The Use of Surfactants as Possible Enhancers in Bioremediation of Creosote Contaminated Soil

A study on five nonionic surfactants (Arkopal-N-060, Arkopal-N-080, Arkopal-N-100, Hosaf-541-KS and Tween-80)commercially available in South Africa was carried out todetermine their effect on the desorption and degradation ofcreosote in a soil contaminated with 250 000 mg kg^-1creosote with a view to developing a cost effective methodologyfor treating creosote contaminated soils. The surfactants werestudied in concentrations of 0.01, 0.1, 0.35, 0.5 and 1.0% (v/v) in liquid cultures. Results from the studies showedthat all the surfactants studied were able to enhance thedesorption and degradation of creosote to different extents. Theenhancement ranged from as little as <10% in 0.1% surfactant toas high as 45% in 0.5% surfactant. The effect on degradation ofcreosote was more obvious (30–65%) in the different surfactantsat different concentrations. Arkopal-N-060 was observed to be themost effective in the desorption and degradation of creosote. Theeffect of Hosaf-541-KS on the degradation of creosote was foundto be comparable with those of Arkopal-N-060, however, itsdesorption capabilities were much lower than those of Arkopa-N-060.The concentration of the surfactant was found to play asignificant role in desorption of creosote. It was observed thatsurfactant concentrations of 0.35 and 0.5% were the mosteffective in the desorption of creosote. Above and below theseconcentrations, the effect of the surfactants was observed todecrease. All surfactants studied were not found to inhibitmicrobial growth at the concentrations studied.     

Fungal Bioremediation of Creosote-Contaminated Soil: A Laboratory Scale Bioremediation Study Using Indigenous Soil Fungi

The aim of the study is to determine the efficacy of indigenous soil fungi in removing (PAHs) from creosote-contaminated soil with a view to developing a bioremediation strategy for creosote-contaminated soil. Five fungal isolates, Cladosporium, Fusarium, Penicillium, Aspergillus and Pleurotus, were separatelyinoculated onto sterile barley grains and incubated in the dark. Thecolonized barley was inoculated onto creosote-contaminated (250 000 mg kg^?1) soil in 18 duplicate treatments and incubated at 25 °C forseventy days. The soil was amended with nutrient supplements to give a C:N:Pratio of 25:5:1 and tilled weekly. Creosote removal was higher (between 78and 94%) in nutrient supplemented treatments than in the un-supplementedones (between 65 and 88%). A mixed population of fungi was more effective(94.1% in the nutrient amended treatment) in creosote removal than singlepopulations wit a maximum of 88%. Barley supported better fungal growthand PAH removal. Pleurotus sp. removed the creosote more than the other isolates. Two andthree-ring PAHs were more susceptible to removal than the 4- and 5-ringPAHs, which continued to remain in small amounts to the end of thetreatment. Reduction of creosote in the present study was higher than wasobserved in an earlier experiment using a consortium of microorganisms, mainly bacteria, on the same contaminated soil (Atagana, 2003).     

Microtox技术检测多环芳烃生物毒性的研究

利用Microtox技术检测 5种多环芳烃化合物生物毒性结果表明 ,二甲亚砜配制的测试液中萘、菲及荧蒽均对发光细菌具有一定生物毒性 ,且随浓度的增大而增强 ,相同浓度下毒性菲 >萘 ;测试液中当萘浓度小于其溶解度时即产生 10 0 %的抑光率 ,萘EC50 为 4 .32mg/L ,而菲及荧蒽浓度近其溶解度时所产生的最大抑光率分别为 <5 0 %和15 %左右 ;芘及蒽最大浓度时则对发光细菌无生物毒性显示。表明Microtox技术可有效检测低环化合物萘的生物毒性 ,但对高环化合物 (≥ 3环 )的检测因受其低水溶性的限制而灵敏度降低 ,利用二甲亚砜获取多环芳烃污染物提取液的生物毒性主要与低分子化合物萘及菲有关     

Isolation and Determination of Polycyclic Aromatic Hydrocarbons in Surface Runoff and Sediments

