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النتائج 761 - 770 من 5,151
Comparison of greenhouse and open field cultivations across China: Soil characteristics, contamination and microbial diversity النص الكامل
2018
Sun, Jianteng | Pan, Lili | Li, Zhiheng | Zeng, Qingtao | Wang, Lingwen | Zhu, Lizhong
A national scale survey was conducted to determine an array of inorganic and organic contaminants in agricultural soils from two cultivation modes (greenhouse vs. open field) in 20 provinces across China. The investigated contaminants include organochlorine pesticides (OCPs), phthalate esters (PAEs), polycyclic aromatic hydrocarbons (PAHs), lead (Pb), zinc (Zn), copper (Cu) and cadmium (Cd). The large amounts of agrochemicals used and special cultivation mode in greenhouse caused substantial soil pollution and deterioration of soil quality. Mean concentrations of both OCPs and PAEs in greenhouse soil were approximately 100% higher than those in open field. The pH values were 6.85 ± 1.04 and 7.34 ± 0.84 for greenhouse and open field, respectively (p > 0.05). The soil microbial community was predicted to be affected by pollution in greenhouse through the PICRUSt analysis of 16s rRNA sequences. The 12 variables including various chemicals and soil properties together explained 15% of the observed variation in the community composition. In the studied variables, PAEs and lead were the primary factors affecting microbial diversity in greenhouse soils, while pH had the greatest impact on the microbial community in open field soils. These findings enhanced our understanding of the environmental impact and contamination management of greenhouses worldwide.
اظهر المزيد [+] اقل [-]Effect of physicochemical factors on transport and retention of graphene oxide in saturated media النص الكامل
2018
Chen, Chong | Shang, Jianying | Zheng, Xiaoli | Zhao, Kang | Yan, Chaorui | Sharma, Prabhakar | Liu, Kesi
Fate and transport of graphene oxide (GO) have received much attention recently with the increase of GO applications. This study investigated the effect of salt concentration on the transport and retention behavior of GO particles in heterogeneous saturated porous media. Transport experiments were conducted in NaCl solutions with three concentrations (1, 20, and 50 mM) using six structurally packed columns (two homogeneous and four heterogeneous) which were made of fine and coarse grains. The results showed that GO particles had high mobility in all the homogeneous and heterogeneous columns when solution ionic strength (IS) was low. When IS was high, GO particles showed distinct transport ability in six structurally heterogeneous porous media. In homogeneous columns, decreasing ionic strength and increasing grain size increased the mobility of GO. For the column containing coarse-grained channel, the preferential flow path resulted in an early breakthrough of GO, and further larger contact area between coarse and fine grains caused a lower breakthrough peak and a stronger tailing at different IS. In the layered column, there was significant GO retention at coarse-fine grain interface where water flowed from coarse grain to fine grain. Our results indicated that the fate and transport of GO particles in the natural heterogeneous porous media was highly related to the coupled effect of medium structure and salt solution concentration.
اظهر المزيد [+] اقل [-]Evaluation of microplastic release caused by textile washing processes of synthetic fabrics النص الكامل
2018
De Falco, Francesca | Gullo, Maria Pia | Gentile, Gennaro | Di Pace, Emilia | Cocca, Mariacristina | Gelabert, Laura | Brouta-Agnésa, Marolda | Rovira, Angels | Escudero, Rosa | Villalba, Raquel | Mossotti, Raffaella | Montarsolo, Alessio | Gavignano, Sara | Tonin, Claudio | Avella, Maurizio
A new and more alarming source of marine contamination has been recently identified in micro and nanosized plastic fragments. Microplastics are difficult to see with the naked eye and to biodegrade in marine environment, representing a problem since they can be ingested by plankton or other marine organisms, potentially entering the food web. An important source of microplastics appears to be through sewage contaminated by synthetic fibres from washing clothes. Since this phenomenon still lacks of a comprehensive analysis, the objective of this contribution was to investigate the role of washing processes of synthetic textiles on microplastic release. In particular, an analytical protocol was set up, based on the filtration of the washing water of synthetic fabrics and on the analysis of the filters by scanning electron microscopy. The quantification of the microfibre shedding from three different synthetic fabric types, woven polyester, knitted polyester, and woven polypropylene, during washing trials simulating domestic conditions, was achieved and statistically analysed. The highest release of microplastics was recorded for the wash of woven polyester and this phenomenon was correlated to the fabric characteristics. Moreover, the extent of microfibre release from woven polyester fabrics due to different detergents, washing parameters and industrial washes was evaluated. The number of microfibres released from a typical 5 kg wash load of polyester fabrics was estimated to be over 6,000,000 depending on the type of detergent used. The usage of a softener during washes reduces the number of microfibres released of more than 35%. The amount and size of the released microfibres confirm that they could not be totally retained by wastewater treatments plants, and potentially affect the aquatic environment.
