滇池沉积物氮内源负荷特征及影响因素

研究了滇池沉积物间隙水氮浓度垂向分布特征,根据Fick扩散定律定量估算了沉积物-水界面氮扩散通量,并探讨了其影响因素.结果表明:滇池沉积物间隙水溶解性总氮(DTN)主要以氨态氮(NH4+-N)形式存在,占其总量的72.30%,其浓度随深度增加而升高;其次为溶解性有机氮(DON),占其总量的24.59%,其浓度随深度的增加先升高后降低,最后趋于稳定;硝态氮(NO3--N)所占比例较低,浓度随深度的增加而降低.滇池沉积物-水界面NH4+-N扩散通量分布范围为12.73~59.74mg/(m2·d)[均值30.18mg/(m2·d)],全湖年均氨氮释放量为3305.04t,其中草海、外海北部、东北部及南部湖区扩散通量较大,达35mg/(m2·d),全湖呈由北向南逐渐降低的空间分布特征;全湖年均DON释放量为1147.55t,其全湖分布特征与氨氮一致;NO3--N扩散通量分布范围为-2.70~0.27mg/(m2·d)[均值-0.50mg/(m2·d)],总体表现为由上覆水向沉积物扩散.与我国其他湖泊相比,滇池具有较大沉积物氮内负荷,其沉积物-水界面NH4+-N扩散通量较高,对湖泊水体氨氮浓度贡献较大,且其与沉积物总氮、有机质、可交换态氮和可交换态氨氮含量呈显著正相关,即滇池沉积物NH4+-N释放主要受其可交换态氮,特别是可交换态中氨氮含量影响;同时,滇池沉积物DON潜在释放风险也较大,且与沉积物C/N有关.     

重庆园博园龙景湖新建初期内源氮磷分布特征及扩散通量估算

采集重庆园博园龙景湖不同区域沉积物样柱,分析沉积物上覆水和孔隙水中氮磷垂直分布特征,并利用一维孔隙水扩散模型(Fick定律)来估算氨氮和正磷酸盐的扩散通量和年负荷贡献量.结果表明,龙景湖沉积物-水界面氨氮从上覆水到孔隙水在垂直剖面上总体都呈现出增大趋势;表层(0~5 cm)沉积物孔隙水中氨氮平均浓度为6.13 mg·L-1±3.07 mg·L-1,是上覆水氨氮平均含量10倍.正磷酸盐垂直分布特征总体表现为先增大再减小,在表层孔隙水出现极大值;沉积物孔隙水中正磷酸盐平均浓度为2.01 mg·L-1±1.05 mg·L-1.所有区域氨氮均表现为由沉积物向上覆水释放,新增淹没区库湾区域氨氮扩散通量低于6.0 mg·(m2·d)-1,龙景沟水库、龙景湖主湖原有湖区氨氮扩散通量分别高达47.19 mg·(m2·d)-1、40.29mg·(m2·d)-1.原有湖区正磷酸盐表现为由沉积物向上覆水释放,扩散通量仍以龙景湖主湖及龙景沟水库最大,为7.89mg·(m2·d)-1、6.13 mg·(m2·d)-1.新增淹没区的河道、库湾及赵家溪部分区域正磷酸盐却表现为由上覆水向沉积物中扩散,扩散通量为-1.93~-2.78 mg·(m2·d)-1.整个湖区氨氮年负荷贡献量为3.95 t·a-1,新增淹没区贡献率为85%;正磷酸盐年负荷贡献量为0.357 t·a-1,新增淹没区贡献率为72%.     

