خيارات البحث
النتائج 791 - 800 من 8,010
Investigating and identifying the effects of rural wastewater in Dena protected area and presenting an environmental management pattern النص الكامل
2021
Mohammad Reza Sadegh Ali | Ali Zare | Mansour Pournouri
The purpose of this study was to identify the effects of discharge and discharge of wastewater from rural communities on biodiversity in the Dena Protected Area in the Central Zagros. This research is an applied grandson that has been done by library and field method. GIS tools and Landsat satellite have been used to extract and draw maps. In order to develop a comprehensive management plan and determine objectives and operational plans, the approach (SMART + P) and factor analysis method were used. For this purpose, the general principles of water resources management related to rural areas were extracted from global guidelines. In the next step, through library studies and questionnaires, the key stakeholders of water resources management in the study area were identified and the factor burden of each was determined, the highest factor weight belongs to the Ministry of Energy and rural water and sewage companies (16.50), followed by the General Department of Environmental Protection (15.30) and finally, local and rural communities have the lowest weight (10.43). Most of the rural wastewater in Dena protected area belongs to agricultural wastewater (53%), followed by domestic wastewater (28%) and finally, industrial wastewater (11%). The results of the good fit evaluation of the model show that GFI is equal to 0.977 and considering that it is more than 0.9, so it is acceptable in the region. Finally, the proposed model was designed to prepare a plan to assess the effects of rural wastewater on biodiversity in the region in 5 steps.
اظهر المزيد [+] اقل [-]Investigating the role and importance of sustainable architecture in optimal fuel consumption and pollution reduction (Case study: Semnan wind-Catchers) النص الكامل
2021
Mahdi Yahyaei | Seyed Majid Mofidi Shemirani | Vahid Ahmadi
The purpose of this study is to investigate the role and importance of traditional Iranian architecture with emphasis on wind-catcher in reducing energy consumption in residential homes. Semnan province was selected as a study area and in the first step, suitable areas were identified for the establishment of wind-catcher in the province. In the second step, using two indices of Olgyay and effective temperature index (ET), the ted-cmperature of thermal comfort in the province was determined. Finally, the temperature difference was calculated by comparing the temperature in the residential houses adjacent to the wind-catcher and the internal temperature of the traditional buildings that had win-catchers. In the final step, the amount of energy consumption for heating or cooling in residential houses in Semnan province was estimated to determine the role and importance of wind-catchers. The results showed that April, May, June and October are in the zone of thermal comfort and there are times when wind-catchers will not be very useful in the province. On the other hand, July, August and September due to high temperatures and December, January, February and March due to high cold are good times to use wind-catchers. Also, the highest degree of conformity of the measured temperatures is observed in the cities of Semnan, Garmsar, Damghan and Shahrood, respectively. The amount of energy required to produce cooling is equal to 1700 kWh. However, if a wind-catcher is used, due to the reduction of coefficients and refrigeration losses, this amount will be equal to 1200 kWh.
