Effects Of Organic Contaminants Research Articles

Effects of organic contaminants in reactive oxygen species, protein carbonylation and DNA damage on digestive gland and haemolymph of land snails

The present study focused on early responses of land snails Eobania vermiculata to organic environmental contaminants, by investigating the use of a newly-established method for the measurement of protein carbonylation as a new biomarker of terrestrial pollution, as well as by measuring the ROS production and the DNA damage. Land snails were exposed to different concentrations of chlorpyrifos, parathion-methyl or PAHs in vivo or in vitro in the laboratory. The susceptibility of exposed snails was increased in relation to oxidative stress induced by contaminants tested. A statistically significant increase in ROS production, protein carbonylation and DNA damage was revealed in the snails treated with pollutants, compared to the untreated ones. The results indicated the effectiveness of measuring ROS production and DNA damage and reinforce the application of the present ELISA method in organic terrestrial pollution biomonitoring studies.

Discharge Plasma for the Treatment of Industrial Wastewater

The treatment of industrial wastewaters collected from petrochemical works, gypsum plant, and printing and dyeing mill, was investigated at atmospheric pressure in air discharge plasma. The degradation effects of organic contaminants in water were compared for the printing and dyeing wastewater under different discharging conditions and for the wastewater from the other two plants under the same discharging conditions. The influences of several factors on chemical oxygen demand (COD) remove rate were studied experimentally. The results showed that the treatment effects for the same industrial wastewater differed significant under different discharge conditions. There may be a suitable discharge plasma treatment to specific industrial wastewater. Due to the removal rates of COD of industrial wastewaters with discharge plasma isn’t very high, therefore the discharge plasma water treating needs to combine conventional water treating methods or addition other catalyst to effectively remove organic pollutants in wastewater and obtain the expected treatment effect.

Identifying biological effects of organic contaminants in surface- and groundwater

Thousands of chemicals are in daily use; many of these reach the aquatic environment, which serves as a medium of transport and deposition into sediment and organisms. It is often unknown which effects these contaminants, alone or in combination with other stressors, may have on organisms, populations and communities in the aquatic environment. Ecotoxicology strives to identify and mechanistically understand contaminant–biota interactions with the ultimate goal to predict potential adverse effects. There are two general routes to addressing this goal. The first is to understand how organisms and populations respond according to anticipated exposure routes, organisms’ genome and physiology, and structure- physico-chemical properties of chemicals. This knowledge should lead to improved criteria for chemical design and approval. The second general route is to identify the cause–effect relationships of effects detected in the environment without prior knowledge on the chemical’s identity. This approach serves to pinpoint critical chemicals in complex environmental samples to enable decisions or technologies for their reduction or removal. An example will be presented in which biological effect assessment contributed to a better understanding of groundwater contamination.

The role of biochar in modifying the environmental fate, bioavailability, and efficacy of pesticides in soils: a review

The role of biochar in sequestration of carbon, reducing the emission of greenhouse gases, and improving the soil fertility is increasingly being recognised and is leading to the recommendations of biochar amendment of soils. However, the implications of such amendments to the environmental fate and efficacy of pesticides are not well understood. The published work on the role of black carbon (which includes charcoal, soot, and other pyrolytic carbon materials) in the environmental fate and effect of organic contaminants is reviewed here, together with the studies on bioavailability and efficacy of some herbicides in soils amended with freshly produced biochars. Biochars, due to their unique properties especially their highly carbonaceous and aromatic nature and high specific surface area, have been reported to be up to >2000 times more effective than soil in sorbing pesticides. The incorporation of relatively small amounts of fresh biochars in soil (0.05% by wt) has also been shown to inhibit the microbial degradation of organic compounds including pesticides as well as reduce their plant availability and efficacy. Based on limited published research on biochars and related research on black carbon reviewed here, biochar amendments to soils are likely to reduce the bioavailability and efficacy of pesticides. Furthermore, these amendments can influence the potential accumulation and ecotoxicological impact of pesticides and other organic contaminants in the soil environment. The implications of heterogeneity and ageing of biochars applied to soils for sorption and desorption processes and in turn for other environmental fate processes need to be understood to seek the appropriate balance between carbon sequestration and pesticide efficacy. While biochar amendment of soil holds appeal from a carbon accounting and soil conditioning perspective, further research is urgently required to determine how biochar influences the efficacy and environmental fate of agrochemicals such as pesticides.

