长江口及邻近海域异戊二烯的浓度变化及海-气通量研究

于2014年2月(枯水季)和7月(丰水季)对长江口及其邻近海域海水中异戊二烯的浓度分布、季节变化及影响因素进行了研究,并计算了其海-气释放通量.分析结果表明:枯水季和丰水季表层海水中异戊二烯平均浓度(范围)分别为(6.28±2.33)((2.96～13.68))和(57.01±80.60)((6.82～432.6)) pmol·L~(-1),季节变化明显,但两个季节浓度高值均出现在长江口东侧及浙江东南部海域.丰水季异戊二烯在不同盐度梯度的浓度分布表明,海水中异戊二烯主要来源于浮游植物的原位生产,而不是直接由陆源输入.相关性分析中,仅发现枯水季温度与异戊二烯浓度存在一定的相关性.此外,枯水季和丰水季异戊二烯海-气通量平均值(范围)分别为(3.82±5.29)(0.07～27.18)和(12.29±16.61)(0.08～61.14) nmol·m~(-2)·d~(-1),表明长江口海域是大气中异戊二烯的源.

Concentration variation and sea-to-air flux of isoprene in the Yangtze River Estuary and the adjacent East China Sea

Spatial distribution, seasonal variation and influencing factors of isoprene were investigated in the Yangtze River Estuary and the adjacent East China Sea during the wet and dry seasons in 2014. The sea-to-air flux of isoprene was also estimated. The results showed that the mean isoprene concentrations in surface water were (6.28±2.33) ((2.96~13.68)) and (57.01±80.60) ((6.82~432.54)) pmol·L^-1 during the dry and wet seasons, with an obvious seasonal variation. The high concentration values of isoprene occurred in the east of the Yangtze River Estuary and the southeast coastal sea area of Zhejiang in the both seasons. The concentration distribution of isoprene along the salinity-gradient transect in wet season indicated that the main source of isoprene in seawater was in situ production of phytoplankton rather than the direct runoff input. A positive correlation was found between temperature and isoprene in the dry season. In addition, the sea-to-air fluxes of isoprene were estimated to be (3.82±5.29) ((0.07~27.18)) and (12.29±16.61) ((0.08~61.14)) nmol·m^-2·d^-1 during the dry and wet seasons, indicating the Yangtze River Estuary and the adjacent East China Sea is a source of atmosphere isoprene.