اظهر المزيد [+] اقل [-]Associations between air pollutant exposure and renal function: A prospective study of older adults without chronic kidney disease النص الكامل
2021
Li, Ang | Mei, Yayuan | Zhao, Meiduo | Xu, Jing | Li, Runkui | Zhao, Jiaxin | Zhou, Quan | Ge, Xiaoyu | Xu, Qun
We used real-world exposure scenarios to evaluate the effect of six ambient air pollutant (PM₂.₅, PM₁₀, NO₂, SO₂, CO, and O₃) exposure on renal function among older adults without chronic kidney disease (CKD). We recruited 169 older adults without CKD in Beijing, China, for a longitudinal study from 2016 to 2018. The Modification of Diet in Renal Disease (MDRD) and the Chronic Kidney Disease Epidemiology Collaboration (EPI) equations were employed to derive the estimated glomerular filtration rate (eGFR). A linear mixed-effects model with random intercepts for participants was employed to determine the effects of air pollutants on renal function evaluated on the basis of eGFR and urinary albumin/creatinine ratio at different exposure windows (1-, 2-, 3-, 5-, 7-, 14-, 28-, 45-, and 60-days moving averages). An interquartile range (IQR) increase in NO₂ for was associated with significant decreases of in eGFR (MDRD equation) [percentage changes: −4.49 (95% confidence interval: −8.44, −0.37), −5.51 (−10.43, −0.33), −2.26 (−4.38, −0.08), −3.71 (−6.67, −0.65), −5.44 (−9.58, −1.11), −5.50 (−10.24, −0.51), −6.15 (−10.73, −1.33), and −6.34 (−11.17, −1.25) for 1-, 2-, 5-, 7-, 14-, 28-, 45-, and 60-days moving averages, respectively] and in eGFR (EPI equation) [percentage changes: −5.04 (−7.09, −2.94), −6.25 (−8.81, −3.62), −5.16 (−7.34, −2.92), −5.10 (−7.85, −2.28), −5.83 (−8.23, −3.36), −6.04 (−8.55, −3.47) for 1-, 2-, 14-, 28-, 45-, and 60-days moving averages, respectively]. In two-pollutant model, only the association of NO₂ exposure with eGFR remained robust after adjustment for any other pollutant. This association was stronger for individuals with hypertension for the EPI equation or BMI <25 kg/m² for the MDRD equation at lags 1 and 1–2. Our findings suggest that NO₂ exposure is associated with eGFR reduction among older adults without CKD for short (1-, 2-days) and medium (14-, 28-, 45-, 60-days) term exposure periods; thus, NO₂ exposure may contribute to renal impairment.
اظهر المزيد [+] اقل [-]Carbamazepine at environmentally relevant concentrations caused DNA damage and apoptosis in the liver of Chinese rare minnows (Gobiocypris rarus) by the Ras/Raf/ERK/p53 signaling pathway النص الكامل
2021
Yan, Saihong | Chen, Rui | Wang, Miao | Zha, Jinmiao
To assess genetoxicity and the underlying mechanisms of carbamazepine (CBZ) toxicity in fish, adult Chinese rare minnows (Gobiocypris rarus) were exposed to 1, 10, and 100 μg/L CBZ for 28 d. Comet assays indicated that hepatic DNA damage was significantly increased in groups of minnows exposed to CBZ at all concentrations in a dose-dependent manner compared to those of the control groups (p < 0.05). Liver levels of 8-hydroxydeoxyguanosine (8-OHdG) were significantly increased at 10 and 100 μg/L CBZ (p < 0.05). TUNEL assays indicated that the average apoptotic rates of the livers of female and male minnows were significantly increased following exposure to CBZ at all concentrations for 28 d (p < 0.05). Significant increases in caspase 3 and 9 activities after CBZ exposure at all concentrations and caspase 8 at 10 and 100 μg/L CBZ exposure reflected the presence of mitochondrial apoptosis (p < 0.05). The mRNA levels of gadd45a, mdm2, casp3 and casp9 in female and male minnows exposed to CBZ at all concentrations were significantly increased compared with those in the control groups (p < 0.05). Significant increases in the levels of p21 in female minnows exposed to 1 and 100 μg/L CBZ, p53 in female minnows at all CBZ treatments and bcl2 in male minnows exposed to 1 and 100 μg/L CBZ were observed, indicating p53 pathway activation. The inhibition of ras levels in females and males exposed to CBZ at all concentrations and increased levels of raf1 in males exposed to CBZ at all concentrations indicated Ras/Raf1/MAPK (ERK) activation. Therefore, the present study demonstrates that CBZ at environmentally relevant levels induces DNA damage and apoptosis in Chinese rare minnows by the Ras/Raf/ERK/p53 signaling pathway.
