Group Of Organic Contaminants Research Articles

Effects of organic contaminants on arbuscular mycorrhiza formation: A meta-analysis

Arbuscular mycorrhizal fungi (AMF) function mostly depends on their colonization to roots. However, it has not been systematically clear how arbuscular mycorrhiza (AM) formation is affected by organic contaminants. In this study, a meta-analysis was performed to estimate the effects of three groups of organic contaminants (polycyclic aromatic hydrocarbons (PAHs), crude oil, and pesticide) in soil on mycorrhizal colonization rates (MCRs) from various moderators, such as AMF (genus, species, and inoculation mode), contaminant (level, type, and source), and experimental conditions (plant type, duration, and soil sterilization). Our results showed that all MCRs (total, vesicular, arbuscular and hyphal) significantly decreased under the stresses of three contaminants. Generally, pesticide caused larger decrease in all MCRs than PAHs and crude soil except for vesicular MCRs. Mixed AMF showed larger decrease in the total and vesicular MCRs than single AM fungus, but contrary trends in the arbuscular and hyphal MCRs. Moreover, man-made contaminant seemed to produce larger negative effects on the total, vesicular, and arbuscular MCRs than industry contaminant. The inhibitive effects of three contaminants on the total and vesicular MCRs increased with increasing experimental duration, and were larger in the non-sterilized soil than in the sterilized soil. Hyphal and spore growth were also inhibited by three contaminants in most cases. Hyphal length and spore number of single AM fungus were lower than those of mixed AMF, and pesticide produced larger inhibition on the hyphal length and spore number than PAHs and crude oil. Similar trend was found in the non-sterilized soil relative to the sterilized soil. This study indicated that AM formation and AM structure were negatively affected by three organic contaminants, whereas the inhibitive degrees varied with AMF, organic contaminant and experimental conditions.

Engineering Pseudomonas putida To Produce Rhamnolipid Biosurfactants for Promoting Phenanthrene Biodegradation by a Two-Species Microbial Consortium.

ABSTRACTPolycyclic aromatic hydrocarbons (PAHs) are a group of organic contaminants that pose a significant environmental hazard. Phenanthrene is one of the model compounds for the study of biodegradation of PAHs. However, the biodegradation of phenanthrene is often limited by its low water solubility and dissolution rate. To overcome this limitation, we engineered a strain of Pseudomonas putida to produce rhamnolipid biosurfactants and thereby promote phenanthrene biodegradation by an engineered strain of Escherichia coli constructed previously in our lab. The E. coli-P. putida two-species consortium exhibited a synergistic effect of these two distinct organisms in degrading phenanthrene, resulting in an increase from 61.15 to 73.86% of the degradation ratio of 100 mg/L phenanthrene within 7 days. After additional optimization of the degradation conditions, the phenanthrene degradation ratio was improved to 85.73%.IMPORTANCE Polycyclic aromatic hydrocarbons (PAHs), which are recalcitrant, carcinogenic, and tend to bioaccumulate, are widespread and persistent environmental pollutants. Based on these characteristics, the U.S. Environmental Protection Agency has listed PAHs as priority contaminants. Although there are many methods to treat PAH pollution, these methods are mostly limited by the poor water solubility of PAHs, which is especially true for the biodegradation process. Recent evidence of PAH-contaminated sites suffering from increasingly severe impact has emerged. As a result, the need to degrade PAHs is becoming urgent. The significance of our study lies in the development of nonpathogenic strains of biosurfactant-producing Pseudomonas aeruginosa for promoting the degradation of phenanthrene by engineered Escherichia coli.

Soil Characteristics Constrain the Response of Microbial Communities and Associated Hydrocarbon Degradation Genes during Phytoremediation.

