خيارات البحث
النتائج 1491 - 1500 من 5,149
Evaluation of heavy metals and environmental risk assessment in the Mangrove Forest of Kuala Selangor estuary, Malaysia النص الكامل
2018
ELTurk, Mohammed | Abdullah, Rosazlin | Rozainah, M.Z. | Abu Bakar, Nor Kartini
This study was carried out to evaluate the distribution, enrichment and ecological risk of heavy metals (arsenic (As), zinc (Zn), manganese (Mn), copper (Cu) and lead (Pb)) concentration in Kuala Selangor estuary at the Kuala Selangor Nature Park. The results suggested that As and Pb in sediment were as high as the background value, suggesting the presence of anthropogenic contamination. The risk assessment of sediment Igeo, CD, and PERI, on the other hand, showed low risk of heavy metals in Kuala Selangor estuary. Meanwhile, risk assessment code (RAC) results showed that Mn, As and Zn presented medium to high level of environmental risk. The translocation factor and bioaccumulation factors of heavy metal concentration by mangrove vegetation showed a variety of trends, which indicates the different partitioning and uptake ability of heavy metal in the tissues of different mangrove species. Therefore, underscores the importance of preserving the high diversity of mangroves at securing the health and productivity of the coastal region. These results may play a critical role in facilitating decision makers in managing the sustainability of mangrove forests.
اظهر المزيد [+] اقل [-]Evaluation of the environmental quality of Parangipettai, Southeast Coast of India, by using multivariate and geospatial tool النص الكامل
2018
The anthropogenic pressure in recent years has driven us to investigate the environmental quality at 22 stations in Parangipettai by collecting seawater samples monthly from 2014 to 2015. The sampling stations were grouped into three different environments, namely, Vellar Estuary (VE), Coleroon Estuary (CE), and Open Sea (OS). Factor analysis showed a total variance of 65.63% and exhibited a strong factor loading for atmospheric temperature (0.914), water temperature (0.917), ammonia (0.767), inorganic phosphate (0.897), total phosphorus (0.783), and phytoplankton (0.829). The index value showed water quality was good in OS (74.18), whereas it was moderate in VE (69.73) and CE (68.47). The visual model developed using Geographical Information System (GIS) displayed a spatial pattern of water temperature and phytoplankton dispersion in a distinct manner. The results obtained through multivariate analysis and GIS-based model are imperative to establish reference for a comparative study with other similar ecosystem for better planning and management of tropical seawaters.
اظهر المزيد [+] اقل [-]Development of analytical methods used for the study of 2,4,6-trinitrotoluene degradation kinetics in simulated sediment samples from the Baltic Sea النص الكامل
2018
Large amounts of ammunition containing 2,4,6-trinitrotoluene (TNT) and other substances were dumped in the Baltic Sea after WWII. Considering progressive corrosion processes, studying the transformation of TNT occurring in the environment constitutes an important aspect of a possible associated risk. This study focused on the transformations of TNT in simulated conditions of the Baltic Sea bottom sediment. Methods of analysis of TNT and selected products of its transformations were developed for that purpose. The developed methods allowed for the determination of selected compounds below 1 ng/g. Systematic monitoring of TNT transformations in the environment of the bottom sediment was performed. This allowed for the determination of the kinetics of TNT degradation and identification of degradation reaction products. Based on the obtained results, the TNT decay half-time in conditions present in the Baltic Sea was estimated to be 16.7 years for the abiotic environment and 5.6 for the biotic environment.
اظهر المزيد [+] اقل [-]Organochlorine pesticide accumulation in seabirds and marine mammals from the Northwest Pacific النص الكامل
2018
Tsygankov, Vasiliy Yu | Lukyanova, Olga N. | Boyarova, Margarita D.