The distribution of Polycyclic Aromatic Hydrocarbons (PAHs) was investigated in surface runoff and sediments of Lagos, Osogbo and Ile-Ife Western areas of Nigeria. Method for the analysis of PAHs was based on Liquid-Liquid extraction of the runoff and a soxhlet extraction of the sediments followed by a clean up adsorption procedure. The PAHs were separated and quantified by Gas Chromatography-Mass spectrometry (GC-MS) technique. A blank experiment was done using triply distilled water and following the same procedure for the samples to establish blank levels. In both street runoff and sediments 13 PAHs were identified and quantified. At Osogbo and Ile-Ife areas, the mean levels of PAHs in surface runoff ranged between 0.10–15.81 mg L^-1 while in the Lagos area the levels were between 0.1–73.72 mg L^-1. Generally, the PAH levels in surface runoff of Lagos constitute 53.03 mg L^-1 average ∑ PAH detected in the study area compared to 31.96 mg L^-1 average ∑ PAH contribution made by samples from Osogbo and Ile-Ife. The levels of PAHs in sediments are relatively higher compared to those of the street runoff in the study area. PAHs in sediment of Lagos contribute an average of 228.57 mg kg^-1 ∑ PAH to the total sediment PAH burden compared to Osogbo and Ile-Ife areas that contribute only 91.13 mg kg^-1 average ∑ PAH to the total PAH burden of the study area. The relatively higher average ∑ PAHs reported for Lagos area compared with those of Osogbo and Ile-Ife, is consistent with higher industrial activities and traffic density of the former (1000–10000 vehicles/hr) than the later (450–1500 vehicles/hr).     

源于松针的可溶性有机物对土壤多环芳烃吸附和解吸行为的影响研究

Study of the relationship between plant litter-derived dissolved organic matter（DOM） and organic pollutant transport in soil is important for understanding the role of forest litter carbon cycling in influencing pollutant behaviour and fate in forest soil.With the aim of providing insight into the capacity of plant litter-derived DOM to influence sorption and desorption of selected polycyclic aromatic hydrocarbons（PAHs） on soil, batch experiments were carried out with application of a sorption-desorption model incorporating DOM effects. Freshly fallen pine（Pinus elliottii） needles were used as the source of organic matter. Input of the pine needle litter-derived DOM was found to significantly decrease desorption hysteresis as well as soil adsorption capacity of phenanthrene（PHE） and fluoranthene（FLA）. Addition of 1 728 mg L-1dissolved organic carbon（DOC） lowered the organic carbon-normalized sorption distribution coefficient of PHE from 7 776 to 2 541 L kg-1C and of FLA from 11 503 to 4 368 L kg-1C. Decreases of the apparent sorption-desorption distribution coefficients of PHE and FLA with increased DOC concentration indicated that DOM favored desorption of PAHs from soil. Increases in the fraction of apparently dissolved PAHs were attributable to the dissolved PAH-DOM complexes, accounting for the dissolved proportions of 39% to 69% for PHE and 26% to 72% for FLA in the sorption and desorption processes as the concentration of the added DOM solution rose from 0 to 1 728 mg L-1. Our results suggest that pine needle litterderived DOM can have a substantial effect of inhibiting PAHs sorption and promoting PAHs desorption, thus leading to enhanced leaching in soil, which should be taken into account in risk assessment of PAHs accumulated in forest soil.     

长江三角洲地区污泥中多环芳烃的污染研究

To ascertain the contaminated conditions of polycyclic aromatic hydrocarbons （PAHs） in sludge and to evaluate the risk of application of this sludge for agricultural purposes, 44 sludge samples obtained from 15 cities in the Yangtze River Delta area of China were investigated using capillary gas chromatography/mass spectrometry （GC/MS） after ultrasonic extraction and silica gel cleanup. PAHs＇ contents ranged from 0.0167 to 15.4860 mg kg^-1 （dry weight, DW） and averaged 1.376 mg kg^-1, with most samples containing 〈 1.5 mg kg^-1. Pyrene （PY）, fluoranthene （FL）, benzo[b]fluoranthene （BbF）, indeno[1,2,3-cd]pyrene （IND）, benzo[a]pyrene （B[a]P）, and benzo[g,h,i]perylene （BghiP） were the most dominant compounds, ranging from 0.1582 to 0.2518 mg kg^-1. Single PAH, such as naphthalene （NAP, 2-benzene rings）, phenanthrene （PA, 3-benzene rings）, PY （4-benzene rings）, and FL （3-benzene rings）, had high detection rates （76.1%-93.5%）. The distribution patterns of PAHs were found to vary with the sludge samples; however, the patterns showed that a few compounds with 2- and 3-benzene rings were commonly found in the samples, whereas those with 4-, 5-, and 6-benzene rings were usually less commonly found. All the 44 sludge samples were within the B[a]P concentration limit for sludge applied to agricultural land in China （〈 3.0 rag kg^-1）. The probable sources of PAH contamination in the sludge samples were petroleum, petroleum products, and combustion of liquid and solid fuel. The concentrations and distributions of the 16 PAHs in sludge were related to sludge type, source, and treatment technology, together with the physicochemical properties.     