Effects of Organic Contaminants during Metal Oxide Semiconductor Processes

Adverse influences of organic contaminants on electronic devices have been studied and the results are reported. Contamination of silicon wafers by organic compounds during their manufacturing processes has been clearly demonstrated by a few surface analytical techniques. Silicon wafers were intentionally contaminated by one of the major contaminants, bis(2-ethylhexyl) phthalate; its incorporation into the silicon oxide layer during the thermal oxidation of silicon and its influences on device performances have been evaluated in detail by monitoring the breakdown voltages. During thermal oxidation of the contaminated silicon surface, the atomized carbon species produced from the pyrolysis of organic contaminants help grow the oxide thicker, expand the silicon oxide lattice, and degrade the silicon oxide, which was shown by transmission electron microscopy and secondary ion mass spectroscopy, and finally exert adverse influences on the device performance.

Chemical Partitioning to Foliage: The Contribution and Legacy of Davide Calamari

Davide Calamari and his colleagues were among the first to appreciate that vegetation could play a key role in determining the fate and effects of organic contaminants. They conducted pioneering experiments to investigate the uptake of contaminants by plants from the atmosphere and they sought to model the observed phenomena. In the nearly two decades since there has been a marked increase in understanding of these phenomena as a result of both experimental and modelling studies. In this study we briefly review our current understanding of chemical partitioning between foliage and air. A model in both fugacity and concentration format is described, based on that of Tolls and McLachlan (1994), in which the leaf is treated as consisting of two layers, a waxy cuticle with an underlying 'reservoir' layer, the cuticle being surrounded by an air boundary layer and containing stomata that provide direct access from the air to the 'reservoir'. The model quantifies the dynamic penetration of a defined chemical into a defined leaf as a function of time. The model is applied for illustrative purposes to a hypothetical but typical leaf for a set of illustrative chemicals to demonstrate the effect of changes in physical-chemical properties and leaf characteristics. The results are compared qualitatively with a variety of field and laboratory studies of foliage uptake and clearance of chemicals. It is concluded that the model yields results that are generally consistent with observations. It is suggested that with appropriate parameterisation and validation, the model can contribute to an improved understanding of the process of foliage uptake from the atmosphere and to the development of an improved predictive capability.

Relative importance of macrofaunal burrows for the microbial mineralization of pyrene in marine sediments: impact of macrofaunal species and organic matter quality

The significance of macrofaunal burrows for microbial organic matter mineralization is well recognized. However, despite the importance of marine sediments as main sinks for organic particle-reactive contaminants such as polyaromatic hydrocarbons (PAHs), the significance of biogenic structures for microbial pollutant mineralization is largely unknown. We measured microbial mineralization of the PAH pyrene in different sediment compartments (surface, burrow and reduced bulk sediments) as a function of contamination history (uncontaminated and pyrene-exposed), macrofaunal species (Amphiura filiformis and Nereis diversicolor) and sediment organic matter quality (labile Tetraselmis sp. and refractory lignin). Sediments were exposed to combinations of the 3 factors for 43 d, after which sediment samples from the 3 compartments were incubated for radio-respirometric measurements in 1 4 C-pyrene-coated flasks to monitor 1 4 CO 2 production (i.e. pyrene mineralization) for 128 d. Pyrene exposure enhanced microbial pyrene mineralization (MPM) rates by an order of magnitude in all compartments, signifying MPM as inducible. MPM rates increased successively from reduced bulk to burrow and surface sediments in uncontaminated treatments, while MPM rates were highest in burrows when exposed to pyrene. This emphasizes the oxygen dependence of MPM and pinpoints burrows as MPM hot spots. Enrichment with labile organic matter doubled MPM rates in pyrene-exposed surface sediment, likely fertilizing MPM where oxygen is readily available. Burrow sediment MPM rates were doubled with A. filiformis, suggesting species-specific stimulation of the microbial community within the burrows. In conclusion, burrow sediment appears to be at least as important as surface sediment for microbial PAH degradation in marine sediments. Furthermore, macrofaunal biodiversity, sedimentation events and the trophic state of the system should be taken into account when the fate and effects of organic contaminants are assessed in marine systems.

