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Phytoremediation of contaminated soils and groundwater: lessons from the field 全文
2009
Vangronsveld, Jaco | Herzig, Rolf | Weyens, Nele | Boulet, Jana | Adriaensen, Kristin | Ruttens, Ann | Thewys, Theo | Vassilev, Andon | Meers, Erik | Nehnevajova, Erika | van der Lelie, Daniel | Mench, Michel
Phytoremediation of contaminated soils and groundwater: lessons from the field 全文
2009
Vangronsveld, Jaco | Herzig, Rolf | Weyens, Nele | Boulet, Jana | Adriaensen, Kristin | Ruttens, Ann | Thewys, Theo | Vassilev, Andon | Meers, Erik | Nehnevajova, Erika | van der Lelie, Daniel | Mench, Michel
Background, aim, and scope The use of plants and associated microorganisms to remove, contain, inactivate, or degrade harmful environmental contaminants (generally termed phytoremediation) and to revitalize contaminated sites is gaining more and more attention. In this review, prerequisites for a successful remediation will be discussed. The performance of phytoremediation as an environmental remediation technology indeed depends on several factors including the extent of soil contamination, the availability and accessibility of contaminants for rhizosphere microorganisms and uptake into roots (bioavailability), and the ability of the plant and its associated microorganisms to intercept, absorb, accumulate, and/or degrade the contaminants. The main aim is to provide an overview of existing field experience in Europe concerning the use of plants and their associated microorganisms whether or not combined with amendments for the revitalization or remediation of contaminated soils and undeep groundwater. Contaminations with trace elements (except radionuclides) and organics will be considered. Because remediation with transgenic organisms is largely untested in the field, this topic is not covered in this review. Brief attention will be paid to the economical aspects, use, and processing of the biomass. Conclusions and perspectives It is clear that in spite of a growing public and commercial interest and the success of several pilot studies and field scale applications more fundamental research still is needed to better exploit the metabolic diversity of the plants themselves, but also to better understand the complex interactions between contaminants, soil, plant roots, and microorganisms (bacteria and mycorrhiza) in the rhizosphere. Further, more data are still needed to quantify the underlying economics, as a support for public acceptance and last but not least to convince policy makers and stakeholders (who are not very familiar with such techniques).
显示更多 [+] 显示较少 [-]Phytoremediation of contaminated soils and groundwater: lessons from the field 全文
2009
Vangronsveld, Jaco | Herzig, Rolf | Nele Weyens, Nele Weyens | Boulet, Jana | Adriaensen, Kristin | Ruttens, Ana | Thewys, Theo | Vassilev, Andon | Meers, Erik | Nehnevajova, Erika | van Der Lelie, Daniel | Mench, Michel | Centre for Environmental Sciences ; Hasselt University (UHasselt) | Phytotech-Foundation ; Partenaires INRAE | AGB-Arbeitsgemeinschaft für Bioindikation ; Partenaires INRAE | Agricultural University [Plovdiv] | Universiteit Gent = Ghent University = Université de Gand (UGENT) | Brookhaven National Laboratory [Upton, NY] (BNL) ; UT-Battelle, LLC-Stony Brook University [SUNY] (SBU) ; State University of New York (SUNY)-State University of New York (SUNY)-U.S. Department of Energy [Washington] (DOE) | Biodiversité, Gènes & Communautés (BioGeCo) ; Institut National de la Recherche Agronomique (INRA)-Université de Bordeaux (UB)
COST ACTION 859 | International audience | Background, aim, and scope: The use of plants and associated microorganisms to remove, contain, inactivate, or degrade harmful environmental contaminants (generally termed phytoremediation) and to revitalize contaminated sites is gaining more and more attention. In this review, prerequisites for a successful remediation will be discussed. The performance of phytoremediation as an environmental remediation technology indeed depends on several factors including the extent of soil contamination, the availability and accessibility of contaminants for rhizosphere microorganisms and uptake into roots (bioavailability), and the ability of the plant and its associated microorganisms to intercept, absorb, accumulate, and/or degrade the contaminants. The main aim is to provide an overview of existing field experience in Europe concerning the use of plants and their associated microorganisms whether or not combined with amendments for the revitalization or remediation of contaminated soils and undeep groundwater. Contaminations with trace elements (except radionuclides) and organics will be considered. Because remediation with transgenic organisms is largely untested in the field, this topic is not covered in this review. Brief attention will be paid to the economical aspects, use, and processing of the biomass. Conclusions and perspectives: It is clear that in spite of a growing public and commercial interest and the success of several pilot studies and field scale applications more fundamental research still is needed to better exploit the metabolic diversity of the plants themselves, but also to better understand the complex interactions between contaminants, soil, plant roots, and microorganisms (bacteria and mycorrhiza) in the rhizosphere. Further, more data are still needed to quantify the underlying economics, as a support for public acceptance and last but not least to convince policy makers and stakeholders (who are not very familiar with such techniques).