اظهر المزيد [+] اقل [-]Chronic exposure to copper and zinc induces DNA damage in the polychaete Alitta virens and the implications for future toxicity of coastal sites النص الكامل
2018
Watson, Gordon J. | Pini, Jennifer M. | Richir, Jonathan
Chronic exposure to copper and zinc induces DNA damage in the polychaete Alitta virens and the implications for future toxicity of coastal sites النص الكامل
2018
Watson, Gordon J. | Pini, Jennifer M. | Richir, Jonathan
Copper and zinc are metals that have been traditionally thought of as past contamination legacies. However, their industrial use is still extensive and current applications (e.g. nanoparticles and antifouling paints) have become additional marine environment delivery routes. Determining a pollutant's genotoxicity is an ecotoxicological priority, but in marine benthic systems putative substances responsible for sediment genotoxicity have rarely been identified. Studies that use sediment as the delivery matrix combined with exposures over life-history relevant timescales are also missing for metals. Here we assess copper and zinc's genotoxicity by exposing the ecologically important polychaete Alitta virens to sediment spiked with environmentally relevant concentrations for 9 months. Target bioavailable sediment and subsequent porewater concentrations reflect the global contamination range for coasts, whilst tissue concentrations, although elevated, were comparable with other polychaetes. Survival generally reduced as concentrations increased, but monthly analyses show that growth was not significantly different between treatments. The differential treatment mortality may have enabled the surviving worms in the high concentration treatments to capture more food thus removing any concentration treatment effects for biomass. Using the alkaline comet assay we confirm that both metals via the sediment are genotoxic at concentrations routinely found in coastal regions and this is supported by elevated DNA damage in worms from field sites. However, combined with the growth data it also highlights the tolerance of A. virens to DNA damage. Finally, using long term (decadal) monitoring data we show stable or increasing sediment concentrations of these metals for many areas. This will potentially mean coastal sediment is a significant mutagenic hazard to the benthic community for decades to come. An urgent reappraisal of the current input sources for these ‘old pollutants’ is, therefore, required.
