Arbuscular mycorrhizae enhance metal lead uptake and growth of host plants under a sand culture experiment

A sand culture experiment was conducted to investigate whether mycorrhizal colonization and mycorrhizal fungal vesicular numbers were influenced by metal lead, and whether mycorrhizae enhance host plants tolerance to metal lead. Metal lead was applied as Pb(NO3)2 in solution at three levels (0, 300 and 600 mg kg(-1) sand). Five mycorrhizal host plant species, Kummerowia striata (Thunb.) Schindl, Ixeris denticulate L., Lolium perenne L., Trifolium repens L. and Echinochloa crusgalli var. mitis were used to examine Pb-mycorrhizal interactions. The arbuscular mycorrhizal inoculum consisted of mixed spores of mycorrhizal fungal species directly isolated from orchard soil. Compared to the untreated control, both Pb concentrations reduced mycorrhizal colonization by 3.8-70.4%. Numbers of AM fungal vesicles increased by 13.2-51.5% in 300 mg Pb kg(-1) sand but decreased by 9.4-50.9% in 600 mg Pb kg(-1) sand. Mycorrhizae significantly enhanced Pb accumulation both in shoot by 10.2-85.5% and in root by 9.3-118.4%. Mycorrhizae also enhanced shoot biomass and shoot P concentration under both Pb concentrations. Root/shoot ratios of Pb concentration were higher in highly mycorrhizal plant species (K.striata, I. denticulate, and E. crusgalli var. mitis) than that in poorly mycorrhizal ones (L. perenne and T. repens,). Mycorrhizal inoculation increased the root/shoot ratio of Pb concentration of highly mycorrhizal plant species by 7.6-57.2% but did not affect the poorly mycorrhizal ones. In the treatments with 300 Pb mg kg(-1) sand, plant species with higher vesicular numbers tended to show higher root/shoot ratios of the Pb concentration. We suggest that under an elevated Pb condition, mycorrhizae could promote plant growth by increasing P uptake and mitigate Pb toxicity by sequestrating more Pb in roots.     

Investigation on the influence of methanol on adsorption and leaching of pesticides with soil column liquid chromatography

The effect of methanol of low concentration on adsorption and leaching of atrazine and tebuconazole was studied in this paper. The adsorption coefficients and the retardation factors (R^m) of pesticides on EUROSOIL 3# log-linearly decreased as volumetric fraction of methanol (f^c) was increased in the binary solvent mixtures of methanol and water. These data are consistent with solvophobic theory formerly outlined for describing the adsorption and transport of hydrophobic organic chemicals from mixed solvents. Nevertheless, the adsorption of these pesticides in soil–water system slightly increased when the soil was pre-washed with methanol in comparison with that pre-washed with water (pure water system). Furthermore, their adsorption coefficients were still higher in binary solvent systems with methanol of very low concentrations, i.e. f^c<0.03 for atrazine and f^c<0.01 for tebuconazole, than those in pure water system. The adsorption coefficients (logK^w) of atrazine and tebuconazole predicted by solvophobic theory were 0.5792 and 1.6525, respectively, and their experimental logK^w were 0.3701 and 1.6275 in pure water system. Obviously, the predicted logK^w of the two pesticides was higher than the experimental log K^w in pure water system. The predicted K^w and the retardation factor (R^w) in pure water system by solvophobic theory are thus possibly inaccurate.     

Persistent organic pollutants in water and surface sediments of Taihu Lake,China and risk assessment

Organic pollutants, especially persistent organic pollutants were examined in the water and surface sediments of Taihu Lake, China. Both 12 water and 12 sediment samples were collected over the lake. C-18 solid-phase extraction technique was applied to extract organic pollutants in collected water samples. Soxhlet extraction procedure was used to extract organic pollutants in sediment samples. The analysis was performed by GC-MS controlled by a Hewlett Packard chemstation. Two hundred and seventy-three kinds of organic chemicals in water were examined, 200 more than that detected in 1985; 188 kinds of chemicals in sediments were detected as well. Among them 21 kinds of chemicals belong to priority pollutants as well as 17 kinds to be the endocrine disruptors. The concentrations of the pollutants were more than 2 times higher than that in 1985. The possible source and relation to anthropogenic activity were discussed.     

等离子体协同光催化去除模拟烟气中SO2的实验研究

近年来,低温等离子体技术以及纳米TiO₂光催化技术在烟气脱硫中的应用越来越引起人们的关注。利用填充床反应器将这2种技术有机地结合起来，进行了大量脱硫实验研究。研究结果表明，等离子体协同光催化去除烟气中的SO₂与单独采用等离子体技术相比，其SO₂的去除率可提高5%～20%。同时，探讨了等离子体协同TiO₂光催化剂的脱硫机理，分别研究了外加电压、气体流量和SO₂初始浓度等因素对脱硫效率的影响。实验结果表明，当SO₂初始浓度为800 mg/m³，输入电压为17.5 kV，气体流量为0.2 m³/h时，SO₂脱除率可以达到77.6%。     

新型高效污水处理设备--集成一体化生物转筒反应器

介绍了一种新型高效污水处理设备--集成一体化生物转筒反应器(IBDR).IBDR具有微生物浓度高、活性强、生物相分级明显、耐冲击负荷、污泥沉降性能好和不产生污泥膨胀、操作简单灵活、运行成本低等显著特点;并成功地运用于处理餐饮污水和深圳某厂洗涤剂生产废水.在处理餐饮污水时,IBDR比传统的生物转盘处理效果高出20%.     

