不同植物与水力负荷对人工湿地脱氮除磷的影响

通过6种湿地植物的表流 (SF) 和潜流(SSF)人工湿地对比实验,分析了不同植物的SF和SSF人工湿地去除率随水力负荷(HL)变化的规律,得到了6种不同植物的SF和SSF人工湿地的最优HL、最优去除率.实验结果表明:6种植物的SF和SSF人工湿地对TP、TN去除率随HL的增加而降低,且植物不同,去除率降低趋势不同,且SSF人工湿地去除率降低值比SF小.SF人工湿地TP、TN去除率比SSF低,且TP去除率比TN大.SF人工湿地中水葱对TP、TN去除率降低最大,水芹菜对TP去除率降低最小,美人蕉对TN去除率降低最小;SSF人工湿地中美人蕉对TP去除率降低最大,水芹菜最小对TP去除率降低最小.芦苇对TN 去除率降低最大,水葫芦对TN去除率降低最小.6种植物SF人工湿地去除TP和TN的平均最优HL分别为0.53,0.47t/(m2×d);SSF人工湿地去除TP、TN平均最优HL分别为0.68,0.44t/(m2×d).     

人工湿地处理污染河水和湿地植物腐烂分解影响研究

以高原复合型人工湿地为研究对象,在水力负荷为0.067 m/d的条件下,监测湿地对CODCr、TN、TP、氨氮的去除率达到了66.3%、82.5%、43.2%、76%;采集了梭鱼草、美人蕉、芦苇、水葱、茭白、再力花6种挺水植物地上部分,测定了它们的TN、TP、有机质等营养物质含量和它们腐烂分解过程中TN、TP、COD等释放强度。结果表明:梭鱼草、美人蕉、茭白释放强度较强,再力花和芦苇释放强度较弱,在选择湿地植物时综合考虑植物吸收污染物能力情况下,可以优先考虑再力花、芦苇等植物。     

洱海湖滨带挺水植物残体腐解特征及其环境效应初探

采用试验模拟的方法,研究洱海4种主要挺水植物茭草(Zizania caduciflora)、香蒲(Typha latifolia)、水葱(Scirpus validus)和芦苇(Phragnites australis)在水体中的腐解特征. 结果表明:在21 d的腐解试验中,水葱腐解速率最快,茭草和香蒲其次,芦苇最慢; 挺水植物单位干物质TN释放量表现为水葱>茭草≈香蒲>芦苇,TP释放量表现为水葱>茭草>香蒲>芦苇; 4种植物TP释放率均高于TN,腐解出的TP进入水体的比例也明显高于TN. 水体中ρ(TN),ρ(TP)及ρ(COD_Cr)均在腐解初期(1～3 d)快速上升,pH和ρ(DO)快速下降; 随后,ρ(TN),ρ(TP)及ρ(COD_Cr)均缓慢下降,pH和ρ(DO)则缓慢回升. 结合洱海湖滨带挺水植物空间分布的调查结果,估算全湖湖滨带4种挺水植物中TN和TP的总质量分别为17.622和2.870 t,其中茭草和香蒲中的TN和TP分别占91%和95%,对茭草和香蒲进行适时、适宜的收割对改善湖滨带的水质具有重要的意义.      

人工湿地处理污染河水和湿地植物腐烂分解影响研究

以高原复合型人工湿地为研究对象,在水力负荷为0．067m／d的条件下,监测湿地对CODCr、TN、TP、氨氮的去除率达到了66．3％、82．5％、43．2％、76％;采集了梭鱼草、美人蕉、芦苇、水葱、茭白、再力花6种挺水植物地上部分,测定了它们的TN、TP、有机质等营养物质含量和它们腐烂分解过程中TN、TP、COD等释放强度。结果表明：梭鱼草、美人蕉、茭白释放强度较强,再力花和芦苇释放强度较弱,在选择湿地植物时综合考虑植物吸收污染物能力情况下,可以优先考虑再力花、芦苇等植物。     

农田排灌水的稳定塘-植物床复合系统处理

采用稳定塘-植物床系统处理农田排灌水,植物床栽植茭草和芦苇.监测结果表明,雨季、旱季平均流量分别为417.1,206.8m3/d,无降雨期间渗漏、蒸发蒸腾损失的水量之和占进水的42.1%～60.5%.系统雨季进水COD、总氮(TN)、氨氮和总磷(TP)平均浓度分别为97.9,8.09,3.38,0.69mg/L,旱季分别为112,7.76,3.78,0.98mg/L.各项污染物平均去除率大于57%.芦苇和茭草的生长速度在5月最大.因植物收割去除的N和P量分别占进水的14.6%和27.1%.从2002年4月~2003年7月湿地截留SS量为297.5m³.     

