有机肥源磺胺类抗生素在土壤中的降解规律及影响因素分析

运用室内模拟降解法,研究了有机肥源磺胺类抗生素(磺胺嘧啶、磺胺甲嘧啶、磺胺二甲嘧啶、磺胺二甲氧嘧啶和磺胺甲恶唑)在光照或避光条件下、不同类型土壤中的降解能力.结果表明,5种磺胺类药物在土壤-粪便混合基质中的降解规律均呈"L"型;不同磺胺在土壤中的降解性与药物自身性质相关,江西红壤中降解半衰期长短顺序为:磺胺甲恶唑磺胺二甲嘧啶磺胺嘧啶磺胺甲嘧啶磺胺二甲氧嘧啶;土壤中有机质含量越高,磺胺类药物在土壤中降解性越强,其降解速率大小为:东北黑土≈太湖水稻土江西红壤;磺胺类药物在土壤-粪便混合基质中的降解速率显著大于单一土壤,粪便的加入对磺胺类抗生素的降解性有较大促进作用,光照作用则相对影响较小.     

重金属铜在黑土和棕壤中解吸行为的比较

采用一次平衡法研究吸附态Cu²⁺在黑土和棕壤上的解吸行为并进行了比较.结果表明,与棕壤相比,黑土吸附态Cu²⁺解吸有更长的滞后阶段,黑土在Cu²⁺的吸附量低于729.00mg·kg^-1(Cu²⁺处理浓度小于40 mg·L^-1),棕壤在Cu²⁺的吸附量低于393.29 mg·kg^-1(Gu²⁺处理浓度小于20 mg·L^-1)时,土壤吸附态Cu²⁺几乎不发生解吸.2种土壤吸附态Cu²⁺的解吸率均较低,尤其是黑土.在试验所采用的Gu²⁺处理浓度范围内,黑土与棕壤吸附态Cu²⁺的最高解吸率分别为6.60%和13.56%.Freundlich方程为描述2种土壤Cu²⁺等温解吸过程的最佳方程.黑土和棕壤吸附态Cu²⁺的解吸速率均较快,在40min左右基本达到平衡.描述黑土和棕壤解吸动力学过程的最优模型为双常数速率方程,其次为Elovich方程.     

改性土壤对模拟含油废水中油的吸附

研究季铵盐阳离子表面活性剂四甲基铵离子 ( TMA)和十六烷基三甲基铵离子 ( HDTMA)改性的土壤 (黑土、黄棕壤、红壤 )对水中油的吸附作用 .结果表明 :改性土壤和未改性土壤均可吸附水中的油 ,但改性土壤对水中油的吸附能力明显高于未改性土壤 .改性土壤吸附油能力的顺序依次为 :1 CEC- HDTMA黑土 >1 CEC-HDTMA黄棕壤 >1 CEC- HDTMA红壤 >1 CEC-TMA黑土 >1 CEC-TMA黄棕壤 >1 CEC- TMA红壤 .未改性土壤和 HDTMA改性土壤对油的吸附通过分配来进行 ,吸附等温线可由 Henry方程表示 ,得出 logK_SOM为 2.69,logK_HDTMA为 3.35;TMA改性土壤对油的吸附符合 Langmuir方程 ,其对油的饱和吸附量分别为 1150 mg/kg( TMA黑土 ) ,751 mg/kg( TMA黄棕壤 ) ,172 mg/kg( TMA红壤 )     