اظهر المزيد [+] اقل [-]Spatial distribution patterns and identification of microplastics on intertidal sediments from urban and semi-natural SW Atlantic estuaries النص الكامل
2021
Díaz-Jaramillo, Mauricio | Islas, María Soledad | González, Mariana
Although estuaries act as a sink of many pollutants, the assessment of microplastics pollution in these transition environments remain scarce or unknown. Sediments from estuarine intertidal areas possess a great ecological concern but also could act as a sink of both buoyant and non-buoyant plastic debris. In this work, we have compared microplastic abundances and their main characteristics (size, shape, colour and polymer type) on intertidal sediments from SW Atlantic Argentinean estuaries (Samborombón, Mar Chiquita, Quequén Grande and Bahía Blanca). The mean microplastics abundance in surface sediments among estuaries was ranged from 0 to 1030 ± 657 items per kg d. w. Upper intertidal areas have shown significant higher microplastic abundances in comparison with lower intertidal zones (p < 0.05). In general, higher mean abundances were observed in surface (0–10 cm) compared to deeper sediments (10–30 cm), which revealed recent deposition trends of microplastics particles. However, higher microplastic abundances were observed in deeper sediments from Bahía Blanca (p < 0.05). Large (MPs, 1–5 mm) and small microplastics (MMPs, 1–0.1 mm) were observed in sediments from all estuaries, representing from 17 to 100% of total microplastics abundance. In terms of shape, fragments and films forms were dominant in all samples while fibers and foams were moderately or poorly represented. White, black, blue and transparent particles were observed as the main colour contribution of microplastics in sediments. The most common polymers identified included polyethylene, polyethylene terephthalate/polyester, polyvinyl chloride and polypropylene. The results showed that microplastic characteristics are different among the estuarine environments, which suggests different anthropogenic sources. Besides, deeper sediments should also be included on intertidal sediment monitoring to identify potential environmental liabilities from anthropogenically impacted estuaries.
اظهر المزيد [+] اقل [-]Arsenic dynamics in paddy soil under traditional manuring practices in Bangladesh النص الكامل
2021
Hossain, Mahmud | Mestrot, Adrien | Norton, Gareth J. | Deacon, Claire | Islam, M Rafiqul | Meharg, Andrew A.
Fertilization with organic matter (farm yard manure and/or rice straw) is thought to enhance arsenic (As) mobilization into soil porewaters, with subsequent As assimilation by rice roots leading to enhanced translocation to the grain. Here, interlinked experiments (field manuring and soil batch culture) were conducted to find the effect of organic matter at a field application rate practiced in Bangladesh (5 t/ha) on As mobilization in soil for paddies impacted by As contaminated groundwater irrigation, a widespread phenomenon in Bangladesh where the experiments were conducted. Total As concentration in a paddy soil (Sonargaon) ranged from 21.9 to 8.1 mg/kg down the soil profile and strongly correlated with TOC content. Arsenic, Fe, Mn, and DOC release into soil solution, and As speciation, are intimately linked to OM amendment, soil depth and temporal variation. Organic matter amendments lead to increased mobilization of As into both soil porewaters and standing surface waters. The As speciation in the porewater was dominated by inorganic As (Asᵢ) (arsenite and arsenate), with traces amounts of methylated species (DMAⱽ and MMAⱽ) only being found with OM amendment. It was noted in field trials that OM fertilization greatly enhanced As mobility to surface waters, which may have major implications for the fate of As in paddy agronomic ecosystems.
اظهر المزيد [+] اقل [-]ADME/T-based strategies for paraquat detoxification: Transporters and enzymes النص الكامل
2021
Wang, Xianzhe | Wang, Xumei | Zhu, Yanyan | Chen, Xiuping
Paraquat (PQ) is a toxic, organic herbicide for which there is no specific antidote. Although banned in some countries, it is still used as an irreplaceable weed killer in others. The lack of understanding of the precise mechanism of its toxicity has hindered the development of treatments for PQ exposure. While toxicity is thought to be related to PQ-induced oxidative stress, antioxidants are limited in their ability to ameliorate the untoward biological responses to this agent. Summarized in this review are data on the absorption, distribution, metabolism, excretion, and toxicity (ADME/T) of PQ, focusing on the essential roles of individual transporters and enzymes in these processes. Based on these findings, strategies are proposed to design and test specific and effective antidotes for the clinical management of PQ poisoning.