Bioaccumulation of organochlorine pesticides by marine organisms is one of the methods of environmental quality. Concentrations of organochlorine pesticides (HCH isomers (α-, β-, γ-HCH), p,p′-DDT and its metabolites (p,p′-DDD, p,p′-DDE)) in samples of seabirds (Northern fulmar Fulmarus glacialis, Crested auklet Aethia cristatella, Auklet-crumb Aethia pusilla, Pacific gull Larus schistisagus, and Gray petrel Oceanodroma furcate) and marine mammals (Gray whales Eschrichtius robustus and Pacific walrus Odobenus rosmarus divergens) were measured by a GC–MS. The total concentration of OCPs in mammals was higher than in seabirds. Environmental biomonitoring with the use of seabirds and marine mammals, as a long-lived species, is used for global monitoring, since bioaccumulation in these organisms occurs throughout life. The environmental assessment of the Northwest Pacific marine ecosystems revealed that the levels of OCP contamination in this area are similar to the other subarctic regions of the World Ocean.
اظهر المزيد [+] اقل [-]Food selection of a generalist herbivore exposed to native and alien seaweeds النص الكامل
2018
Understanding which factors influence the invasion of alien seaweed has become a central concern in ecology. Increasing evidence suggests that the feeding preferences of native herbivores influence the success of alien seaweeds in the new community. We investigated food selection of a generalist native grazer Paracentrotus lividus, in the presence of two alien seaweeds (Caulerpa cylindracea and Caulerpa taxifolia var. distichophylla) and two native seaweeds (Dictyopteris membranacea and Cystoseira compressa). Sea urchins were fed with six experimental food items: C. cylindracea, C. taxifolia var. distichophylla, a mixture of C. cylindracea and C. taxifolia var. distichophylla, D. membranacea, C. compressa and a mixture of D. membranacea and C. compressa. P. lividus ingested all the combinations of food offered, though it preferentially consumed the alien mixture, C. cylindracea and D. membranacea. The alien C. taxifolia var. distichophylla was consumed significantly less than the other food items and, interestingly, it was ingested in a greater amount when mixed with C. cylindracea than when on its own. This finding suggests that C. taxifolia var. distichophylla may become vulnerable to sea urchin grazing when it grows intermingled with C. cylindracea, which does not gain immediate protection from the presence of the very low palatable congeneric seaweed. The present study highlights the potential role of native grazers to indirectly affect the interspecific competition between the two alien seaweeds in the Mediterranean Sea.
اظهر المزيد [+] اقل [-]Sedimentary mercury (Hg) in the marginal seas adjacent to Chinese high-Hg emissions: Source-to-sink, mass inventory, and accumulation history النص الكامل
2018
Kim, Jihun | Lim, Dhongil | Jung, Dohyun | Kang, Jeongwon | Jung, Hoisoo | Woo, Hanjun | Jeong, Kapsik | Xu, Zhaokai
We comprehensively investigated sedimentary Hg in Yellow and East China Seas (YECSs), which constitute potentially important depocenters for large anthropogenic Hg emissions from mainland China. A large dataset of Al-TOC-Hg concentrations led to an in-depth understanding of sedimentary Hg in the entire YECSs, including distribution and its determinants, source-to-sink, background levels, inventory in flux and budget, and accumulation history. Especially, the net atmospheric Hg flux to the sediments was estimated to be 1.3 × 10−5 g/m2/yr, which corresponded reasonably well to that calculated using a box model. About 21.2 tons of atmospheric Hg (approximately 4% of the total anthropogenic atmospheric Hg emissions from China) were buried annually in the YECS basin. This result implies that most of atmospheric Hg from China is transferred to the surface of the Pacific (including the East/Japan Sea and South China Sea) by the westerlies and, consequently, can play a critical role in open-sea aquatic ecosystems.