太湖内源营养盐负荷状况及其对上覆水水质的影响

以太湖沉积物-上覆水界面为研究对象,于2013年夏季采集46个样点的沉积物柱状样,分析表层沉积物孔隙水中营养盐(正磷酸盐、氨氮、硝氮)的浓度空间分布,估算表层沉积物中磷、氮的扩散通量,明确营养盐在沉积物-水界面的分布规律,以探明内源营养盐负荷对太湖上覆水的污染贡献,并为沉积物-水界面氮磷的转移过程理论补充证据.结果表明:太湖西北部区域的表层沉积物孔隙水中正磷酸盐和硝氮浓度较高,分别达到1.11 mg·L~(-1)和1.25 mg·L~(-1)以上;大部分湖区的氨氮浓度超过2 mg·L~(-1).全湖区范围内,从表层沉积物的上覆水到孔隙水,氨氮含量呈现升高趋势而硝氮含量呈现降低趋势.北部3个湖湾区的沉积物营养盐扩散通量最高,正磷酸盐为2.69~4.60 mg·m~(-2)·d~~(-1),氨氮为17.8~45.7 mg·m-2·d~(-1),而湖岸河口区是沉积物硝氮内源释放显著的区域.沉积物向上覆水释放正磷酸盐和氨氮的年内源污染负荷分别为64.6 t·a~(-1)和1756 t·a~(-1);而上覆水向沉积物汇入硝氮的年负荷为1102 t·a~(-1).氨氮的内源污染负荷与外源污染负荷之比高达18.7%,氨氮、总磷和总氮内源污染为上覆水贡献的浓度分别为0.361、0.013和0.134 mg·L~(-1),表明自由扩散带来的内源负荷会使太湖水中营养盐污染恶化,需引起重视.     

巢湖西部河口区沉积物氮磷分布特征与原位扩散通量估算

选取巢湖西部重污染入湖河口区,研究表层沉积物氮磷污染特征,并运用Fick定律估算沉积物-水界面氮磷原位扩散通量.结果表明:南淝河、派河、十五里河河口表层沉积物总氮平均含量达到2208.17 mg·kg~(-1),氮形态以有机氮为主,占比达到90%以上.表层沉积物总磷平均含量为704.59 mg·kg~(-1),其中铁铝结合磷、活性有机磷和钙镁结合磷分别占比27%、28%和18%.河口区水体氨氮浓度从上覆水到孔隙水中总体呈上升趋势,沉积物表层(0~5 cm)孔隙水中氨氮平均浓度为25.42 mg·L~(-1),是上覆水中的7倍.沉积物孔隙水中硝氮与正磷酸盐浓度在垂向上随深度的增加呈先上升后降低的趋势,在沉积物-水界面附近达到浓度最高值.3个河口沉积物孔隙水中氮磷营养盐均向上覆水扩散,其中氨氮扩散通量分别为25.87、74.85与18.08 mg·m~(-2)·d~(-1).硝氮与正磷酸盐扩散通量较低,范围分别在1.38~2.78和0.011~0.024 mg·m~(-2)·d~(-1)之间.总体上看,巢湖西部河流入湖河口区表层沉积物氮污染严重,且存在较高的氮磷营养盐释放风险,应是巢湖富营养化控制过程中重点关注的区域.     

滏阳河表层沉积物氮分布特征和界面无机氮扩散通量估算

为了揭示非常规水源补给河流沉积物-水界面氮交换过程及其特点,为非常规水源补给河流富营养化机制提供基础数据.选择典型非常规水源补给河流(滏阳河)为研究对象,分析河流沉积物中氮素空间分布及上覆水-孔隙水氮营养盐垂直分布特征,并估算滏阳河不同区段沉积物-水界面无机氮扩散通量.结果表明,滏阳河整体表层沉积物总氮含量范围在770~10590 mg·kg~(-1)之间,其中有机态氮为氮素的主要存在形式,占总氮比例达84.9%~99.3%.NH3-N为无机氮的主要形态,含量范围为3.23~1135.00 mg·kg~(-1).溶氧量作为影响沉积物-水界面无机氮分布的主要因素.邯郸段硝氮浓度在孔隙水中随深度逐渐升高,孔隙水平均硝态氮浓度达3.54 mg·L~(-1),为上覆水8倍之多.邢台、衡水、沧州段硝氮浓度随深度而逐渐降低;滏阳河下游衡水段和沧州段进入沉积物-水界面后氨氮浓度呈下降趋势.滏阳河上游邯郸段与邢台段沉积物-水界面NH3-N由沉积物向上覆水扩散,扩散通量为48.9~1471.0μmol·m~(-2)·d-1.下游河段部分点位NH3-N表现为上覆水向沉积物中扩散,扩散通量在-932~-456μmol·m~(-2)·d-1之间.非常规水源补给河流在氮营养盐外源得到控制后,仍存在内源释放风险,将会加大河流治理与修复的难度.     

