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2013~2015年,在长江口-杭州湾及其邻近海区采集表层底质样品112个,进行总有机碳(TOC)、总氮(TN)、有机碳同位素(δ~(13)C)、有机氮同位素(δ~(15)N)和C/N的测定,得到碳氮元素的空间分布特征;并与2006年的数据对比,观察TOC、TN和有机碳δ~(13)C的空间变化。将研究区划分为北部的长江水下三角洲和南部的浙闽内陆架沉积区两部分,结果表明:TOC和TN在北部由陆向海先升高后降低,在浙闽内陆架沉积区表现为向海增加,并在122°~123°E范围内的29°N附近出现高值;有机碳δ~(13)C由陆向海变轻,且在长江水下三角洲比浙闽内陆架沉积区要低,变化较南部慢;2006年和2015年的数据对比表明,近年来,TOC和TN降低,有机碳δ~(13)C变轻,碳氮元素的空间分布更加均一,这些变化在123.5°E以西的长江口地区表现得尤为明显。
A total of 112 surface sediment samples were collected from the Yangtze River estuary-Hangzhou Bay and its adjacent sea areas from 2013 to 2015. Total organic carbon (TOC), total nitrogen (TN), organic carbon isotope (δ ~ (13) C) (Δ ~ (15) N) and C / N, the spatial distribution characteristics of carbon and nitrogen were obtained. Compared with 2006 data, the spatial variations of TOC, TN and δ 13 C were observed. . The study area is divided into two parts, namely, the Yangtze River Delta in the north and the Zhejiang-Fujian Inner Continental shelf in the south. The results show that the TOC and TN firstly increase and then decrease from the seaward to the sea in the north, Increasing to the sea and reaching high values around 29 ° N in the range of 122 ° -123 ° E. The δ 13 C of organic carbon turned lighter from the seaward to the sea and was lower in the Yangtze River Delta than in the Zhejiang-Fujian Inner-continental shelf sedimentary areas And the changes are slower than those in the south. Comparison of the data from 2006 to 2015 shows that in recent years, the TOC and TN decreased while the δ13C in the organic carbon became lighter and the spatial distribution of carbon and nitrogen became more uniform. The changes were at 123.5 The Yangtze Estuary west of ° E performed especially well.