خيارات البحث
النتائج 2381 - 2390 من 3,197
Pesticide pollution of multiple drinking water sources in the Mekong Delta, Vietnam: evidence from two provinces
2015
Chau, N. D. G. | Sebesvari, Z. | Amelung, W. | Renaud, F. G.
Pollution of drinking water sources with agrochemicals is often a major threat to human and ecosystem health in some river deltas, where agricultural production must meet the requirements of national food security or export aspirations. This study was performed to survey the use of different drinking water sources and their pollution with pesticides in order to inform on potential exposure sources to pesticides in rural areas of the Mekong River delta, Vietnam. The field work comprised both household surveys and monitoring of 15 frequently used pesticide active ingredients in different water sources used for drinking (surface water, groundwater, water at public pumping stations, surface water chemically treated at household level, harvested rainwater, and bottled water). Our research also considered the surrounding land use systems as well as the cropping seasons. Improper pesticide storage and waste disposal as well as inadequate personal protection during pesticide handling and application were widespread amongst the interviewed households, with little overall risk awareness for human and environmental health. The results show that despite the local differences in the amount and frequency of pesticides applied, pesticide pollution was ubiquitous. Isoprothiolane (max. concentration 8.49 μg L⁻¹), fenobucarb (max. 2.32 μg L⁻¹), and fipronil (max. 0.41 μg L⁻¹) were detected in almost all analyzed water samples (98 % of all surface samples contained isoprothiolane, for instance). Other pesticides quantified comprised butachlor, pretilachlor, propiconazole, hexaconazole, difenoconazole, cypermethrin, fenoxapro-p-ethyl, tebuconazole, trifloxystrobin, azoxystrobin, quinalphos, and thiamethoxam. Among the studied water sources, concentrations were highest in canal waters. Pesticide concentrations varied with cropping season but did not diminish through the year. Even in harvested rainwater or purchased bottled water, up to 12 different pesticides were detected at concentrations exceeding the European Commission’s parametric guideline values for individual or total pesticides in drinking water (0.1 and 0.5 μg L⁻¹; respectively). The highest total pesticide concentration quantified in bottled water samples was 1.38 μg L⁻¹. Overall, we failed to identify a clean water source in the Mekong Delta with respect to pesticide pollution. It is therefore urgent to understand further and address drinking water-related health risk issues in the region.
اظهر المزيد [+] اقل [-]Effects of ultrasonic-assisted thermophilic bacteria pretreatment on hydrolysis, acidification, and microbial communities in waste-activated sludge fermentation process
2015
Yang, Chunxue | Zhou, Aijuan | He, Zhangwei | Jiang, Lei | Guo, Zechong | Wang, Aijie | Liu, Wenzong
A novel pretreatment method combining ultrasonic with thermophilic bacteria (Geobacillus sp. G1) was employed to pretreat waste-activated sludge (WAS) for enhancing the WAS hydrolysis and subsequent volatile fatty acids (VFAs) production. The soluble protein and carbohydrate were mostly released from intracellular ultrasonic-assisted Geobacillus sp. G1 pretreatment, and accumulated to 917 ± 70 and 772 ± 89 mg COD/L, respectively, which were 2.53- and 2.62-fold higher than that obtained in control test. Excitation emission matrix (EEM) fluorescence spectroscopy revealed the highest fluorescence intensity (FI) of protein-like substances, indicating the synergistic effect of ultrasonic and Geobacillus sp. G1 pretreatments on WAS hydrolysis. The maximum VFAs accumulation was 4437 ± 15 mg COD/L obtained in ultrasonic-assisted Geobacillus sp. G1 pretreatment test. High-throughput pyrosequencing analysis investigated that the microbial communities were substantial determined by the pretreatment used. The hydrolysis enhancement was caused by an increase in extracellular enzymes, which was produced by one of dominant species Caloramator sp. The positive effect was well explained to the enhancement of WAS hydrolysis and final VFAs accumulation.
اظهر المزيد [+] اقل [-]Endocrine actions of pesticides measured in the Flemish environment and health studies (FLEHS I and II)
2015
Croes, K. | Den Hond, E. | Bruckers, L. | Govarts, E. | Schoeters, G. | Covaci, A. | Loots, I. | Morrens, B. | Nelen, V. | Sioen, I. | Van Larebeke, N. | Baeyens, W.
