不同耕作方式对民勤绿洲耕层土壤理化性状及重金属含量的影响

为研究不同耕作方式对绿洲灌区玉米耕层土壤重金属的影响,分析土壤重金属总量及有效态含量与土壤理化性质的内在联系。依托设置在民勤绿洲区2年重复试验,采用田间试验与室内分析相结合的方法,研究了免耕(NT)、少耕(MT)、秋翻(MPT)和深松(ST)4种不同耕作方式下玉米田耕层土壤理化性状及土壤重金属(Cr、Ni、Cu、Cd、Pb、As、Hg)总量和有效态含量变化,以期为农田重金属污染治理提供理论参考。结果表明,(1)短期内耕作方式对耕层土壤理化性状和重金属总量没有显著性影响,但相对于少耕、秋翻及深松,免耕有利于降低土壤耕层pH,提高耕层有机质、全氮含量和电导率。(2)深松能显著降低有效Cd含量,秋翻地有效As含量显著低于少耕,耕作方式对土壤耕层其他有效性重金属的影响不显著。(3)土壤Ni、Cu、Cd、Cr、Pb总量与pH达到显著或极显著负相关,与有机质达到显著或极显著正相关。有效Cu含量与土壤pH呈极显著负相关。有效Hg含量与有机质含量呈显著负相关。有机质、电导率、全氮含量与有效Cu、有效Pb含量呈显著或极显著正相关。总之,免耕在降低耕层土壤pH、提高有机质的同时,提高了土壤Cu、Cd总量和有效Cu含量,但深松可有效降低耕层土壤有效Cd含量。     

云贵地区磷矿分布区农田土壤重金属污染特征及对农产品质量的影响

为了解云贵地区磷矿背景下农田土壤重金属污染和生物有效性特征,对云贵地区重点磷矿分布区玉米、水稻和设施蔬菜3种农田土壤和作物可食部分重金属(Cd、Cu、Pb和Zn)含量进行测定,分析农田土壤重金属污染特征,并探究其对农产品重金属含量的影响。结果表明,云贵地区磷矿分布区农田土壤普遍富集Cd和Pb,与当地背景值相比,Cd和Pb的平均富集系数分别达到2.31和2.39;玉米、水稻和大棚青菜可食部分中Cd的生物富集因子平均值分别为0.09、0.17和0.32,而Pb的生物有效性水平较低;磷矿分布区不同类型农作物对土壤重金属的吸收能力不同,大棚青菜对重金属的富集能力最强,水稻对Cd和Pb的吸收能力高于玉米;回归模型结果表明,土壤有效态重金属含量以及pH、有机质和MgO等理化性质显著影响3种农作物可食部分重金属含量(P0.05)。     

凹凸棒粘土对镉污染农田的原位钝化修复效果研究

原位钝化修复在重金属污染土壤修复中有着不可替代的作用,而修复材料在污染农田中的长期应用效果一直是人们关注的焦点。通过野外大田钝化修复试验,研究了不同添加剂量(0、1.25、1.75、2.50、3.25 kg·m~(-2))凹凸棒粘土对镉(Cd)污染土壤理化性质及对水稻(Oryza sativa L.)和小麦(Triticum aestivum L.)吸收Cd的影响,采用梯度扩散薄膜技术(DGT)评价修复前后土壤中生物可利用态Cd含量的变化。结果表明,施用凹凸棒粘土显著抑制水稻和小麦籽粒中Cd富集量,第一季降幅分别为68.8%~83.3%与54.7%~75.5%,其中2.5 kg·m~(-2)施加剂量对Cd污染土壤的修复效果最佳。施加凹凸棒粘土同样抑制了作物对Zn、Ni等其他重金属的吸收,而对Se吸收影响并不显著。施加凹凸棒粘土显著提高了土壤p H、阳离子交换量(CEC)和土壤细颗粒含量,相关性分析表明,水稻和小麦籽粒中Cd含量与土壤p H呈极显著负相关性(相关系数分别为-0.72和-0.64),推测土壤p H的升高是导致水稻、小麦籽粒中重金属含量降低的一个重要原因。不同施用量凹凸棒粘土均在一定程度上降低了土壤DGT提取态Cd含量,分别下降了82.8%、85.1%、84.4%和67.1%。连续3年原位钝化修复效果跟踪观察结果表明,凹凸棒粘土可持续降低水稻和小麦籽粒中Cd含量,1.25 kg·m~(-2)和1.75 kg·m~(-2)处理组产出的水稻籽粒中Cd含量由2014年的0.140 mg·kg~(-1)与0.215 mg·kg~(-1)分别降低为2016年的0.094 mg·kg~(-1)和0.120 mg·kg~(-1)。综上,凹凸棒粘土在修复Cd污染农田土壤方面具有广阔的应用前景。     