多级垂直流人工湿地对北方农村生活污水的处理分析

文章采用多级垂直流人工湿地处理北方农村生活污水,考察了稳定运行期水力负荷、植物收割以及季节对COD、NH~+_4-N、TN和TP的去除影响。结果表明:COD、TN和TP去除随水力负荷增加呈递减趋势,在0.15 m~3/(m~2·d)时去除最佳,出水浓度分别为18～30、9～25和0.4～0.5 mg/L。NH~+_4-N去除随水力负荷增加呈先增后减趋势,在0.25 m~3/(m~2·d)时去除率最佳,出水浓度为0～6 mg/L。在水力负荷为0.15 m~3/(m~2·d)时,植物收割后COD、NH~+_4-N、TN和TP的去除均有所降低。不同季节时,夏季湿地处理效果最佳,冬季最差。同时对比实验表明,夏季水力负荷为0.15 m~3/(m~2·d)时,多级垂直流人工湿地对COD、NH~+_4-N、TN和TP的去除效果优于单级水平流人工湿地,其出水达到城镇污水处理厂污染物排放一级A标准。     

高水力负荷对人工湿地处理精养虾塘排水效果的影响

通过水平潜流人工湿地处理精养虾塘排水的中试试验,探讨了在不同高水力负荷条件下[1.10～5.34 m3.(m2.d)-1]人工湿地对有机物、氮磷以及悬浮物的去除效果,以期为其设计运行提供参考.结果表明,水力负荷与COD、TN、TP、SS的去除率呈负相关;COD、TN、SS去除速率随水力负荷的升高,先升后降,最高分别达到69、1.8和117.6 g.(m2.d)-1;TP的去除速率随水力负荷的升高变化并不明显.人工湿地在水力负荷2.52～3.24 m3.(m2.d)-1范围内运行时,污染物去除总量最高处理效果最佳.     

表面流人工湿地中水生植被的净化效应与组合系统净化效果

以无植物空白系统为对照,通过批量盆栽试验探讨了表面流人工湿地中不同类型水生植被(苦草(沉水植物)、水葫芦(浮水植物)、芦苇(挺水植物))的引人对富营养化水体不同污染物净化效果的影响;根据不同污染物去除的阶段性特征设计了分段式表面流人工湿地(好氧塘-水葫芦湿地一苦草湿地),并通过示范工程探讨了富营养河流的原位净化效果.研究表明,批量盆栽试验中,与无植物空白系统相比,芦苇的引入显著增加了表面流人工湿地的蒸发蒸腾量(为无植物空白系统的1.5倍),而水葫芦和苦草的引入则显著降低了表面流人工湿地的蒸发蒸腾量(分别为无植物空白系统的80%和30%);3种水生植物的引入均显著促进了CODcr、TN、NH 4-N的去除(与无植物空白系统相比),其中水葫芦系统具有最好的CODcr和TN去除效果(起始CODcr和TN水平分别为35.8 mg·L-1和6.86 mg˙L-1时,去除率分别为58.91%、76.67%),而苦草的引入则显著地促进了水体中氧化态氮的形成与积累.分段式表面流人工湿地的原位净化研究表明,水力负荷为6.2cm.d-1时,分段式表面流人工湿地对CODcr的净化效果较好,水力负荷过高会影响分段式表面流人工湿地的净化效果.     

植物吸收在人工湿地脱氮除磷中的贡献

通过研究人工湿地植物对氮、磷的吸收能力,评价植物吸收在人工湿地脱氮除磷方面的贡献. 结果表明,不同湿地植物其组织中w(TN)和w(TP)差异极显著,湿地植物对TN和TP的吸收量分别为6.1～94.0和0.5～9.0 g/(m2·a). 按全年衡算,湿地植物对TN和TP的吸收量分别占人工湿地TN和TP去除量的0.6%～17.3%和1.4%～41.2%. 但由于湿地植物吸收的TN和TP中有相当一部分是储存在湿地植物的地下部,通过收获植物地上部的TN和TP吸收量仅占人工湿地TN和TP去除量的0.3%～14.1%和0.8%～19.6%. 由此可见,湿地植物的直接吸收在人工湿地系统氮、磷去除中不占重要地位,人工湿地植物的选择和利用应该更注重其间接生态效应的发挥.      

一种多介质层波形潜流人工湿地处理重污染河水试验

我国河流污染严重,城市黑臭水体的比率日益增加。人工湿地作为一种高效低耗能的绿色处理技术,已被广泛应用于污染河水的治理。通过对比分析分层装填复合填料的多介质层波形潜流人工湿地和单一砾石填料的普通人工湿地处理重污染河水的效果,研究了特种基质填料强化脱氮除磷作用以及不同水力负荷条件的影响。试验结果表明:在水力负荷为0.2 m~3/(m~2·d)时,普通湿地对COD、NH3-N、TN和TP的去除率分别达到55.95%、77.85%、39.80%和54.94%;多介质层湿地对COD、NH3-N、TN和TP的去除率分别达到58.52%、75.99%、67.08%和57.31%。在水力负荷为0.5 m~3/(m~2·d)时,普通湿地对COD、NH3-N、TN和TP的去除率分别达到68.46%、90.73%、42.13%和53.70%;多介质层湿地对COD、NH3-N、TN和TP的去除率分别达到69.61%、89.94%、77.58%和68.63%,其脱氮效果明显好于普通湿地。以复合填料包分层装填的波形潜流人工湿地系统具有良好的脱氮除磷效果,有很好的推广应用价值。     

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.     

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.     

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.     

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.