不同类型表面活性剂增效去除焦化厂污染土壤中多环芳烃的研究

Surfactant enhanced remediation is thought to be an effective method for the remediation of soils polluted with hydrophoblc organic compounds. Desorption of polycyclic aromatic hydrocarbons （PAHs） from an abandoned manufactured gas plant （MGP） soil was evaluated using four eluting agents including Triton X-100 （TX100）, sodium dodecylbenzene sulfonate （SDBS）, rhamnolipid water solution （RWS） and rhamnolipid fermentation broth （RFB）. The weight solubilization ratios for acenaphthene and fluorene were in the order of TX100 〉 SDBS 〉 RWS 〉 RFB. The Sm value, which indicates the maximum amounts of surfactants adsorbed in the soil, was in the order of RWS 〉 RFB 〉 SDBS 〉 TX100. By using 8 g L-1 of TX100, SDBS and RWS and 100% of RFB, the T-PAHs removal for the MGP soil contaminated with 207.86 mg T-PAHs kg-1 dry soil was 48.0%, 45.7%, 1.9%, and 8.6%, respectively, while that decreased to 41.6%, 37%, 0.38%, and 1.3% for the soil contaminated with 3494.78 mg T-PAHs kg-1 dry soil. Only 8 g L-1 TX100 could remove all types of the 16 PAHs partly in the MGP soil, and the removal efficiencies of different PAHs ranged from 13% to 77.8%. The results of this study herein provide valuable information for the selection of TX100 surfactant for remediating PAH-contaminated soils in MGP.     

纳米银对城郊菜地土壤微生物群落结构及细菌硝化作用的影响

Silver nanoparticles (AgNPs) are widely used antimicrobial compounds;however,they may pose a threat to non-targeted bacteria in the environment.In this study high-throughput sequencing was used to investigate the effects of different concentrations of AgNPs (10,50,and 100 mg kg-1) on soil microbial community structure during short-term (7 d) exposure.The amounts of Acidobacteria,Actinobacteria,Cyanobacteria,and Nitrospirac significantly decreased with increasing AgNP concentration;meanwhile,several other phyla (e.g.,Proteobacteria and Planctomycetes) increased and dominated.Nitrosomonas europaea,a well-characterized ammoniaoxidizing bacterium,was used to study the sensitivity of bacteria to AgNPs and ionic silver (Ag+).Flow cytometry was used to monitor the toxicity of low (1 mg L-1),middle (10 mg L-1),and high concentrations (20 mg L-1) of AgNPs,as well as Ag+ (1 mg L-1) released into the medium from 20 mg L-1 concentration of AgNPs,towards N.europaea.After 12 h of exposure,the survival rate of N.europaea treated with 1 mg L-1 Ag+ was significantly lower than those treated with low (1 mg L-1) and middle concentrations (10 mg L-1) of AgNPs,but the survival rate in the treatment with high concentration (20 mg L-1) of AgNPs was much lower.Additionally,necrosis rates were higher in the treatment with 20 mg L-1 AgNPs.Electron microscopy showed that Ag+ caused serious damage to the cell wall of N.europaea,disintegrated the nucleoids,and condensed next to the cell membrane;however,dissolved Ag+ is only one of the antibacterial mechanisms of AgNPs.     

纳米磺化石墨烯用于异位洗脱污染土壤多环芳烃工艺的优化

Ex-situ soil washing technology offers advantages such as speed and efficiency of remediation and range of application and has been developed to conform with legal requirements and best management practices in USA and some European countries. In this study,nano-sulfonated graphene(SGE) was used as a washing agent to evaluate different processing(washing) parameters for the ectopic leaching removal of polycyclic aromatic hydrocarbons(PAHs) from a coking plant soil. X-ray photoelectron spectroscopy(XPS) and fourier transform infrared spectroscopy(FTIR) were used to analyze the characteristics of the SGE tested. The results showed that SGE had a strong adsorption capacity for PAHs through the role of π-π, H-π, and anion-π interactions. The washing parameters, an SGE concentration of 2 000 mg L~(-1), a liquid/soil(L/S) ratio of 10:1, and 4 cycles of successive washing, were set to arrive to the optimum condition for achieving more than 80% of PAH removal. Under the optimum condition, the PAH removal rate decreased with increasing ring numbers. After one washing cycle at SGE concentration of 2 000 mg L~(-1) and L/S ratio of 10:1, the PAH removal rate of the SGE tested was much higher than that of Tween 80(TW80) or methyl-β-cyclodextrin(MCD)(P 0.01). Therefore, SGE is a promising material for the nanoremediation of PAH-contaminated soils.     

