马岭河河口段水-气界面二氧化碳排放特征

Characteristics of Air-water CO_2 Exchange in Estuary of Malinghe River

为研究峡谷型河流入库过程中河流二氧化碳分压(pCO_2)分布特征及水-气界面碳交换通量,于2016年9月,在万峰湖水库主要支流马岭河进行连续不间断走航采样调查,经现场测定和实验分析水体理化参数,利用亨利定律计算水体二氧化碳分压(pCO_2)。结果表明:马岭河pH值在7.7～8.16之间,呈弱碱性。表层水体pCO_2值为140.32～382.58 Pa,均值236.71 Pa,pCO_2从河口到上游呈下降的趋势。马岭河水体表层pCO_2是空气二氧化碳分压的3～10倍,河流表现为碳源,二氧化碳释放通量在6.53～22.09 mmol/(m^2·d)之间,均值12.70 mmol/(m^2·d)。碳排放量呈现从河口向河流上游地区强源-弱源的空间变化特征。相关性分析结果表明:pCO_2与温度、pH呈现显著负相关(-0.57*,-0.94**);与氧化还原电位(ORP)呈显著正相关(0.54*),说明水生生物光合作用和流域内碳酸盐体系影响水体pCO_2的分布。

In order to determine the law of water-air interface of carbon cycling in valley river,water samples were carried out by continuous underway sampling survey in Malinghe River in September 2016.The partial pressure of CO2(pCO2)was calculated using the water-chemical balance and the Henry's law.Results showed the pH was weakly alkaline with values from 7.7 to 8.16.pCO2 in the River surface ranged from 140.32 to 382.58Pa,with mean values of 236.71Pa and showed a downward trend from the estuary to the river valley generally.The River was the carbon source because pCO2 was 3to 10 times compared with air.The carbon dioxide emission flux in surfer ranged from 6.53 to 22.09mmol/(m^2·d)with mean values of 12.70mmol/(m^2·d).The correlation analysis showed pCO2 was negatively correlated with temperature and pH (-0.57*, -0.94**),pCO2 was positively correlated with redox potential (ORP)(0.54*).