4种改良剂对土壤-黑麦草系统中镉行为的影响

以黑麦草（Lolium perenne L.）作为修复植物,开展了石灰、磷灰石、木炭、猪粪4种改良剂对重金属Cd污染土壤的田间原位修复试验研究。结果表明：改良剂提高了土壤pH值并促进土壤Cd从生物可利用性高的形态向迟效态转化,降低对生物和环境的直接毒害作用,促进黑麦草的生长。以黑麦草生物量和Cd富集量的增加作为评价指标,4种改良剂修复Cd污染土壤效果依次为：石灰〉磷灰石〉木炭〉猪粪。石灰处理中黑麦草Cd富集量为13.11 mg,与其他处理均呈现显著差异。污染土壤重金属Cd的化学形态与黑麦草对Cd的吸收密切相关。黑麦草地上部分Cd质量分数,与土壤B-2态Cd呈极显著正相关关系,相关系数为0.730。黑麦草地下部分Cd质量分数,与B-2、B-3态Cd均呈极显著正相关关系,相关系数分别为0.756、0.786;黑麦草地上部分和地下部分Cd质量分数均与B-4态Cd呈极显著负相关关系,相关系数分别为0.757和0.708。     

某铀矿区农田土壤重金属生物有效性分析

为探究某铀矿区附近农田土壤的重金属生物有效性,以该铀矿采矿区、冶炼厂和尾矿坝附近农田土壤为研究对象,分析土壤理化性质并采用经改良后的BCR四步提取法对土壤重金属Pb、Cd、Cr、Cu和U生物有效性进行评估。结果表明:研究区农田土壤偏酸性;不同区位农田土壤有机质含量由大到小依次为尾矿坝、冶炼厂和采矿区;重金属赋存形态主要为残渣态;重金属元素Pb、Cd、Cr和Cu生物有效态含量分别占其总含量的27%～42%,放射性核素U生物有效态含量为U总含量的43%～45%;不同区位农作物对重金属Cr、Cd、Cu和Pb富集系数由大到小依次为采矿区、冶炼厂和尾矿坝;各区位农作物对U的富集效果均最强。综上,研究区农田土壤重金属生物有效性受pH值、有机质含量及重金属生物有效态含量等因素的综合影响,重金属生物有效性越强,其引起的生态风险越大;不同区位农田土壤中重金属Cr、Cd、Cu和Pb生物有效性由大到小依次为采矿区、冶炼厂和尾矿坝;不同区位农田土壤重金属中U的生物有效性均最强;由于受提炼铀矿石的影响,冶炼厂相较于其他研究区域具有更强的U生物有效性;虽然尾矿坝农田农作物对重金属元素的富集效果较差,但考虑到该区位土壤重金属含量较大,其带来的生态风险仍值得关注。研究结果可为今后该矿区重金属污染的科学生物防治提供重要理论依据。     