Rhizodegradation is a promising cleanup technology where microorganisms degrade soil contaminants in the rhizosphere. A symbiotic relationship is expected to occur between plant roots and soil microorganisms in contaminated soils that enhances natural microbial degradation. However, little is known about how different initial microbiotas influence the rhizodegradation outcome. Recent studies have hinted that soil initial diversity has a determining effect on the outcome of contaminant degradation. To test this, we either planted (P) or not (NP) balsam poplars (Populus balsamifera) in two soils of contrasting diversity (agricultural and forest) that were contaminated or not with 50 mg kg-1 of phenanthrene (PHE). The DNA from the rhizosphere of the P and the bulk soil of the NP pots was extracted and the bacterial genes encoding the 16S rRNA, the PAH ring-hydroxylating dioxygenase alpha subunits (PAH-RHDα) of Gram-positive and Gram-negative bacteria, and the fungal ITS region were sequenced to characterize the microbial communities. The abundances of the PAH-RHDα genes were quantified by real-time quantitative PCR. Plant presence had a significant effect on PHE degradation only in the forest soil, whereas both NP and P agricultural soils degraded the same amount of PHE. Fungal communities were mainly affected by plant presence, whereas bacterial communities were principally affected by the soil type, and upon contamination the dominant PAH-degrading community was similarly constrained by soil type. Our results highlight the crucial importance of soil microbial and physicochemical characteristics in the outcome of rhizoremediation.IMPORTANCE Polycyclic aromatic hydrocarbons (PAH) are a group of organic contaminants that pose a risk to ecosystems' health. Phytoremediation is a promising biotechnology with the potential to restore PAH-contaminated soils. However, some limitations prevent it from becoming the remediation technology of reference, despite being environmentally friendlier than mainstream physicochemical alternatives. Recent reports suggest that the original soil microbial diversity is the key to harnessing the potential of phytoremediation. Therefore, this study focused on determining the effect of two different soil types in the fate of phenanthrene (a polycyclic aromatic hydrocarbon) under balsam poplar remediation. Poplar increased the degradation of phenanthrene in forest, but not in agricultural soil. The fungi were affected by poplars, whereas total bacteria and specific PAH-degrading bacteria were constrained by soil type, leading to different degradation patterns between soils. These results highlight the importance of performing preliminary microbiological studies of contaminated soils to determine whether plant presence could improve remediation rates or not.

Organic contaminants in the effluent of Chinese wastewater treatment plants.

The effluents of wastewater treatment plants (WWTPs) are the important sources for pollutants. These pollutants may entry into surface water, groundwater, and soil by recharging and irrigation then pose risk to human beings. Using reports from the past 20years (n = 58), we conducted this review of organic contaminants (OCs) in the effluent of Chinese WWTPs. All the studies were during 2005 to 2017 and more than two papers were conducted in every year. Nineteen provinces (20 cities) were covered and most of the studies were located in the eastern part of China, especially the most developed and highest density of population areas. Two hundred eighty-four OCs were contained. E antibiotics, endocrine-disrupting chemicals (EDCs), and pharmaceuticals were the most commonly studied groups of OCs, and ofloxacin, norfloxacin, and sulfamethoxazole were the three most commonly reported OCs. The highest concentration appeared for bisphenol A (BPA). The relative standard deviations (RSDs) of concentrations of the most commonly studied compounds were high. In the future, more studies should pay attention on national analysis and more pollutants.

Exposure to airborne polycyclic aromatic hydrocarbons during pregnancy and risk of preterm birth

BackgroundPreterm birth is an important marker of health and has a prevalence of 12–13% in the U.S. Polycyclic aromatic hydrocarbons (PAHs) are a group of organic contaminants that form during the incomplete combustion of hydrocarbons, such as coal, diesel and gasoline. Studies suggest that exposure to PAHs during pregnancy is related to adverse birth outcomes. The aim of this study is to evaluate the association between exposure to PAHs during the pregnancy and preterm birth. MethodsThe study population included births from years 2001 to 2006 of women whose maternal residence was within 20km of the primary monitoring site in Fresno, California. Data in the Fresno area were used to form a spatio-temporal model to assign daily exposure to PAHs with 4, 5, or 6 rings at the maternal residence throughout pregnancy of all of the births in the study area. Gestational age at birth and relevant covariates were extracted from the birth certificate. ResultsWe found an association between PAHs during the last 6 weeks of pregnancy and birth at 20–27 weeks (OR=2.74; 95% CI: 2.24–3.34) comparing the highest quartile to the lower three. The association was consistent when each quartile was compared to the lowest (OR2nd=1.49, 95% CI: 1.08–2.06; OR3rd=2.63, 95% CI:1.93–3.59; OR4th=3.94, 95% CI:3.03–5.12). Inverse associations were also observed for exposure to PAHs during the entire pregnancy and the first trimester and birth at 28–31 weeks and 20–27 weeks. ConclusionAn association between PAH exposure during the 6 weeks before delivery and early preterm birth was observed. However, the inverse association with early preterm birth offers an unclear, and potentially complex, inference of these associations.

