Effect of crude oil pollution on heavy metal contents, microbial population in soil, and maize and cowpea growth

The effect of crude oil pollution on heavy metal content in the soil, microbial population, and growth performance of maize and cowpea was investigated. The heavy metals determined were lead, cadmium, iron, nickel, zinc and copper. Microbial population and growth performance of maize and cowpea in both polluted and unpolluted soils samples were evaluated. Results showed that higher concentration of heavy metals was observed in all crops planted in polluted soil, polluted site vegetation and soils. The total heterotrophic bacteria was 89% lower in the polluted soil than in the unpolluted soil while fungi was 78% lower in the polluted soil when compared to the unpolluted soil. However, hydrocarbon utilizing bacteria and fungi was 22% and 24% higher in the polluted soil than in the unpolluted soil respectively. Maize and Cowpea performed poorly in polluted soil when compared with unpolluted soil as evidenced in the growth parameters measured for both crops.

Effects of Heavy Metal Pollution of Apple Orchard Surface Soils Associated with Past Use of Metal-Based Pesticides on Soil Microbial Biomass and Microbial Communities

Apple orchard surface soils in Japan are polluted with copper (Cu), lead (Pb), and arsenic (As) due to long-term use of metal-based pesticides. We investigated the effects of heavy metals accumulated in the surface soils in apple orchards on the microbial biomass and the microbial communities. Soil samples were taken from a chestnut orchard (unpolluted control) and five apple orchards with different degrees of heavy metal pollution. Total concentrations of Cu, Pb, and As in soil ranged from 29 to 931 mg/kg, 35 to 771 mg/kg, and 11 to 198 mg/kg, respectively. The amount of microbial biomass carbon expressed on a soil organic carbon basis decreased with increasing concentrations of heavy metals. Thus, the heavy metals that accumulated in apple orchard surface soils had adverse effects on the soil microbial biomass. The analysis of phospholipid fatty acid (PLFA) composition indicated that the microbial community structure had changed because of the pesticide-derived heavy metals in soil. The relative abundance of gram-positive bacterial marker PLFAs increased and that of fungal marker PLFA decreased with increasing concentrations of heavy metals in soil. Denaturing gradient gel electrophoreses targeting the 16S ribosomal RNA gene of bacteria and the 18S ribosomal RNA gene of fungi also showed shifts in the composition of bacterial and fungal communities induced by soil pollution with heavy metals. However, the diversity of microbial communities was not significantly affected by the heavy metal pollution. This was attributable to the adaptation of the microbial communities in apple orchard surface soils to heavy metals derived from previously used pesticides.

Effects of heavy metal pollution on soil microbial biomass

This paper reviewed the effects of heavy metals on microbial biomass in metal polluted soils. Laboratory and field investigations where metals were applied as inorganic or organic salts demonstrated a significant decline in the size of soil microbial biomass. In most of the cases, negative effects were evident at metal concentrations below the European Communitys (EC) current permissible metal levels in the soil. Application of metal enriched sludges and composts caused significant inhibition of microbial biomass at surprisingly modest concentrations of metals in the soil that were indeed smaller than those likely to decrease the growth of sensitive crop species. On the whole, relative toxicity of metals decreased in the order of Cd>Cu>Zn>Pb, but a few exceptions to this trend also existed. A significant decline in the biomass carbon to organic carbon ratio(C min /C org ) in metal polluted soils indicated that this parameter can serve as a good indicator of the toxicity of metals on soil microflora. The knowledge regarding the response of soil biota to metal interactions and the factors affecting metal toxicity to soil microorganisms is still very limited and warrants further study.

Effects of soil metal(loid)s pollution on microbial activities and environmental risks in an abandoned chemical smelting site