蚯蚓在植物修复铜、镉污染土壤中的作用

以红壤和高砂土为供试土壤,分别加入3个浓度的重金属铜离子Cu2 (100,200,400 mg kg-1)或镉离子Cd2 (5,10,20 mg kg-1),每钵接种6条蚯蚓(Pheretimasp.),种植黑麦草(Lolium multiflorum),以不加蚯蚓为对照(CK),研究蚯蚓活动对Cu、Cd污染土壤中黑麦草生长及铜、镉生物有效性的影响.结果表明,添加蚯蚓显著提高了Cu2 、Cd2 污染的高砂土中黑麦草地上部分的生物量,增幅为33%~96%;仅增加了Cu2 污染浓度低于200 mg kg-1的红壤中黑麦草地上部分的生物量;添加蚯蚓显著增加了两种土壤中速效N的含量,促进了黑麦草地上部分对N的吸收,对速效P、K的含量以及黑麦草中P、K含量无显著影响;添加蚯蚓显著提高了红壤中铜(Cu)、镉(Cd)DTPA提取态的含量,对高砂土中DTPA提取态Cu、Cd的含量无显著影响;增加了高砂土中和添加Cu污染浓度低于200 mg kg-1的红壤中黑麦草地上部分吸收Cu的总量,而对黑麦草吸收Cd的量无显著影响.加入蚯蚓可以不同程度地改善植物修复技术应用中受制的两个主要因素.表4参30     

高镉地质背景区设施菜地土壤镉生物有效性主控因子分析

以贵州织金县某设施蔬菜基地为例,运用简单相关、主成分分析和路径分析等方法,研究高Cd地质背景区设施菜地蔬菜Cd累积特征,土壤Cd的主要来源、生物有效性及其与土壤pH、有机质(SOM)、碱解氮(NA)等土壤基本理化性质的相关性,并分析土壤Cd生物有效性的主控因子。结果表明,该基地耕作层土壤Cd含量大于贵州省耕作层土壤Cd背景值(0.659 mg·kg~(-1))的点位占比为75.32%,基地设施蔬菜对Cd的累积规律表现为白菜番茄豇豆,3种蔬菜均未超标。从食品安全角度考虑,在设施菜地土壤污染风险评价中,土壤有效Cd比土壤全Cd能更准确表征土壤Cd的安全风险。该基地设施菜地Cd主要来源为成土母质风化,其高Cd含量与高施氮量分别是提高土壤Cd生物有效性的直接因子和间接因子,土壤SOM、P和K等养分指标对土壤Cd生物有效性的影响不显著。因此,在高Cd地质背景区发展设施蔬菜栽培,可以考虑种植豇豆,并严格控制氮肥施用量,从而保证"菜篮子"安全。     

添加硝酸铁对Cd在土壤-水稻体系中迁移转化的效应及其机制

土壤改良剂能调节和改变Cd等重金属的物理化学性质,改变重金属在环境中的可迁移性和生物有效性。研究硝酸铁的添加对Cd在土壤-水稻体系中迁移转化的效应及其机制,对于制定降低水稻对Cd的吸收的污染控制措施具有重要的指导意义。该研究通过在污染土壤中复合施加木本泥炭(Peat)和Fe(NO_3)_3进行盆栽实验,分析其对土壤Cd和Fe分布的影响,进而分析土壤Cd、Fe形态变化与水稻积累Cd之间的关系,阐明其对Cd在土壤-水稻系统中的迁移转化的影响。结果表明,(1)与对照相比,泥炭+Fe(NO_3)_3的施加提高了土壤的pH值,降低了孔隙水Cd、土壤中生物有效性Cd,提高了土壤中固定态Cd的含量,降低了水稻对Cd的吸收。而泥炭的添加则降低了土壤pH值,提高了孔隙水Cd、土壤中生物有效性Cd的含量,促进了水稻对Cd的吸收。(2)土壤中易于迁移的Cd形态(如Dis-Cd、F1-Cd、F2-Cd等)与水稻各部位Cd含量之间存在显著的正相关性,而土壤中固定态的Cd(Ox-Cd、Plaque-Cd)则与水稻各部位Cd含量之间存在显著的负相关性,这表明土壤中Cd的形态是影响其在土壤-水稻体系中迁移的重要决定因素。(3)土壤Ox-Fe、Plaque-Fe和水稻各部位Cd含量之间存在显著的负相关性;土壤pH、Ox-Fe、Plaque-Fe与易于迁移的Cd形态(如Dis-Cd、F1-Cd、F2-Cd等)之间存在显著的负相关性,这表明土壤铁循环是影响Cd在土壤-水稻体系中迁移转化的重要因素。(4)土壤pH值与易于迁移的Cd形态、水稻各部位Cd含量之间具有显著的负相关性。土壤pH升高,铁氧化物表面负电性增加,从而对土壤中易于迁移的Cd产生强烈的吸附固定作用,进而降低水稻对Cd的吸收。     