اظهر المزيد [+] اقل [-]Characteristics of bacterial community structure and function associated with nutrients and heavy metals in coastal aquaculture area النص الكامل
2021
Wang, Caixia | Wang, Yibo | Liu, Pengyuan | Sun, Yanyu | Song, Zenglei | Hu, Xiaoke
Coastal aquaculture area has become one of the critical zones that are more susceptible to the influence of human activity. Many aquaculture operations invariably result in the accumulation of nutrients and heavy metals in the coastal ecosystem. Our study investigated sediment bacterial community structure and function across 23 sites under the influence of nutrients and heavy metals in the coastal aquaculture area. The habitat environment of the sediment was described by analyzing physicochemical characteristics. Sediment bacterial community structure and diversity were investigated by 16S rRNA sequencing. The sequencing data presented that Proteobacteria, Bacteroidetes, Planctomycetes, Acidobacteria and Chloroflexi were predominant at phylum level. Variations in the bacterial community composition and diversity were significant (P < 0.01) among different groups (according to the distance from the bank side) which indicated that specific environmental conditions had shaped distinct bacterial community. Specifically, bacterial diversity and composition were significantly influenced by the temperature, salinity, pH, dissolved oxygen (DO), TOC, TON, nitrite, nitrate and heavy metals (P < 0.05). Results related to functional prediction demonstrated that carbon, nitrogen and sulfur metabolism were the dominant processes in the coastal aquaculture area. In the meantime, the potential pathogens such as Arcobacter was found in site S3, which indicated the possible threat to the cultured species in this area. Overall, variations in bacterial communities caused by nutrients and heavy metals can affect biogeochemical cycles, which may provide an indication for the protection of coastal aquaculture environments.
اظهر المزيد [+] اقل [-]Investigating the effects of municipal and hospital wastewaters on horizontal gene transfer النص الكامل
2021
Hutinel, Marion | Fick, Jerker | Larsson, D.G Joakim | Flach, Carl-Fredrik
Horizontal gene transfer (HGT) plays an important role in the dissemination of antibiotic resistance genes. In sewer systems, human-associated and environmental bacteria are mixed together and exposed to many substances known to increase HGT, including various antibacterial compounds. In wastewaters, those substances are most often detected below concentrations known to induce HGT individually. Still, it is possible that such wastewaters induce HGT, for example via mixture effects. Here, a panel of antibiotics, biocides and other pharmaceuticals was measured in filter-sterilized municipal and hospital wastewater samples from Gothenburg, Sweden. The effects on HGT of the chemical mixtures in these samples were investigated by exposing a complex bacterial donor community together with a GFP-tagged E. coli recipient strain. Recipients that captured sulfonamide resistance-conferring mobile genetic elements (MGEs) from the bacterial community were enumerated and characterized by replicon typing, antibiotic susceptibility testing and long read sequencing. While exposure to municipal wastewater did not result in any detectable change in HGT rates, exposure to hospital wastewater was associated with an increase in the proportion of recipients that acquired sulfonamide resistance but also a drastic decrease in the total number of recipients. Although, concentrations were generally higher in hospital than municipal wastewater, none of the measured substances could individually explain the observed effects of hospital wastewater. The great majority of the MGEs captured were IncN plasmids, and resistance to several antibiotics was co-transferred in most cases. Taken together, the data show no evidence that chemicals present in the studied municipal wastewater induce HGT. Still, the increased relative abundance of transconjugants after exposure to hospital wastewater could have implications for the risks of both emergence and transmission of resistant bacteria.
اظهر المزيد [+] اقل [-]Natural daily patterns in fish behaviour may confound results of ecotoxicological testing النص الكامل
2021
Thoré, Eli S.J. | Brendonck, Luc | Pinceel, Tom
Low doses of neuroactive chemicals end up in the environment and disrupt behaviour of non-target organisms. Although a whole range of studies have documented pollutant-induced changes in behaviour, natural daily variability in behaviour is rarely taken into account. This is surprising because biological rhythms may affect the outcome of experiments, are adaptive and are expected to be sensitive to neurochemical exposure. Here, we exploit daily behavioural variation in the fish model Nothobranchius furzeri to examine if behavioural effects of chronic exposure (74 days) to an environmentally relevant level (28 ng/L) of the neurochemical fluoxetine depend on the time of day. Fluoxetine exposure induced an increase in anxiety-related behaviour that was slightly more pronounced in the evening compared to the morning. Moreover, open-field locomotor activity was disrupted and daily patterns in activity lifted upon exposure to the compound. These results imply that short-term behavioural variability should be considered both to standardise ecological risk assessment of neuroactive chemicals as well as to better understand the environmental impact of such compounds in aquatic ecosystems.
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