Potential for Enhancement of Biodegradation of Crude Oil in Louisiana Salt Marshes using Nutrient Amendments

Salt marsh ecosystems in Louisiana are at high risk of an oil contamination event while remediation of these systems is mainly limited to intrinsic bioremediation due to the physical sensitivity of salt marshes. This study investigated both the intrinsic and nutrient enhanced rates of crude oil degradation both in microcosm and core studies. In addition, limiting elements, loading rates and optimum nitrogen forms (NH ₄ ⁺ or NO ₃ ^- ) were determined. Salt marshes have relatively low intrinsic degradation rates (0–3.9% day^-1) of the alkane component (C11-C44) but high rates (8–16% day^-1) of degradation of the polycyclic aromatic hydrocarbon (PAH) fraction (naphthalene, C1, and C2-Naphthalene and Phenanthrene, C1, and C2-Phenanthrene). Additions of nitrogen statistically enhanced degradation of many alkanes and total PAHs while naturally present phosphorous was found to be sufficient. Nitrogen was found to be most effective if applied as NH ₄ ⁺ in the range of 100-500-N mg kg^-1 of soil producing a pore water range of 100-670-N mg L^-1. Core studies indicate that similar trends are observed when applying fertilizers to intact portions of salt marsh.     

Column Studies on Nitrate Removal from Potable Water

Biological processes can achieve nitrate removal from groundwater. The sulfur/limestone autotrophic denitrification by Thiobacillus denitrificans was evaluated with three laboratory-scale column reactors. The optimum sulfur/limestone ratio was determined to be 2:1 (mass/mass). Different hydraulic retention times were used during the column tests to examine nitrate removal efficiencies. Under an HRTs of 13 h, nitrate concentration of 60 mgNO₃ ^--N L^-1 was reduced to less than 5 mg NO₃ ^--N L^-1. On a higher HRT of 26 h the nitrate removal efficiency was close to 100% for all nitrate-nitrogen loading rates. Different initial nitrate-nitrogen concentrations (30, 60, and 90 mg NO₃ ^--N L^-1) were used in the study. Column tests showed that the nitrate-nitrogen loading rate in this study was between 50 to 100 g NO₃ ^--N m^-3 d^-1 to obtain a removal efficiency of 80–100%. It was found that approximately 6 mg SO₄ ^2- was produced for 1 mg NO₃ ^--N removed. Nitrite-nitrogen in all cases was less than the maximum allowable concentration of 1 mg NO₂ ^--N L^-1. Effluent pH was stable in the range of 7 to 8; the effluent dissolved oxygen was less than 0.15 mg L^-1 and the oxidation-reduction potential in all columns was in the range of –110 to –250 mV.     

Toxic and Sublethal Effects of Ammonium Chloride on a Freshwater Fish Oreochromis mossambicus

The effects of ammonium chloride on survival and feeding energetics of the freshwater fish Oreochromis mossambicus were studied. At a concentration of 600 mg L^-1 ammonium chloride, 100% mortality was observed within 24 h; no mortality occurred at 400 mg L^-1 within 96 h; Concentration of 450 mg L^-1 ammonium chloride was found as median lethal concentration at 96 h exposure. Rearing the fish in increasing sublethal concentrations of ammonium chloride, it was found that the feeding rate decreased from 20.309 ± 0.506 mg g live fish^-1 day^-1 (mg g^-1 d^-1 (control) to 11.594 ± 0.479 mg g^-1 d^-1 at the highest sublethal concentration (100 mg L^-1. Growth rate was drastically reduced.     