显示更多 [+] 显示较少 [-]Adapting a geographical information system-based water resource management to the needs of the Romanian water authorities 全文
2009
Soutter, Marc | Alexandrescu, Maria | Schenk, Colin | Drobot, Radu
Background, aim, and scope The need for global and integrated approaches to water resources management, both from the quantitative and the qualitative point of view, has long been recognized. Water quality management is a major issue for sustainable development and a mandatory task with respect to the implementation of the European Water Framework Directive as well as the Swiss legislation. However, data modelling to develop relational databases and subsequent geographic information system (GIS)-based water management instruments are a rather recent and not that widespread trend. The publication of overall guidelines for data modelling along with the EU Water Framework Directive is an important milestone in this area. Improving overall water quality requires better and more easily accessible data, but also the possibility to link data to simulation models. Models are to be used to derive indicators that will in turn support decision-making processes. For this whole chain to become effective at a river basin scale, all its components have to become part of the current daily practice of the local water administration. Any system, tool, or instrument that is not designed to meet, first of all, the fundamental needs of its primary end-users has almost no chance to be successful in the longer term. Materials and methods Although based on a pre-existing water resources management system developed in Switzerland, the methodological approach applied to develop a GIS-based water quality management system adapted to the Romanian context followed a set of well-defined steps: the first and very important step is the assessment of needs (on the basis of a careful analysis of the various activities and missions of the water administration and other relevant stakeholders in water management related issues). On that basis, a conceptual data model (CDM) can be developed, to be later on turned into a physical database. Finally, the specifically requested additional functionalities (i.e. functionalities not provided by classical commercial GIS software), also identified during the assessment of needs, are developed. This methodology was applied, on an experimental basin, in the Ialomita River basin. Results The results obtained from this action-research project consist of a set of tangible elements, among which (1) a conceptual data model adapted to the Romanian specificities regarding water resources management (needs, data availability, etc.), (2) a related spatial relational database (objects and attributes in tables, links, etc.), that can be used to store the data collected, among others, by the water administration, and later on exploited with geographical information systems, (3) a toolbar (in the ESRI environment) offering the requested data processing and visualizing functionalities. Lessons learned from this whole process can be considered as additional, although less tangible, results. Discussion The applied methodology is fairly classical and did not come up with revolutionary results. Actually, the interesting aspects of this work are, on the one hand, and obviously, the fact that it produced tools matching the needs of the local (if not national) water administration (i.e. with a good chance of being effectively used in the day-to-day practice), and, on the other hand, the adaptations and adjustments that were needed both at the staff level and in technical terms. Conclusions This research showed that a GIS-based water management system needs to be backed by some basic data management tools that form the necessary support upon which a GIS can be deployed. The main lesson gained is that technology transfer has to pay much attention to the differences in existing situations and backgrounds in general, and therefore must be able to show much flexibility. The fact that the original objectives could be adapted to meet the real needs of the local end-users is considered as a major aspect in achieving a successful adaptation and development of water resources management tools. Time needed to setup things in real life was probably the most underestimated aspect in this technology transfer process. Recommendations and perspectives The whole material produced (conceptual data model, database and GIS tools) was disseminated among all river basin authorities in Romania on the behalf of the national water administration (ANAR). The fact that further developments, for example, to address water quantity issues more precisely, as envisaged by ANAR, can be seen as an indication that this project succeeded in providing an appropriate input to improve water quality in Romania on the long term.
