| 春、夏季长江口及其邻近海域溶解N2O的分布和海-气交换通量 |
| 摘要点击 2964 全文点击 1235 投稿时间：2014-04-27 修订日期：2014-07-13 |
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| 中文关键词 长江口 氧化亚氮 分布 季节变化 气体交换 |
| 英文关键词 the Yangtze River estuary nitrous oxide distributions seasonal variations gas exchange |
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| 中文摘要 |
| 分别于2012年3月和7月对长江口及其邻近海域进行了调查，对水体中溶解氧化亚氮（N2O）的分布及海-气交换通量进行了研究. 结果表明，春季长江口及其邻近海域表层海水中溶解N2O浓度范围为9.34~49.08 nmol·L-1，平均值为（13.27±6.40） nmol·L-1. 夏季表层溶解N2O浓度范围为7.27~27.81 nmol·L-1、平均值为（10.62±5.03） nmol·L-1. 两航次表、底层海水中溶解N2O浓度相差不大. 长江口溶解N2O浓度由近岸向外海逐渐降低，受陆源输入影响显著. 溶解N2O浓度高值出现在长江口最大浑浊带附近，这主要是由于水体中较高的硝化速率造成的. 温度是影响N2O分布的另一个重要因素，对溶解N2O浓度有双重作用. 春季和夏季表层海水中N2O饱和度范围分别为86.9%~351.3%和111.7%~396.0%，平均值分别为（111.5±41.4）%和（155.9±68.4）%，大部分站位处于过饱和状态. 利用LM86、W92和RC01公式分别计算了长江口及其邻近海域N2O的海-气交换通量，春季分别为（3.2±10.9）、（5.5±19.3）和（12.2±52.3） μmol·（m2·d）-1，夏季分别为（7.3±12.4）、（12.7±20.4）和（20.4±35.9） μmol·（m2·d）-1，初步估算出长江口及其邻近海域的年平均释放量分别为0.6×10-2 Tg·a-1（LM86）、1.1×10-2 Tg·a-1（W92）、2.0×10-2 Tg·a-1（RC01）. 长江口及其邻近海域虽然只占全球海洋总面积的0.02%，但其释放的N2O占全球海洋释放量的0.06%，表明长江口及其邻近海域是产生和释放N2O的活跃区域. |
| 英文摘要 |
| Distributions and air-sea fluxes of nitrous oxide (N2O) in the seawaters of the Yangtze River estuary and its adjacent marine area were investigated during two cruises in March and July 2012. Dissolved N2O concentrations in surface waters ranged from 9.34 to 49.08 nmol·L-1 with an average of (13.27±6.40) nmol·L-1 in spring and ranged from 7.27 to 27.81 nmol·L-1 with an average of (10.62±5.03) nmol·L-1 in summer. There was no obvious difference between surface and bottom N2O concentrations. N2O concentrations in both surface and bottom waters decreased along the freshwater plume from the river mouth to the open sea. High values of dissolved N2O were found in turbidity maximum zone, which suggests that maximal turbidity enhances nitrification. Temperature had dual effects on dissolved N2O concentrations. N2O saturations in surface waters ranged from 86.9% to 351.3% with an average of (111.5±41.4)% in spring and ranged from 111.7% to 396.0% with an average of (155.9±68.4)% in summer. N2O were over-saturated at most stations. The sea-to-air fluxes of N2O were estimated to be (3.2±10.9), (5.5±19.3) and (12.2±52.3) μmol·(m2·d)-1 in spring and (7.3±12.4), (12.7±20.4) and (20.4±35.9) μmol·(m2·d)-1 in summer using the LM86, W92 and RC01 relationships, respectively. The annual emissions of N2O from the Yangtze River estuary and its adjacent marine area were estimated to be 0.6×10-2 Tg·a-1(LM86), 1.1×10-2 Tg·a-1(W92) and 2.0×10-2 Tg·a-1(RC01). Although the area of the Yangtze River estuary and its adjacent marine area only accounts for 0.02% of the total area of the world's oceans, their emission of N2O accounts for 0.06% of global oceanic N2O emission, indicating that the Yangtze River estuary and its adjacent marine area is an active area to produce and emit N2O. |