اظهر المزيد [+] اقل [-]Chronic exposure to copper and zinc induces DNA damage in the polychaete Alitta virens and the implications for future toxicity of coastal sites النص الكامل
2018
Watson, G. J. | Pini, J. M. | Richir, Jonathan | Institute of Marine Sciences, School of Biological Sciences, University of Portsmouth
peer reviewed | Copper and zinc are metals that have been traditionally thought of as past contamination legacies. However, their industrial use is still extensive and current applications (e.g. nanoparticles and antifouling paints) have become additional marine environment delivery routes. Determining a pollutant's genotoxicity is an ecotoxicological priority, but in marine benthic systems putative substances responsible for sediment genotoxicity have rarely been identified. Studies that use sediment as the delivery matrix combined with exposures over life-history relevant timescales are also missing for metals. Here we assess copper and zinc's genotoxicity by exposing the ecologically important polychaete Alitta virens to sediment spiked with environmentally relevant concentrations for 9 months. Target bioavailable sediment and subsequent porewater concentrations reflect the global contamination range for coasts, whilst tissue concentrations, although elevated, were comparable with other polychaetes. Survival generally reduced as concentrations increased, but monthly analyses show that growth was not significantly different between treatments. The differential treatment mortality may have enabled the surviving worms in the high concentration treatments to capture more food thus removing any concentration treatment effects for biomass. Using the alkaline comet assay we confirm that both metals via the sediment are genotoxic at concentrations routinely found in coastal regions and this is supported by elevated DNA damage in worms from field sites. However, combined with the growth data it also highlights the tolerance of A. virens to DNA damage. Finally, using long term (decadal) monitoring data we show stable or increasing sediment concentrations of these metals for many areas. This will potentially mean coastal sediment is a significant mutagenic hazard to the benthic community for decades to come. An urgent reappraisal of the current input sources for these ‘old pollutants’ is, therefore, required. Chronic exposure of zinc and copper via sediment at environmentally relevant concentrations induces DNA damage in a marine polychaete. © 2018 Elsevier Ltd
اظهر المزيد [+] اقل [-]Chemical composition and source-apportionment of sub-micron particles during wintertime over Northern India: New insights on influence of fog-processing النص الكامل
2018
Rajput, Prashant | Singh, Dharmendra Kumar | Singh, Amit Kumar | Gupta, Tarun
A comprehensive study was carried out from central part of Indo-Gangetic Plain (IGP; at Kanpur) to understand abundance, temporal variability, processes (secondary formation and fog-processing) and source-apportionment of PM₁-bound species (PM₁: particulate matter of aerodynamic diameter ≤ 1.0 μm) during wintertime. A total of 50 PM₁ samples were collected of which 33 samples represent submicron aerosol characteristics under non-foggy condition whereas 17 samples represent characteristics under thick foggy condition. PM₁ mass concentration during non-foggy episodes varied from 24–393 (Avg.: 247) μg m⁻³, whereas during foggy condition it ranged from 42–243 (Avg.: 107) μg m⁻³. With respect to non-foggy condition, the foggy conditions were associated with higher contribution of PM₁-bound organic matter (OM, by 23%). However, lower fractional contribution of SO₄²⁻, NO₃⁻ and NH₄⁺ during foggy conditions is attributable to wet-scavenging owing to their high affinity to water. Significant influence of fog-processing on organic aerosols composition is also reflected by co-enhancement in OC/EC and WSOC/OC ratio during foggy condition. A reduction by 5% in mineral dust fraction under foggy condition is associated with a parallel decrease in PM₁ mass concentration. However, mass fraction of elemental carbon (EC) looks quite similar (≈3% of PM₁) but the mass absorption efficiency (MAE) of EC is higher by 30% during foggy episodes. Thus, it is evident from this study that fog-processing leads to quite significant enhancement in OM (23%) contribution (and MAE of EC) with nearly equal and parallel decrease in SO₄²⁻, NO₃⁻ and NH₄⁺ and mineral dust fractions (totaling to 24%). Characteristic features of mineral dust remain similar under foggy and non-foggy conditions; inferred from similar ratios of Fe/Al (≈0.3), Ca/Al (0.35) and Mg/Al (0.22). Positive matrix factorization (PMF) resolves seven sources: biomass burning (19.4%), coal combustion (1.1%), vehicular emission (3%), industrial activities (6.1%), leather tanneries (4%), secondary transformations (46.2%) and mineral dust (20.2%).
اظهر المزيد [+] اقل [-]Environmental risk assessment of triclosan and ibuprofen in marine sediments using individual and sub-individual endpoints النص الكامل
2018
Pusceddu, F.H. | Choueri, R.B. | Pereira, C.D.S. | Cortez, F.S. | Santos, D.R.A. | Moreno, B.B. | Santos, A.R. | Rogero, J.R. | César, A.
