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Результаты 1421-1430 из 2,459
Capability of the natural microbial community in a river water ecosystem to degrade the drug naproxen
2014
Grenni, Paola | Patrolecco, Luisa | Ademollo, Nicoletta | Di Lenola, Martina | Barra Caracciolo, Anna
The present work aims at evaluating the ability of the River Tiber natural microbial community to degrade naproxen in water samples collected downstream from a wastewater treatment plant. For this purpose, different water microcosms were set up (microbiologically active vs sterile ones) and treated with naproxen (100 μg/L) alone or in the co-presence of gemfibrozil in order to evaluate if the co-presence of the latter had an influence on naproxen degradation. The experiment was performed in the autumn and was compared with the same experimental set performed in spring of the same year to highlight if seasonal differences in the river water influenced the naproxen degradation. Pharmaceutical concentrations and microbial analysis (total cell number, viability, and microbial community composition) were performed at different times in the degradation experiments. The overall results show that the natural microbial community in the river water had a key role in the naproxen degradation. In fact, although there was a transient negative effect on the natural microbial community in all the experiments (3 h after adding the pharmaceutical), the latter was able to degrade naproxen within about 40 days. On the contrary, no decrease in the pharmaceutical concentration was observed in the sterile river water. Moreover, the co-presence of the two drugs lengthened the naproxen lag phase. As regards the natural microbial community composition detected by Fluorescence in situ Hybridization, Alpha and Gamma-Proteobacteria increased when the pharmaceutical halved, suggesting their role in the degradation. This study shows that with the concentration studied, naproxen was degraded by the natural microbial populations collected from a river chronically contaminated by this pharmaceutical.
Показать больше [+] Меньше [-]A field study on phytoremediation of dredged sediment contaminated by heavy metals and nutrients: the impacts of sediment aeration
2014
Wu, Juan | Yang, Lihua | Zhong, Fei | Cheng, Shuiping
Compared to traditional chemical or physical treatments, phytoremediation has proved to be a cost-effective and environmentally sound alternative for remediation of contaminated dredged sediment. A field study was conducted in a sediment disposal site predominantly colonized by Typha angustifolia under different sediment moisture conditions to estimate the phytoremediation effects of dredged sediment. The moisture content was 37.30 % and 48.27 % in aerated and waterlogged sediment, respectively. Total nitrogen (TN) content was higher in the waterlogged sediment than in the aerated sediment. The total Cd contents were lower in aerated sediment, which was mainly resulted from the lower exchangeable fraction of Cd. The bioaccumulation of P, Cu and Pb in T. angustifolia was promoted by waterlogging, and the belowground tissue concentrations and accumulation factors (AFs) of Cu were higher than that of other metals, which can be explained by that Cu is an essential micronutrient for plants. Consistent with many previous studies, T. angustifolia showed higher metal levels in roots than in above-ground tissues at both the sediment conditions. Due to the improved biomass produced in the aerated sediment, the removals of nutrients and the metals by plant harvest were higher from aerated sediment than from waterlogged sediment. It was indicated that maintaining the dredged sediment aerated can avoid release risk and plant uptake of metals, while the opposite management option can promote phytoextraction of these contaminants.
Показать больше [+] Меньше [-]Assessing the effects of heavy metal contamination on the proteome of the moss Pseudoscleropodium purum cross-transplanted between different areas
2014
Boquete, M Teresa | Bermúdez-Crespo, José | Aboal, Jesús R. | Carballeira, Alejo | Fernández, J Ángel
Protein expression was assessed in samples of Pseudoscleropodium purum cross-transplanted between one unpolluted (UNP) and two polluted (POLL) sites. Firstly, the level of expression (LE) of 17 proteins differed between native mosses from both types of sites, but differences were only maintained throughout the experiment for 5 of them. The LE of these five proteins changed over time in mosses transplanted from UNP to POLL and vice versa, becoming similar to that in autotransplants. However, these changes occurred slower than changes in the heavy metal concentrations measured in the same samples, and therefore they were not related to atmospheric pollution. Although the proteins identified were associated with moss metabolism, the expected growth reduction in samples autotransplanted within POLL (as a result of the down-regulation of photosynthesis-related proteins), did not occur. This supports the hypothesis that mosses growing in polluted areas adapt to heavy metal pollution and are able to reduce/overcome their toxic effects (i.e., reduced growth). Nevertheless, further specific research must be carried out to identify the proteins involved in this type of response, as lack of information on the bryophyte genome precludes us from reaching further conclusions.