Abandoned chemical smelting sites containing toxic substances can seriously threaten and pose a risk to the surrounding ecological environment.Soil samples were collected from different depths(0 to 13 m)and analyzed for metal(loid)s content and fractionation,as well as microbial activities.The potential ecological risk indices for the different soil depths(ordered from high to low)were:1 m(D-1)>surface(S-0)>5 m(D-5)>13 m(D-13)>9 m(D-9),ranging between 1840.65-13,089.62,and representing extremely high environmental risks,of which Cd(and probably not arsenic)contributed to the highest environmental risk.A modified combined pollution risk index(MCR)combining total content and mobile proportion of metal(loid)s,and relative toxicities,was used to evaluate the degree of contamination and potential environmental risks.For the near-surface samples(S-0 and D-1 layers),the MCR considered that As,Cd,Pb,Sb,and Zn achieved high and alarming degrees of contamination,whereas Fe,Mn,and Ti were negligible or low to moderate pollution degrees.Combined microcalorimetry and enzymatic activity measurements of contaminated soil samples were used to assess the microbial metabolic activity characteristics.Correlation analysis elucidated the relationship between metal(loid)s exchangeable fraction or content and microbial activity characteristics(p<0.05).The microbial metabolic activity in the D-1 layer was low presumably due to heavy metal stress.Enzyme activity indicators and microcalorimetric growth rate(k)measurements were considered sensitive indicators to reflect the soil microbial activities in abandoned chemical smelting sites.

Comparison of Di-n-methyl Phthalate Biodegradation by Free and Immobilized Microbial Cells

To compare the biodegradation of di-n-methyl pathalate by free and immobilized microbial cells. Methods The enrichment and isolation technique was used to isolate the microorganism. The PAV-entrapment method was utilized to immobilize the microorganisms. The scanning electron microscophy (SEM) was used to observe the growth and distribution of microbial cells immobilized inside the PVA bead gels. The GC/MS method was used to identify the main intermediates of DMP degradation. Results The microbial cells could grow quite well in PVA gel. The metabolic pathway did not change before and after immobilization of the microbial cells. The degradation rate of immobilized cells was higher than that of free cells. Conclusion The immobilized microbial cells possess advantages than free cells when applied to the biodegradation of toxic organic pollutants.

Restoration processes of pollution zones in Hanjiang River

Two pollution zones in middle and lower reaches of Hanjiang River were selected for studying restoration processes. In each zones 6 stations were set up in upper stream of sewage outfall, 50m, 100 or 150m, 250 or 525m and 1250 or 3500m apart from the outfall. Chemical monitoring and microbial community biomonitoring were carried out simultaneously. Either the chemical monitoring or the biological monitoring proved the self-purification process of water body along with the increased distance from the sewage outfall. 4 biological parameters (species number of protozoa, percentage of phytomastigophora, diversity index and heterotrophy index) and parameter Seq of the colonization process all have statistically significant correlations with chemical comprehensive pollution indexes Pa and Pb.

Tolerance of Grasses to Heavy Metals and Microbial Functional Diversity in Soils Contaminated with Copper Mine Tailings

Copper(Cu) mine tailings,because of their high content of heavy metals,are usually hostile to plant colonization.A pot experiment was conducted to determine the tolerance of four forage grasses to heavy metals in Cu mine tailings and to examine the variation in the microbial functional diversity of soils from the tailing sites in southern China.All the four grass species survived on Cu mine tailings and Cu mine tailing-soil mixture.However,on pure mine tailings,the growth was minimal,whereas the growth was maximum for the control without mine tailings.The tolerance of grasses to heavy metals followed the sequence:Paspalum notatum > Festuca arundinacea > Lolium perenne > Cynodon dactylon.The planting of forage grasses enhanced the soil microbial biomass.The Biolog data indicated that the soil microbial metabolic profile values(average well color development,community richness,and Shannon index) of the four forage grasses also followed the sequence:P.notatum > F.arundinacea > L.perenne > C.dactylon.Thus,P.notatum,under the experimental conditions of this study,may be considered as the preferred plant species for revegetation of Cu mine tailing areas.

Sludge Pollution Control from Crude Oil Tank Cleaning

This study investigated the use of microbial analysis as a bioremediation option for remediating petroleum sludge, which is part of the waste stream generated in the petroleum industry. The aim is to reduce environmental burden caused by the discharge of untreated sludge. Sludge sample was cultured in other to isolate microorganisms for the sludge treatment. The selected strain of the organisms after screening were Aspergillus flavus, Aspergillus niger, Verticillus sp, Penicillum sp, and Microsporium audouinii. Bioreactors (labeled A, B, C, D and O) were designed for the treatment of petroleum sludge. These reactors contain 2.0 × 10-2 m3 of the diluted sludge samples and the isolated organisms for the treatment process. On a weekly basis, the control reactors received 1.5 × 10-3 m3 of fresh and saline water respectively. After 12 weeks of treatment, sludge physicochemical characteristics showed distinct variations. From the result, reactor D was the best in terms of remediating the sludge as compared to other reactors. Friedman non-parametric test was performed to check if the weeks of treatment affected the reduction of the total hydrocarbon content (THC) in the five reactors and also checked for significant differences in the THC after treatments. The drop in the THC of the treated sludge ranged from 56.0% to 67.3%. These results showed the possibility of enhanced biodegradation of petroleum sludge by hydrocarbon utilizing microorganisms (fungi).

