摘要
研究针对长江口岛屿沙洲湿地陆向发育的不同时期表层沉积物中氮营养盐的变化规律,得出:(1)长江口岛屿沙洲湿地陆向发育过程中,表层沉积物环境也在不断变化,氮营养盐含量逐步增加,处在陆向发育前期的白茆沙,全氮含量较低,仅为30mgkg,而发育较为成熟的崇明东滩全氮含量较高,达470mgkg;同时随着岛屿沙洲湿地陆向发育,表层沉积物全氮分布越来越不均匀;(2)长江口岛屿沙洲湿地随高程梯度,全氮的含量逐步增加,其中芦苇带最高,420mgkg,光滩最低,110mgkg;这也说明岛屿沙洲陆向发育过程中,表层沉积物全氮含量逐步增加;另外,各形态无机氮含量占其所在高程无机氮的比例相对稳定,其中氨氮最高,59%～60%,亚硝酸盐最低,17%～19%,氨氮是无机氮的主要存在形式。
The Yangtze River estuary is one of the largest estuaries in the world and is comprised of four main channels （North Branch, North Passage, North Channel and South Channel） separated by the islands of Chongming, Changxing, Hengsha and jiuduansha. These islands have been formed by rapid sedimentation. As sedimentation has progressed, there have been associated changes in total nitrogen and inorganic nitrogen in the surface sediments. Island wetland is one of the most important part of the estuary wetland and island sediments are the key ＂sink＂ for many nutrients and have a strong purification function, on the one hand; on the other hand, human activity upstream in the catchment leads to complicated migration and transformation of the nutrient elements, so, sometimes, the region is the ＂source＂ of nutrients. Little previous research has been completed on nitrogen concentrations in surface sediments of the estuary islands in relation to recent sediment accumulation. This research investigates the variation in concentrations of nitrogen compounds within sediments in relation to the pattern of recent island sedimentation.
Results show： （1） The most recent sediments, such as on Baimaosha, had a total nitrogen concentration in the surface layer of only 30 mg/kg. In contrast, the oldest sediments, on the east beach of Chongming island, had a concentration of 470 mg/kg. （2） The total nitrogen in the surface sediment of Yangtze River cstuarine island wetlands decreased gradually with decrease in altitude, the highest concentrations were in the reed zone, 420 mg/kg, and the lowest were around the low water mark of the beach region, with 110 mg/kg. （3） The proportion of the various inorganic nitrogen compounds to total inorganic nitrogen was relatively stable at all sites. Ammonia contributed the highest proportion at 60 %, and nitrite was the lowest, at 17 % ～ 19 %. Ammonia was therefore the main form of inorganic nitrogen in the Yangtze River estuafine island wetlands. So, with the development of the island to land, the content of the total nitrogen and inorganic nitrogen in the surface sediments would increase.
出处
《生态学报》
CAS
CSCD
北大核心
2006年第4期1116-1121,共6页
Acta Ecologica Sinica
基金
国家自然科学基金重点资助项目(40131020)
国家973科技攻关资助项目(2002CB412406)~~
关键词
氮
营养盐
长江口
岛屿
沉积物
nitrogen
nutritive salt
Yangtze River estuary
islands
sedimentation