诺氟沙星在4种土壤中的吸附-解吸特征

采用批平衡吸附试验,研究了诺氟沙星在河南封丘潮土、江西鹰潭红壤、苏南常熟水稻土和南京黄棕壤等4种土壤中的吸附行为.结果表明,诺氟沙星的土壤吸附-解吸不同程度地偏离线性模型,但均可用Freundlich模型和Langmuir模型进行良好的线性拟合.其K_f值变化较大,分别为潮土82.0 L/kg、黄棕壤432 L/kg、水稻土5 677 L/kg和红壤8 790 L/kg,显示诺氟沙星在4种土壤中的吸附行为存在较大的差异.此外,诺氟沙星在4种土壤上的解吸过程存在滞后现象.其中,诺氟沙星在红壤中的滞后现象明显与其他3种土壤不同,其滞后系数至少大5倍以上.研究表明4种土壤中诺氟沙星的吸附参数K_f值与土壤pH呈极显著负相关,与土壤溶液中诺氟沙星阳离子形态比例则呈极显著正相关.在不同pH（5～9）下,红壤和水稻土的诺氟沙星吸附参数lgK_d随pH的升高先增加而后降低,黄棕壤和潮土中则不同程度地线性下降.可见,阳离子吸附可能是诺氟沙星土壤吸附的重要机理,而低pH下红壤和水稻土中诺氟沙星的吸附是阳离子吸附和土壤溶液共存阳离子竞争性吸附共同作用的结果.     

三种草坪草对石油烃污染土壤修复效应的模拟研究

以红壤、黑土、棕壤、灰潮土和黄棕壤5种自制石油烃(TPH)污染土壤为研究对象,设置不同培养时间和TPH浓度进行了狗牙根、黑麦草、高羊茅对TPH的修复模拟实验。研究结果表明:种植草坪后土壤TPH的降解率较对照更高,且生物量较大的高羊茅和黑麦草处理TPH降解率高于生物量较小的狗牙根处理;随着培养时间增加,所有处理TPH降解率和降解菌数量呈先增加后降低的趋势,但低浓度TPH污染土壤TPH降解率和降解菌数量及植物生物量高于高浓度TPH污染土壤;土壤TPH降解率与茎鲜重和总鲜重呈极显著正相关,与茎干重和总干重呈显著正相关,但与根鲜重和根干重无相关性;此外,受土壤C/N、C/P的影响,不同供试土壤TPH的降解率由大到小顺序为黑土黄棕壤≈灰潮土棕壤红壤。     

抗生素磺胺嘧啶和磺胺甲恶唑在土壤中的淋溶行为研究

农业生产中畜禽粪污还田会将残留的抗生素带入农田土壤,并能通过淋溶作用迁移至深层土壤最终进入地下水. 该研究采用模拟土壤柱淋溶试验方法,研究了2种磺胺类抗生素——磺胺嘧啶(sulfadiazine,SDZ)和磺胺甲恶唑(sulfamethoxazole,SMX)在农田土壤中的淋溶行为,以及表层土抗生素含量、淋溶液pH和有机质对各土柱剖面SDZ和SMX残留水平的影响. 结果表明:①不同表层土抗生素含量下,SDZ和SMX在供试土壤中均呈向下迁移的趋势,但淋溶结束后上层土壤中二者含量明显高于下层,土柱各层抗生素的含量随表层土抗生素含量的增加而增加. ②淋溶液pH为3.00和5.00时,各层土壤中SDZ和SMX的含量均高于淋溶液pH为7.00时. 淋溶液pH较高时两种磺胺类抗生素多以阴离子形态存在,会与带负电荷的土壤颗粒产生静电斥力而易于向下迁移;随着淋溶液pH的降低,两种磺胺类抗生素阴离子形态占比减少,上层土壤中保留的抗生素含量变高,向下迁移的能力减弱. ③粪便添加组上层土壤中SDZ和SMX的含量明显高于未添加组,抗生素向下迁移的能力减弱,这与有机质的添加使得上层土柱吸附能力增强有关. 通过模型模拟,SDZ和SMX的地下水污染指数分别为3.50和4.45,均大于2.8,表明在供试土壤中这2种磺胺类抗生素的淋溶迁移性较强. 研究显示,淋溶试验结果与模型模拟结果一致,表明SDZ和SMX对地下水存在潜在污染风险.      