Urban Soil Microbial Features and Their Environmental Significance as Exemplified by Aberdeen City, UK

Urban soil research has invoked great interest in recent years. Previous studies were mainly focused on urban soil physics and chemistry, and soil geography to constrain the source, distribution, transport and deposition of pollutants such as heavy metals and health\|hazardous organic matter, but little has been done on soil microbiology. In this paper, the authors reported the variation of microbial features in urban soils compared with those from adjacent rural areas. The results show great changes in basal respiration rates, microbial biomass and ecophysiological parameters have taken place in urban environment because of the anthropogenic stress, thus activating the microorganisms. As a result, much more energy carbon is consumed at a low utilization efficiency. So microbial biosensors can be used to indicate urban environmental pollution effectively.

Application of Microbial BOD Sensors in Marine Monitoring

A strain of yeast, which can endure high osmotic pressure, is employed for the sensitive material of the microbial BOD sensor. Two immobilization methods are used, I.e. Calcium alginate gel be ads and PV A gel beads. The results show that the PVA gel beads is better. The influences of osmosis and heavy metal ions on the yeast entrapped in the PVA gel beads are also studied in the experiment.

Toxicity of Heavy Metals and Microbial Analysis of Soil Samples Collected from the Area around Zliten Cement Factory

Soil samples were collected from and around Zliten cement factory, Zliten town, Libya. Soil metals and microbial contents were determined. The results obtained for the examined physiochemical characteristics of soil in the area studied prove that cement dust from the Zliten cement factory inLibyahas had a significant impact on the soil. The affected soil properties are pH and total calcium content. These characteristics were found to be higher than those in similar soils from the same area (unpolluted). The increment of soil pH in the same area may be a result of precipitation of cement dust over the years. Metal uptake from cement to plants and soil then affects organisms’ bodies, a fact that seems to be reflected in this study. Different responses were found in each site. For instance, the dominance of fungi of soil was lowest at100 mfrom the factory and the evenness and diversity increased at this site compared to300 mfrom the factory and the control area.

Assessment of Indoor Microbial Quality of Library’s Premise: Case of Central Library of the University of YaoundéI

Background: Good indoor air quality is important for human health and comfort, because people spend a most of their time within buildings. Microbial pollution is a key element of indoor air pollution. Bacteria and fungi growing indoors when sufficient moisture is available usually cause indoor air pollution. Methods: This study was conducted to assess the microbial concentration and to identify the main bacteria and fungi in the indoor environment of Central Library of the University of Yaoundé I. A total of 76 samples were taken from indoor air, surfaces and mouldy books. Bioaerosol sampling and air concentration were made by passive air sampling technique using petri dishes containing different culture media and exposed for 30, 60 and 90 min in the morning and afternoon. Sampling of surfaces and mouldy books were made by rubbing using sterile swab. The identification of the isolated microorganisms was based on macroscopic, microscopic and biochemical characters. Results: The concentrations of bacteria and fungi in the indoor environment of Central Library of the University of Yaoundé I ranged between 747 and 2324 CFU/m for the air and 40 and 500 CFU/cm2 for surfaces. In the examined area, the predominant culturable species of microflora were members of the following bacteria genera;Bacillus spp, Staphylococcus spp, Micrococcus spp, Pseudomonas spp, Rhodococcus spp, Enterobacter spp, Klebsiella spp and Escherichia spp and fungi;Aspergillus spp, Penicillium spp, Curvularia spp, Mucor spp, Cladosporium spp, Candida spp Rhodotorula spp, Fusarium spp, Trichophyton spp, Acremonium spp, Aureobasidium spp, Rhizopus spp and Chrysonilia spp. Conclusion: High concentrations of bacteria and fungi were observed in the central library of the University of Yaoundé I. Precautions and safety measures should be taken to reduce microbial pollution at universities libraries by improving libraries ventilation and disinfection.

