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Результаты 851-860 из 3,207
Assessing water quality by ratio of the number of dominant bacterium species between surface/subsurface sediments in Haihe River Basin Полный текст
2015
Ke, Xin | Wang, Chunyong | Jing, Debing | Zhang, Yun | Zhang, Haijun
Sedimentary microorganisms can be used as a sensitive indicator of integrated aquatic environment quality assessment and indicate long-term water quality or toxicity. According to the Chinese National Standards of GB 3838-2002 and GB 18918-2002, the comprehensive water quality in Haihe River Basin has been described. Results showed that the comprehensive water quality in 6 sites, 4 sites, and 20 sites were good, bad, and medium. Furthermore, 162 dominant bacterial species were identified in surface and subsurface sediments in the 30 sampling sites. As revealed by two initial models constructed by logistic regression, the comprehensive water quality exhibited a pattern from good to bad as the ratio of the number of dominant bacterial species in surface sediments to that in subsurface sediments increased from 1 to 2.1. This finding possibly bridged a traditional gap between aquatic microbe indicators and water quality assessment or monitoring techniques.
Показать больше [+] Меньше [-]Indoor environmental quality in chemistry and chemical engineering laboratories at Izmir Institute of Technology Полный текст
2015
Indoor air pollution in university research laboratories may be important to building occupants, especially for those who work in the laboratories. In this study, indoor air quality (IAQ) and indoor environmental comfort were investigated in research laboratories of two departments at a university. PM2.5, PM10, TVOC (total volatile organic compounds), and CO concentrations, and three comfort variables which are temperature, relative humidity, and CO2 were measured. PM2.5 concentration was determined gravimetrically by collecting particles on glass fiber filters, whereas the remaining pollutants and comfort variables were measured using a monitoring device. IAQ measurements showed that levels of all pollutants were under the limits in both of the departments except for TVOC in one laboratory which had a mean concentration of 182ppb. The comfort variables were in the comfort ranges for laboratories in both of the departments except for temperature in one laboratory with a mean value of 30 °C. In conclusion, measures are needed for extensive uses of organic solvents because ventilation may not be sufficient to keep VOC concentrations within the limits, and to provide thermal comfort.
Показать больше [+] Меньше [-]Global change effects on biogeochemical processes of Argentinian estuaries: An overview of vulnerabilities and ecohydrological adaptive outlooks Полный текст
2015
The aims of this work are to provide an overview of the current stresses of estuaries in Argentina and to propose adaptation strategies from an ecohydrological approach. Several Argentinian estuaries are impacted by pollutants, derived mainly from sewage discharge and agricultural or industrial activities. Anthropogenic impacts are expected to rise with increasing human population. Climate-driven warmer temperature and hydrological changes will alter stratification, residence time, oxygen content, salinity, pollutant distribution, organism physiology and ecology, and nutrient dynamics. Good water quality is essential in enhancing estuarine ecological resilience to disturbances brought on by global change. The preservation, restoration, and creation of wetlands will help to protect the coast from erosion, increase sediment accretion rates, and improve water quality by removing excess nutrients and pollutants. The capacity of hydrologic basin ecosystems to absorb human and natural impacts can be improved through holistic management, which should consider social vulnerability in complex human–natural systems.
Показать больше [+] Меньше [-]Determination of mercury and vanadium concentration in Johnius belangerii (C) fish in Musa estuary in Persian Gulf Полный текст
2015
Fard, Neamat Jaafarzadeh Haghighi | Ravanbakhsh, Maryam | Ramezani, Zahra | Ahmadi, Mehdi | Angali, Kambiz Ahmadi | Javid, Ahmad Zare
The main aim of this study was to determine the concentrations of mercury and vanadium in Johnius belangerii (C) fish in the Musa estuary. A total of 67 fishes were caught from the Musa estuary during five intervals of 15days in the summer of 2013. After biometric measurements were conducted, the concentrations of mercury and vanadium were measured in the muscle tissue of fish using a direct method analyzer (DMA) and a graphite furnace atomic absorption spectrophotometer, respectively. The mean concentration of mercury and vanadium in the muscle tissue of fish was 3.154±1.981 and 2.921±0.873mg/kg w.w, respectively. The generalized linear model (GLM) analysis showed a significantly positive relationship among mercury concentration, length, and weight (P=0.000). In addition, there was a significantly negative relationship between vanadium concentration and fish length (P=0.000). A reverse association was found between concentrations of mercury and vanadium. Mercury concentration exceeded the allowable standards of the Environmental Protection Agency (EPA), the World Health Organization (WHO), and the Food and Drug Administration (FDA) in J. belangerii (C).
Показать больше [+] Меньше [-]The New York Bight 25years later: Use impairments and policy challenges Полный текст
2015
Ofiara, Douglas D.
This paper reexamines policies and outcomes concerning the NY Bight Restoration Plan, and the NY–NJ Harbor Estuary Program (NYNJHEP) precipitated by washups of marine debris and medical wastes in the New York Bight some 25-years ago. Findings indicate progress has been made but further work is necessary. Extensive beach closures have not occurred since 1987–88, although localized closings occur annually from pathogens. Objectives of “0” beach closures may not be feasible for some beaches, not to exceed 5% closures may be more achievable. Pathogen and DO data show further reductions of the last 10–20% will be more challenging and costly, suggesting “hot spots” be a focus for further remediation. Marine debris show increasing trends on beaches; presence of balloons, plastic bags, syringes and personal hygiene items found annually is another concern. Future challenges are on two fronts, upstream (harbor estuary based)-toxics, nutrient/organic loads, and atmospheric (bight based)-toxics, metals.