印刷线路板废弃物的热解与动力学实验研究

分别应用管式炉反应器和热重分析手段对印刷线路板废弃物的热解行为和热解动力学进行了实验研究。在管式炉中，研究不同的热解温度：700～950℃，对产物分布和气体成分分布的影响。实验结果表明：PCB热解气体的主要成分是H2和CO2，气体的热值较低，仅为2．09～5．41MJ/m^3，PCB不适合以气体产物为目标的能源利用方式。应用Friedman方法对PCB的热解动力学进行了研究，求得PCB的热解动力学参数分别是：表观活化能190．92kJ/mol，反应级数5．97，指前因子lnA47．14min^-1。     

地下水环境中反硝化作用

地下水氮污染已是全球性的环境问题 ,反硝化作用是地下水脱氮的主要机制。本文综述了地下水环境中反硝化作用的判据、速率、影响因素以及人工强化措施 ,指出了存在的问题和今后的发展方向     

Recolonization and succession of marine macrobenthos in organic-enriched sediment deposited from fish farms

High organic loading deposited on the sea bottom by marine fish farming activities often eliminates benthic organisms in the vicinity. In this study, organic-enriched sediment collected underneath a fish farm was defaunated, placed in settling trays and exposed to the subtidal area of a clean site of similar hydrography. Trays were sampled monthly for a consecutive period of 5 months, and recolonization and successional patterns of macrobenthos were studied using univariate and multivariate statistics. Recolonization occurred rapidly, and averages of 144 animals/tray and 26 species/tray were recorded within the first month. Molluscs accounted for 49% of species and polychaetes for 77% of abundance during the first month of recolonization. Temporal changes in abundance, diversity and species composition found in subsequent months resembled spatial changes of benthic community along a decreasing pollution gradient generalised by Pearson and Rosenberg (1978, Oceanography & Marine Biology Annual Review 16, 229-311). Abundance reached a peak after 3 months (434 animals/tray) and then declined. Species number also increased, peaked after 4 months (47 species/tray), and was followed by a decrease. The polychaete Prionospio malmgreni succeeded Pseudopolydora paucibranchiata as the dominant species after the first month, reached a peak (194 animals/tray) after 3 months, then declined sharply. The rapid recolonization and succession of the macrobenthic community on organic-enriched sediment suggested that present fish farming methods are unlikely to have a long-term impact on benthic communities once farming activities are reduced/ceased.     

Occurrence and behavior of wastewater indicators in the Santa Ana River and the underlying aquifers.

The occurrence and behavior of wastewater indicator compounds in the Santa Ana River (SAR) water and the underlying aquifer recharged by the SAR has been studied. The SAR contains a high proportion of tertiary treated wastewater effluents, up to 100% during summer and fall. The following water quality parameters were quantified: four specific wastewater indicator compounds, ethylene diaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), a naphthalene dicarboxylate (NDC) isomer, alkylphenol polyethoxy carboxylates (APECs), and selected haloacetic acids (HAAs), nitrate, dissolved oxygen (DO), DOC, total carbohydrate, and phenolic substances. Statistical analysis indicated that normal distribution was adequate to describe the probability distribution of the constituents in most cases. In the river, the concentrations of wastewater indicator compounds decreased as the fraction of storm runoff increased. EDTA and NDC were detected in a monitoring well near the river and in two production wells 1.8 and 2.7 km down gradient with little apparent attenuation. By contrast, NTA, APECs, bromochloro- and dibromoacetic acids appeared to be attenuated significantly during infiltration of river water and groundwater transport.     

净化烹饪油污微生物菌种的选育

利用正交试验方法优化了净化烹饪油污菌种选育的环境和营养条件 ,即 :油 :2 0mL、NaNO3( 2g L) :4mL、KH2 PO4( 0 .5g L) :3mL、微量元素溶液 (CuSO4·5H2 O 0 .0 3g L ,ZnSO4·7H2 O 0 .1g L ,MnCl2 ·4H2 O 0 .0 5g L) :1mL和温度 3 7℃ ;而且得出氮源是影响菌体增长的最重要因素 ,温度是影响微生物降解的重要因素 ,而微量元素和磷源对菌种培育结果影响较小。在此优化条件下选育出了合适降解烹饪油污的c种子菌液 ,其每天可降解油 2 2mg L以上 ,并鉴定出主要的微生物是嗜水性气单孢菌 (Aeromonashydrophila 4AK4)、黄丝藻属 (Tribonema)和多甲藻属 (Peridinium)等菌体 ;分析了选育过程活性微生物、目标污染物和微生物的代谢产物三者之间的关系 ,发现所选微生物能利用油类物质作为碳源进行生长代谢