商陆(Phytolacca acinosa Roxb.)的锰耐性和超积累

超积累植物的确证对成功实施重金属污染环境植物修复是必不可少的。通过野外调查和营养液培养试验 ,研究超积累植物商陆 (PhytolaccaacinosaRoxb )的锰富集特性 ,结果表明 ,商陆对生长介质中的Mn具有很强的耐性和累积能力。商陆在锰含量高达 114× 10 3 mgkg-1的尾矿废弃地上依然生长良好 ,叶锰含量最高达 19 3× 10 3 mgkg-1。温室培养条件下 ,当生长介质中Mn浓度为 8 0 0 0mmolL-1时 ,虽然其生物量与对照相比有所降低 ,但植株仍能生长。随着生长介质中Mn浓度的升高 ,商陆叶和茎的Mn含量逐渐增加 ,生物富集系数则逐渐降低 ,但是地上部分锰积累量则先增加后减少。当Mn浓度为 5 0 0 0mmolL-1时 ,商陆地上部分锰积累量达到最大值 2 5 8 2mgplant-1;当Mn浓度为 12 0 0 0mmolL-1时 ,商陆仍能完成整个生命周期 ,叶锰含量达到最大值 36 4× 10 3 mgkg-1,生物富集系数为 5 5。不同锰供应水平下 ,商陆吸收的锰有87%～ 95 %被转移到地上部分。这进一步验证商陆的锰超积累特性 ,为利用超积累植物对大面积污染土壤实施植物修复提供了有力证据 ,对锰污染土壤和水体实施植物修复具有很大的应用前景     

污染区千金子和酢浆草根际土壤中PAHs结合态残留的梯度分布

采集某污染区千金子(Euphorbia lathyris L.)和酢浆草(Oxalis corniculata L.)的离根表0~3、3~6、6~9 mm的根际土壤,分析了多环芳烃(PAHs)结合态残留中母体化合物(Parent compound of bound residue,PCBR)在根际土壤中的含量及梯度分布规律。供试土壤类型为黄棕壤。结果表明,在非根际和根际土壤中均可检出10种PAHs的PCBR,非根际土壤中PCBR总含量为3.31 mg kg-1,高于根际土壤(1.07~1.82mg kg-1)。根际土壤中PAHs的PCBR含量随离根表距离(0~9 mm)的增加而增大。可用根际效应(R)来衡量根际土壤中PAHs的PCBR含量与非根际土壤相比减少的比例;R值随离根表距离(0~9 mm)的增加而变小。3个连续根际区中,PAHs总PCBR的R值为45.15%~67.66%,其中2环PAH的R值最大(61.18%~93.50%),4环和5环PAHs的R值最小(2.39%~6.31%),低环PAHs的PCBR在根际土壤中更易转化。PAHs的PCBR在千金子根际土壤中R值大于酢浆草,表明前者有更利于PAHs结合态残留转化的根际环境。PAHs结合态残留的根际梯度分布与根系分泌物的梯度分布关系密切,而PAHs种类、植物根际环境对PAHs结合态残留的分布影响显著。     

水溶性有机物与多环芳烃结合特征的红外光谱学研究

水溶性有机物（DOM）与多环芳烃（PAHs）之间的相互作用一直是尚未弄清的理论问题。对其正确阐释有利于更好地理解DOM对PAHs环境行为与生态效应的影响及科学地评估PAHs的环境风险，并对PAHs污染土壤的修复具有极其重要的意义。本研究以有机物料猪粪、污水污泥和带根茬水稻土作为DOM的提取材料，以菲（Phenanthrene，Phe）和芘（Pyrene，Pyr）为PAHs代表，采用红外光谱学技术研究DOM与PAHs的相互作用。红外图谱显示，供试DOM在4000—3000cm^-1、2969—2900cm^-1、1700-1375cm^-1、1300—1000cm^1和900-600cm^-1存在明显的吸收峰，这说明DOM中含有-OH或酚-OH、-NH、苯环、-C-O及-CH2等功能团。对比DOM与DOM—Phe／Pyr的图谱发现，DOM—Phe／Pyr在4000—3000cm^-1、1700—1375cm^-1和900—600cm^-1的吸收峰发生不同程度的朝长波方向飘移，表明NH-π和π-π作用参与了DOM与Phe及Pyr结合物的形成。     

Composting Wastes Contaminated with Naphthalene

Recent data show composting as an alternative for treatment of PAHs contaminated wastes. Nevertheless, the presence of highly volatile compounds like naphthalene might compromise the interest of this treatment and thus its careful evaluation is justified. A bench scale composting system was built to evaluate the importance of volatilization in the transformation of naphthalene by composting. Naphthalene concentration was measured in solid, aqueous and gas phases by HPLC and GC. Preliminary results have shown that the presence of microorganisms able to degrade naphthalene reduces naphthalene loss by volatilization.     