Effect of Adsorption on Crystal Nucleation in Binary Droplets: Implication for the Formation of Nitric Acid Hydrate Particles

The adsorption of surfactant molecules at the droplet-vapor interface can affect the droplet surface tension and thus alter the rate of surface-stimulated crystal nucleation. Recently, we have shown that if the condition of partial wetting holds for at least one crystal facet then the crystallization process is most likely to initiate at the droplet surface. Here, we outline an adsorption model to determine the main physical characteristics of the interior and surface layer of a binary droplet. The theoretical model is illustrated by numerical calculations for aqueous nitric acid droplets. As expected, an increase in the surfactant concentration in the droplet interior lowers the droplet surface tension, which has an impeding effect on the surface-stimulated crystallization. However, we show that an increase in the surface-to-volume ratio of a droplet favors crystal nucleation at the surface not only kinetically but also thermodynamically. This occurs because for a given droplet composition smaller droplets have a higher surface tension. Thus, the impeding effect of a soluble surfactant on the surface mode of crystal nucleation becomes weaker as the droplet size decreases. Our results also show that for a fixed overall droplet composition the excess surface coverage decreases with decreasing droplet radius. The effect of organic contaminants on crystallization in aqueous nitric acid droplets is also qualitatively studied.

Effect of Organic Contamination on the Electrical Degradation of Hydrogen-Terminated Silicon upon Exposure to Air under Ambient Conditions

The degradation of the electrical characteristics of hydrogen-terminated silicon (both n- and p-doped) under typical laboratory environments was investigated. When a hydrogen-terminated silicon (H-Si) surface was exposed to air under ambient conditions, the current density/bias voltage (J-V) curve of the mercury-silicon junction thus formed changed significantly during the first 50 h. For n-type H-Si surfaces, the J-V curve initially maintained ohmic characteristics for a period of 8-12 h, then evolved to diode behavior; for p-doped samples, the current density showed a rapid increase and reached a maximum in about 20 h. In both cases, the electrical property was recovered to some extent after sonication in organic solvents. In agreement with infrared spectroscopic results, organic contamination upon exposure to ambient air is suggested to play an important role in the change of the electrical performance of hydrogen-terminated silicon. © 2003 The Electrochemical Society. All rights reserved.

Recycling of sewage sludge and household compost to arable land: fate and effects of organic contaminants, and impact on soil fertility