Guidance Manual for the minimisation of NDMA and other Nitrosamines in Drinking and Recycled Water

N-nitrosodimethylamine (NDMA) is a nitrogen-containing organic compound that has known carcinogenic properties. NDMA has been a health concern for some industries for a number of years as it is used in rubber formulations, as a fire retardant, antioxidant, additive for lubricants and softener of copolymers; it is also a degradation product of dimethylhydrazine, an additive to rocket fuel. Most people are exposed to NDMA via a number of diverse routes including cigarette smoke (actively or passively) and processed foods, for example smoked meat products. However, it has only come to the attention of the international water industry since it was recognised as a disinfection by-product (DBP) of chloramination or chlorination in the presence of ammonia. The aim of this guidance manual is to answer commonly asked questions about this emerging issue, such as: This Guidance Manual has a companion document, Generic Management Plan for Nitrosamines in Drinking Water which provides provide background information on the group of organic contaminants, nitrosamines. This title is Co-published with WaterRA . ISBN: 9781780406237 (eBook) ISBN: 9781780406220 (Print)

Generic Management Plan for Nitrosamines in Drinking water

The purpose of the Generic Management Plan for Nitrosamines in Drinking Water is to provide background information on the group of organic contaminants known as nitrosamines, as well as help water quality managers and treatment plant managers and operators in three main aspects of nitrosamine management, namely: This is a companion document to the Guidance manual for the minimisation of nitrosamines in drinking and recycled water . The latest edition of the guidelines has been published and a guideline value of 100 ng/L for NDMA has since been promulgated. A comprehensive survey of drinking water systems in Australia undertaken as part of project 1018 showed that the majority have levels of NDMA well below the guideline value. It also helped clarify and validate the risks and supported the suggested mitigation measures outlined in this document that can be applied for the production of drinking water that continuously complies with the guidelines. This title is Co-published with WaterRA . ISBN: 9781780406244 (eBook)

Recycled paper–paperboard for food contact materials: Contaminants suspected and migration into foods and food simulant

Contaminant residues in food packaging is a new challenge of our time, as it may pose a threat for consumers. Higher levels of contaminants were observed in food packaging made by recycled materials, even if little information is available for some groups of contaminants. The present study proposes a procedure for analyzing three different groups of organic contaminants in recycled paper and paperboard. Seventeen commercial samples were analyzed for the presence of bisphenol A (BPA), bis (2-ethylhexyl) phthalate (DEHP), nonylphenol monoethoxylate (NMP) and nonylphenol di-ethoxilate (NDP). Not all the samples contained all the contaminants; BPA was the only substance present in all the samples. The concentrations detected were quite high and, in most of the cases, in agreement with results reported in previous studies. Substance migration tests from spiked/non-spiked samples for two dry foods and Tenax® food simulant were undertaken. BPA migration quotients were always lower than 1%, whereas the migration quotients of DEHP were higher than 2.0%. The highest nonylphenols migration quotients were 6.5% for NMP and 8.2% for NDP. Tenax® simulates well the contaminants migration from paperboard to dry food, in some cases being even more severe than the food.

Selected personal care products and endocrine disruptors in biosolids: An Australia-wide survey

