Acid mine-drainage toxicity testing

The BOD inhibition test, the activated sludge respiration inhibition test, and the Microtox® Bioassay procedure were examined for their potential as rapid toxicity screening methods for acid mine drainage (AMD) and for setting toxicity threshold levels in receiving waters. The BOD inhibition test proved to be unsuitable due to the high chemical oxygen demand of the toxicant. The long incubation time (minimum 5 d at 20°C) allowed growth of chemo-autotrophic bacteria and resulted in excessive flocculation and precipitation of metals, making accurate and meaningful measurements of inhibition impossible. The activated sludge respiration inhibition test was successful in measuring AMD toxicity, and for deriving toxicity threshold levels for the basic heterotrophic community in surface waters. However, it is a very time-consuming technique and is not sensitive enough to be used as a routine screening technique. The variability in toxicity was found to be due to the availability of metals as well as the effect of pH on metabolism. Simple linear models were derived to estimate inhibition within surface waters. Prediction of the inhibition caused by AMD can be made as long as the pH of the river water after mixing and the dilution of the AMD are known. Most accurate predictions are made using equations for specific pH ranges, but a useful estimation of inhibition can be obtained using the general equation: inhibition (%) = -2.34 pH + 6.41 AMD (%) + 22.1. The Microtox® Bioassay method, although expensive, was rapid and simple to use. It was the most sensitive test of the three, with the toxic response of marine bacteria increasing notably from 5 to 15 min due to the presence of bivalent metals in the toxicant. The problem of repeatability and reproducibility encountered with the activated sludge inhibition test was overcome with the highly standardised Microtox® method, making it an ideal screening method for AMD. However, the advantage of the activated sludge inhibition test is that the types of heterotrophic micro-organisms found in activated sludge are similar to those found in receiving waters such as the Avoca River and so more meaningful toxicity threshold values can be obtained.     

Toxicological evaluation of bacterial decolourised anaerobically treated distillery effluent with common duckweed (Lemna minor)

Duckweed (Lemna minor) a small vascular plant, grows rapidly, is sensitive to a wide variety of toxicants and is easy to culture. A method is described that measures duckweed frond growth, chlorophyll, protein and biomass content as indicator of growth inhibition. The physico-chemical analysis of anaerobically treated distillery effluent revealed high BOD (28,000 mg/l), COD (52,400 mg/l) and dark brown colour (180,000 Co. Pt.). This effluent showed high toxicity to Lemna minor after 96 h of exposure in laboratory condition. EC50 of the fronds for chlorophyll, protein and biomass was found to be 25%, however, the bacterial decolourised effluent showed reduction of BOD (87.50%), COD (84.50%) and colour (76%). Further the toxicity evaluation with Lemna minor showed toxicity reduction up to 63% for all tested parameters. The EC50 noted for chlorophyll, protein and biomass was 100% concentration of decolourised effluent.     

Biological treatments of textile industrial effluents in Lagos metropolis, Nigeria

The assessment of the effluents from two textile industries in Ilupeju in Lagos metropolis, Nigeria showed that they were high in conductivity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS) and contained traces of heavy metals like Ca, Zn but high concentrations of Cr and Pb. These wastewaters are normally discharged into neighbouring water bodies. Five bacterial groups, namely Micrococcus sp., Enterobacter sp., Alcaligens sp., Bacillus sp. and Acinetobacter sp. were isolated from these effluents. They were used individually for biotreatment and found to be able to utilize the components of the wastewaters for growth, Bacillus sp. and Acinetobacter sp. being the most efficient utilizers as they were able to reduce BOD to zero. The total viable count (TVC) increased significantly depicting growth of the bacterial population. The pH was regulated from 3.4-6.80 for NSF effluent and 12.2-10.29 for STI effluent. The work emphasises the level of industrial pollution in our environment as wastes are indiscrimately dumped into surrounding water bodies in urban areas, the textile industry being a case study. The treatment of any form of waste before disposal into the environment is important and ensures safety of the populace.     