Effective use of organic wastes for agricultural production requires that risks and benefits be documented. Two types of sewage sludge, household compost and solid pig manure were studied under field and greenhouse conditions to describe their fertilizer value and effects on soil properties and soil biota, the fate of selected organic contaminants, and their potential for plant uptake. A 3-year field trial on two soil types showed no adverse effects of waste amendment on crop growth, and a significant fertilizer value of one sludge type. Accumulation of N and Pi was indicated, as well as some stimulation of biological activity and micro-arthropod populations, but these effects differed between soil types. There was no detectable accumulation of polycyclic aromatic hydrocarbons (PAH), di(2-ethylhexyl)phthalate (DEHP), nonylphenol and ethoxylates (NP+NPE) or linear alkylbenzene sulfonates (LAS) after three repeated waste applications, and no plant uptake was suggested by analysis of the third crop. A plot experiment with banded sludge was conducted to examine sludge turnover and toxicity in detail. Less than 5% of NP or LAS applied in organic wastes was recovered after 6 months, and less than 6% of DEHP applied was recovered after 12 months. Potential ammonium oxidation (PAO) at 0–1 cm distance from the banded sludge was stimulated despite toxic concentrations in the sludge, which suggested that contaminants were degraded inside sludge particles. Phospholipid fatty acid (PLFA) profiles suggested a gradual shift in the composition of the microbial community within sludge, partly due to a depletion of degradable substrates. A pot experiment with sludge-amended soil and soil spiked with contaminants showed no plant uptake of NP, DEHP or LAS. Degradation of LAS and NP added in sludge was delayed and the degradation of DEHP was faster than when the contaminants were added directly to the soil. In conclusion, adverse effects of organic waste application on soil or crop were not found in this study, and for some waste products positive effects were observed.

Organic contaminants in soil

For scientists, there is no shortcut to performing serious soil ecotoxicology. A fate description of the contaminants is included to explain effects; sometimes the effect assessment must be used to point to the presence of a chemical even though the fate is not clearly understood. Details of fate and effects are sometimes useless for risk assessment due to a lack of precision or a failure to link convincingly the fate to the effects or the biological parameters to the healthiness of the ecosystem. This is not a surprise in the single risk assessment case because limited resources preclude an iterative research strategy to reveal the mechanisms. Widespread risk assessment practices based on legislation, however, provide shortcuts by requiring an effect assessment derived from single-species laboratory tests. To derive predicted no-effect concentrations (PNECs) such tests have hitherto been used in connection with assessment factors and more recently with species sensitivity distribution models [1]. The latter assumes that the PNEC can be based on a complement of independent single-species toxicity data. During a conference held in Copenhagen Denmark that focussed on the fate and effects of organic contaminants in soil, it was shown that species interactions indeed are important for the toxicity levels of the individual species. Multispecies tests performed in a standardized manner are now slowly emerging, and they obviously include species interactions. Realism is gained at the cost of interpretability. This does not pose a problem, however, because interpretability is not paramount for risk assessment. There is still an important need to integrate the available information on the effects of all kinds of factors exerting environmental influences. Aging and bioavailability of the organic contaminants must be included and will greatly change the ecotoxicological setting of limit concentration in soil [2]. Subtle knowledge of chemical fate and effects is useless in the process of making sound environmental risk assessment if concomitant disturbances from other human or natural sources are not included. The risk assessment procedure would gain respect from all parties—academia, industry and environmental protection agencies—if it could be done in an integrated risk assessment process. Soil management in agriculture is a good example of an important factor whose impact can surmount effects of chemicals in many cases or change bioavailability in others. The reluctance to provide more environmental information is not rational; improved risk assessments will most probably ease the burden of administrating low-limit values and ensure that hazard is not overestimated. Variability in soil physicochemical properties represents a substantial scientific challenge to understanding the toxicology of soil contaminants. Bioavailability of organic soil contaminants became the driving theme of the Copenhagen meeting, and the role of this subject will have increased importance in the future. Scientists must focus on the general applicability of their results and consider the soil-aging factor as a major sink of persistent organic compounds. The political importance of this subject was clearly demonstrated: One leading Danish newspaper devoted its front page to quoting Martin Alexander on the role of aging in risk assessment of contaminated soils. In this issue of Environmental Toxicology and Chemistry you will find a selection of papers presenting current research on biodegradation and chemical availability.

