基于脂肪酸探究青虾扰动作用对沉积物中有机质降解的影响

Effects of the Macrobrachium nipponense bioturbation on organic matter degradation based on fatty acid composition

为了探索池塘沉积物中有机质过度积累导致养殖环境污染问题,以青虾(Macrobrachium nipponense)为养殖对象,探究其扰动作用对沉积物中有机质降解的影响。实验设置青虾实验组和空白对照组,分别测定沉积物理化性质、脂肪酸及碳氮含量,并以脂肪酸为生物标记物指征沉积物中有机质降解状态。结果显示:青虾扰动作用显著提高了沉积物的含水率(MC)和氧化还原电位(ORP),并显著降低了pH值;沉积物中定量分析出18种脂肪酸,其中以C16∶0和低碳偶碳链脂肪酸为主,实验组平均碳链长度(average carbon length,ACL)较空白组显著增大,ACL与ORP、MC分别呈显著正相关;青虾扰动作用对沉积物碳氮含量影响不显著,但能显著降低沉积物的碳氮比,并改善沉积物的有机污染状况。结果表明:青虾扰动作用能降低沉积物pH值、提高沉积物MC及ORP。同时,ACL指征青虾扰动作用可以促进沉积物中有机质的降解。

Laboratory simulation experiments were set up to explore the solution of excessive accumulation of organic matter in aquaculture pond sediments and investigate the effects of Macrobrachium nipponense bioturbation on organic matter degradation in sediments.Fatty acids were used as biomarkers to indicate the degradation of organic matter.The experiments set up the M.nipponense treatment and the control.The physical and chemical properties of sediments,fatty acids and carbon and nitrogen contents were determined.The results showed that bioturbation of M.nipponense significantly increased the moisture content(MC)and oxidation-reduction potentiometer(ORP)of sediments and decreased the pH of sediments.A total of 18 fatty acids were quantitatively analyzed in sediments,of which C16∶0 and low carbon chain fatty acids were dominant.The average carbon length(ACL)in the M.nipponense group was significantly bigger than that in the control group.The ACL was positively correlated with ORP and positively correlated with MC.Bioturbation of M.nipponense had no significant effect on the carbon and nitrogen content of sediments,but significantly decreased the carbon/nitrogen ratio of sediments and improved the organic pollution of sediments.The results showed that bioturbation of M.nipponense significantly decreased the pH of sediments and increased MC and ORP of sediments.The ACL indicated that bioturbation of M.nipponense may promote the degradation of organic matter in sediments.