Nitrification model with an inhibitory effect of sea water

A dynamic model of nitrification including bacterial growth equations was developed for the understanding of nitrification in estuaries. Sensitivity analysis based on the model revealed that not only maximum specific growth rates of nitrifiers but also yield constants and initial bacterial concentrations have great effect on the nitrification process.Batch experiments were carried out in order to investigate nitrification rates and an inhibitory effect on nitrification by sea water. The maximum specific growth rate of ammonia oxidizing bacteria in fresh water was estimated as 0.04 (h^?1) using a nonlinear regression method. The sea water content of 10%, 25%, 50% and 100% reduced the maximum specific growth rate of ammonia oxidizing bacteria to 0.027, 0.016, 0.0085 and 0.0028 (h^?1) respectively. The effect of sea water on nitrification was interpreted as noncompetitive inhibition. The computed results of inhibition of nitrification based on the noncompetitive inhibition model are presented.     

Bakterielle Biotestverfahren zur Bestimmung der Toxizität von Abfällen

For a risk assessment of wastes, fast and sensitive screening methods are required to detect possible toxic effects. In this study, different leachability methods (DIN 38414, part 4; EPA 1310; EPA 1320) were used to prepare aqueous leachates from different wastes; these leachates were rested in different bacterial toxicity test systems for possible toxic effects. As bacterial toxicity tests, the luminescent bacteria test and the growth inhibition test with activated sludge bacteria were used. The test systems showed a good agreement of the results from the different leaching methods, thereby indicating the reliability of the test systems used. The luminescent bacteria inhibition test showed a higher sensitivity than the growth inhibition test which is in good accordance with literature data. We conclude that both test systems are well suited to assess the toxic potential of aqueous waste leachates.     

Bacterial toxicity testing and antibacterial activity of parabens

Parabens are used because of their antimicrobial effects, yet they have multiple adverse effects. The aim of this work was to evaluate the bactericidal activity and bacterial toxicity of the most common parabens: methylparaben, ethylparaben, propylparaben, isopropylparaben, butylparaben, isobutylparaben and phenylparaben. The bactericidal action was evaluated by means of the dilution-neutralization method against Escherichia coli and Staphylococcus aureus, and the biotest of inhibition of growth of E. coli was applied for the bacterial toxicity assay. Bactericidal concentrations were reached only for propylparaben, butylparaben and isobutylparaben. The toxicity study showed methylparaben to be the least toxic, whereas the most toxic one was phenylparaben. It can be concluded that the disinfectant activity of the parabens studied is insignificant against S. aureus and E. coli. Acute toxicity is very low, and the inhibitory effect is weak. Our results provide information about the risk–benefit balance of parabens use.     

A comprehensive evaluation of the potential chemical defenses of antarctic ascidians against sympatric fouling microorganisms

The present study analyzed the bioactivity of whole body extracts from six solitary and eight colonial ascidian taxa against 20 sympatric bacterial isolates and one sympatric diatom species from the Western Antarctic Peninsula. Ascidians had crude lipophilic and hydrophilic extracts assayed against 20 bacterial strains. The lipophilic extract of one ascidian caused growth inhibition in all bacterial isolates at 3× tissue-level concentrations. The lipophilic and hydrophilic extracts were fractionated into seawater-soluble and insoluble fractions and assayed at three concentrations against a sympatric diatom species. Significant diatom mortality was detected at 3× and 1× concentrations in all but one ascidian taxon. Lipophilic fractions caused higher diatom mortality than hydrophilic extracts. The specificity of secondary metabolites against diatom fouling and the lack of activity against bacteria suggest high selective pressure for chemical defenses against diatom fouling or the potential that bacterial pathogens are controlled by the ascidian immune system.     