Bactericidal Treatment of Hatching Eggs III: Effect of Organic Contaminants on Efficacy of Egg Sanitizers

The effectiveness of three sanitizers in killing Salmonella during room temperature storage with and without contaminating feces, egg, or chicken rinse for 48 h was tested. Uncontaminated sanitizers were tested, as were 50-mL solutions of 0.035% polyhexamethylenebiguanide hydrochloride (PHMB), 0.39% (1:256) Tektrol, and 1.4% H2O2, which were contaminated with 10 mL of a feces slurry, 10 mL of mixed egg, or 10 mL of chicken rinse. Each container was inoculated with approximately 1,000 cells of S. typhimurium and cultured after 1 and 5 min. After 24 and 48 h of storage, each original container was reinoculated and assayed for the new inoculum at 1 and 5 min postinoculation. Complete eradication of Salmonella was noted after 1 or 5 min exposure to fresh or stored uncontaminated sanitizer solutions. Tektrol became less active against Salmonella when contaminated with egg and stored for 24 h or more. However, feces or chicken rinse did not interfere with the activity of Tektrol. Hydrogen peroxide deteriorated most with storage with chicken feces and to a lesser extent chicken rinse. PHMB lost efficacy when exposed to chicken feces for 24 h or more, but was not affected by the other contaminants.

Cost-effective cleaning and high-quality thin gate oxides

Some recent findings in the area of wafer cleaning and thin oxide properties are presented in this paper. Results are shown for a practical implementation of a simplified cleaning concept that combines excellent performance in terms of metal and particle removal with low chemical and DI-water consumption. The effect of organic contamination on ultrathin gate-oxide integrity is illustrated, and the feasibility of using ozonated DI water as an organic removal step is discussed. Metal outplating from HF and HF/HCl solutions is investigated. Also, the final rinsing step is critically evaluated. It is demonstrated that Si surface roughness without the presence of metal contaminants does not degrade gate-oxide integrity. Finally, some critical remarks on the reliability measurements for ultrathin gate oxides are given; it is shown that erroneous conclusions can be drawn from constant-current charge-to-breakdown measurements.

Effect of organic contaminants on the oxidation kinetics of silicon at room temperature

The oxidation kinetics of HF-etched n- and p-doped silicon in air at room temperature have been studied by electron spectroscopy for chemical analysis. No great differences have been found between the n- and p-type oxidation kinetics at the low doping level of the studied samples. The rate of oxide growth on the HF-etched surface is much lower than that on a silicon surface obtained by fracture in air of a silicon monocrystal. The behavior of a silicon sample fractured in de-ionized water and then oxidized in air at room temperature is intermediate. The above findings have been interpreted on the basis of surface reactions involving the plasticizers of the HF and water containers. These reactions produce carbon-rich hydrophobic surfaces which retard the silicon oxide growth. A mechanism for the involved surface reactions is proposed.

Effect of organic contamination upon microbial distributions and heterotrophic uptake in a Cape Cod, Mass., aquifer.

Bacterial abundance, distribution, and heterotrophic uptake in a freshwater aquifer contaminated by treated sewage were determined from analyses of groundwater and sediment-core samples. The number of free-living (unattached) bacteria in contaminated groundwater declined steadily with increasing distance from the source of sewage infiltration, from 1.94 (+/- 0.20) X 10(6) ml-1 at 0.21 km to 0.25 (+/- 0.02) X 10(6) ml-1 at 0.97 km. Bacterial abundance in groundwater sampled at 0.31 km correlated strongly with specific conductance and increased sharply from 4.0 (+/- 0.3) X 10(4) ml-1 at a depth of 6 m to 1.58 (+/- 0.12) X 10(6) ml-1 at 14 m, then declined at 20 and 31 m to 1.29 (+/- 0.12) X 10(6) and 0.96 (+/- 0.12) X 10(6) ml-1, respectively. A majority of the bacteria in contaminated and uncontaminated zones of the aquifer were bound to the surfaces of particulates, less than 60 micron in diameter. The glucose uptake rate, assayed at in situ and 5 microM concentrations, declined steadily in contaminated groundwater sampled along a transect. A preparative wet-sieving technique for use in processing core samples for bacterial enumeration is described and evaluated.