基于CDOM光学特性的近海环境富营养化监测

Based on Optical Properties of Chromophoric Dissolved Organic Matter in the Monitoring of Coastal Eutrophication

富营养化是河口港湾一个重要的生态环境问题。传统的富营养化监测与评价需要依靠费时费力的人工采样、实验室分析测定,周期较长,难以实现现场实时快速监测与评价。本文依据2009年2月、5月、8月和10~11月在厦门湾海域的有色溶解有机物(CDOM)与主要环境要素的调查资料,探讨了利用CDOM的光学性质反演COD,TN,TP等富营养化参数的可行性。结果表明:(1)厦门湾表层水体CDOM存在明显的空间和季节性变化,九龙江河口区的丰度最高;(2)陆源输入及浮游植物的现场生产是水体中CDOM的主要来源,因此可建立利用盐度和叶绿素a浓度估算厦门湾CDOM丰度的经验算法,该经验算法的相关系数达0.96,经验算法估算值与实测CDOM之间的相对误差为11.1%±0.71%,精度较高;(3)厦门湾各个季节COD,TN,TP与CDOM吸收系数、荧光组分之间有很好的相关性,总体表现春夏较高、秋季次之、冬季最差;(4)结合上述研究成果,利用厦门湾已建立的水质自动监测系统实时获取的盐度、叶绿素a以及经验公式推导出的CDOM荧光资料,有望克服COD,TN和TP等富营养化指标只能通过人工采样和实验室分析获取的缺点;实现对海域富营养化程度的快速监测与评价。

Eutrophication is an important ecological environment problem in estuary and coastal area .The traditional monitoring technology for eutrophication is laborious and time-consuming ,so it is difficult to realize the real-time and on-site monitoring and then rapid evaluate the eutrophication degree .Based on the investigation of chromophoric dissolved organic matter（CDOM ） and other environmental parameters in Xiamen Bay in February ,May ,August and from October to November 2009 ,the feasibility of using CDOM optical properties to retrieve eutrophication parameters （COD、TN and TP） in coastal environment was evaluated . CDOM showed large spatial and seasonal changes in Xiamen Bay ,with the highest CDOM abundance occurring in the Jiulong River Estuary .The terrestrial input and phytoplankton production were the main sources of CDOM in Xiamen Bay .The empiri-cal formula to estimate the CDOM abundance in seawater was then established by using the salinity and chlorophyll-a data .The correlation coefficient of this empirical formula was 0.96 and the relative errors between fitted values and measured values for CDOM of different survey stations were （11.1% ＆#177; 0.71% .There were high correlations between CDOM absorption coefficient and fluorescence components with chemical oxygen demand（COD） ,total nitrogen（TN） ,total phosphorus（TP） in all seasons , with the highest correlations in spring and summer ,and the lowest in winter .Combined with the above results ,instead of the data including COD ,TN and TP got only through manual samplings and laboratory analysis ,the data of salinity and chlorophyll-a could be provided by water quality automatic monitoring system and CDOM data got by above empirical formula ,so it is possi-ble to realize the rapid monitoring and evaluation for the degree of coastal eutrophication by using in situ buoy system with CDOM sensor .