Rate of change of bod for milk in natural sea water

As part of a project to determine the fate of contaminated milk in the marine environment (Elliott et al ., 2001), the Biochemical Oxygen Demand (BOD) of unprocessed natural milk in sea water was followed in standard BOD bottles and in an open system. The best estimate for the BOD was ¨ 170,000 r mg - l m 1 although measurable effects could still be seen with dilutions up to one in a million. If incubated in the light, simulating summer conditions, the algae produced oxygen and offset some of the loss through bacterial degradation thereby reducing any slump in oxygen. There was also a "nutrient effect" where the presence of milk increased the oxygen production at low concentrations in sea water. In an open system akin to a slick being dispersed, the change in BOD was exponential after an initial activation period. The length of this activation period was greater in more concentrated mixtures of milk and sea water. These results have been utilised in a model to determine the best strategy for disposing of contaminated milk (Elliott et al ., 2001).     

Restoration of the Marine Ecological Environment Along the Charting Coast: Primary Productivity and Biomass Study

Since 1986, when green oysters occurred due to the copper and organic pollution in the Charting coastal area, the government banned all maricultural activity. It has been claimed that growing algae in a polluted environment may clean the water of pollutants and restore the marine ecosystem. to test this hypothesis, in the Charting coastal area a three-year programme (from August 1992 to July 1995) was carried out. the survey programme included environmental components such as salinity, temperature, pH, dissolved oxygen, biological oxygen demand (BOD), particulate organic carbon (POC), heavy metals and ecological indicators such as nutrients, chlorophyll-a, primary productivity. in the first year study, the environmental background data collected was used to select the suitable season and locations for growing large algae transferred from the laboratory to the field study area. Since September 1993, various species of large algae have been cultured. Although some of the growing algae were damaged by a typhoon in August 1994, the impact of the growing algae on the environmental conditions in the area has been monitored throughout. Elsewhere, we have reported that in the algae growing area higher dissolved oxygen with lower values of BOD and POC were found, and the concentrations of heavy metals in both water and sediments decreased. the purpose of this paper is to evaluate the possible impact of growing large algae on the ecological conditions in Charting coastal waters through the period from August 1983 to May 1995. As a result of the positive results obtained, large amounts of algae have again been cultured in the same area during the period from April 29 to May 25, 1995. We expect that inorganic and organic pollutants will be reduced by the algal growth, oyster mariculture will be restored and finally, the fishery resources potential will be increased.     

Restoration of the Marine Ecological Environment Along the Charting Coast: Primary Productivity and Biomass Study

Since 1986, when green oysters occurred due to the copper and organic pollution in the Charting coastal area, the government banned all maricultural activity. It has been claimed that growing algae in a polluted environment may clean the water of pollutants and restore the marine ecosystem. to test this hypothesis, in the Charting coastal area a three-year programme (from August 1992 to July 1995) was carried out. the survey programme included environmental components such as salinity, temperature, pH, dissolved oxygen, biological oxygen demand (BOD), particulate organic carbon (POC), heavy metals and ecological indicators such as nutrients, chlorophyll-a, primary productivity. in the first year study, the environmental background data collected was used to select the suitable season and locations for growing large algae transferred from the laboratory to the field study area. Since September 1993, various species of large algae have been cultured. Although some of the growing algae were damaged by a typhoon in August 1994, the impact of the growing algae on the environmental conditions in the area has been monitored throughout. Elsewhere, we have reported that in the algae growing area higher dissolved oxygen with lower values of BOD and POC were found, and the concentrations of heavy metals in both water and sediments decreased. the purpose of this paper is to evaluate the possible impact of growing large algae on the ecological conditions in Charting coastal waters through the period from August 1983 to May 1995. As a result of the positive results obtained, large amounts of algae have again been cultured in the same area during the period from April 29 to May 25, 1995. We expect that inorganic and organic pollutants will be reduced by the algal growth, oyster mariculture will be restored and finally, the fishery resources potential will be increased.     