Effects of lead pollution on soil microbial community diversity and biomass and on invertase activity

Lead(Pb)pollution is one of the most widespread and harmful environmental problems worldwide.Determination of changes in soil properties and microbial functional diversity due to land use is needed to establish a basis for remediation of soil pollution.This study aimed to investigate soils contaminated by Pb from different sources and to analyze the functional diversity and metabolism of soil microbial communities using Biolog technology.Pb pollution(>300 mg kg-1)significantly influenced the diversity and metabolic functions of soil microbial communities.Specifically,Pb contamination significantly reduced soil microbial biomass carbon(C)and nitrogen(N)levels and catalase activity while increasing invertase activity.Furthermore,Biolog EcoPlate assays revealed that Pb pollution reduced the general activities of soil microorganisms,suppressing their ability to utilize C sources.In Pb-contaminated areas lacking vegetation cover,Shannon,Simpson,and McIntosh diversity indices of soil microorganisms were significantly reduced.The microbial diversity and biomass C and N levels were affected by land use and soil properties,respectively,whereas soil enzyme activity was primarily affected by the interaction between land use and soil properties.Our results provide a reference and a theoretical basis for developing soil quality evaluation and remediation strategies.

有机污染场地土壤化学氧化耦合微生物修复技术

化学氧化耦合微生物修复是通过适度氧化预处理降解转化污染土壤中的高浓度、难降解有机污染物,并增强其生物可利用性,再利用微生物降解有机污染物的技术,在有机污染场地土壤修复中具有良好的应用潜力.本文评述了化学氧化耦合微生物修复技术的研究进展,重点介绍了土壤氧化还原电位精准预测、土著微生物优化或工程菌强化方法,阐述了基于机器学习的土壤污染修复调控策略,以期提升化学氧化耦合微生物修复效率,为有机污染场地土壤绿色、经济、安全、高效修复的工程应用提供参考.

土壤中微塑料与环境污染物的复合作用及其对微生物的影响

随着塑料制品在工农业和生产生活中的广泛使用,大量微塑料被释放到土壤中,带来不可忽视的生态环境与健康风险。长久以来,人们更关注微塑料本身的生态毒性,对微塑料与环境中的其他化学污染物的联合作用及其环境效应研究较少。由于土壤微生物在微塑料降解过程中起着关键作用,认识土壤微塑料是如何通过影响土壤环境而直接或间接影响土壤中微生物群落和土壤生态功能的微观机理,已成为未来推进微塑料的降解和科学认识微塑料生态系统风险的关键。本文综述了近年来微塑料在土壤中吸附和迁移机理,以及微塑料的吸附程度和位置对其迁移行为的影响。总结了微塑料与土壤中有机污染物和重金属的复合作用的进展,探讨了这些复合作用对土壤环境风险的影响,包括污染物的毒性、生物利用度和迁移性的变化。评述了微塑料对土壤微生物群落的影响及作用机制,微塑料对微生物的物种丰富度、活性和结构的影响,以及微塑料表面的定殖和选择性富集能力。建议未来应该加强以下三方面的研究:①深入探索微塑料与环境污染物的复合作用及其生态毒理作用的微观机理;②认识土壤中微塑料对土壤微生物群落结构改变的微观机制;③探索通过科学调控土壤理化特性、特异性微生物在微塑料表面的定殖与富集能力等途径来控制土壤中微塑料及微塑料-其他环境污染物复合污染的可能性。

微生物燃料电池处理畜禽养殖废水研究进展及展望

随着畜禽养殖业向规模化、集约化方向发展,畜禽养殖过程中产生的大量废水成为畜禽养殖场周围环境污染的重要因素。微生物燃料电池(Microbial Fuel Cell,MFC)作为一种电化学微生物技术,能够在去除废水中有机物的同时产生电能,在处理高浓度畜禽养殖废水方面具有广阔的发展和应用前景。本文介绍了MFC的分类,并从污染物(化学需氧量、氨氮、总磷和抗生素)去除和产电性能两个方面分析MFC在畜禽养殖废水处理领域的研究现状,并拓展性地阐述了新型耦合MFC技术处理畜禽养殖废水的应用前景,最后指出MFC处理畜禽养殖废水存在的问题,并提出未来可行的发展方向,包括放大装置尺寸、开发新型耦合MFC技术、研究参数的交互作用、深入发掘污染物去除机理和电子传递机制。