显示更多 [+] 显示较少 [-]Farmer knowledge and a priori risk analysis: pre-release evaluation of genetically modified Roundup Ready wheat across the Canadian prairies 全文
2009
Mauro, Ian J. | McLachlan, Stéphane M. | Van Acker, Rene C.
Background, aim, and scope The controversy over the world's first genetically modified (GM) wheat, Roundup Ready wheat (RRW), challenged the efficacy of 'science-based' risk assessment, largely because it excluded the public, particularly farmers, from meaningful input. Risk analysis, in contrast, is broader in orientation as it incorporates scientific data as well as socioeconomic, ethical, and legal concerns, and considers expert and lay input in decision-making. Local knowledge (LK) of farmers is experience-based and represents a rich and reliable source of information regarding the impacts associated with agricultural technology, thereby complementing the scientific data normally used in risk assessment. The overall goal of this study was to explore the role of farmer LK in the a priori risk analysis of RRW. Materials and methods In 2004, data were collected from farmers using mail surveys sent across the three prairie provinces (i.e., Manitoba, Saskatchewan, and Alberta) in western Canada. A stratified random sampling approach was used whereby four separate sampling districts were identified in regions where wheat was grown for each province. Rural post offices were randomly selected in each sampling district using Canada Post databases such that no one post office exceeded 80 farms and that each sampling district comprised 225-235 test farms (n = 11,040). In total, 1,814 people responded, representing an adjusted response rate for farmers of 33%. A subsequent telephone survey showed there was no non-response bias. Results The primary benefits associated with RRW were associated with weed control, whereas risks emphasized the importance of market harm, corporate control, agronomic problems, and the likelihood of contamination. Overall, risks were ranked much higher than benefits, and the great majority of farmers were highly critical of RRW commercialization. In total, 83.2% of respondents disagreed that RRW should have unconfined release into the environment. Risk was associated with distrust in government and corporations, previous experience with GM canola, and a strong belief in the importance of community and environment. Farmers were critical of expert-based risk assessment, particularly RRW field trials, and believed that their LK was valuable for assessing agbiotechnology as a whole. Discussion Over 90% of canola production across the Canadian prairies makes use of herbicide-tolerant (HT) varieties. Yet, respondents were generally uniform in their criticism of RRW, regardless whether they were HT users, non-HT-users, conservation tillage or organic in approach. They had a sophisticated understanding of how GM trait confinement was intrinsically tied to grain system segregation and, ultimately, market accessibility, and were concerned that gene flow in RRW would not be contained. Organic farmers were particularly critical of RRW, in large part because certification standards prohibit the presence of GM traits. Farmers practicing conservation tillage were also at relatively great risk, in part because their dependence on glyphosate to control weeds increases the likelihood that RRW volunteer would become more difficult and costly to control. Conclusions This research is the first of its kind to include farmer knowledge in the a priori risk analysis of GM crops and, arguably, given its prairie-wide scope, is the largest scale, independent-farmer-focused study on GM crops ever conducted. The surprising uniformity in attitudes between users and non-users of GM technology and among organic, conventional, conservation tillage and GM using farmers speaks to the ability of farmers to discriminate among HT varieties. Our results clearly show that prairie farmers recognize that the risks associated with RRW commercialization outweigh any benefits. Recommendations and perspectives Farmer knowledge systems are holistic in nature, incorporating socioeconomic, cultural, political, and agroecological factors that all can contribute meaningfully to the pre-release evaluation of GM crops. The inclusion of farmers and other stakeholders in risk assessment will also help enhance and even restore public confidence in science-focused approaches to risk assessment. Although farmers are highly knowledgeable regarding RRW and arguably any agricultural technology, their expertise continues to be overlooked by decision-makers and regulators across North America.