驯化菌株降解油制气废水能力的比较

从3种污泥中驯化筛选出10种菌株,研究了各菌株对油制气废水不同污染指标的处理能力差别,以及各菌株对废水中芳烃化合物的降解能力.结果表明,各菌株可在初始阶段提高废水的BOD值,在高低废水浓度条件的降解能力基本一致;酚的去除率可达93.9%,但对废水中氨氮的去除率小于27.3%;实验采用的3种菌株对废水中的芳烃化合物都能降解,但其对芳环数≤3的芳烃化合物的降解能力强于对芳环数为4~6的芳烃化合物的降解能力.图4表2参10     

Effect of cadmium on germination, coleoptile and root growth of barley seeds in the presence of gibberellic acid and kinetin

Effect of cadmium on barley seeds treated with kinetin and gibberellic acid was investigated. As usual, cadmium has inhibited seed germination, and showed important inhibitory effects on roots and coleoptile growth after germination. In general, increase in cadmium concentration caused a greater inhibition of germination, root and coleoptile growth. The adverse effect of cadmium on root and coleoptile growth was more pronounced than that on germination. While testa was pierced by radicle (an indication of germination), no root or coleoptile development was observed above at concentration of 3-9.5 mM CdCl2xH2O. Low concentrations of cadmium have inhibited the root growth more than it did on coleoptile growth. Treatment of seeds with gibberellic acid and kinetin did not show any significant difference on the effect of cadmium in germination. However, inhibition of coleoptile elongation by cadmium has decreased a very much after kinetin application. The same result, although with lower rates when compared to kinetin, has been obtained for GA3 as well. In addition, the inhibitory effect of cadmium on root growth increased even more after kinetin application. The results have been found statistically significant through the least significant different (LSD) test at levels ofp < 0.05 and p < 0.01.     

Impact of anaerobically treated and untreated (raw) distillery effluent irrigation on soil microflora, growth, total chlorophyll and protein contents of Phaseolus aureus L

Impact of distillery effluent (untreated and treated) irrigation on soil microflora of the pots used for growing Phaseolus aureus L. was investigated. The growth of the P. aureus plants as affected by distillery effluent irrigation was also evaluated. The irrigation of the pots by 1-10% distillery effluent (anaerobically treated) stimulated the growth of the soil microflora (increased number of bacteria, fungi and actinomycetes) and P. aureus plants (increased shoot and root lengths, biomass, chlorophyll and protein contents). Further, 15-20% distillery effluent (anaerobically treated) had toxic effect on soil micro flora as indicated by reduced number of bacteria, fungi and actinomycetes. Reduction in shoot, root, lengths, biomass, chlorophyll, protein contents of P. aureus was also observed when irrigated by 15-20% treated distillery effluent. All the concentrations of raw distillery effluent reduced the bacterial population. However, the treated distillery effluent concentrations <10% had stimulatory effect on fungal and actinomycetes population. However, raw effluent concentrations >5% reduced the same. Raw distillery effluent was more toxic to P. aureus than treated distillery effluent as concentrations >5%, had reduced the growth (shoot, root length and biomass) of the test plant. Raw distillery effluent had adverse effect to total chlorophyll contents and all the test concentrations reduced the total chlorophyll level. However, untreated (raw) distillery effluent stimulated the protein content initially. It has been concluded from-present study that lower concentrations of the raw distillery effluent (1-5%) and treated distillery effluent (1-10%) had stimulated the growth of P. aureus and soil microflora except soil bacteria (inhibited by all the concentration of the raw effluent). However, higher concentrations (raw effluent: 10-20%; treated effluent 15-20%) had toxicity to test parameters.     