土壤性质对水稻土中外源镉与铅生物有效性的影响

为定量了解土壤理化性质对进入土壤中的外源镉和铅生物有效性的影响,采集了性质相差较大的16个水稻土,通过添加Cd(或Pb)培养和老化处理(Cd的加入量为0、0.2、0.5、1、2和5 mg·kg-1;Pb加入量为0、20、50、100、200和500 mg·kg-1,培养时间为1年),研究了不同土壤中Cd(或Pb)负荷与土壤中水溶态和交换态Cd(或Pb)的关系.结果表明,随着Cd(或Pb)污染水平的提高,土壤中水溶态和交换态Cd(或Pb)均显著增加,但不同土壤中水溶态和交换态Cd(或Pb)随土壤Cd(或Pb)积累的增加幅度有很大的差异.相关分析表明,水稻土中水溶性Cd(或Pb)主要与土壤Cd(或Pb)污染水平和pH值有关;而交换态Cd(或Pb)主要与土壤Cd(或Pb)污染水平、pH值、CEC及质地等有关.数据显示,pH值较高、质地较黏的土壤可大大减缓因污染引起的CA和Pb生物有效性的提高.     

武夷山茶园土壤中五种重金属的化学形态和生物有效性

测定了武夷山茶园土壤中5种有毒重金属(汞、镉、铅、铬和砷)的总量和形态分布,运用风险评价编码法(RAC)评价与比较重金属生物有效性,通过次生相与原生相分布比值(RSP)法解析重金属的自然与人为来源,并利用相关系数分析土壤理化性质对重金属形态组分的影响.结果表明:(1)Cd以离子交换态为优势形态;Hg和Pb以残渣态为优势形态;Cr和As元素以残渣态为主.(2)RAC法评价的污染程度大小排序为:CdPbAsCrHg.其中,Cd以人为来源为主,Hg在很大程度上受农业活动的影响,Pb受人为来源影响不显著,Cr和As以自然来源为主,基本未受人为来源的影响.(3)重金属形态受土壤理化性质的影响与元素属性有关.(4)5种重金属对比得出,武夷茶区土壤Cd富集最显著,生物有效性最高.因此,该茶区应首要关注Cd的污染并采取相应防控措施.     

铅胁迫下黄瓜幼苗内源多胺变化动态的初步研究

以黄瓜幼苗为材料,采用高效液相色谱法测定黄瓜幼苗叶和茎中内源多胺的含量,研究了铅胁迫下黄瓜幼苗生长及内源多胺的变化。结果表明:铅质量浓度为100mg·L-1时促进黄瓜幼苗的生长,铅质量浓度高于100mg·L-1时,黄瓜幼苗茎高和根长逐渐下降;铅胁迫下黄瓜幼苗地上部的腐胺含量明显高于对照值,且随着铅质量浓度增加和处理时间的延长呈下降趋势。黄瓜幼苗叶片精胺和亚精胺在处理第5d时高于对照值,茎中精胺和亚精胺含量在处理第7d高于对照值,而其它时间内的都低于对照值,而且其含量均随铅质量浓度的增加而呈下降趋势;过氧化物酶活性变化与内源多胺含量(腐胺、精胺和亚精胺之和)的变化相似,表明铅胁迫能改变黄瓜幼苗内源多胺的含量和调节过氧化物酶活性,从而影响着黄瓜植株的生长。     