Показать больше [+] Меньше [-]Derivation of site-specific surface water quality criteria for the protection of aquatic ecosystems near a Korean military training facility
2014
Jeong, Seung-Woo | An, Youn-Joo
This study suggested the first Korean site-specific ecological surface water quality criteria for the protection of ecosystems near an artillery range at a Korean military training facility. Surface water quality (SWQ) criteria in Korea address human health protection but do not encompass ecological criteria such as limits for metals and explosives. The first objective of this study was to derive site-specific SWQ criteria for the protection of aquatic ecosystems in Hantan River, Korea. The second objective was to establish discharge criteria for the artillery range to protect the aquatic ecosystems of Hantan River. In this study, we first identified aquatic organisms living in the Hantan River, including fishes, reptiles, invertebrates, phytoplankton, zooplankton, and amphibians. Second, we collected ecotoxicity data for these aquatic organisms and constructed an ecotoxicity database for Cd, Cu, Zn, TNT, and RDX. This study determined the ecological maximum permissible concentrations for metals and explosives based on the ecotoxicity database and suggested ecological surface water quality criteria for the Hantan River by considering analytical detection limits. Discharge limit criteria for the shooting range were determined based on the ecological surface water quality criteria suggested for Hantan River with further consideration of the dilution of the contaminants discharged into the river.
Показать больше [+] Меньше [-]Europe-wide survey of estrogenicity in wastewater treatment plant effluents: the need for the effect-based monitoring
2014
Jarošová, Barbora | Erseková, Anita | Hilscherová, Klára | Loos, Robert | Gawlik, Bernd M. | Giesy, John P. | Bláha, Ludek
A pan-European monitoring campaign of the wastewater treatment plant (WWTP) effluents was conducted to obtain a concise picture on a broad range of pollutants including estrogenic compounds. Snapshot samples from 75 WWTP effluents were collected and analysed for concentrations of 150 polar organic and 20 inorganic compounds as well as estrogenicity using the MVLN reporter gene assay. The effect-based assessment determined estrogenicity in 27 of 75 samples tested with the concentrations ranging from 0.53 to 17.9 ng/L of 17-beta-estradiol equivalents (EEQ). Approximately one third of municipal WWTP effluents contained EEQ greater than 0.5 ng/L EEQ, which confirmed the importance of cities as the major contamination source. Beside municipal WWTPs, some treated industrial wastewaters also exhibited detectable EEQ, indicating the importance to investigate phytoestrogens released from plant processing factories. No steroid estrogens were detected in any of the samples by instrumental methods above their limits of quantification of 10 ng/L, and none of the other analysed classes of chemicals showed correlation with detected EEQs. The study demonstrates the need of effect-based monitoring to assess certain classes of contaminants such as estrogens, which are known to occur at low concentrations being of serious toxicological concern for aquatic biota.