Characterization and optimization of conditions for biodegradation of sella-rice mill effluent

The sella-rice mill effluent is a major environmental pollutant requiring proper treatment before disposal. The present study has been conducted to isolate and characterize micro-organisms capable of growing on sella-rice effluent and to optimize conditions for its rapid bioremediation. Using three different types of media (LB, YEPDA and PDA), a total of 139 isolates were isolated from effluent samples collected from three different locations. Out of these, 45 isolates were found to utilize starch on starch medium, eight isolates showing high efficiency. For the optimization of conditions for maximum utilization of starch by selected isolates, parameters such as effect of addition of carbon and nitrogen sources, effect of growth factors, temperature and pH were studied. Maximum growth (absorbance of 2.10) and starch-utilization (varying in the range of 2.33 to 3.62) was observed on starch medium supplemented with peptone and yeast extract at 30 degrees C with a pH of 6.0. These bacterial isolates also reduced the amount of starch (80.10%), BOD (64.24%) and COD (75.0%) of sella-rice mill effluent after 15 days of incubation. On the basis of morphological and biochemical characteristics, the selected isolates were found to belong to the genera Lactobacillus and Micrococcus.     

Effects of Fe(II) on anammox community activity and physiologic response

• 0.12 mmol/L Fe(II) enhanced the total anammox activity and bacterial abundance best. • 0.09 mmol/L Fe(II) led to the best performance on relative anammox activity. • 0.75 mmol/L Fe(II) had an immediate but recoverable inhibition on anammox activity. • More genes but not relative level were expressed at higher Fe(II) concentration. Though there are many literatures studying the effects of iron on anammox process, these studies only focus on the reactor performance and/or the microbial community changes, the detailed effects and mechanisms of Fe(II) on anammox bacterial activity and physiology have not been explored. In this study, four Fe(II) concentrations (0.03, 0.09, 0.12 and 0.75 mmol/L) were employed into the enriched anammox culture. The enhancement and inhibition effects of Fe(II) on anammox process and bacterial physiology were investigated. It was discovered that the anammox process and bacterial growth were enhanced by 0.09 and 0.12 mmol/L Fe(II), in which the 0.12 mmol/L Fe(II) had advantage in stimulating the total anammox activity and bacterial abundance, while 0.09 mmol/L Fe(II) enhanced the relative anammox activity better. The anammox activity could be inhibited by 0.75 mmol/L Fe(II) immediately, while the inhibition was recoverable. Both 0.09 and 0.12 mmol/L Fe(II) induced more genes being expressed, while didn’t show a stimulation on the relative expression level of functional genes. And anammox bacteria showed a stress response to detoxify the Fe inhibition once inhibited by 0.75 mmol/L Fe(II). This study provides more information about physiologic response of anammox bacteria to external influence (enhancement and inhibition), and may also instruct the future application of anammox process in treating various sources of wastewater (containing external disturbances such as heavy metals) and/or different treatment strategies (e.g. from side-stream to main-stream).     

A study on genotoxicity of textile dyeing industry effluents from Rajshahi,Bangladesh, by the Allium cepa test

Textile dye effluents are believed to be toxic as they might exert various harmful effects on living organisms including genotoxicity. These effluents are the main source of direct and continuous input of pollutants into the aquatic ecosystems. In this study, dye effluents from a local silk dyeing industry were analysed for their genotoxic potential by the Allium cepa genotoxicity test. The A. cepa test is characterised as a genotoxicity test where the roots of A. cepa are grown in different concentrations of the test material. The macroscopic results clearly showed that the toxicity of the dye effluents prompted A. cepa root growth inhibition, and this effect increased with higher concentrations of the effluents. At the cellular level, no dividing cells were found at higher concentrations such as 60%, 80% and 100% of the effluents. However, at a lower concentration of 20%, dividing cells were identified, although the mitotic index was much lower than that of the control. Microscopic analysis showed that the dye effluents induced chromosomal aberrations at significant levels. Taken together, these results revealed that the textile dyeing industry effluents are toxic to eukaryotic cells and these dyes have genotoxic properties that can potentially lead to cancer development and adverse health conditions.     

