN during the wet season were(71.29±14.24)％,(18.96±13.89)％,(6.78±5.91)％,and(2.97±2.28)％,respectively;during the usual flow season,these contributions accounted for(57.51±15.53)％,(25.01±16.45)％,(15.24±8.19)％,and(2.25±2.28)％,respectively;during the low flow season,they constituted(57.60±16.27)％,(26.75±17.58)％,(13.03±7.95)％and(2.61±2.55)％,respectively.Stronger uncertainties associated with soil nitrogen and manure and sewage contributions were found according to the uncertainty analysis.The DIN source apportionment method proposed in this study effectively facilitates the quantification of contributions from diverse pollution sources to DIN,thereby addressing the limitation observed in previous studies that solely identified nitrate or ammonium sources.
plain river networksdissolved inorganic nitrogenstable isotopespollution source apportionmentSIAR model
万方数据