The guidelines for the Environmental Risk Assessment (ERA) of pharmaceuticals and personal care products (PPCP) recommend the use of standard ecotoxicity assays and the assessment of endpoints at the individual level to evaluate potential effects of PPCP on biota. However, effects at the sub-individual level can also affect the ecological fitness of marine organisms chronically exposed to PPCP. The aim of the current study was to evaluate the environmental risk of two PPCP in marine sediments: triclosan (TCS) and ibuprofen (IBU), using sub-individual and developmental endpoints. The environmental levels of TCS and IBU were quantified in marine sediments from the vicinities of the Santos submarine sewage outfall (Santos Bay, São Paulo, Brazil) at 15.14 and 49.0 ng g⁻¹, respectively. A battery (n = 3) of chronic bioassays (embryo-larval development) with a sea urchin (Lytechinus variegatus) and a bivalve (Perna perna) were performed using two exposure conditions: sediment-water interface and elutriates. Moreover, physiological stress through the Neutral Red Retention Time Assay (NRRT) was assessed in the estuarine bivalve Mytella charruana exposed to TCS and IBU spiked sediments. These compounds affected the development of L. variegatus and P. perna (75 ng g⁻¹ for TCS and 15 ng g⁻¹ for IBU), and caused a significant decrease in M. charruana lysosomal membrane stability at environmentally relevant concentrations (0.08 ng g⁻¹ for TCS and 0.15 ng g⁻¹ for IBU). Chemical and ecotoxicological data were integrated and the risk quotient estimated for TCS and IBU were higher than 1.0, indicating a high environmental risk of these compounds in sediments. These are the first data of sediment risk assessment of pharmaceuticals and personal care products of Latin America. In addition, the results suggest that the ERA based only on individual-level and standard toxicity tests may overlook other biological effects that can affect the health of marine organisms exposed to PPCP.
اظهر المزيد [+] اقل [-]Removal, biotransformation and toxicity variations of climbazole by freshwater algae Scenedesmus obliquus النص الكامل
2018
Pan, Chang-Gui | Peng, Feng-Jiao | Ying, Guang-Guo
Climbazole (CBZ) is an antibacterial and antifungal agent widely used in personal care products. In this study, we investigated the interactions between climbazole (CBZ) and freshwater microalgae Scenedesmus obliquus (S. obliquus). Dose-effect relationships between CBZ concentrations and growth inhibitions or chlorophyll a content were observed. After 12 days of incubation, the algae density and chlorophyll a content in 2 mg/L treatment group was 56.6% and 15.8% of those in the control group, respectively. Biotransformation was the predominant way to remove CBZ in the culture solution, whereas the contribution of bioaccumulation and bioadsorption were negligible. More than 88% of CBZ was removed by S. obliquus across all treatments after 12 days of incubation, and the biotransformation of CBZ followed the first order kinetic model with half-lives of approximately 4.5 days at different treatments. CBZ-alcohol (CBZ-OH) was the only biotransformation product identified in algal solution. Moreover, the toxicity of biotransformation products was much lower than its corresponding precursor compound (CBZ). The results of this study revealed that S. obliquus might have a great impact on the environmental fates of CBZ and could be further applied to remove organic pollutants in aquatic environment.
اظهر المزيد [+] اقل [-]Enzyme activity indicates soil functionality affectation with low levels of trace elements النص الكامل
2018
Martín-Sanz, Juan Pedro | Valverde-Asenjo, Inmaculada | de Santiago-Martín, Ana | Quintana-Nieto, José Ramón | González-Huecas, Concepción | López-Lafuente, Antonio L. | Diéguez-Antón, Ana
The use of the soil can alter its functionality and influence the (bio)availability of any contaminants present. Our study considers two types of agricultural soils, rainfed and olive soils, managed according to conventional practices that apply contaminants directly to the soil (fertilizers, pesticides, fungicides, etc.) and receive contaminants from the atmosphere (traffic, industry, etc.); and a forest soil that is not subject to these agricultural practices. In this scenario, we consider a mixture of 16 trace elements (As, Ba, Be, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sb, Sn, V and Zn), since their interactions with the soil can produce synergistic and/or antagonistic effects that are not considered in most studies. We studied whether the content and (bio)availability of low concentrations of a mixture of trace elements affect the soil functionality in terms of the activity of some key enzymes We analysed the total, potentially and immediately available fractions, the soil parameters and soil enzyme activity. The results show that the functionality of the soils studied was affected despite the low concentrations of trace elements. The highest concentrations of total trace elements and available fractions were found in forest soils compared to the other two uses. Soil enzyme activity is best explained by the potentially available fraction of a mixture of trace elements and physico-chemical soil variables. In our study, pH, total nitrogen, organic carbon and fine mineral particles (silt and clay) had an influence on soil enzyme activity and the (bio)available fractions of trace elements.