Within the Flemish Environment and Health studies (FLEHS I, 2002–2006, and FLEHS II, 2007–2012), pesticide exposure, hormone levels and degree of sexual maturation were measured in 14–15-year-old adolescents residing in Flanders (Belgium). In FLEHS II, geometric mean concentrations (with 95 % confidence interval (CI)) of 307 (277–341) and 36.5 ng L⁻¹ (34.0–39.2) were found for p,p′-dichlorophenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB). These values were respectively 26 and 60 % lower than levels in FLEHS I, 5 years earlier. Metabolites of organophosphorus pesticides (OPPs) and of para-dichlorobenzene were measured for the first time in FLEHS II, yielding concentrations of 11.4, 3.27 and 1.57 μg L⁻¹ for the sum of dimethyl- and diethyl phosphate metabolites and 2,5-dichlorophenol (2,5-DCP), respectively. Data on internal exposure of HCB showed a positive correlation with sexual maturation, testosterone and the aromatase index for boys and with free thyroxine (fT4) and thyroid stimulating hormone (TSH) (both boys and girls). For both p,p′-DDE and HCB, a negative association with sexual development in girls was found. The OPP metabolites were negatively associated with sex hormone levels in the blood of boys and with sexual maturation (both boys and girls). The pesticide metabolite 2,5-DCP was negatively correlated with free T4, while a positive association with TSH was reported (boys and girls). These results show that even exposure to relatively low concentrations of pesticides can have significant influences on hormone levels and the degree of sexual maturation in 14–15-year-old adolescents.
اظهر المزيد [+] اقل [-]Proteomic tools to decipher microbial community structure and functioning
2015
Arsène-Ploetze, Florence | Bertin, Philippe N. | Carapito, Christine
Recent advances in microbial ecology allow studying microorganisms in their environment, without laboratory cultivation, in order to get access to the large uncultivable microbial community. With this aim, environmental proteomics has emerged as an appropriate complementary approach to metagenomics providing information on key players that carry out main metabolic functions and addressing the adaptation capacities of living organisms in situ. In this review, a wide range of proteomic approaches applied to investigate the structure and functioning of microbial communities as well as recent examples of such studies are presented.
اظهر المزيد [+] اقل [-]Changes in cellular energy allocation in Enchytraeus crypticus exposed to copper and silver—linkage to effects at higher level (reproduction)
2015
Gomes, Susana I. L. | Soares, Amadeu M. V. M. | Amorim, Mónica J. B.
Under stressful conditions, organisms often try to detoxify by mobilizing certain energy sources with costs to various functions, e.g. growth or reproduction. Cellular energy allocation (CEA) is a commonly used methodology to evaluate the energetic status of an organism. In the present study, the effects of copper (Cu) and silver (Ag) were evaluated on the total energy budget of Enchytraeus crypticus (Oligochaeta) over periods of exposure (0–2, 2–4 and 4–8 days). The parameters measured were the total energy reserves available (protein, carbohydrate and lipid budgets) and the energy consumption (based on electron transport system activity) being further integrated to obtain the CEA. Results showed that Enchytraeids responded differently to Ag and Cu, mobilizing lipids and proteins in response to Ag and carbohydrates and proteins in response to Cu. Overall, it was possible to distinguish between effect concentrations (reproduction effect concentrations—EC₁₀ and EC₅₀), with EC₁₀ causing an increase in energy consumption (Ec); while for the EC₅₀, the increase in Ec is followed by a steep decrease in Ec, with a corresponding decrease in CEA in the longer exposure periods. These results could be linked with effects at higher levels of biological organization (effects on reproduction) providing evidences that CEA can be used as faster and sensitive endpoints towards metal exposure in E. crypticus.
اظهر المزيد [+] اقل [-]The effectiveness of various treatments in changing the nutrient status and bioavailability of risk elements in multi-element contaminated soil
2015
García Sánchez, Mercedes | García-Romera, Inmaculada | Száková, Jiřina | Kaplan, Lukáš | Tlustoš, Pavel
Potential changes in the mobility and bioavailability of risk and essential macro- and micro-elements achieved by adding various ameliorative materials were evaluated in a model pot experiment. Spring wheat (Triticum aestivum L.) was cultivated under controlled condition for 60 days in two soils, uncontaminated Chernozem and multi-element contaminated Fluvisol containing 4900 ± 200 mg/kg Zn, 35.4 ± 3.6 mg/kg Cd, and 3035 ± 26 mg/kg Pb. The treatments were all contained the same amount of sulfur and were as follows: (i) digestate from the anaerobic fermentation of biowaste, (ii) fly ash from wood chip combustion, and (iii) ammonium sulfate. Macro- and micro-nutrients Ca, Mg, K, Fe, Mn, Cu, P, and S, and risk elements Cd, Cr, Pb, and Zn were assayed in soil extracts with 0.11 mol/l solution of CH₃COOH and in roots, shoots, and grain of wheat after 30 and 60 days of cultivation. Both digestate and fly ash increased levels of macro- and micro-nutrients as well as risk elements (especially Cd and Zn; the mobility of Pb decreased after 30 days of cultivation). The changes in element mobility in ammonium sulfate-treated soils appear to be due to both changes in soil pH level and inter-element interactions. Ammonium sulfate tended to be the most effective measure for increasing nutrient uptake by plants in Chernozem but with opposite pattern in Fluvisol. Changes in plant yield and element uptake in treated plants may have been associated with the higher proline content of wheat shoots cultivated in both soils compared to control. None of the treatments decreased uptake of risk elements by wheat plants in the extremely contaminated Fluvisol, and their accumulation in wheat grains significantly exceeded maximum permissible levels; these treatments cannot be used to enable cereal and other crop production in such soils. However, the combination of increased plant growth alongside unchanged element content in plant biomass in pots treated with digestate and fly ash suggests that these treatments have a beneficial impact on yield and may be effective treatments in crops grown for phytoremediation.