Personal care products (PCPs) and endocrine disrupting compounds (EDCs) are groups of organic contaminants that have been detected in biosolids around the world. There is a shortage of data on these types on compounds in Australian biosolids, making it difficult to gain an understanding of their potential risks in the environment following land application. In this study, 14 biosolids samples were collected from 13 Australian wastewater treatment plants (WWTPs) to determine concentrations of eight compounds that are PCPs and/or EDCs: 4-t-octylphenol (4tOP), 4-nonylphenol (4NP), triclosan (TCS), bisphenol A (BPA), estrone (E1), 17β-estradiol (E2), estriol (E3) and 17α-ethinylestradiol (EE2). Concentration data were evaluated to determine if there were any differences between samples that had undergone anaerobic or aerobic treatment. The concentration data were also compared to other Australian and international data. Only 4tOP, 4NP, TCS, and BPA were detected in all samples and E1 was detected in four of the 14 samples. Their concentrations ranged from 0.05 to 3.08 mg/kg, 0.35 to 513 mg/kg, < 0.01 to 11.2 mg/kg, < 0.01 to 1.47 mg/kg and < 45 to 370 μg/kg, respectively. The samples that were obtained from WWTPs that used predominantly anaerobic treatment showed significantly higher concentrations of the compounds than those obtained from WWTPs that used aerobic treatment. Overall, 4NP, TCS and BPA concentrations in Australian biosolids were lower than global averages (by 42%, 12% and 62%, respectively) and 4tOP concentrations were higher (by 25%), however, of these differences only that for BPA was statistically significant. The European Union limit value for NP in biosolids is 50 mg/kg, which 4 of the 14 samples in this study exceeded.

Wastewater reuse in Mediterranean semi-arid areas: The impact of discharges of tertiary treated sewage on the load of polar micro pollutants in the Llobregat river (NE Spain)

The presence of sewage-borne micro contaminants in environmental waters is directly related to the discharge of treated effluents from wastewater treatment plants (WWTP) and the flow rate of the receiving river waters. Mediterranean rivers, in particular, are characterized by important fluctuations in the flow rates and heavy pollution pressures resulting from extensive urban, industrial and agricultural activities. This translates into contamination levels in these rivers often higher than those in other larger European basins. The present work provides an overview of the occurrence of five groups of organic contaminants (131 compounds) namely pharmaceuticals, illicit drugs, polar pesticides, estrogens, alkylphenols and related ethoxylates in WWTP tertiary treatment effluents. Data gathered during a period of water reuse carried out in the lower stretch of the Llobregat river (NE Spain), in the surroundings of the town of Barcelona as a consequence of the severe drought that took place along the years 2007–2008 are presented as illustrative example. In general, measured concentrations of the target compounds were in the low to mid ng L −1 range. The total concentration of each compound class downstream to the discharge point was similar or slightly higher than that found upstream. Regarding the loads calculated for each compound, the relative contribution from the river upstream and the tertiary effluent were highly compound depending with no apparent trend. However, estimation of the overall bulk loads for each compound class determined in the Llobregat river showed the following rank order: pharmaceuticals > alkylphenols > pesticides > illicit drugs ≫ estrogens.

Effects of solution pH on adsorption of chlorophenols by cross‐linked polyvinyl pyrrolidone (PVP XL) polymers

AbstractWidely used as insecticides, fungicides, and disinfectants and regarded as having relatively high toxicities, chlorophenols are a group of organic contaminants whose solubility and sorptive properties on different substrates vary greatly with solution pH. In this study, the feasibility and applicability of using cross‐linked polyvinyl pyrrolidone (PVP XL) polymers to adsorb and remove chlorophenols from water under different pH conditions were investigated. The adsorption of chlorophenols on PVP XL was instantaneous and followed a linear sorption isotherm under the tested concentrations from 0.05 to 10 mg L–1, suggesting a partitioning mechanism. The chlorophenol adsorption increased as the degree of chlorination, thus the octanol–water partitioning coefficient, increased. A decrease in contaminant distribution coefficients with an increase in solution pH suggested that the deprotonated species had a weaker affinity for PVP XL surfaces than their protonated counterparts. The free energy of adsorption of 2,3,4,6‐tetrachlorophenol (TeCP) on PVP XL was negative, suggesting a spontaneous adsorption. The negative enthalpy values of TeCP adsorption on PVP XL indicated an exothermic process. The results from this study show that PVP XL could be a viable alternative for the adsorption of chlorinated phenols in aqueous media as a remediation tool. The instantaneous adsorption will make PVP XL a possible choice for ultra filtration to remove chlorophenols from water. © 2010 American Institute of Chemical Engineers Environ Prog, 2011

Assessing the Phytoremediation Potential of Tall Fescue and Sericea Lespedeza for Organic Contaminants in Soil