Показать больше [+] Меньше [-]Soil-extractable phosphorus and phosphorus saturation threshold in beef cattle pastures as affected by grazing management and forage type
2014
Sigua, Gilbert C. | Chase, Chad C., Jr | Albano, Joseph
Grazing can accelerate and alter the timing of nutrient transfer, and could increase the amount of extractable phosphorus (P) cycle from soils to plants. The effects of grazing management and/or forage type that control P cycling and distribution in pasture's resources have not been sufficiently evaluated. Our ability to estimate the levels and changes of soil-extractable P and other crop nutrients in subtropical beef cattle pastures has the potential to improve our understanding of P dynamics and nutrient cycling at the landscape level. To date, very little attention has been paid to evaluating transfers of extractable P in pasture with varying grazing management and different forage type. Whether or not P losses from grazed pastures are significantly greater than background losses and how these losses are affected by soil, forage management, or stocking density are not well understood. The objective of this study was to evaluate the effect of grazing management (rotational versus “zero” grazing) and forage types (FT; bahiagrass, Paspalum notatum, Flugge versus rhizoma peanuts, Arachis glabrata, Benth) on the levels of extractable soil P and degree of P saturation in beef cattle pastures. This study (2004–2007) was conducted at the Subtropical Agricultural Research Station, US Department of Agriculture–Agricultural Research Service located 7 miles north of Brooksville, FL. Soil (Candler fine sand) at this location was described as well-drained hyperthermic uncoated Typic Quartzipsamments. A split plot arrangement in a completely randomized block design was used and each treatment was replicated four times. The main plot was represented by grazing management (grazing vs. no grazing) while forage types (bahiagrass vs. perennial peanut) as the sub-plot treatment. Eight steel exclosures (10 × 10 m) were used in the study. Four exclosures were placed and established in four pastures with bahiagrass and four exclosures were established in four pastures with rhizoma peanuts to represent the “zero” grazing treatment. The levels of soil-extractable P and degree of P saturation (averaged across FT and soil depth) of 22.1 mg kg⁻¹and 11.6 % in pastures with zero grazing were not significantly (p ≤ 0.05) different from the levels of soil-extractable P and degree of P saturation of 22.8 mg kg⁻¹and 12.9 % in pastures with rotational grazing, respectively. On the effect of FT, levels of soil-extractable P and degree of P saturation were significantly higher in pastures with rhizoma peanuts than in pastures with bahiagrass. There was no net gain of soil-extractable P due to the presence of animals in pastures with rotational grazing. Averaged across years, soil-extractable P in pastures with rotational grazing and with “zero” grazing was less than 150 mg kg⁻¹, the water quality protection. There had been no movement of soil-extractable P into the soil pedon since average degree of P saturation in the upper 15 cm was 14.3 % while the average degree of P saturation in soils at 15–30 cm was about 9.9 %. Overall, average extractable P did not exceed the crop requirement threshold of 50 mg P kg⁻¹and the soil P saturation threshold of 25 %, suggesting that reactive P is not a problem. Our study revealed that rhizoma peanuts and bahiagrass differ both in their capacity to acquire nutrients from the soil and in the amount of nutrients they need per unit growth. Rhizoma peanuts, which are leguminous forage, would require higher amounts of P compared with bahiagrass. The difference in the amount of P needed by these forages could have a profound effect on their P uptake that can be translated to the remaining amount of P in the soils. Periodic applications of additional P may be necessary especially for pastures with rhizoma peanuts to sustain their agronomic needs and to potentially offset the export of P due to animal production. Addition of organic amendments could represent an important strategy to protect pasture lands from excessive soil resources exploitation.
Показать больше [+] Меньше [-]Occurrence and suitability of pharmaceuticals and personal care products as molecular markers for raw wastewater contamination in surface water and groundwater
2014
Tran, Ngoc Han | Li, Jinhua | Hu, Jiangyong | Ong, Say Leong
This study aimed to provide the first and comprehensive data on the occurrence of 17 target pharmaceuticals and personal care products (PPCPs) in urban water environment in Singapore. Meanwhile, this study also verified the suitability of these PPCPs as specific markers of raw wastewater contamination in receiving water bodies in highly urbanized areas where both surface water and groundwater are not impacted by the discharge of treated wastewater effluents. Analytical results of wastewater showed that among 17 target PPCPs examined, only 5 PPCPs were detected in 100 % of raw wastewater samples, including acetaminophen (ACT), carbamazepine (CBZ), caffeine (CF), diethyltoluamide (DEET), and salicylic acid (SA). Similarly, these PPCPs were found in most surface water and groundwater. Interestingly, the three PPCPs (ACT, CBZ, and SA) were only detected in surface water and groundwater in the sampling sites close to relatively older sewer systems, while they were absent in background samples that were collected from the catchment with no known wastewater sources. This suggests that ACT, CBZ, and SA can be used as specific molecular markers of raw wastewater in surface water and groundwater. This study also confirmed that CF and DEET were not really associated with wastewater sources, thus cannot serve well as specific molecular markers of wastewater contamination in receiving water bodies. To the best knowledge of the authors, the use of ACT and SA as specific molecular markers of raw wastewater contamination in urban surface waters and groundwater was first reported. Further studies on the use of ACT, CBZ, and SA along with other chemical/microbial markers are recommended to identify and differentiate contamination sources of surface waters/groundwater.