显示更多 [+] 显示较少 [-]Occurrence of benzotriazoles in the rivers Main, Hengstbach, and Hegbach (Germany) 全文
2009
Kiss, Aliz | Fries, Elke
Background, aim, and scope Benzotriazoles (BT) as 1H-benzotriazole (1H-BT), 5-methyl-1H-benzotriazole (5Me-BT), and 4-methyl-1H-benzotriazole (4Me-BT) are frequently used as corrosion inhibitors in dish washer detergents, aircraft de-icing/anti-icing fluids (ADAF), automotive antifreeze formulations, brake fluids, fluids for industrial cooling systems, metal-cutting fluids, and in solid cooling lubricants. Discharge of treated municipal waste water and controlled over-runs of combined waste water sewers are potential point sources for BT in rivers. The aim of this monitoring study was to yield an overview on exposure concentrations and loads of BT in the German rivers Main, Hengstbach, and Hegbach. Materials and methods Concentrations of 1H-BT, 5Me-BT, and 4Me-BT were determined in grab samples collected from different sampling points in the rivers Main, Hengstbach, and Hegbach at four different sampling times. Main and Hengstbach rivers were sampled close to Frankfurt International Airport. Both rivers receive domestic waste water effluents. BT were extracted from 2.5 L of river water by solid phase extraction using Bond Elut ppl cartridges (200 mg/3 mL). The extracts were analyzed by gas chromatography/mass spectrometry in full scan mode. Mass flows of BT were calculated by concentrations multiplied by mean daily river flow rates. Median concentrations and mass flows were compared for different rivers. Mass flows were also compared for selected sampling points at different sampling times. Results 1H-BT, 5Me-BT, and 4Me-BT were detected in Main and Hengstbach rivers. 1H-BT and 5Me-BT were also detected in Hegbach River. Concentrations ranged from 38 to 1,474 ng/L for 1H-BT, from 25 to 281 ng/L for 5Me-BT, and from 25 to 952 ng/L for 4Me-BT. Median concentrations of 1H-BT, 5Me-BT, and 4Me-BT were lower in Main than in Hengstbach River. Much higher median mass flows of all BT were calculated for Main than for Hengstbach River. At sampling points P9 (Main) and P5 (Hengstbach) concentrations of 4Me-BT and 5Me-BT increased from March 29, 2008 to May 1, 2008 to June 22, 2008 whereas daily mean river flow rate decreased simultaneously. However, concentration of 1H-BT in Main and Hengstbach River increased from March 29, 2008 to May 1, 2008 and decreased again on June 22, 2008. In the Main River, lowest and highest mass flows for all BT were calculated on June 22, 2008 and May 1, 2008, respectively. In the Hengstbach River lowest and highest mass flows for 1H-BT and 4Me-BT were also calculated on June 22, 2008 and May 1, 2008, respectively. However, mass flows of 5Me-BT in Hengstbach River were rather similar at all three sampling times. In all grab samples, 1H-BT was more abundant than 5Me-BT and 4Me-BT in Main and Hengstbach River, except on June 22, 2008. Ratios of 1H-BT/(5Me-BT + 4Me-BT) determined on March 15, 2008, March 29, 2008, and May 1, 2008 varied between 1.6 and 9.0 with a median value of 1.9 (n = 9) whereas on June 22, 2008 the ratios varied between 0.4 and 0.7 with a median value of 0.6 (n = 5). Discussion Due to the absence of waste water effluents in the Hegbach River, other input sources as controlled over-runs of combined waste water sewers and/or atmospheric deposition of BT must be regarded as possible input sources. Exfiltration of ground water containing BT to Hegbach River must be also regarded, especially when considering the high polarity of BT. Median concentrations of BT in Main River were much lower than in Hengstbach River due to dilution. However, median mass flows were higher in the Main River than in the Hengstbach River. Higher mass flows could be attributed to higher source strengths and/or numerous emissions sources in the Main River. Mass flows determined on June 22, 2008 in Main and Hengstbach rivers probably reflect emissions of BT only from dishwasher detergents since de-icing operations were unlikely at that time. Emissions of BT from dish washer detergents are rather constant without any seasonal variations. Assuming the absence of additional input sources and constant in-stream removal processes, mass flows calculated for all other sampling times must be nearly similar to mass flows for June 22, 2009 as it was only observed for 5Me-BT in Hengstbach River. The higher mass flows for 1H-BT and 4Me-BT in March and May in both rivers could be an indication for temporal variations of emission pattern and/or of in-stream removal processes. 