研究报告
陈学兵,贾珺杰,田琳琳,高扬,陈有超,张方方,蔡延江.南苕溪流域水体溶解性有机碳、氮时空变化及驱动机制[J].环境科学学报,2023,43(2):254-265
南苕溪流域水体溶解性有机碳、氮时空变化及驱动机制
- Spatiotemporal changes and the driving mechanisms of dissolved organic carbon and nitrogen in water in Nantiaoxi River Watershed
- 基金项目：国家自然科学基金（No.41907268）；长江水利委员会长江科学院开放基金（No.CKWV2019760/KY）；浙江农林大学校科研发展基金（No.2018FR005，2018FR006，2018FR061）
- 作者
- 单位
- 陈学兵
- 浙江农林大学省部共建亚热带森林培育国家重点实验室，杭州 311300;浙江农林大学环境与资源学院，杭州 311300
- 贾珺杰
- 中国科学院地理科学与资源研究所，生态系统网络观测与模拟重点实验室，北京 100101
- 田琳琳
- 浙江农林大学省部共建亚热带森林培育国家重点实验室，杭州 311300;浙江农林大学林业与生物技术学院，杭州 311300
- 高扬
- 中国科学院地理科学与资源研究所，生态系统网络观测与模拟重点实验室，北京 100101
- 陈有超
- 浙江农林大学省部共建亚热带森林培育国家重点实验室，杭州 311300;浙江农林大学环境与资源学院，杭州 311300
- 张方方
- 浙江农林大学环境与资源学院，杭州 311300
- 蔡延江
- 浙江农林大学省部共建亚热带森林培育国家重点实验室，杭州 311300;浙江农林大学环境与资源学院，杭州 311300
- 摘要：以太湖流域上游重要支流南苕溪流域河流水体为研究对象，于2019年7月—2021年5月持续监测河流溶解性有机碳（DOC）和有机氮（DON）浓度，探讨DOC和DON浓度的时空变化特征并揭示相关驱动机制.结果表明：研究期间该流域内水体DOC和DON浓度均值分别为（2.57±0.09）和（0.40±0.01） mg·L-1，DOC/DON均值为9.43±0.46.流域内水体DOC和DON浓度均在夏季最高，DOC/DON值在春季和秋季显著 高于夏季和冬季；DOC浓度与叶绿素a（Chl-a）和氮素浓度均呈正相关，DON浓度与颗粒态氮（PN）浓度呈正相关；夏季雨热条件和高氮污染物浓度促使浮游植物具有较高的初级生产力，进而释放更多的DOC和DON，这可能是夏季DOC和DON浓度最高的主要原因.研究期内农业和居民区水体DOC浓度和DOC/DON值均显著高于森林区水体，农业区水体DON浓度显著高于森林和居民区水体；森林区水体DOC以内源途径产生为主且有较高的生物可利用性，而农业和居民区水体中外源DOC所占比例增大，水体DON有更高的生物可利用性；上述空间差异主要受人为活动的影响，农业生产和居民生活排放污染物可造成区域内水体DOC浓度和DOC/DON值升高；农业区肥料施用等农业活动是区域内 水体DON浓度较高的主要原因.
- Abstract：The concentrations of dissolved organic carbon （DOC） and nitrogen （DON） in water bodies were continuously monitored from July 2019 to May 2020 in Nantiaoxi river （an important tributary in the upper reaches of the Taihu Lake Basin） Watershed. We explored the temporal and spatial variations in DOC and DON concentrations of water and revealed the associated driving mechanisms. The results showed that the mean water DOC and DON concentrations in the watershed were （2.57±0.09） and （0.40±0.01） mg·L-1， respectively， and the mean DOC/DON ratio was 9.43±0.46. The highest water DOC and DON concentrations appeared in summer， and the DOC/DON ratio in spring and autumn were significantly higher than that in summer and winter. The DOC concentration increased with increasing chlorophyll a （Chl-a） and nitrogen concentrations， while DON concentration was positively correlated with granular nitrogen （PN） concentration. The highest water DOC and DON concentrations in summer were probably due to the release of more DOC and DON from the higher primary productivity of phytoplankton， which was likely caused by the favorable condition of high rainfall， air temperature and a high concentration of nitrogen pollutant in summer. The water DOC concentration and DOC/DON ratio in agricultural and residential regions were significantly higher than those in forest region during the study period， and water DON concentrations in agricultural region were significantly higher than those in forest and residential regions. Our findings indicated that water DOC from forest region was mainly generated by endogenous pathway and possessed higher bioavailability， while the proportion of exogenous DOC in water from agricultural and residential increased， and water DON in these two regions had higher bioavailability. The spatial variations were mainly mediated by anthropogenic activities， i.e.， the pollutant discharge from agricultural and residential activities could increase water DOC concentration and DOC/DON ratio in these regions， while agricultural activities such as fertilizer and manure application were the main reason for the higher water DON concentration in agricultural region.
- Key words：headwater stream dissolved organic carbon （DOC） dissolved organic nitrogen （DON） DOC/DON ratio land-use type spatial and temporal variation
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