Partial pressure of carbon dioxide in the Xinfengjiang Reservoir of Guangdong Province and its influencing factors

于2012年7月和2013年1月定点采集新丰江水库表层水样，测定水样的理化及生物学参数，计算水体中二氧化碳分压（p（CO₂））大小并分析其时空变化，探讨新丰江水库p（CO₂）的影响因素及其CO₂源/汇机制.结果表明：丰水期p（CO₂）变化范围为16~3545 μatm，均值为999 μatm，从水库上游到坝前p（CO₂）逐渐升高；枯水期p（CO₂）变化范围为399~1355 μatm，均值为756 μatm，从水库上游到坝前p（CO₂）呈下降趋势.丰水期p（CO₂）受温度影响较小，与营养盐（NO₃⁻、DSi）浓度呈正相关，与叶绿素a（Chl.a）、溶解有机碳（DOC）浓度呈负相关，与溶解无机碳（DIC）浓度没有明显相关性；枯水期p（CO₂）受温度影响也较小，受碳酸盐体系的影响，与NO₃⁻、DSi、Chl.a、DIC浓度呈正相关，与DOC浓度没有明显相关性.新丰江水库相对于大气来说是一个通量值偏低的CO₂源.;In order to understand the influencing factors and the diffusion characteristics of CO₂ partial pressure (p(CO₂)) and CO₂ source/sink mechanism in the Xinfengjiang Reservoir, the physicochemical and biological quality parameters of surface water samples collected in July 2012 and January 2013 were measured, and the value of p(CO₂) in water was calculated as well. The results showed that:In wet season, the p(CO₂) ranged from 16 to 3545 μatm with an average of 999 μatm, which increased from the reservoir head region to the dam; During dry season, p(CO₂) ranged from 399 to 1355 μatm with an average of 756 μatm, which decreased from the reservoir head region to the dam. p(CO₂) was less likely affected by the temperature in both wet and dry season. In wet season, there was no obvious relationship between p(CO₂) and dissolved inorganic carbon (DIC). p(CO₂) was positively correlated with nutrient salts (NO₃⁻, DSi) concentrations, but negatively correlated with chlorophyll-a (Chl.a) and dissolved organic carbon (DOC) concentrations; In dry season, owing to the carbonate systems, there was no significant correlation between p(CO₂) and DOC concentration, whereas it was positively associated with NO₃⁻, DSi, Chl.a and DIC concentrations. The Xinfengjiang Reservoir was the CO₂ source to the atmosphere with a low flux value.