Показать больше [+] Меньше [-]Sedimentology and geochemistry of mud volcanoes in the Anaximander Mountain Region from the Eastern Mediterranean Sea Полный текст
2015
Talas, Ezgi | Duman, Muhammet | Küçüksezgin, Filiz | Brennan, Michael L. | Raineault, Nicole A.
Investigations carried out on surface sediments collected from the Anaximander mud volcanoes in the Eastern Mediterranean Sea to determine sedimentary and geochemical properties. The sediment grain size distribution and geochemical contents were determined by grain size analysis, organic carbon, carbonate contents and element analysis. The results of element contents were compared to background levels of Earth’s crust. The factors that affect element distribution in sediments were calculated by the nine push core samples taken from the surface of mud volcanoes by the E/V Nautilus. The grain size of the samples varies from sand to sandy silt. Enrichment and Contamination factor analysis showed that these analyses can also be used to evaluate of deep sea environmental and source parameters. It is concluded that the biological and cold seep effects are the main drivers of surface sediment characteristics from the Anaximander mud volcanoes.
Показать больше [+] Меньше [-]Increased risk of exposure to microcystins in the scum of the filamentous cyanobacterium Aphanizomenon flos-aquae accumulated on the western shoreline of the Curonian Lagoon Полный текст
2015
Šulčius, Sigitas | Pilkaitytė, Renata | Mazur-Marzec, Hanna | Kasperovičienė, Jūratė | Ezhova, Elena | Błaszczyk, Agata | Paškauskas, Ričardas
Concentration of toxic cyanobacteria blooms on the downwind shore of high recreational amenity water bodies with largely increases the risk of exposure to cyanotoxins. In this study analysis of phytoplankton structure, cyanotoxin composition and concentration was performed on cyanobacteria scum material, high- and low-density bloom samples in the Curonian Lagoon. We found that the concentration of cyanotoxins in the scum material increased from ∼30 to ∼300-fold compared to bloom samples. In Microcystis aeruginosa dominated samples microcystin-LR was present at the highest concentration, while the dominance of Planktothrix agardhii was associated with the occurrence of dmMC-RR as the major microcystin variant. The toxicological potential of cyanobacterial scums in the Curonian Lagoon is emphasized, and management by removal of these scums is proposed.
Показать больше [+] Меньше [-]Assessment of metal contamination in coastal sediments of the Maluan Bay (China) using geochemical indices and multivariate statistical approaches Полный текст
2015
Wang, Zaosheng | Wang, Yushao | Chen, Liuqin | Yan, Changzhou | Yan, Yijun | Chi, Qiaoqiao
Total concentrations and chemical forms of heavy metals in surface sediments of Maluan Bay were determined and multiple geochemical indices and guidelines were applied to assess potential contamination and environmental risks. Metal concentrations exhibited significant spatial variation and the speciation of Cr was presented dominantly in the residual fraction, while Cd was found mostly in the non-residual fraction and thus of high potential bioavailability. Cluster analysis separated four subgroups of sampling sites with different levels of contamination. Further, a multivariate method offered the specific interpretation of possible contaminant sources and/or pathways. Factor scores characterized the sampling locations and elucidated the pollution status, pointing out the impact of multiple “hidden hotspots” of contaminants and providing further evidence of the existence of clear pollution-risk gradients in lagoon areas. The study supports the integrative approach as powerful tool to diagnose the pollution status scientifically for management decisions in coastal sediment of complex environment.
Показать больше [+] Меньше [-]Climatic impact on community of filamentous macroalgae in the Neva estuary (eastern Baltic Sea) Полный текст
2015
Gubelit, Yulia I.
In presented study the impact of climatic factors and North Atlantic Oscillation (NAO) on macroalgal community was analysed. Also the factors influencing algal community were defined with help of Principal Component and Classification analysis. It was found that climatic impact may depend on habitat features and that on different sites biomass of macroalgae correlated with different weather factors. Wind and surf may affect biomass of macroalgae adversely on some sites and at the same time on other sites they may accumulate biomass, transferring it is from adjacent areas. High direct correlation with temperature was found on sites which were protected from surf and had no stagnant events. Seasonal biomass inversely significantly correlated with average seasonal wind speed and annual NAO-index.
Показать больше [+] Меньше [-]Environmental conditions influence tissue regeneration rates in scleractinian corals Полный текст
2015
Sabine, Alexis M. | Smith, Tyler B. | Williams, Dana E. | Brandt, Marilyn E.
Natural and anthropogenic factors may influence corals’ ability to recover from partial mortality. To examine how environmental conditions affect lesion healing, we assessed several water quality parameters and tissue regeneration rates in corals at six reefs around St. Thomas, US Virgin Islands. We hypothesized that sites closer to developed areas would have poor water quality due to proximity to anthropogenic stresses, which would impede tissue regeneration. We found that water flow and turbidity most strongly influenced lesion recovery rates. The most impacted site, with high turbidity and low flow, recovered almost three times slower than the least impacted site, with low turbidity, high flow, and low levels of anthropogenic disturbance. Our results illustrate that in addition to lesion-specific factors known to affect tissue regeneration, environmental conditions can also control corals’ healing rates. Resource managers can use this information to protect low-flow, turbid nearshore reefs by minimizing sources of anthropogenic stress.
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