اظهر المزيد [+] اقل [-]Environmental quality indicators and financial development in Malaysia: unity in diversity
2015
Alam, Arif | Azam, Muhammad | Abdullah, Alias Bin | Malik, Ihtisham Abdul | Khan, Anwar | Hamzah, Tengku Adeline Adura Tengku | Faridullah, | Khan, Muhammad Mushtaq | Zahoor, Hina | Zaman, Khalid
Environmental quality indicators are crucial for responsive and cost-effective policies. The objective of the study is to examine the relationship between environmental quality indicators and financial development in Malaysia. For this purpose, the number of environmental quality indicators has been used, i.e., air pollution measured by carbon dioxide emissions, population density per square kilometer of land area, agricultural production measured by cereal production and livestock production, and energy resources considered by energy use and fossil fuel energy consumption, which placed an impact on the financial development of the country. The study used four main financial indicators, i.e., broad money supply (M2), domestic credit provided by the financial sector (DCFS), domestic credit to the private sector (DCPC), and inflation (CPI), which each financial indicator separately estimated with the environmental quality indicators, over a period of 1975–2013. The study used the generalized method of moments (GMM) technique to minimize the simultaneity from the model. The results show that carbon dioxide emissions exert the positive correlation with the M2, DCFC, and DCPC, while there is a negative correlation with the CPI. However, these results have been evaporated from the GMM estimates, where carbon emissions have no significant relationship with any of the four financial indicators in Malaysia. The GMM results show that population density has a negative relationship with the all four financial indicators; however, in case of M2, this relationship is insignificant to explain their result. Cereal production has a positive relationship with the DCPC, while there is a negative relationship with the CPI. Livestock production exerts the positive relationship with the all four financial indicators; however, this relationship with the CPI has a more elastic relationship, while the remaining relationship is less elastic with the three financial indicators in a country. Energy resources comprise energy use and fossil fuel energy consumption, both have distinct results with the financial indicators, as energy demand have a positive and significant relationship with the DCFC, DCPC, and CPI, while fossil fuel energy consumption have a negative relationship with these three financial indicators. The results of the study are of value to both environmentalists and policy makers.
اظهر المزيد [+] اقل [-]Environmental fate and exposure; neonicotinoids and fipronil
2015
Bonmatin, J.-M. | Giorio, C. | Girolami, V. | Goulson, D. | Kreutzweiser, D. P. | Krupke, C. | Liess, M. | Long, E. | Marzaro, M. | Mitchell, E. A. D. | Noome, D. A. | Simon-Delso, N. | Tapparo, A.
Systemic insecticides are applied to plants using a wide variety of methods, ranging from foliar sprays to seed treatments and soil drenches. Neonicotinoids and fipronil are among the most widely used pesticides in the world. Their popularity is largely due to their high toxicity to invertebrates, the ease and flexibility with which they can be applied, their long persistence, and their systemic nature, which ensures that they spread to all parts of the target crop. However, these properties also increase the probability of environmental contamination and exposure of nontarget organisms. Environmental contamination occurs via a number of routes including dust generated during drilling of dressed seeds, contamination and accumulation in arable soils and soil water, runoff into waterways, and uptake of pesticides by nontarget plants via their roots or dust deposition on leaves. Persistence in soils, waterways, and nontarget plants is variable but can be prolonged; for example, the half-lives of neonicotinoids in soils can exceed 1,000 days, so they can accumulate when used repeatedly. Similarly, they can persist in woody plants for periods exceeding 1 year. Breakdown results in toxic metabolites, though concentrations of these in the environment are rarely measured. Overall, there is strong evidence that soils, waterways, and plants in agricultural environments and neighboring areas are contaminated with variable levels of neonicotinoids or fipronil mixtures and their metabolites (soil, parts per billion (ppb)-parts per million (ppm) range; water, parts per trillion (ppt)-ppb range; and plants, ppb-ppm range). This provides multiple routes for chronic (and acute in some cases) exposure of nontarget animals. For example, pollinators are exposed through direct contact with dust during drilling; consumption of pollen, nectar, or guttation drops from seed-treated crops, water, and consumption of contaminated pollen and nectar from wild flowers and trees growing near-treated crops. Studies of food stores in honeybee colonies from across the globe demonstrate that colonies are routinely and chronically exposed to neonicotinoids, fipronil, and their metabolites (generally in the 1–100 ppb range), mixed with other pesticides some of which are known to act synergistically with neonicotinoids. Other nontarget organisms, particularly those inhabiting soils, aquatic habitats, or herbivorous insects feeding on noncrop plants in farmland, will also inevitably receive exposure, although data are generally lacking for these groups. We summarize the current state of knowledge regarding the environmental fate of these compounds by outlining what is known about the chemical properties of these compounds, and placing these properties in the context of modern agricultural practices.