Показать больше [+] Меньше [-]Treatment of a wastewater from a pesticide manufacture by combined coagulation and Fenton oxidation
2014
Pliego, G. | Zazo, J. A. | Pariente, M. I. | Rodríguez, I. | Petre, A. L. | Leton, P. | Garcia, J.
The treatment of a non-biodegradable agrochemical wastewater has been studied by coupling of preliminary coagulation—flocculation step and further Fenton oxidation. High percentages of chemical oxygen demand (COD) removal (up to 58 %) were achieved in a first step using polyferric chloride as coagulant. This reduced significantly the amount of H₂O₂ required in the further Fenton oxidation. Using the stoichiometric amount relative to COD around 80 % of the remaining organic load was mineralized. The combined treatment allowed achieving the regional discharge limits of ecotoxicity at a cost substantially lower than the solution used so far where these wastewaters are managed as hazardous wastes.
Показать больше [+] Меньше [-]Toxicity of atrazine and its bioaccumulation and biodegradation in a green microalga, Chlamydomonas mexicana
2014
Kabra, Akhil N. | Ji, Min-Kyu | Choi, Jaewon | Kim, Jung Rae | Govindwar, Sanjay P. | Jeon, Byong-Hun
This study evaluated the toxicity of herbicide atrazine, along with its bioaccumulation and biodegradation in the green microalga Chlamydomonas mexicana. At low concentration (10 μg L⁻¹), atrazine had no profound effect on the microalga, while higher concentrations (25, 50, and 100 μg L⁻¹) imposed toxicity, leading to inhibition of cell growth and chlorophyll a accumulation by 22 %, 33 %, and 36 %, and 13 %, 24 %, and 27 %, respectively. Atrazine 96-h EC50 for C. mexicana was estimated to be 33 μg L⁻¹. Microalga showed a capability to accumulate atrazine in the cell and to biodegrade the cell-accumulated atrazine resulting in 14–36 % atrazine degradation at 10–100 μg L⁻¹. Increasing atrazine concentration decreased the total fatty acids (from 102 to 75 mg g⁻¹) and increased the unsaturated fatty acid content in the microalga. Carbohydrate content increased gradually with the increase in atrazine concentration up to 15 %. This study shows that C. mexicana has the capability to degrade atrazine and can be employed for the remediation of atrazine-contaminated streams.
Показать больше [+] Меньше [-]Environmental and health risk assessment of Pb, Zn, As and Sb in soccer field soils and sediments from mine tailings: solid speciation and bioaccessibility
2014
Pascaud, Grégoire | Leveque, Thibaut | Soubrand, Marilyne | Boussen, Salma | Joussein, Emmanuel | Dumat, Camille
Areas polluted by the persistent presence of metal(loid)s induce health problems, especially when recreational activities (on land or water) promote human exposure to the pollutants. This study focuses on one of the most encountered worldwide mining waste, i.e. those from the extraction of Pb–Zn–Ag. The representative Pb–Zn-rich tailing (about 64,100 m³) sampled is located near a soccer field and a famous river for fishing. The scientific interests is relative to: (1) mobility and bioaccessibility of metal(oid)s, (2) human risk assessments and (3) relationship between human risks and solid-bearing phases in the environment. Soccer field soils, tailings and sediments from the nearby river were sampled; moreover, metal(loid) speciation (from BCR experiments) and bioaccessibility were measured and solid speciation performed by X-ray diffraction and electron microscopy in order to highlight metal(loid) dispersion and impact. Results demonstrate that the soccer field is highly contaminated by Pb, Zn, As and Sb due primarily to waste runoff. In terms of risk assessment, Pb and As human bioaccessibility highlights the major health risk (48 and 22.5 % of human bioaccessibility, respectively). Since local populations are regularly in close contact with metal(loid)s, the health risk due to pollutant exposure needs to be reduced through sustainable waste disposal and the rehabilitation of polluted sites.
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