于桥水库沉积物-水界面氮磷剖面特征及交换通量

于桥水库是天津市重要的饮用水源地,但近年来呈现富营养化加重趋势,而其内源负荷及污染分布特征尚不清楚.本研究利用Peeper(pore water equilibrium)技术获取沉积物-水界面氮磷剖面特征,分析于桥水库间隙水氮磷分布的空间差异;采集沉积物无扰动柱样分析沉积物中易释放态氮及磷的赋存特征,并利用原柱样静态培养法对其水土界面氮磷交换速率进行估算.结果表明:(1)沉积物中活性磷、氨氮、硝态氮和亚硝态氮的含量分别为0.5~6.5、0.5~10.9、2.2~16.2和0.05~0.6 mg·kg~(-1),在垂直方向随深度增加营养盐含量降低,而在空间分布上差异显著.(2)上覆水中PO_4~(3-)-P和NH_4~+-N质量浓度较低,间隙水中PO_4~(3-)-P和NH_4~+-N质量浓度远大于上覆水,表明于桥水库间隙水具有向上覆水体扩散营养盐的潜力.在垂直方向上间隙水中PO_4~(3-)-P和NH_4~+-N具有在0~5 cm快速增加,之后表现出逐渐降低的趋势.(3)静态释放结果表明,PO_4~(3-)-P和NH_4~+-N从沉积物间隙水扩散至上覆水中,其释放通量分别为1.1~13.3 mg·(m~2·d)~(-1)和20.6~250.5 mg·(m~2·d)~(-1);NO-3-N交换通量在-20.4~33.4 mg·(m~2·d)~(-1)之间,NO_2~--N交换通量在-7.4~0.4 mg·(m~2·d)~(-1)之间.PO_4~(3-)-P和NH_4~+-N为于桥水库主要的沉积物内源向上覆水释放营养盐,总体释放速率在空间上呈现南高北低、淋河口和水坝前较高的释放特征.与类似研究比较可知,于桥水库沉积物-水界面通量相对较高,表明沉积物是于桥水库上覆水营养盐的重要来源.     

象山港河纯养殖区沉积物-海水界面N、P营养盐的扩散通量

2008年1月、5月和7月3次对象山港河纯网箱养殖区海底沉积物进行了底质表层间隙水和上覆水营养盐(NH4-N,NO2-N,NO3-N,P04-P)的分析,并使用Fick第一定律对该港湾沉积物--海水界面N、P营养盐的扩散通量进行了估算.研究结果表明,养殖区沉积物间隙水中N、P营养盐含量显著高于非养殖区,上覆水和沉积物间隙水中的N从1月份NH4-N为主逐渐转变到7月份以NO3-N为主.养殖区上覆水中NH4-N最高浓度为234.66μmoL/L,NO3-N最高浓度为79.25μmol/L.养殖区上覆水中N、P营养盐的含量均严重超标.N、P营养盐的扩散通量估算结果显示:随着养殖高峰期的到来,沉积物-海水界面N、P营养盐的扩散方向由从沉积物向上覆水扩散逐渐转向从上覆水向沉积物扩散;养殖区扩散通量值相对于非养殖区显著扩大化;NH4-N通量变化最大,从1月份最高700.41μmoL/(m2·d)降低到7月份27.87 μmoL/(m2·d).海水养殖对沉积物中N、P营养盐扩散通量影响显著.     

