降雨对不同形态土壤铅迁移转化的影响研究

以修正的BCR连续提取法为基础,将土壤铅分为酸可提取态铅、可还原态铅、可氧化态铅和残渣态铅这4种形态,运用室内土柱淋溶模拟实验,研究了降雨pH及降雨量对土壤中不同形态铅迁移转化的影响。结果表明,降雨pH能明显影响土壤pH;土壤中酸可提取态铅在降雨作用下最易迁移,经pH=7.04的降雨淋溶后,酸可提取态铅基本释放完;可还原态铅含量随降雨pH的降低及降雨量的增加而逐渐降低;可氧化态铅较稳定,基本不受降雨pH及降雨量的影响;而残渣态铅经pH=4.28的降雨淋溶后,含量反而增加,这可能是其他形态铅向其转化造成的;在降雨作用下,不同形态土壤铅表现出迁移性:酸可提取态铅可还原态铅可氧化态铅残渣态铅;另外,降雨pH及降雨量对土壤中铅的形态分布也有明显影响。     

硫酸净化工序的改造及稀酸的利用

硫酸净化工序污水或稀酸中，不仅含有硫酸和大量的矿尘，而且还含有的砷、氟等有害物质，采用半封闭酸洗流程，可减少排污和中和量，回收利用稀酸，稳定达标排污，有着明显的企业经济效益和社会经济效益。水洗流程改为半封闭酸洗流程，投资少，工期短，见效快，对现在仍然采用水洗流程的中小硫酸装置具有借鉴作用。     

某铬盐厂Cr(Ⅵ)污染土壤还原稳定化效果研究

以某铬盐厂铬渣堆存场地内Cr(Ⅵ)污染土壤为研究对象,采用七水硫酸亚铁(Fe SO_4·7H_2O)、多硫化钙(Ca Sx)、Fe SO_4·7H_2O和Ca Sx、Fe SO_4·7H_2O和水泥4种药剂开展Cr(Ⅵ)污染土壤的还原稳定化实验,并利用BCR连续提取法进行铬形态分析。结果表明,Cr(Ⅵ)还原效果:Fe SO_4·7H_2O和Ca Sx复配药剂在4种药剂中对Cr(Ⅵ)的整体还原效果最好。铬稳定效果:Fe SO_4·7H_2O和水泥复配药剂在4种药剂中对土壤铬的稳定性最好,Fe SO_4·7H_2O和水泥复配药剂处理对铬的形态分布的影响是使弱酸提取态、可还原态和可氧化态转化成残渣态,处理后残渣态铬质量分数高达30.98%。污染土壤中铬的形态分布为可氧化态(63.67%)残渣态(23.29%)弱酸提取态(6.80%)可还原态(6.25%),4种药剂处理后土壤中铬的形态分布为可氧化态残渣态可还原态弱酸提取态。     

硝酸、氢氟酸酸洗废液的再生

不锈钢的表面,在加工过程中产生一层氧化物(通称铁鳞),一般用8—12％的硝酸和3—5％的氢氟酸酸洗去除。经多次酸洗,酸洗液中的金属离子增加到一定的浓度(铁20—25克/升时),失去酸洗能力成为废液而外排。此废液中的总酸度还是相当高的,并含有大量的铁、镍、铬盐。如任其外排,将引起不良后果。硝、氟酸是强腐蚀剂;硝酸盐能助长浮游生物的繁殖;氟离子会在鱼体内累积;铬是剧毒物质,严重的污染环境。所以必须禁止酸洗废液不经处理任意外排。此外,硝、氟酸的价格较贵(硝酸0.5元/公斤,氢氟酸4元/公斤,硫酸0.18元/公斤),1立方米     

不同畜禽粪与化肥配施对黑土中Cu有效性的影响及相关因素分析

本文通过培养试验,研究了不同畜禽粪与化肥配施对黑土中Cu总量及形态3年内动态变化的影响,并对影响Cu形态变化的相关因素进行了分析.研究结果显示:不同畜禽粪与化肥配施增加了土壤中Cu的总量,增加效果依次为:猪粪与化肥配施鸡粪与化肥配施牛粪与化肥配施.不同畜禽粪与化肥配施导致了土壤中各形态Cu含量增加,增幅依次为:猪粪与化肥配施鸡粪与化肥配施牛粪与化肥配施.此外,不同畜禽粪与化肥配施还导致了土壤中酸可提取态Cu和残渣态Cu比例增加,可还原态Cu和可氧化态Cu比例减少,变化幅度均呈现猪粪与化肥配施鸡粪与化肥配施牛粪与化肥配施的规律.由于酸可提取态Cu占全Cu比例较小(增加后比例仍不足2%),故其对Cu有效性的影响微乎其微,而残渣态Cu的增加,可还原态、可氧化态Cu的减少均表明:不同畜禽粪与化肥配施降低了土壤中Cu的有效性.对于影响Cu形态的相关因素分析,研究结果表明:土壤中各形态Cu与pH值间相关性不显著,但其与有机质含量间相关性极其显著.酸可提取态、残渣态Cu与有机质含量呈显著负相关,可还原态、可氧化态Cu与有机质含量呈显著正相关.此外,畜禽粪与化肥配施增加了土壤中各形态Cu与pH值间的相关性,但对其与有机质含量间关系影响不大.     