اظهر المزيد [+] اقل [-]Assessment of long-term phosphorus retention in an integrated constructed wetland treating domestic wastewater
2015
Dzakpasu, Mawuli | Scholz, Miklas | McCarthy, Valerie | Jordan, Siobhán N.
Due to the nature of the phosphorus (P) removal mechanisms associated with constructed wetlands, the sustainability of P treatment is usually of high interest. As a result, a 4-year dataset from a typical multi-celled integrated constructed wetland (ICW) located at Glaslough in Co. Monaghan, Ireland was evaluated to determine the effects of long-term P loadings and hydrological inputs on P treatment. The ICW was intensively monitored year-round from February 2008 through March 2012 for total P and molybdate reactive phosphate (MRP). Domestic wastewater was loaded at 16.4 ± 0.96 g m² year⁻¹ for total P and 11.2 ± 0.74 g m² year⁻¹ for MRP. Average mass reductions over the monitoring period were 91.4 and 90.1 %, respectively. The area-based kinetic coefficients (K ₍₂₀₎) of 11.8 for total P and 15.6 m year⁻¹ for MRP indicated a high area-specific retention rate. The ICW appeared to have a sustained capacity for P adsorption and retention, but the treatment was influenced mainly by external hydrological inputs and fluctuations in wastewater loadings. Linear regression analyses showed a reduction in mass retention of both total P and MRP with increased effluent flow volumes. Monthly mass reductions exceeded 90 % when the effluent flow volumes were less than 200 m³ day⁻¹. When monthly effluent flow volumes exceeded 200 m³ day⁻¹, nonetheless, mass reductions became highly variable. Designs and management of ICW systems should adopt measures to limit external hydrological loadings in order to maintain sufficient P treatment.
اظهر المزيد [+] اقل [-]Response of the microbial community to seasonal groundwater level fluctuations in petroleum hydrocarbon-contaminated groundwater
2015
Zhou, Ai-xia | Zhang, Yu-ling | Dong, Tian-zi | Lin, Xue-yu | Su, Xiao-si
The effects of seasonal groundwater level fluctuations on the contamination characteristics of total petroleum hydrocarbons (TPH) in soils, groundwater, and the microbial community were investigated at a typical petrochemical site in northern China. The measurements of groundwater and soil at different depths showed that significant TPH residue was present in the soil in this study area, especially in the vicinity of the pollution source, where TPH concentrations were up to 2600 mg kg⁻¹. The TPH concentration in the groundwater fluctuated seasonally, and the maximum variation was 0.8 mg L⁻¹. The highest TPH concentrations were detected in the silty clay layer and lied in the groundwater level fluctuation zones. The groundwater could reach previously contaminated areas in the soil, leading to higher groundwater TPH concentrations as TPH leaches into the groundwater. The coincident variation of the electron acceptors and TPH concentration with groundwater-table fluctuations affected the microbial communities in groundwater. The microbial community structure was significantly different between the wet and dry seasons. The canonical correspondence analysis (CCA) results showed that in the wet season, TPH, NO₃ ⁻, Fe²⁺, TMn, S²⁻, and HCO₃ ⁻ were the major factors correlating the microbial community. A significant increase in abundance of operational taxonomic unit J1 (97 % similar to Dechloromonas aromatica sp.) was also observed in wet season conditions, indicating an intense denitrifying activity in the wet season environment. In the dry season, due to weak groundwater level fluctuations and low temperature of groundwater, the microbial activity was weak. But iron and sulfate-reducing were also detected in dry season at this site. As a whole, groundwater-table fluctuations would affect the distribution, transport, and biodegradation of the contaminants. These results may be valuable for the control and remediation of soil and groundwater pollution at this site and in other petrochemical-contaminated areas. Furthermore, they are probably helpful for reducing health risks to the general public from contaminated groundwater.
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