اظهر المزيد [+] اقل [-]Adsorption of antibiotics on microplastics النص الكامل
2018
Li, Jia | Zhang, Kaina | Zhang, Hua
Microplastics and antibiotics are two classes of emerging contaminants with proposed negative impacts to aqueous ecosystems. Adsorption of antibiotics on microplastics may result in their long-range transport and may cause compound combination effects. In this study, we investigated the adsorption of 5 antibiotics [sulfadiazine (SDZ), amoxicillin (AMX), tetracycline (TC), ciprofloxacin (CIP), and trimethoprim (TMP)] on 5 types of microplastics [polyethylene (PE), polystyrene (PS), polypropylene (PP), polyamide (PA), and polyvinyl chloride (PVC)] in the freshwater and seawater systems. Scanning Electron Microscope (SEM) and X-ray diffractometer (XRD) analysis revealed that microplastics have different surface characterizes and various degrees of crystalline. Adsorption isotherms demonstrated that PA had the strongest adsorption capacity for antibiotics with distribution coefficient (Kd) values ranged from 7.36 ± 0.257 to 756 ± 48.0 L kg−1 in the freshwater system, which can be attributed to its porous structure and hydrogen bonding. Relatively low adsorption capacity was observed on other four microplastics. The adsorption amounts of 5 antibiotics on PS, PE, PP, and PVC decreased in the order of CIP > AMX > TMP > SDZ > TC with Kf correlated positively with octanol-water partition coefficients (Log Kow). Comparing to freshwater system, adsorption capacity in seawater decreased significantly and no adsorption was observed for CIP and AMX. Our results indicated that commonly observed polyamide particles can serve as a carrier of antibiotics in the aquatic environment.
اظهر المزيد [+] اقل [-]Source apportionment of PM2.5 organic carbon in the San Joaquin Valley using monthly and daily observations and meteorological clustering النص الكامل
2018
Skiles, Matthew J. | Lai, Alexandra M. | Olson, Michael R. | Schauer, James J. | de Foy, Benjamin
Two hundred sixty-three fine particulate matter (PM2.5) samples collected on 3-day intervals over a 14-month period at two sites in the San Joaquin Valley (SJV) were analyzed for organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC), and organic molecular markers. A unique source profile library was applied to a chemical mass balance (CMB) source apportionment model to develop monthly and seasonally averaged source apportionment results. Five major OC sources were identified: mobile sources, biomass burning, meat smoke, vegetative detritus, and secondary organic carbon (SOC), as inferred from OC not apportioned by CMB. The SOC factor was the largest source contributor at Fresno and Bakersfield, contributing 44% and 51% of PM mass, respectively. Biomass burning was the only source with a statistically different average mass contribution (95% CI) between the two sites. Wintertime peaks of biomass burning, meat smoke, and total OC were observed at both sites, with SOC peaking during the summer months. Exceptionally strong seasonal variation in apportioned meat smoke mass could potentially be explained by oxidation of cholesterol between source and receptor and trends in wind transport outlined in a Residence Time Analysis (RTA). Fast moving nighttime winds prevalent during warmer months caused local emissions to be replaced by air mass transported from the San Francisco Bay Area, consisting of mostly diluted, oxidized concentrations of molecular markers. Good agreement was observed between SOC derived from the CMB model and from non-biomass burning WSOC mass, suggesting the CMB model is sufficiently accurate to assist in policy development. In general, uncertainty in monthly mass values derived from daily CMB apportionments were lower than that of CMB results produced with monthly marker composites, further validating daily sampling methodologies.Strong seasonal trends were observed for biomass and meat smoke OC apportionment, and monthly mass averages had lowest uncertainty when derived from daily CMB apportionments.
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