象山港河鲀养殖区沉积物—海水界面N、P营养盐的扩散通量

2008年1月、5月和7月3次对象山港河鲀网箱养殖区海底沉积物进行了底质表层间隙水和上覆水营养盐(NH4-N,NO2-N,NO3-N,PO4-P)的分析,并使用Fick第一定律对该港湾沉积物——海水界面N、P营养盐的扩散通量进行了估算。研究结果表明,养殖区沉积物间隙水中N、P营养盐含量显著高于非养殖区,上覆水和沉积物间隙水中的N从1月份NH4-N为主逐渐转变到7月份以NO3-N为主。养殖区上覆水中NH4-N最高浓度为234.66μmol/L,NO3-N最高浓度为79.25μmol/L。养殖区上覆水中N、P营养盐的含量均严重超标。N、P营养盐的扩散通量估算结果显示:随着养殖高峰期的到来,沉积物—海水界面N、P营养盐的扩散方向由从沉积物向上覆水扩散逐渐转向从上覆水向沉积物扩散;养殖区扩散通量值相对于非养殖区显著扩大化;NH4-N通量变化最大,从1月份最高700.41μmol/(m2.d)降低到7月份27.87μmol/(m2.d)。海水养殖对沉积物中N、P营养盐扩散通量影响显著。     

巢湖水华暴发期水-沉积物界面溶解性氮形态的变化

2008年4~10月,连续对巢湖8个样点进行采样,分析了上覆水和表层沉积物间隙水中溶解性氮形态在水华暴发过程中的变化,估算了水-沉积物界面无机氮的扩散通量.结果表明,上覆水中NH4+-N含量随水华暴发强度的增加而减小,溶解性总氮(DTN)含量在水华暴发后明显升高,而NO3--N含量只在水华暴发严重时才明显减少.在大规模水华暴发前(4~5月)上覆水中DTN的主要组成部分是NO3--N和NH4+-N,在水华暴发后则是溶解性有机氮(DON).间隙水中PDTN以NH4+-N为主,其浓度随温度的增加而升高; DON在水华暴发过程中呈先下降后上升的趋势.通量计算结果表明,沉积物作为NH4+-N的“源”一直由间隙水向上覆水释放,西半湖扩散通量在13.06~32.94mg/(m2·d)之间,东半湖扩散通量在4.54~17.41mg/(m2·d)之间.沉积物-水界面交换是湖泊营养盐重要的补充途径,为水华持续暴发提供营养来源.     

汉江襄阳段主要入江支流沉积物营养盐和重金属风险特征研究

采集汉江襄阳段主要入江支流沉积物柱状样,分析沉积物常规理化指标、上覆水和孔隙水中营养盐含量、以及表层沉积物重金属含量,采用一维孔隙水扩散模型(Fick定律)计算营养盐扩散通量,评估沉积物营养盐释放风险,并评价表层沉积物重金属生态风险.结果表明:所有采样点氨氮及磷酸盐均从沉积物向上覆水释放,表明水质存在内源营养盐(氨氮和磷酸盐)释放风险.氨氮、磷酸盐扩散通量范围分别为42.431~81.369 mg·m-2·d-1、0.745~1.437 mg·m-2·d-1,均以航空路样点最大.表层沉积物重金属污染指数SPI值为6.1,总体表现为中度风险;其中小清河样点SPI值为11.8,达到高风险.小清河Cu、Pb和Zn平均含量分别为131.17 mg·kg-1、57.97 mg·kg-1和398.59 mg·kg-1,均超过相应的SEL值(最高效应阈值).富集系数研究表明汉江支流表层沉积物中Cd富集现象严重,平均富集系数高达4.57.汉江襄阳段入江支流沉积物存在内源营养盐释放风险,中度重金属生态风险,且Cd累积风险突出.因水文调控减少汉江干流流量进而导致河流稀释自净能力减弱,从而对汉江水质安全构成较大威胁.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.