环丙氨嗪在我国5种代表性土壤中的吸附特征

采用批平衡法,研究了环丙氨嗪在江西鹰潭红壤、江苏南京黄棕壤、江苏常熟水稻土、河南封丘潮土和黑龙江海伦黑土5种土壤中的吸附特征.结果表明,环丙氨嗪在5种供试土壤中的吸附过程趋于线性吸附,且均能以Freundlich模型和Langmuir模型较好地进行线性拟合.其中,环丙氨嗪的土壤吸附lgKf值分别为:潮土1.650 5、黄棕壤1.671 5、红壤1.715 3、水稻土2.457 9和黑土2.655 7,表明环丙氨嗪在5种土壤中的吸附行为存在较大差异.Kf与土壤有机质含量呈正相关(r=0.989),与土壤pH之间呈显著负相关(r=-0.938).其吸附自由能变化为-20.8~-23.0 kJ/mol,表明环丙氨嗪在土壤中的吸附主要是物理吸附.     

重金属镉在黑土和棕壤中的解吸行为比较

采用一次平衡法对Cd²⁺在黑土和棕壤2种土壤类型中的解吸行为进行了比较研究.结果表明,Cd²⁺在2种土壤中的解吸行为均有明显的滞后性.相对于棕壤,Cd²⁺在黑土中的解吸有更长的滞后阶段.Cd²⁺在2种土壤中的解吸过程是一个快速反应的过程,当解吸平衡时间在30min左右时,吸附态Cd²⁺的解吸量能达到总解吸量的90%以上.Cd²⁺在2种土壤中的解吸效率都比较低,相对于总吸附量而言,Cd²⁺在黑土和棕壤的解吸百分比分别低于9.0%和15.1%.解吸速率随着初始浓度的增加而升高,但随着解吸量和解吸时间增加而下降,土壤性质对解吸速率的下降并没有明显的影响.Freundlich方程是描述Cd²⁺在这2种土壤中等温解吸的最佳方程,而Elovich方程是描述其在这2种土壤中解吸动力学变化的最佳方程.     

铁锰复合氧化物吸附去除五价锑性能研究

对比研究了铁锰复合氧化物(FMBO)、羟基氧化铁(FeOOH)和二氧化锰(MnO₂)吸附去除五价锑(Sb(V))的性能.结果表明FMBO对Sb(V)具有很好的吸附性能,在pH=5.0的条件下,最大吸附容量达到1.05 mmol·g^-1,略高于FeOOH (0.82 mmol·g^-1)及远高于MnO₂ (0.43 mmol·g^-1);采用Freundlich模型可以很好地描述Sb(V)在FMBO的吸附行为(R² = 0.98).就吸附动力学而言,假二级动力学可很好地描述Sb(V)在FMBO (R² = 0.93)和MnO₂表面的吸附过程(R² = 0.96),而Sb(V)在FeOOH表面的吸附过程可用Elovich模型拟合 (R² = 0.94).Sb(V)的吸附量随着pH值的升高而降低;磷酸盐显著抑制了Sb(V)的吸附,而硫酸盐和碳酸盐影响不大.提高体系离子强度可促进Sb(V)在FMBO表面的吸附,推断Sb(V)在FMBO表面形成内层络合物后被吸附去除.     

氟啶胺在土壤中的吸附解吸与淋溶特性

采用批量平衡法研究了氟啶胺在南京黄棕壤、江西红壤、东北黑土中的吸附解吸特性.结果表明,25℃下,氟啶胺在3种供试土壤中的等温吸附-解吸曲线能较好地符合Freundlich模型,其吸附常数分别为南京黄棕壤119.34,江西红壤202.23,东北黑土311.88,与土壤有机质含量、阳离子代换量和粘粒含量有良好的相关性,相关系数分别为0.9973,0.9690,0.8586.土壤对氟啶胺的吸附自由能变化均小于40kJ/mol,属于物理吸附.氟啶胺在3种土壤中均难淋溶.     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.     