1H-BT/(4Me-BT + 5Me-BT) ratios above one in March and May and below one in June could be also an indication for temporal variations of input and/or removal processes. Conclusions 1H-BT, 5Me-BT, and 4Me-BT used as corrosion inhibitors in many applications were detected in the rivers Main, Hengstbach, and Hegbach with relative high temporal and spatial concentration variations. Dilution is a dominant factor that influences exposure concentrations of BT in the studied rivers. We conclude that, especially in smaller rivers (as Hengstbach River), the hydrological situation has to be regarded when predicting exposure concentrations of BT. Characteristic emission strength and in-stream removal processes must be known to relate loads of BT in river water to different sources. The ratio of 1H-BT/(4Me-BT + 5Me-BT) could be possibly used for source apportionment. Recommendations and perspectives Time series analyses of BT in composite river water samples collected at two river sites of the Hengstbach/Schwarzbach catchment area, without any waste water effluents in between, are recommended to study in-stream removal of BT. In addition, exposure modeling is recommended of BT, regarding all input sources and in-stream removal processes to predict exposure concentrations of BT in rivers. In order to calibrate and validate the model, additional monitoring data are required.
显示更多 [+] 显示较少 [-]Endosulfan in China 2--emissions and residues 全文
2009
Jia, Hongliang | Sun, Yeqing | Li, Yi-Fan | Tian, Chongguo | Wang, Degao | Yang, Meng | Ding, Yongshen | Ma, Jianmin
Background, aim, and scope Endosulfan is one of the organochlorine pesticides (OCPs) and also a candidate to be included in a group of new persistent organic pollutants (UNEP 2007). The first national endosulfan usage inventories in China with 1/4° longitude by 1/6° latitude resolution has been reported in an accompanying paper. In the second part of the paper, we compiled the gridded historical emissions and soil residues of endosulfan in China from the usage inventories. Based on the residue/emission data, gridded concentrations of endosulfan in Chinese soil and air have been calculated. These inventories will provide valuable data for the further study of endosulfan. Methods Emission and residue of endosulfan were calculated from endosulfan usage by using a simplified gridded pesticide emission and residue model--SGPERM, which is an integrated modeling system combining mathematical model, database management system, and geographic information system. By using the emission and residue inventories, annual air and soil concentrations of endosulfan in each cell were determined. Results and discussion Historical gridded emission and residue inventories of α- and β-endosulfan in agricultural soil in China with 1/4° longitude by 1/6° latitude resolution have been created. Total emissions were around 10,800 t, with α-endosulfan at 7,400 t and β-endosulfan at 3,400 t from 1994 to 2004. The highest residues were 140 t for α-endosulfan and 390 t for β-endosulfan, and the lowest residues were 0.7 t for α-endosulfan and 170 t for β-endosulfan in 2004 in Chinese agricultural soil where endosulfan was applied. Based on the emission and residue inventories, concentrations of α- and β-endosulfan in Chinese air and agricultural surface soil were also calculated for each grid cell. We have estimated annual averaged air concentrations and the annual minimum and maximum soil concentrations across China. The real concentrations will be different from season to season. Although our model does not consider the transport of the insecticide in the atmosphere, which could be very important in some areas during some special time, the estimated concentrations of endosulfan in Chinese air and soil derived from the endosulfan emission and residue inventories are in general consistent with the published monitoring data. Conclusions To our knowledge, this work is the first inventory of this kind for endosulfan published on a national scale. Concentrations of the chemical in Chinese air and agricultural surface soil were calculated for each grid cell. Results show that the estimated concentrations of endosulfan in Chinese air and soil agree reasonably well with the monitoring data in general. Recommendations and perspectives The gridded endosulfan emission/residue inventories and also the air and soil concentration inventories created in this study will be updated upon availability of new information, including usage and monitoring data. The establishment of these inventories for the OCP is important for both scientific communities and policy makers.