载钯树脂对偶氮类染料的吸附降解及其产物对发光菌的毒性暴露试验

合成了表面负载金属钯的聚丙烯醛异烟酰腙树脂后,通过Q67发光菌的毒性暴露实验研究了该树脂材料对直接大红、直接天蓝和桃红等3种水溶性偶氮染料的催化降解效果及其在降解过程中对发光菌的生物毒性变化情况,并对降解结果进行了气相色谱-质谱(GC-MS)分析.实验结果表明:载钯树脂对直接大红、直接天蓝和桃红等偶氮染料具有良好的吸附...     

Inhibition of the growth of micro-algae and bacteria by extracts of eelgrass (Zostera marina) leaves

The effects of the water-soluble fraction of dead leaves of the eelgrass Zostera marina L. on the growth of 8 species of micro-algae (pennate and centric diatoms, dinoflagellates, and a green flagellate) and a bacterium were studied on agar plates and in liquid culture. The extracts of leaves which had been dead from a few days to 2 wk inhibited growth and often killed cells in all test organisms. Extracts were lethal even at concentrations equivalent to as little as 0.25 mg dry leaf ml^-1, but inhibition decreased when extracts were prepared from leaves aged in the laboratory for 35 d (loss of anti-bacterial activity) or 90 d (loss of anti-algal activity). Extracts of leaves which had aged and dried several months in the field had no effect, except at very high concentrations (13 mg dry leaf ml^-1) when the lag phase of growth was prolonged several days in a culture of the chlorophyte Platymonas sp. The active fraction in eelgrass leaves may be important in controlling initial growth of micro-organisms on eelgrass detritus, and it could determine the composition and activity of the epiphytic community on living leaves.     

杀虫单降解菌的筛选分离与降解特性研究

从农药厂废水排放沟污泥中分离到一株对杀虫单有较强降解能力的菌株LY－4,经鉴定为巨大芽孢杆菌（Bacillus megaterium)。其生长的最适pH为7,最适温度为30℃。该菌对杀虫单有很强的耐受性,在杀虫单浓度ρ＝5000mg/L时,仍能较好地生长并发挥降解作用。当杀虫单初始浓度高于一定值时,一定量的菌剂对杀虫单的降解率随底物浓度的提高而降低,而绝对去除量则随底物浓度的提高而提高。与不加菌的对照相比,加入LY－4后,可使杀虫单浓度在很短的时间内降到很低的水平。图5表1参6     

Nitrogen effects on decomposition: a five-year experiment in eight temperate sites

The influence of inorganic nitrogen (N) inputs on decomposition is poorly understood. Some prior studies suggest that N may reduce the decomposition of substrates with high concentrations of lignin via inhibitory effects on the activity of lignin-degrading enzymes, although such inhibition has not always been demonstrated. I studied the effects of N addition on decomposition of seven substrates ranging in initial lignin concentrations (from 7.4% to 25.6%) over five years in eight different grassland and forest sites in central Minnesota, USA. I predicted that N would stimulate the decomposition of lignin-poor substrates but retard the decomposition of lignin-rich substrates. Across these sites, N had neutral or negative effects on decomposition rates. However, in contrast to my hypothesis, effects of N on decomposition were independent of substrate initial lignin concentrations, and decomposition of the lignin fraction was unaffected by N fertilization. Rather, substrate-site combinations that exhibited more rapid decomposition rates in the control treatment were affected more negatively by addition of N fertilization. Taken together, these results suggest that decreased decomposition with added N did not result from inhibition of lignin-degrading enzyme activity, but may have resulted from abiotic interactions between N fertilizer and products of microbial degradation or synthesis or from N effects on the decomposer community. Low initial substrate N concentrations and N fertilization both stimulated N immobilization, but the differences among substrates were generally much larger than the effects of fertilization. This study suggests that atmospheric N addition could stimulate ecosystem carbon sequestration in some ecosystems as a result of reduced rates of forest floor decomposition.