翡翠贻贝内脏团抗氧化防御系统对菲胁迫的生物响应

实验室条件下研究了海水中不同浓度(2.0、10.0、50.0μg L-1)菲胁迫1、4、8、15 d和清水恢复2、7 d后翡翠贻贝(Perna viridis)内脏团中抗氧化酶(SOD、GSH-Px、CAT)活性和丙二醛(MDA)含量的变化.结果表明,翡翠贻贝内脏团CAT活性在d 1即受到显著诱导(P<0.05),对菲胁迫的反应非常敏感;SOD活性和GSH-Px活性对菲胁迫的生物响应呈先诱导后抑制的变化规律,而MDA含量随曝露时间延长呈现上升的趋势,且浓度越高,这3种指标的变化趋势越明显.因此翡翠贻贝内脏团中SOD、GSH-Px、CAT活性及MDA含量均适合作为菲污染对水生生物毒性效应的指示指标.在清水恢复阶段,相对于对照组各指标均表现出一定程度的恢复,也表明翡翠贻贝能对一定程度的菲胁迫带来的氧化损伤进行自我修复.图2表1参19     

珠江广州河段及其邻近河流表层沉积物中烷基酚的污染状况

为确定珠江广州河段及其邻近河流水体沉积物中烷基酚的时空分布状况,对该河段表层沉积物采样并应用气相色谱-质谱单离子扫描模式进行了烷基酚(APs)含量分析。结果表明壬基酚(NP)和辛基酚(OP)在样品中均有检出,其含量(以干质量计)范围分别在36.04～24694.10ng·g-1之间(中值为3717.52ng·g-1)和0.36～498.54ng·g-1之间(中值为21.10ng·g-1);珠江广州河段整体含量明显高于其邻近支流各采样点。所研究的表层沉积物样品中烷基酚含量普遍高于世界上其它都市和工业中心附近地区的污染水平,其中壬基酚含量均低于对摇蚊属昆虫(Chironomus riparius)的10d半致死浓度(LC50),但两个含量最高值均已与壬基酚对小虾(shrimp)的亚急性毒性最低效应浓度(LOEC)相接近,且大部分样品中的辛基酚含量都超过了对淡水螺(Potamopyrgus antipodarum)的8周最低效应浓度值(LOEC)标准。因此,烷基酚对该区生物造成的生态风险是一个必须加以认真对待的问题。     

A preliminary study of temporal differences in serum concentrations of perfluoroalkyl acids,among New York anglers,in the absence of known changes in manufacturing practices

Perfluorinated compounds have been manufactured in large quantities and used in myriad industrial processes and commercial applications. The aim of this preliminary study was to generate hypotheses with regard to differences in body burdens of perfluoroalkyl acids, among a sub-sample of participants from the New York State Angler Cohort Study, over a time interval during which no known substantial changes occurred in US manufacturing practices or commercial use. Paired serum specimens, collected from 15 subjects in 1993–1994 (time 1), and in 1995–1997 (time 2), with a minimum interval of 2.5 years, were assayed for PFDA, PFHpA, PFHxS, PFNA, PFOA, PFOS, PFOSA and PFUnDA using HPLC with ES-MS/MS. By subject, differences in concentrations between time 1 and time 2 were estimated, employing paired t-tests, correlations, and multivariable linear regression to accommodate heterogeneity in duration between specimens, and in time 1 concentrations. A statistically significant (P < 0.05) adjusted mean decrease of 0.16 ng mL^?1 (18.8%) between time 1 and 2 was detected for PFNA, and an adjusted mean increase of 0.54 ng mL^?1 (56.8%) was detected for PFOA. The results of this study may be indicative of short-term changes in human body burdens of PFNA and PFOA in association with local exposure sources.     