显示更多 [+] 显示较少 [-]Endocrine disruptors in bottled mineral water: total estrogenic burden and migration from plastic bottles 全文
2009
Wagner, Martin | Oehlmann, Jörg
Background, aim, and scope Food consumption is an important route of human exposure to endocrine-disrupting chemicals. So far, this has been demonstrated by exposure modeling or analytical identification of single substances in foodstuff (e.g., phthalates) and human body fluids (e.g., urine and blood). Since the research in this field is focused on few chemicals (and thus missing mixture effects), the overall contamination of edibles with xenohormones is largely unknown. The aim of this study was to assess the integrated estrogenic burden of bottled mineral water as model foodstuff and to characterize the potential sources of the estrogenic contamination. Materials, methods, and results In the present study, we analyzed commercially available mineral water in an in vitro system with the human estrogen receptor alpha and detected estrogenic contamination in 60% of all samples with a maximum activity equivalent to 75.2 ng/l of the natural sex hormone 17β-estradiol. Furthermore, breeding of the molluskan model Potamopyrgus antipodarum in water bottles made of glass and plastic [polyethylene terephthalate (PET)] resulted in an increased reproductive output of snails cultured in PET bottles. This provides first evidence that substances leaching from plastic food packaging materials act as functional estrogens in vivo. Discussion and conclusions Our results demonstrate a widespread contamination of mineral water with xenoestrogens that partly originates from compounds leaching from the plastic packaging material. These substances possess potent estrogenic activity in vivo in a molluskan sentinel. Overall, the results indicate that a broader range of foodstuff may be contaminated with endocrine disruptors when packed in plastics.
显示更多 [+] 显示较少 [-]Climate and land-use changes affecting river sediment and brown trout in alpine countries--a review 全文
2009
Scheurer, Karin | Alewell, Christine | Bänninger, Dominik | Burkhardt-Holm, Patricia
Background, aim, and scope Catch decline of freshwater fish has been recorded in several countries. Among the possible causes, habitat change is discussed. This article focuses on potentially increased levels of fine sediments going to rivers and their effects on gravel-spawning brown trout. Indications of increased erosion rates are evident from land-use change in agriculture, changes in forest management practices, and from climate change. The latter induces an increase in air and river water temperatures, reduction in permafrost, changes in snow dynamics and an increase in heavy rain events. As a result, an increase in river sediment is likely. Suspended sediment may affect fish health and behaviour directly. Furthermore, sediment loads may clog gravel beds impeding fish such as brown trout from spawning and reducing recruitment rates. To assess the potential impact on fine sediments, knowledge of brown trout reproductive needs and the effects of sediment on brown trout health were evaluated. Approach We critically reviewed the literature and included results from ongoing studies to answer the following questions, focusing on recent decades and rivers in alpine countries. Have climate change and land-use change increased erosion and sediment loads in rivers? Do we have indications of an increase in riverbed clogging? Are there indications of direct or indirect effects on brown trout from increased suspended sediment concentrations in rivers or from an increase in riverbed clogging? Results Rising air temperatures have led to more intensive precipitation in winter months, earlier snow melt in spring, and rising snow lines and hence to increased erosion. Intensification of land use has supported erosion in lowland and pre-alpine areas in the second half of the twentieth century. In the Alps, however, reforestation of abandoned land at high altitudes might reduce the erosion risk while intensification on the lower, more easily accessible slopes increases erosion risk. Data from laboratory experiments show that suspended sediments affect the health and behaviour of fish when available in high amounts. Point measurements in large rivers indicate no common lethal threat and suspended sediment is rarely measured continuously in small rivers. However, effects on fish can be expected under environmentally relevant conditions. River bed clogging impairs the reproductive performance of gravel-spawning fish. Discussion Overall, higher erosion and increased levels of fine sediment going into rivers are expected in future. Additionally, sediment loads in rivers are suspected to have considerably impaired gravel bed structure and brown trout spawning is impeded. Timing of discharge is put forward and is now more likely to affect brown trout spawning than in previous decades. Conclusions Reports on riverbed clogging from changes in erosion and fine sediment deposition patterns, caused by climate change and land-use change are rare. This review identifies both a risk of increases in climate erosive forces and fine sediment loads in rivers of alpine countries. Increased river discharge and sediment loads in winter and early spring could be especially harmful for brown trout reproduction and development of young life stages. Recently published studies indicate a decline in trout reproduction from riverbed clogging in many rivers in lowlands and alpine regions. However, the multitude of factors in natural complex ecosystems makes it difficult to address a single causative factor. Recommendations and perspectives Further investigations into the consequences of climate change and land-use change on river systems are needed. Small rivers, of high importance for the recruitment of gravel-spawning fish, are often neglected. Studies on river bed clogging are rare and the few existing studies are not comparable. Thus, there is a strong need for the development of methods to assess sediment input and river bed clogging. As well, studies on the effects to fish from suspended sediments and consequences of gravel beds clogging under natural conditions are urgently needed.