原料乳及牧场环境中的微生物多样性及嗜冷菌污染源分析

原料乳中嗜冷菌超标会产生较高水平的耐热蛋白酶和脂肪酶,这两种酶是导致产品进入货架期后出现质量问题的重要原因。为探究牧场奶牛生活环境以及原料乳在流转过程中不同环节的微生物多样性,找出牧场中嗜冷菌的污染来源,本研究选取河北地区某规模化奶牛养殖场,采集TMR饲料、牛舍垫土、头三把奶、头三把奶之后的常规乳以及储奶罐中的原料乳等样品,利用宏基因组测序技术对所有样品的菌群结构、嗜冷菌种类及丰度进行分析。结果表明:在门水平上,主要微生物为变形菌门、厚壁菌门、放线菌门,在属水平上主要是无形体属、链球菌属、肠球菌属、短螺菌属、芽孢杆菌属、假单胞菌。此外对样品中的关键嗜冷菌(假单胞菌)进行分析,牛舍垫土的多样性最丰富的,包含了牧场中常规乳及储奶罐中乳假单胞菌种类的99.63%和96.39%,说明牛舍垫土是各类假单胞菌潜在的污染源。

复合菌群构建及其石油烃降解特性

为获得高效降解石油烃复合菌群,对实验室保存的菌株进行石油烃降解效果及原油4组分降解能力分析研究,筛选出了4株菌(A1、A3、Y3、Y4),对其进行ITS和16S rRNA分子鉴定,确认4株菌的分类信息,并优化高效降解菌株的复配方式。结果显示:A1属于不动杆菌属(Acinetobacter)、A3属于芽胞杆菌属(Bacillus)、Y3和Y4均为假丝酵母菌属(Candida);A1、A3、Y3、Y4对石油烃的降解率分别为42.27%、40.95%、62.02%、69.84%;其中Y4对烷烃和芳烃降解效果最佳,降解率分别为65.71%和23.69%,沥青质降解效果最好的是A1,胶质降解效果最好的是Y3,降解率分别为22.74%和21.22%,A3对各组分降解能力均衡;A1、A3、Y4复合的菌群降解效果最佳,其降解率高达83.11%,相较于单一菌株提高了1.19—2.03倍;A1、A3、Y4的最佳接种量比例为0.9∶0.9∶1.5,其降解率可达88.34%。该研究成功筛选出一种新的高效降解石油烃的菌群,对进一步研究和应用于石油污染治理具有重要指导意义。

生物慢滤系统处理微污染水体的试验研究:两种滤料的对比

滤料的特性是决定生物慢滤系统对各类污染物去除效果的主要因素之一,然而国内外在不同滤料的生物慢滤系统净化效能比较和微生物机制方面的研究十分有限。本研究选用石英砂和活性炭作为生物慢滤系统的滤料,比较了它们在污染物去除和微生物群落方面的异同,并在滤料堵塞时开展了反冲洗实验。结果表明,两柱均需要26 d完成挂膜。挂膜完成后,活性炭柱对浊度、CODMn和氨氮的去除率分别为92.18%、65.53%和99.37%,而石英砂柱的去除率分别为91.89%、42.91%和98.87%,活性炭柱的去除率优于石英砂柱。在挂膜期间,石英砂柱和活性炭柱都出现了亚硝酸盐氮和硝酸盐氮的积累现象。石英砂柱主要的优势菌群为A0839和Rhodobacter,而活性炭柱主要的优势菌群为Ramlibacter、Pseudomonas和Leptospirillum,从微生物群落的角度解释了活性炭柱对有机物和总氮的去除效果优于石英砂柱。活性炭滤料的穿透深度大于石英砂滤料,石英砂柱的滤料主要是前40 cm发生堵塞,而活性炭柱的滤料是前60 cm发生堵塞。在滤料膨胀系数为30%时,石英砂柱和活性炭柱的反冲洗强度分别为6.83 L·m^(-2)·s^(-1)、3.16 L·m^(-2)·s^(-1),活性炭柱的反冲洗水量比石英砂柱少了53.7%。本研究为农村地区慢滤系统滤料的选择提供了技术依据,为滤料的堵塞问题提供了经济可行的解决方案,为该技术在农村供水技术中的应用提供了技术支持。