AbstractThe phytoremediation potential of using tall fescue (Festuca arundinacea Schreb.) grass and sericea lespedeza (Lespedeza cuneata [Dum. ‐Cours.]) legume species was assessed using three different groups of organic contaminants in soil. One hundred parts per million (ppm) each of a nitroaromatic compound (TNT), a polycyclic aromatic hydrocarbon (Pyrene), and a polychlorinated biphenyl (Aroclor 1248) were used to contaminate the soils. The experiments were conducted using soils with high and low organic‐matter content. The results indicate that recoveries of Pyrene and TNT were very low in all treatments in soil with high organic‐matter content (6.3 percent) compared with recoveries in soil with low organic‐matter content (2.6 percent). In contrast, recoveries of PCB from soil were not dependent on the soil's organic‐matter content. Planting both the legume and grass species had significant effect on the transformations of TNT and PCB in the soil with low organic‐matter content and did not affect the fate of Pyrene in both soils. The amount of TNT transformed in the four months of plant growth was 63 percent in the tall fescue and 46 percent in the sericea‐planted soils, compared with only a 15 percent unaccounted loss in the unplanted control soils. Furthermore, the grass species, with its massive root system, was significantly better at causing TNT dissipation compared with the legume species, which has less root vegetative mass. The plant biomass, particularly the shoot weight of the tall fescue grass, was significantly increased as a result of TNT treatment. Tall fescue and sericea biomass did not appear to have any significant effect on Pyrene transformation. Planting sericea provided a significantly high level of PCB transformation in soils with either high or low amounts of organic matter. Tall fescue did not appear to have any significant effect on PCB transformation. © 2002 Wiley Periodicals, Inc.

The status and trends of trace element and organic contaminants in oysters, Crassostrea virginica, in the waters of the Carolinas, USA.

Concentrations of eight trace elements (As, Cd, Cu, Hg, Ni, Pb, Se and Zn), lindane and six groups of organic contaminants (total-chlordane, total-PCB, total-DDT, Dieldrin and Aldrin, total-butyltins, total-PAHs) at the 11 NOAA mussel watch project (MWP) sites located in North and South Carolina have been compared with the national US MWP data. Three sites from North and South Carolina had concentrations of PAHs in the upper 15th percentile on a national scale. One site had high concentrations of butyltins, and two sites had high Se concentrations. All sites from Beaufort, North Carolina, south had high As concentrations. Decreasing temporal trends were found for As, Cd, total-chlordane, DDT, PCB, and PAHs at some sites.

Laboratory Study of Soil Flushing by Aqueous Solutions

This paper explores the removal of organics from soils in a simulated in-situ environment using aqueous solution extraction. A laboratory investigation is described in which organic compounds representative of the major groups of organic contaminants were adsorbed in low concentrations onto slightly organic, loamy soil, and various aqueous solutions were permeated through the soil under controlled hydraulic gradients and effective stress conditions, simulating the in-situ extraction process. The effectiveness of the extraction process was evaluated by periodically measuring the concentration of the contaminants in the permeameter effluent. Simple contact shaking tests were also performed and compared with the results of the permeation tests to ascertain whether contact shaking tests can be used as an index to the effectiveness of permeation testing. The results may be applicable to injection and extraction wells, in which the solution extract is pumped to a location on the ground surface for treatment.

Simultaneous determination of glycerol, and mono-, di- and triglycerides in vegetable oil methyl esters by capillary gas chromatography

A gas chromatographic procedure for the simultaneous determination of glycerol, mono-, di- and triglycerides in vegetable oil methyl esters has been developed. Quantitative information about this group of organic contaminants is very important for the quality of these oleochemical products when used as automotive diesel fuel substitutes. Trimethylsilylation of glycerol, mono- and diglycerides, followed by GC using a 10-m capillary column coated with a 0.1-μm film of DB-5 allows the determination of all analytes in a single GC run. Calibration is performed by analysis of standard solutions containing glycerol, mono-, di- and triolein as well as two internal standards, 1,2,4-butanetriol and tricaprin. The recovery of the procedure at different concentration levels and the repeatability of the quantitative results are evaluated.