显示更多 [+] 显示较少 [-]Effects of triclosan on zebrafish early-life stages and adults 全文
2009
Oliveira, Rhaul | Domingues, Inês | Grisolia, Cesar Koppe | Soares, Amadeu M. V. M.
Background, aim and scope The biocide triclosan (TCS) is commonly used in personal care, acrylic, plastic, and textiles products. TCS has been detected in surface water in several countries, and its ecological impact is largely unknown. In this work, the toxicity of TCS in zebrafish (Danio rerio), embryos and adults was studied. Several lethal and sub-lethal endpoints were analysed in organisms exposed to TCS such as mortality, embryo development and behaviour, hatching, micronuclei and biochemical markers (cholinesterase (ChE), glutathione S-transferase (GST) and lactate dehydrogenase (LDH)). Materials and methods Embryo/larvae assay followed the OECD guideline on Fish Embryo Toxicity Test. Embryos were exposed at nominal concentrations of 0.1, 0.3, 0.5, 0.7 and 0.9 mg/l of TCS for 6 days and were inspected daily with the help of a stereomicroscopy for mortality, developmental parameters (otolith formation, eye and body pigmentation, somite formation, heart beat, tail circulation, detachment of the tail-bud from the yolk sac) and hatching. A similar test was run to obtain larvae for ChE, GST and LDH analysis. The adult test followed the OECD Guideline TG 203 in semi-static conditions. Adult zebrafish of similar length and age were exposed to nominal concentrations of 0.1, 0.2, 0.3, 0.4 and 0.5 mg/l of TCS for 96 h and were inspected daily for mortality and behaviour alterations. A second test was run to obtain organs for biomarkers analysis: Heads, muscles and gills were isolated and snap-frozen in eppendorfs and used for ChE, LDH and GST determinations, respectively. Adult zebrafish testing also comprised a third test for micronucleus analysis in which the nominal concentrations of 0, 0.175 and 0.350 mg/l were used. Peripheral blood was obtained by cardiac puncture and used for the analysis. Results TCS showed acute toxicity for embryo/larvae (96 h LC₅₀ = 0.42 mg/l) and delayed hatching. Moreover, embryo toxicity was evident: Delay on the otolith formation and eye and body pigmentation were found, and malformations were also evident, including spine malformations, pericardial oedema and undersize. Biomarkers levels were affected: ChE and LDH activity were increased in larvae exposed to 0.25 mg/l, and GST activity was increased in larvae exposed to 0.25 and 0.35 mg/l. TCS also demonstrated acute toxicity to adult zebrafish (96 h LC₅₀ = 0.34 mg/l). However, TCS did not change biomarkers levels and did not elicit a micronucleus in adults. Discussions Despite the fact that similar 96 h LC₅₀ values have been found for D. rerio embryos and adults (0.42 and 0.34 mg/l, respectively), the embryo assay was much more informative, showing important effects at several levels, including teratogenic response, hatching delay and alteration of biomarker levels. TCS does not seem to be genotoxic for adult fish or to interfere with biomarkers levels at the concentrations tested. Conclusions TCS has deleterious effects on zebrafish adults and during early stages, (including embryotoxicity, hatching delay and alterations of biomarkers levels). The range of endpoints used on the embryo test allows an integrated analysis that contributes to a better understanding of the toxicity and mode of action of TCS. Recommendations and perspectives Future works should focus on a deeper investigation of TCS modes of action on zebrafish early-life stages. As embryo testing was revealed to be so informative, a refinement of the test could be made, including other endpoints such as different biochemical markers as well as DNA microarrays to assess a gene expression level for the effect of exposure to TCS. In the perspective of risk assessment, these endpoints should be explored in order to assess their usefulness as early warning signs and links should be sought between these short-term tests and effects of long-term exposures as it is observed in more realistic scenarios.