3种微藻对全氟烷基化合物的生物富集效应

全氟烷基化合物(perfluoroalkyl substances,PFASs)是一系列人工合成的新型有机污染物,由于长链的PFASs具有较高的生物蓄积性,短链PFASs逐渐作为替代品而被广泛利用。为探讨不同碳链长度的PFASs在水生浮游植物中的蓄积能力,选取7种PFASs为目标物,以斜生栅藻(Scenedesmus obliquus)、钝顶螺旋藻(Spirulina platensis)和蛋白核小球藻(Chlorella pyrenoidosa)作为受试生物进行富集动力学实验,测定24 h时的生物富集因子(Bioconcentration factors,BCF)。结果表明,染毒浓度为10μg·L-1时,全氟癸烷羧酸的富集能力最强,在斜生栅藻、钝顶螺旋藻和蛋白核小球藻中的浓度分别为1 894 ng·g~(-1)、88.0ng·g~(-1)、990 ng·g~(-1)。3种微藻中全氟烷基磺酸的BCF均随碳链长度的增加而增大;全氟烷基羧酸的BCF基本遵循同样的规律,只是在钝顶螺旋藻体内,全氟己烷羧酸的BCF高于全氟辛烷羧酸。此外,PFASs在斜生栅藻中的浓度均高于蛋白核小球藻和钝顶螺旋藻,不同藻类的富集能力与其表面积、脂肪及蛋白质组成有关。     

Impacts of advanced treatment processes on elimination of antibiotic resistance genes in a municipal wastewater treatment plant

The distributions of ARGs were monitored in a WWTP in Harbin during six months. CASS had the best removal efficacy of ARGs compared to other processes in the WWTP. UV disinfection could effectively control the HGT. AGAC significantly remove ARGs and organics due to its high absorption capacity. Combination of ozone and AGAC significantly improve removal of ARGs and organics. Antibiotic resistance genes (ARGs) pose a serious threat to public health. Wastewater treatment plants (WWTPs) are essential for controlling the release of ARGs into the environment. This study investigated ARG distribution at every step in the treatment process of a municipal WWTP located in Harbin for six consecutive months. Changes in ARG distribution involved in two advanced secondary effluent treatment processes, ozonation and granular activated carbon (GAC) adsorption, were analyzed. Biological treatment resulted in the highest ARG removal (0.76–1.94 log reduction), followed by ultraviolet (UV) disinfection (less than 0.5-log reduction). Primary treatment could not significantly remove ARGs. ARG removal efficiency increased with an increase in the ozone dose below 40 mg/L. However, amorphous GAC (AGAC) adsorption with a hydraulic retention time (HRT) of 1 h showed better removal of ARGs, total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) than ozonation at a 60 mg/L dose. UV treatment could efficiently reduce the relative ARG abundance, despite presenting the lowest efficiency for the reduction of absolute ARG abundance compared with GAC and ozone treatments. The combination of ozone and AGAC can significantly improve the removal of ARGs, TOC, TN and TP. These results indicate that a treatment including biological processing, ozonation, and AGAC adsorption is a promising strategy for removing ARGs and refractory organic substances from sewage.     

Evaluate HAA removal in biologically active carbon filters using the ICR database

The effects of biologically active carbon (BAC) filtration on haloacetic acid (HAA) levels in plant effluents and distribution systems were investigated using the United States Environmental Protection Agency’s Information Collection Rule (ICR) database. The results showed that average HAA5 concentrations in all locations were 20.4 μg·L^-1 and 29.6 μg·L^-1 in ICR plants with granular activated carbon (GAC) and ICR plants without GAC process, respectively. For plants without GAC, the highest HAA levels were observed in the quarters of April to June and July to September. However, for plants with GAC, the highest HAA levels were observed in the quarters of April to June and January to March. This HAA level profile inversely correlated well with water temperature, or biologic activity. For GAC plants, simulated distribution samples matched well with distribution system equivalent samples for Cl₃AA and THMs. For plants with and without GAC, simulated distribution samples overestimated readily biodegradable HAAs in distribution systems. The study indicated that through HAA biodegradation, GAC process plays an important role in lowering HAA levels in finished drinking water.     

