乳山宫家岛以东牡蛎养殖水域秋季海—气界面CO_2交换通量研究

Sea-air CO_2 flux in Crassostrea gigas aquaculture area of East Gongjia Island,Rushan,Shandong,in autumn

为探讨规模化贝类养殖对海—气界面CO2交换通量的影响,选择山东乳山市宫家岛以东太平洋牡蛎养殖水域作为研究区域,根据2011年10月大面调查获得的pH、总碱度(TA)、叶绿素a等基础数据,分析了该区域表层海水溶解无机碳(DIC)体系各分量的浓度、组成比例及平面分布特征,估算了海—气界面CO2的交换通量,定量了浮游植物的固碳贡献。结果表明,秋季乳山宫家岛以东牡蛎养殖水域表层海水DIC浓度范围1 953.20～2 130.74μmol/L,平均值(2 048.73±57.19)μmol/L;HCO3-是DIC的主要成分,占88.25%;表层海水pCO2范围为220.08～262.29μatm,平均值(246.46±23.00)μatm;该区域秋季海—气界面CO2交换通量在-53.78～-21.93 mmol/(m2.d),平均值为-42.09 mmol/(m2.d),表现为强的CO2汇;该区域浮游植物的固碳强度变化范围为460.27～725.64 mg/(m2.d),平均为(593.27±91.98)mg/(m2.d),海—气界面较强烈的CO2交换通量主要由浮游植物的光合作用贡献;养殖区与对照区海—气界面CO2交换通量差异不显著,表明太平洋牡蛎呼吸、钙化生理活动释放的CO2对海—气界面CO2的交换影响不大。

Recently, several studies indicated that respiration and calcification activities by shellfish represent a net source of CO2. In order to assess the effect of shellfish aquaculture on the sea-air CO2 flux, a Pacific oyster Crassostrea gigas aquaculture area which is located in East Gongjia Island,Rushan City, was selected as the investigation area. Based on the investigation data of pH, total alkalinity （TA）, Chl. a, etc. in October 2011 ,the concentration and horizontal distribution of dissolved inorganic carbon （DIC）system parameters were calculated. Moreover, sea-air CO2 fluxes and the contribution of phytoplankton to the sea-air CO2 flux were estimated. Results showed that the DIC concentration of sea surface water ranged from 1 953.20 to 2 130.74 μmol/L,with an average of （2 048.73 ± 57. 19） μmol/L; the main component of DIC was HCO3- ,which accounted for 88.25% ; the pCO2 ranged from 220.08 to 262.29 μatm,with an average of （246.46 ± 23.00） μatm ; the sea-air flux of CO2 ranged from - 53.78 to - 21.93 mmol/（ m2 · d）, with an average of - 42.09 mmol/（ m2 · d）, which indicated that this area acted as a strong sink of atmosphere CO2 in autumn; Carbon fixed strength of phytoplankton ranged from 460.27 to 725.64 mg/（ m2 · d）, with an average of （593.27± 91.98） mg/（m2 · d）; the higher sea-air flux of CO2 was mostly contributed by the photosynthesis of phytoplankton; there was no significant difference between culture area and non-cultured area in sea-air flux of CO2, which indicated that the respiration and calcification activities of oyster had little effect on the CO2 flux.