显示更多 [+] 显示较少 [-]Reduction of nitrogen loss and Cu and Zn mobility during sludge composting with bamboo charcoal amendment 全文
2009
Hua, Li | Wu, Weixiang | Liu, Yuxue | McBride, Murray B. | Chen, Yingxu
Background, aim, and scope Composting is an effective treatment process to realize sludge land application. However, nitrogen loss could result in the reduction of nutrient value of the compost products and the stabilization effect of composting on heavy metal concentration and mobility in sludge has been shown to be very limited. Materials and methods Laboratory-scale experiments were carried out to investigate the effects of bamboo charcoal (BC) on nitrogen conservation and mobility of Cu and Zn during sludge composting. Results The result indicated that the incorporation of BC into the sludge composting material could significantly reduce nitrogen loss. With 9% BC amendment, total nitrogen loss at the end of composting decreased 64.1% compared with no BC amendment (control treatment). Mobility of Cu and Zn in the sludge may also have been lessened, based on the decline in diethylenetriaminepentaacetic acid-extractable Cu and Zn contents of composted sludge by 44.4% and 19.3%, respectively, compared to metal extractability in the original material. Discussion Ammonia adsorption capability of BC might be the main reason for the retention of nitrogen in sludge composting materials. Decrease of extractable Cu²⁺ and Zn²⁺ in the composting material mainly resulted from the adsorption of both metals by BC. Conclusions Incorporation of BC into composting material could significantly lessen the total nitrogen loss during sludge composting. Mobility of heavy metals in the sludge composting material could also be reduced by the addition of BC. Recommendations and perspectives Bamboo charcoal could be an effective amendment for nitrogen conservation and heavy metal stabilization in sludge composts. Further research into the effect of BC-amended sludge compost material on soil properties, bioavailability of heavy metals, and nutrient turnover in soil needs to be carried out prior to the application of BC-sludge compost in agriculture.
显示更多 [+] 显示较少 [-]Sources and emission of greenhouse gases in Danube Delta lakes 全文
2009
Pavel, Alina | Durisch-Kaiser, Edith | Balan, Sorin | Radan, Silviu | Sobek, Sebastian | Wehrli, Bernhard
Production of methane and carbon dioxide as well as methane concentrations in surface waters and emissions to the atmosphere were investigated in two flow-through lake complexes (Uzlina-Isac and Puiu-Rosu-Rosulet) in the Danube Delta during post-flood conditions in May and low water level in September 2006. Retained nutrients fuelled primary production and remineralisation of bioavailable organic matter. This led to an observable net release of methane, particularly in the lakes Uzlina, Puiu and Rosu in May. Input from the Danube River, from redbuds and benthic release contributed to CH₄ concentrations in surface waters. In addition to significant river input of CO₂, this trace gas was released via aerobic remineralisation within the water column and in top sediments. Emission patterns of CO₂ widely overlapped with those of CH₄. Generally, greenhouse gas emissions peaked in the lake complex adjacent to the Danube River in May due to strong winds and decreased with increasing hydrological distance from the Danube River. Intense remineralisation of organic matter in the Danube Delta lakes results in a net source of atmospheric greenhouse gases.
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