南渡江河口水体氢氧同位素特征及对台风“海鸥”的响应

Water H-O isotopic characteristics of Nandu River estuary and their response to typhoon“Kalmaegi”

夏季亚热带地区频繁的台风天气对河口水体环境具有重要影响。以2014年台风"海鸥"过境前后在南渡江河口地区的水文要素现场观测资料,分析了台风降雨前后南渡江河口地区的水体同位素组成特征和变化规律。研究表明:大气降水是控制台风"海鸥"期间河水氢氧同位素的主要因素,其主要来源为热带太平洋地区输送的水汽。台风"海鸥"过后,降雨补给变少,温度升高,蒸发作用加强,氢氧同位素值有所升高。台风带来的大量河流淡水资源入海改变了河口水体环境,使得潮流界向河口后退,水体混合强烈,口门外形成咸淡水锋面。此次观测研究将有助于认识台风对亚热带地区中小河流河口水循环过程的影响。

Frequent summer typhoon in subtropical regions brings significant impacts on water environment in estuaries.Based on the in-situ hydrographic observation in 2014,this paper portrays the characteristics and changes of water H-O isotope compositions in the Nandu River Estuary during the typhoon Kalmaegi.Results show that atmospheric precipitation,which is mainly derived from the water vapor transported from the tropical Pacific,is the main factor controlling the compositions of the H-O isotope in the typhoon period.After the typhoon,evaporation is strengthened with the decrease in rainfall and increase in temperature,and as the results,the contents of H-O isotopes are increased in water.The large amount of fresh water brought in by the Typhoon Kalmaegi will certainly bring in changes in the estuarine environment.The tidal current limit will move towards the river mouth,water mix strongly,and brackish water front form outside the river mouth.This study provides observational evidence for understanding the impact of typhoon on the water cycle of small-medium rivers in subtropical regions.