西北内陆河城区段入河水体CDOM三维荧光光谱特征

Characteristics of three-dimensional fluorescence on CDOM of the sewage into city segment of a typical northwest inland river

于2017年8月现场采集并测定了西北某内陆河城区段16个入河排放口水体的有色溶解性有机物(CDOM)三维荧光光谱(EEMs),深入探讨和分析了其CDOM荧光光谱特征、组成成分、类型和可能来源,探讨了荧光组分对研究河段溶解性有机物的示踪特征.结果表明,污染物产生途径不同,入河水体CDOM的EEMs特征差异显著,除了工业、城镇生活等受人为处理影响的水体外,同类排放源的EEMs具有类似性,大多数入河水体中都包含有类腐殖质荧光A峰.平行因子分析方法(PARAFAC)解析出入河水体CDOM由3个荧光组分组成,即类腐殖质组分C_1(272,437/545nm)和C3(281,368/437nm),类蛋白组分C_2(<2150,281/366nm),其中C_1和C_3具有同源性,且其A峰、C峰的位置发生老化红移现象,C_2组分的类蛋白荧光T峰则较为稳定,可以作为研究河段溶解性有机物来源的指示参数.入河排放水体CDOM的荧光指数(FI、HIX、BIX)在反映人类活动对水质的干扰方面较为敏感,工业企业、城镇生活废水排放源的荧光指数、生源指数与其他排放源有所差异,可以敏感指示人为污染的存在.入河水体CODM的光学参数(a(280)、a(350)、a(355))及荧光峰强度均与TOC、CODcr有一定的线性关系,可用于指示有机污染程度.三个荧光组分与TOC、TN的线性拟合关系相对较好,表明可以用荧光组分值对各入河排放源的TOC、TN等指标进行有效示踪.

16water samples of wastewater outlets into the city segment of a typical northwest inland river were collected in August 2017,and the EEMs spectroscopy of CDOM were measured.Fluorescence spectral characteristics,composition,types and potential sources of all water samples’CDOM were deeply analyzed.The results showed the same wastewatertype shared some similarities,and most outlets included the humic acid-like fluorescence peak A.However,wastewater affected by anthropogenic activities including industrial sewage and residential sewage was an exception.Three separate fluorescent components were identified as two humic acid-like components(C1:272,437/545nm;C3:281,368/437nm)and one protein-like component(C2:<2150,281/366nm)by using excitation emission matrices fluorescence spectroscopy-parallel factor analysis technique(EEMS-PARAFAC).C1 and C3 shared the same source,and the position of fluorescence peak A and C for humic acid-like components showed degradation and red-shift phenomenon.The fluorescence peak T for protein-like component was stable,indicating that C2 can be used as an indicator for studying the DOM sources of river segment.The fluorescence indexes of CDOM such as FI、HIX、BIX could sensitively reflect anthropogenic activity disturbance to water quality.The FI and BIX of industrial and residential sewage discharges were different from those of otheremission sources,and they indicated the existence of man-made pollution sensitively.Certain linear correlation relationships were found between the optical parameters(a(280),a(350),a(355))of samples’CDOM,fluorescence peak strength and TOC and COD,which can be used to characterize the organic pollution level.Great linear fitting relationships were also found among the scores of C1,C2,C3 and TOC and TN of 16samples,indicating that the scores of C1,C2,C3 could be used to trace the TOC and TN of river discharge source.