Prevention of surgical site infection under different ventilation systems in operating room environment

• The effectiveness of four different ventilation systems was compared in depth. • Airflow and bacteria-carrying particles concentration were quantitatively analyzed. • Vertical laminar airflow with high airflow rate could not achieve desired effect. • Temperature-controlled airflow ventilation could guarantee air cleanliness. Biological particles in the operating room (OR) air environment can cause surgical site infections (SSIs). Various ventilation systems have been employed in ORs to ensure an ultraclean environment. However, the effect of different ventilation systems on the control of bacteria-carrying particles (BCPs) released from the surgical staff during surgery is unclear. In this study, the performance of four different ventilation systems (vertical laminar airflow ventilation (VLAF), horizontal laminar airflow ventilation (HLAF), differential vertical airflow ventilation (DVAF), and temperature-controlled airflow ventilation (TAF)) used in an OR was evaluated and compared based on the spatial BCP concentration. The airflow field in the OR was solved by the Renormalization Group (RNG) k-e turbulence model, and the BCP phase was calculated by Lagrangian particle tracking (LPT) and the discrete random walk (DRW) model. It was found that the TAF system was the most effective ventilation system among the four ventilation systems for ensuring air cleanliness in the operating area. This study also indicated that air cleanliness in the operating area depended not only on the airflow rate of the ventilation system but also on the airflow distribution, which was greatly affected by obstacles such as surgical lamps and surgical staff.     

长江重庆段溶解性有机物的荧光特性分析

利用三维荧光光谱(EEMs),并结合平行因子分析(PARAFAC)及主成分分析(PCA),研究了长江重庆段溶解有机物(DOM)的荧光组分特征及其污染来源,并探讨了荧光强度同溶解性有机碳(DOC)及溶解氧(DO)的相关性.结果表明,PARAFAC模型识别出长江重庆段DOM由2类6个荧光组分组成,即类腐殖质荧光组分C1(350/422 nm)、C4(245,305/395 nm)、C5(260,340/420 nm)、C6(260/480 nm)及类蛋白荧光组分C2(275/300 nm)、C3(227,278/329 nm).在DOM来源组成中,陆源的类腐殖质含量占62.56%,类蛋白物质含量占31.31%.类腐殖质组分的荧光强度同DOC的含量存在明显的线性正相关(r=0.73),类蛋白组分的荧光强度同DO的含量呈明显的线性负相关(r=0.80).EEMs-PARAFAC不仅可以表征长江重庆段DOM的光谱特征,示踪长江重庆段的有机污染程度,还可以为三峡库区水体保护提供依据.     

Characterization of the dissolved organic matter in sewage effluent of sequence batch reactor: the impact of carbon source

Dissolved organic matter (DOM) transformation in sequence batch reactor (SBR) fed with carbon sources of different biodegradability was investigated. During the biologic degradation process, the low molecular weight (MW) fraction (< 1 kDa) gradually decreased, while the refractory compounds with higher aromaticity were aggregated. Size exclusion chromatography (SEC) and fluorescence of excitation emission matrices (EEM) demonstrated that more biopolymers (polysaccharides or proteins) and humic-like substances were presented in the extracellular polymeric substance (EPS) extracted from the SBR fed with sodium acetate or glucose, while the EPS from SBR fed with slowly biodegradable dissolved organic carbon (DOC) substratestarch had relatively less biopolymers. Comparing the EfOM in sewage effluent of three SBRs, the effluent from SBR fed with starch is more aromatic. Organic carbon with MW>1 kDa as well as the hydrophobic fraction in DOM gradually increased with the carbon sources changing from sodium acetate to glucose and starch. The DOC fractionation and the EEM all demonstrated that EfOM from the effluent of the SBR fed with starch contained more fulvic acid-like substances comparing with the SBR fed with sodium acetate and glucose.