Polycyclic aromatic hydrocarbons (PAHs) in peat and plants from selected peat‐bogs in the north‐east of Poland

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were analyzed in samples of peat and of two plant species (Pinus sylvestris and Ledum palustre) overgrowing peat‐bogs in the north‐east of Poland. Peat samples were collected from different depths according to the stratigraphic profile of the peat bogs. The total concentrations of the 16 anthropogenic PAHs (15 from the US EPA list and benzo[e]pyrene) in all peat samples were between 70 and 439 ng g^—1. The concentration for the same compounds in pine needles (Pinus sylvestris) and Dutch Myrthe leaves (Ledum palustre) varied between 194 and 1039 ng g^—1. A noticeably high fluorene concentration in Dutch Myrthe leaves was found at some sites. In all peat samples 3‐ring compounds were predominant (55 to 319 ng g^—1). There were less 4‐ring PAHs (15 to 110 ng g^—1) and the least common PAHs were 5‐ring and 6‐ring compounds (0 to 81 ng g^—1 for both groups). In some peat samples, the perylene concentration largely exceeds of the total concentration of all the other PAHs investigated. The high content of perylene in bottom layers could result from the processes of perylene sorption from water during peat‐bog formation or from biogenic formation of perylene.     

Persistent Organic Pollutants in Singapore's Coastal Marine Environment: Part II,Sediments

Polycyclic aromatic hydrocarbons (PAHs) can enter the marine environment from a variety of anthropogenic sources. As some PAHs are known or suspected carcinogens and mutagens, their potential hazard to human health and the natural environment warrants investigation. This is the first reported study on the prevalence and concentration of PAHs in marine sediments from Singapore's coastal environment, and accompanies the report by Basheer et al. (2003) on the measurement of persistent organic pollutants (POPs) in seawater. The concentration of 16 PAH, classified as USEPA priority pollutants were analysed in sediments from 22 sample stations located within the northeastern and southwestern regions of Singapore's marine waters. The total PAH concentration varied between 15.22 μg g^-1 and 82.41 μg g^-1 in the northeastern region and between 13.63 μg g^-1 and 84.92 μg g^-1in the southwestern region. The highest concentration of total PAH i.e. 84.92 μg g^-1 was recorded at a site adjacent to a petrochemical refinery. Among the sixteen individual PAHs, chrysene, indeno[1,2,3-cd]pyrene and benzo[a]anthracene were most prevalent in the sediments. The relatively low kinetic/thermodynamic isomer ratios for PAHs suggest that PAHs of pyrogenic origin are predominant in Singapore's coastal environment. The distribution of higher molecular weight i.e. (4–5 ring) individual PAHs corresponded to mixture profiles typical of those originating from high temperature combustion processes subjected to photolytic degradation during long-range atmospheric transportation. A comparison of total PAH concentration data for sediments collected from Singapore relative to those reported for other countries indicates a moderate level of PAH contamination in Singapore's coastal marine sediments.     

Bioaccumulation and Toxicity of Zinc in Spirogyra Fluviatilis Hilse (Chlorophyta)

The bioaccumulation and toxicity of zinc in Spirogyra fluviatilis Hilse, from two populations in the River Seyhan, Adana, Turkey, were examined in laboratory flowing-water channels. Plants were subjected to zinc concentrations ranging from 0 to 4.0 mg L^-1 at current velocities of 25–35 cm s^-1 for up to 3 h. There was little difference in zinc bioaccumulation between Spirogyra from the site showing mild organic pollution and that from the site subjected to considerable inputs from urban and motorway runoff. Uptake of zinc increased with increasing concentration in the test solution and was linear and proportional up to 0.5 mg L^-1. Cellular damage was evident in Spirogyra subjected to 0.5 mg L^-1 zinc, and increased with increasing zinc concentration.     

Effect of Lime Application on the Movement of Atrazine and Nitrate-Nitrogen Through Undisturbed-Saturated Soil Columns

Adsorption studies of Cr(III) on biogas residual slurry (BRS) were caried out under varying conditions of shaking time (5–180 min), metal ion concentration (10–40 mg L^-1), adsorbent concentration (1.0 to 8.0 g L^-1) and initial pH (1.5–5.0). Adsorption follows Langmuir isotherm, being endothermic in nature. For a Cr(III) concentration of 10 mg L^-1, a maximum removal of 85% by 4 g L^-1 of adsorbent was obtained at an initial pH ≥ 3.0. Desorption of Cr(III) from the spent adsorbent has also been investigated. Removal of Cr(III) from tannery wastewater by BRS was testified.