Oxidation of As(Ⅲ) by potassium permanganate

The oxidation of As(Ⅲ) with potassium permanganate was studied under conditions including pH, initial As(Ⅲ) concentration and dosage of Mn(Ⅶ). The results have shown that potassium permanganate was an effective agent for oxidizing of As(Ⅲ) in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As(Ⅲ) by Mn(Ⅶ). Although theoretical redox analyses suggest that Mn(Ⅶ) should have better performance in oxidization of As(Ⅲ) within lower pH ranges, the experimental results show that the oxidation efficiencies of As(Ⅲ) under basic and acidic conditions were similar, which may be due to the adsorption of As(Ⅲ) on the Mn(OH)2 and MnO2 resulting from the oxidation of As(Ⅲ).     

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.     

Chlorobenzenes in waterweeds from the Xijiang River （Guangdong section） of the Pearl River

The Xijiang River is the major source of water for about 4.5 millions of urban population and 28.7 millions of rural population. The water quality is very important for the health of the rural population. The concentration and distribution of chlorobenzenes (CBs) in both water and waterweeds collected from 4 stations in the Xijiang River (Gangdong section) of the Pearl River in April and November were determined. The result showed that nearly every congener of CBs was detected. The total contents of CBs (∑CBs) in the river water ranged from 111.1 to 360.0 ng/L in April and from 151.9 to 481.7 ng/L in November, respectively. The pollution level of CBs in the water in April was higher than that in November. The contents of ∑ CBs in waterweeds ranged from 13.53×102 μg/g to 38.27×102μg/g dry weight (dw). There was no significant difference between April and November in waterweeds. The distribution of CBs in roots, caulis, and leaves of Vallisneria spiralis L. showed different patterns. The leaves mainly contained low-molecular-weight CBs(DCBs), whereas the roots accumulated more PCBs and HCBs. The average lgBCFlip (bioconcentration factor) of CBs ranged from 0.64 to 3.57 in the waterweeds. The spatial distribution character of CBs in the Xijiang River was: Fengkai County ＜ Yunan County ＜Yun'an County ＜ Gaoyao County according to the ∑CBs, and the pollution deteriorated from the upstream to the downstream of the Xijiang River. Further analysis demonstrated that the discharge of waste containing CBs may be the main source of CBs pollution in the Xijiang River.     

Degradation of 2,4-dichlorophenol with a novel TiO2/Ti-Fe-graphite felt photoelectrocatalytic oxidation process

Degradation of 2,4-dichlorophenol(2,4-DCP)was studied in a novel three-electrode photoelectrocatalytic(PEC)integrative oxidation process,and the factors influencing the degradation rate,such as applied current,flow speed of O_2,pH,adscititious voltage and initial 2,4-DCP concentration were investigated and optimized.H_2O_2 was produced nearby cathode and Fe~(2 )continuously generated from Fe anode in solution when current and O_2 were applied,so,main reactions,H_2O_2-assisted TiO_2 PEC oxidation and E-Fenton reaction,occurred during degradation of 2,4-DCP in this integrative system.The degradation ratio of 2,4-DCP was 93% in this integrative oxidation process,while it was only 31% in E-Fenton process and 46% in H_2O_2-assisted TiO_2 PEC process.So,it revealed that the degradation of 2,4-DCP was improved greatly by photoelectrical cooperation effect.By the investigation of pH,it showed that this integrative process could work well in a wide pH range from pH 3 to pH 9.     

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied.Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time,the analysis of the extracts from the soil was carried out using gas chromatography (GC).The photodegradation of pyrethroids in water system was conducted under UV irradiation.The effect of Cu~(2 ) on the pesticides degradation was measured with half life (t_(0.5)) of degradation.It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed.But Cu~(2 ) could accelerate photodegradation of the pyrethroids in water.The t_(0.5) for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil.As for photodegradation,t_(0.5) for cyhalothrin reduced from 173.3 to 115.5 rain and for cypermethrin from 115.5 to 99.0 min.The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms.However, it had catalyst tendency for photodegradation in water system.The difference for the degradation efficiency of pyrethroid isomers in soil was also observed.Copper could obviously accelerate the degradation of some special isomers.     

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.