南四湖及主要入湖河流表层沉积物重金属形态组成及污染研究

采用BCR（SM&T）方法对南四湖及主要入湖河流丰水季节表层沉积物中Cr、Cu、Mn、Ni、Pb、Zn 6种重金属元素的酸提取态、可还原态、可氧化态及残渣态进行了连续提取,分析了各水体单元表层沉积物重金属元素的形态组合特征、人为污染状况及潜在生态风险.研究结果表明,泗河、京杭运河、洙赵新河、府河上游、上级湖南部湖区及下级湖区表层沉积物中Cr、Cu、Ni、Zn以残渣态为主,其含量可占到该元素总量的80%～90％,人为污染程度较弱;老运河、府河入湖口、白马河表层沉积物中Cr、Cu、Ni、Zn的残渣态含量明显降低,而可提取态（酸提取态、可还原态、可氧化态）含量可增至80％以上,其中以可氧化态、酸提取态为主,人为污染程度较重;各水体单元表层沉积物中Pb、Mn以残渣态和可氧化态为主,其含量占Pb、Mn含量的95％、70％左右,基本未受人为污染.随着表层沉积物中有机物的矿化分解及环境条件的改变,老运河、府河入湖口、白马河等重金属人为污染较重的沉积物中Cr、Cu、Ni、Zn的可氧化态、酸提取态及可还原态可发生活化,具有较高的潜在生态风险.     

三江平原土地利用方式变化对土壤锰形态影响

在充分调查三江平原不同土地利用方式下土壤中锰含量及其形态分布特征的基础上,探讨了环境因子与土壤中不同锰形态的关系,以揭示锰形态变化对土地利用变化改变的响应.湿地土壤中总锰(Mntot)含量处于较低水平.不同土地利用方式下,林地土壤中Mntot要高于湿地和农田.湿地垦殖为旱田,土壤Mntot有增加趋势;湿地垦殖为水田,土壤Mntot有减少趋势.三江平原土壤中锰主要以残渣态(Mnres)和可还原态(Mnred)为主,可交换态(Mnext)与可氧化态锰(Mnoxi)含量次之.湿地、旱田及水稻田这3种土地利用方式下,土壤中可氧化态锰含量占总锰比例差异显著.湿地垦殖方向不同,对土壤中可氧化态锰影响最大.三江平原土壤中Mntot及不同锰形态含量主要受到土壤中S、pH、DOC这3种环境因子影响.     

白洋淀铁锰的分布水平及迁移特征

为确定白洋淀的铁锰分布水平,在白洋淀国控点采集上覆水和沉积物进行监测分析,并通过潜在迁移指数评价了铁锰的潜在风险。结果表明:白洋淀上覆水中铁锰含量平均值分别为0.10mg/L、0.41mg/L,其中铁能够达到地表水水质标准,锰超标。沉积物中铁含量平均值为2.49mg/kg;锰含量在府河入淀口南刘庄浓度达到2260mg/kg,明显高于其他采样点,其余几个采样点的平均值为95mg/kg。铁的存在形态浓度从大到小依次为:残渣态酸溶态可还原态可氧化态;锰的存在形态浓度顺序为:酸溶态残渣态可还原态可氧化态。沉积物中铁、锰的潜在迁移指数平均值分别为46.95%、62.23%。说明锰的潜在迁移可能性大于铁,更易形成二次污染。     

安溪铁观音茶园土壤重金属赋存形态及生态风险评价

用改进的BCR连续提取法提取安溪铁观音茶园土壤中重金属元素(Li、Fe、Zn、Ba、Sr、Ti、Co、Cr、Cd、Mn、Ni、Pb、V、Mg、Cu)的赋存形态,分析其生物有效性并作出生态风险评价。重金属赋存形态研究结果表明,Cd的形态总体分布为弱酸溶态残渣态可还原态可氧化态,Pb的形态总体分布为可还原态可氧化态弱酸溶态残渣态,Cu的形态总体分布为可还原态可氧化态残渣态弱酸溶态,其余重金属皆以残渣态为主。生物有效性分析结果表明,Pb、Cd、Cu、Mn、Ni、Sr等重金属的潜在生物可利用性较高,其所占百分比分别为90.4%、73.0%、36.6%、32.8%、23.8%、22.9%。对茶园土壤中的重金属作生态风险评价,地累积指数法和潜在生态危害指数法结果均表明,大部分土壤样品是清洁安全的,部分土壤受到Cd元素污染,污染程度达到中度污染级别。     

三峡库区消落带土壤重金属Zn的形态分布特征及其影响因素

以位于三峡库区腹心地带的一级支流—小江消落带为研究区,通过野外采样和室内分析,对消落带上土壤重金属Zn及其化学形态的含量特征进行了分析,并采用相关分析和逐步回归法探讨了影响重金属化学形态的影响因素。结果表明,消落带土壤重金属Zn全量、酸溶态、可还原态、可氧化态、残渣态平均含量分别为126.03mg.kg-1,3.60mg.kg-1、5.44mg.kg-1、10.59mg.kg-1和106.40mg.kg-1。Zn全量及其化学形态含量在小江各区段的分布呈中游段最高,上游、中下游段较低的特征,这主要与小江流域消落带各区段的地质背景有关。Zn不同形态含量受Zn全量及土壤理化性质影响的显著性程度不同。可还原态主要受Zn全量的影响;可氧化态主要受泥粒含量的影响;残渣态受Zn全量和有机质含量的共同影响;酸溶态含量受Zn全量和土壤理化性质的影响均不显著。     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

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.     

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.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

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.     

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.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.