اظهر المزيد [+] اقل [-]The need for a formalised system of Quality Control for environmental policy-science النص الكامل
2018
Research science used to inform public policy decisions, herein defined as “Policy-Science”, is rarely subjected to rigorous checking, testing and replication. Studies of biomedical and other sciences indicate that a considerable fraction of published peer-reviewed scientific literature, perhaps half, has significant flaws. To demonstrate the potential failings of the present approaches to scientific Quality Control (QC), we describe examples of science associated with perceived threats to the Great Barrier Reef (GBR), Australia. There appears a serious risk of efforts to improve the health of the GBR being directed inefficiently and/or away from the more serious threats. We suggest the need for a new organisation to undertake quality reviews and audits of important scientific results that underpin government spending decisions on the environment. Logically, such a body could also examine policy science in other key areas where governments rely heavily upon scientific results, such as education, health and criminology.
اظهر المزيد [+] اقل [-]Source identification and risk assessment based on fractionation of heavy metals in surface sediments of Jiaozhou Bay, China النص الكامل
2018
Liang, Xianmeng | Song, Jinming | Duan, Liqin | Yuan, Huamao | Li, Xuegang | Li, Ning | Qu, Baoxiao | Wang, Qidong | Xing, Jianwei
To identify sources and evaluate ecological risks of heavy metals in sediments of Jiaozhou Bay, contents and chemical fractions of Cd, Cr, Cu, Pb, Zn, Ni, Sb and Sn were studied. Results suggested that higher metal contents appeared at inner bay and near marine dumping area. Labile fractions of heavy metals accounted for 0.5–77% (~36%) of total contents indicating their significant anthropogenic sources. The enrichment levels of Cd and Sb were relatively higher. Cu, Ni, Cd and Zn were at low to medium risks. Cr, Pb, Sn and Sb were at no or low risks. Total contents of heavy metals were mainly controlled by natural sources, while anthropogenic inputs were important sources of labile fractions of heavy metals in sediments of Jiaozhou Bay with industrial and domestic activities as main contributors for Cu, Pb, Zn, Cr, Ni and Sn, and agricultural activities for Cd and regional coal combustion for Sb.
اظهر المزيد [+] اقل [-]Environmental status assessment using biological traits analyses and functional diversity indices of benthic ciliate communities النص الكامل
2018
Xu, Yuan | Stoeck, Thorsten | Forster, Dominik | Ma, Zuhang | Zhang, Liquan | Fan, Xinpeng
In this study, we tested the hypothesis that the functional diversity of benthic ciliates has high potential to monitor marine ecological status. Therefore, we investigated the spatial and temporal variation of functional diversity of benthic ciliates in the Yangtze Estuary during one year using biological traits analyses and functional diversity indices. Traits and community compositions showed clear spatial and temporal variations. Among a variety of biological traits, feeding type and body size emerged as strongest predictable variables. Functional divergence (FDiv) had an advantage over two other functional diversity indices, as well as over classical diversity measures (i.e. richness, evenness, Shannon-Wiener) to infer environmental status. Significant correlations between biological traits, FDiv and environmental variables (i.e. nutrients, temperature, salinity) suggested that functional diversity of benthic ciliates might be used as a bio-indicator in environmental status assessments. Further mandatory researches need to implement functional diversity of ciliates in routine monitoring programs were discussed.
اظهر المزيد [+] اقل [-]Effective and easy to use extraction method shows low numbers of microplastics in offshore planktivorous fish from the northern Baltic Sea النص الكامل
2018
Budimir, Stjepan | Setälä, Outi | Lehtiniemi, Maiju
Although the presence of microplastics in marine biota has been widely recorded, extraction methods, method validation and approaches to monitoring are not standardized. In this study a method for microplastic extraction from fish guts based on a chemical alkaline digestion is presented. The average particle retrieval rate from spiked fish guts, used for method validation, was 84%. The weight and shape of the test particles (PET, PC, HD-PE) were also analysed with no noticeable changes in any particle shapes and only minor weight change in PET (2.63%). Microplastics were found in 1.8% of herrings (n=164) and in 0.9% of sprat (n=154). None of the three-spined sticklebacks (n=355) contained microplastic particles.
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