大亚湾不同海洋功能区表层海水无机碳体系的比较研究

摘要

于2014年分4个季度对大亚湾4个典型功能区(人工鱼礁区、水产养殖区、核电站温排区和石化排污区)以及湾口区表层海水的温度、盐度、pH、总碱度(TA)等进行了调查, 比较分析了不同区域表层水体溶解无机碳(DIC)体系的组成和分布特征, 估算了海?气界面CO2的交换通量(FCO2), 并对FCO2的主要影响因素进行了分析.结果显示, 调查海域表层水体的 DIC、HCO3–、CO32–浓度和 CO2 分压 pCO2年变化范围分别为 1248.8~1841.9μmol·kg–1(1624.8?143.1μmol·kg–1)、1069.2~1615.7μmol·kg–1(1382.5?126.1μmol·kg–1)、152.7~283.5μmol·kg–1(236.2?35.4μmol·kg–1)、11.4~44.9Pa (21.2?7.4Pa);各区域间的 DIC、HCO3–、CO32–和 pCO2 无显著差异(P>0.05).表层海水 FCO2 的年变化范围为–37.3~4.5mmol·(m2·d)–1 [–22.4?9.8mmol·(m2·d)–1], 各区域 FCO2(按正负数值大小)的季节变化呈现夏季>秋季>春季>冬季的特征, 且夏季显著高于其他季节(P<0.05); 在全年尺度上, 各区域的 FCO2均为负值, 表现为大气 CO2的汇, 碳汇强度呈现湾口区>鱼礁区>排污区>温排区>养殖区的特征, 而各区域间无显著差异(P>0.05).偏回归分析显示, 大亚湾湾口区和养殖区的FCO2时空分布主要受盐度影响, 在鱼礁区和温排区主要受温度的影响, 而在排污区则主要受海水pH的影响.%In four different seasons during March-December 2014, four oceanic function areas in Daya Bay, including in an artificial reef area, an aquaculture area, a thermal discharge area, and a petrochemical sewage discharge area, as well as the bay mouth area, were selected as the survey areas. Data of surface temperature, salinity, pH, and total alkalinity (TA) were analyzed to show the distribution of dissolved inorganic carbon (DIC) system, and to estimate sea-air CO2 flux (FCO2) and its influential factors. The results showed that the concentrations of surface DIC, HCO3–, CO32–, andpCO2ranged from 1248.8 to 1841.9μmol·kg–1(1624.8±143.1μmol·kg–1), 1069.2 to 1615.7μmol·kg–1(1382.5±126.1μmol·kg–1), 152.7 to 283.5μmol·kg–1 (236.2±35.4μmol·kg–1), 11.4 to 44.9 Pa (21.2?7.4 Pa), respectively. There were no significant differences among the surveyed areas in terms of concentrations of DIC, HCO3–, CO32–, andpCO2 (P> 0.05).FCO2 ranged from–37.3 to 4.5 mmol·(m2·d) –1 [–22.4? 9.8 mmol·(m2·d)–1]. The seasonal variation ofFCO2showed an order of summer > autumn > spring > winter, according to positive or negative data; and this parameter in summer was significantly higher than those in the other seasons (P< 0.05). At the annual scale,FCO2in each investigated area had a negative value, indicating a sink of atmosphere CO2. The distribution of regional carbon sink was in the order of bay mouth area > artificial reef area > petrochemical sewage discharge area > thermal discharge area > aquaculture area, no significant difference being found among these areas (P> 0.05). Based on partial regression coefficients, salinity was the main influencing factor forFCO2 in the bay mouth area and agriculture area; water temperature was, in the artificial reef area and thermal discharge area; and pH was, in the petrochemical sewage discharge area.