近海养殖水体溶解性有机质的荧光特征及环境指示意义

FLUORESCENCE CHARACTERISTICS OF DISSOLVED ORGANIC MATTER IN OFFSHORE AQUACULTURE WATER AND ITS ENVIRONMENTAL SIGNIFICANCE

为探究近海养殖水体溶解性有机质(dissolved organic matter,DOM)的荧光特征及环境指示意义,以山东省东营市凡纳滨对虾池塘为研究对象,利用三维荧光光谱-平行因子分析(EEMs-PARAFAC)技术对2020年9月14日至10月17日凡纳滨对虾池塘养殖水体中DOM的荧光特征进行了分析,以期揭示其来源及环境指示意义。结果表明,养殖池水体DOM有4种荧光组分,包括1种类蛋白质物质(C4)和3种类腐殖酸物质(C1、C2与C3),前者作为养殖池水体DOM特有组分,且其荧光强度高于对照池各组分。养殖池水体DOM总荧光强度、总有机碳和溶解有机碳含量于采样时期均明显高于对照池。综合3种荧光指数(FI、BIX、HIX),对照池和养殖池水体DOM以内源输入为主,自生源特征明显。对照池和养殖池水体DOM组分与营养盐(氮、磷营养盐为主)具有显著相关性,表明DOM组分的产生与利用和营养盐的消耗与生成过程相耦合。养殖池DOM组分C1和C4与chl a呈显著正相关性,表明浮游藻类是养殖水体DOM类蛋白质和类腐殖酸物质的重要来源。该研究揭示了养殖水体有机质高度积累,对养殖环境的富营养化带来潜在威胁,同时为进一步揭示养殖水体DOM的光化学性质提供了科学依据。

To explore the fluorescence characteristics and environmental indication significance of dissolved organic matter(DOM) in offshore aquaculture water body, Litopenaeus vannamei pond in Dongying City, Shandong Province was chosen as the research object, for which three-dimensional fluorescence spectrum parallel factor analysis(EEMs-PARAFAC) technology was used to analyze the dissolved organic matter(DOM) in Litopenaeus vannamei pond aquaculture water body from September 14 to October 17, 2020, and to reveal the source and environmental indicative significance of DOM. The DOM in the aquaculture pond water was consisted of four fluorescent components, including one type of protein(C4) and three types of humic acid(C1, C2, and C3). The former is a unique component of DOM in the aquaculture pond water, and its fluorescence intensity is higher than that in the control pond water. The content of organic matter(OM) in the aquaculture pond was higher as indicated by the observed significantly higher total fluorescence intensity of DOM and the contents of TOC and DOC in the aquaculture pond, than those in the control pond during the sampling period. Based on the three fluorescence indexes(FI, BIX, and HIX), the DOM in the control pond and aquaculture pond is mainly endogenous input, and the characteristics of endogenous source are obvious. The DOM components in both control and aquaculture pond had significant correlations with NO;、NO;、PO;, indicating the coupling between the generation/utilization of DOM components and the consumption/generation of nutrients. In addition, there was a significant positive correlation between chl a and DOM components C1 and C4, which indicated that the phytoplankton was an important source of DOM proteins and humic acids in aquaculture pond water. This study reveals that the high accumulation of organic matter in aquaculture water brings a potential threat to the eutrophication of aquaculture environment, and provides a scientific basis for further revealing the photochemical properties of DOM in aquaculture water.