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Results 1471-1480 of 4,302
Vertical distribution, composition profiles, sources and toxicity assessment of PAH residues in the reclaimed mudflat sediments from the adjacent Thane Creek of Mumbai
2017
Basavaiah, N. | Mohite, R.D. | Singare, P.U. | Reddy, A.V.R. | Singhal, R.K. | Blaha, U.
A study on vertical distribution of magnetic susceptibility, carcinogenic and endocrine disrupting PAHs was performed in the reclaimed mudflat sediments adjacent to the Thane Creek of Mumbai. The 5-rings PAHs and ΣC-PAHs were more dominant at 120cm depth contributing 52.23% and 60.19% respectively to ∑PAHs. The average ratio values of LMW/HMW PAHs (0.58); Fla/(Fla+Pyr) (0.50); Ant/(Ant+Phe) (0.50); BaA/(Chry+BaA) (0.48); BaP/BghiP (2.06), Phe/Ant (1.03) and BaA/Chr (0.93) indicate that the PAH contamination might have raised due to inefficient combustion and pyrogenic emissions during the open burning of solid waste in the vicinity. This was further supported by the anthropogenic ferri(o)magnetic loading over the last 100years influencing the Creek sediments. The PAHs toxicity estimation was performed by calculating the toxic equivalent quantity (TEQ) value of 8.62ng TEQ/g which was below the safe level (600ng TEQ/g) suggested by the Canadian risk-based soil criterion for protection of human health.
Show more [+] Less [-]Green oysters occurring in an industrial harbor in Central Taiwan
2017
Fang, Tien-Hsi | Dai, Shi-Yan
Green oysters were found within the Mailiao industrial harbor (MIH) located in Central Taiwan. The metal concentrations in seawater (dissolved and particulate phases), sediment and oyster samples collected within the MIH were analyzed to examine the green oysters. The dissolved and particulate metal concentrations ranged within 0.008–1.47μgl−1 and 0.97–799.2mgkg−1, respectively. The Cu concentration in seawater was dominated in the dissolved phase. In contrast, Cr, Pb and Zn in seawater were chiefly present in the particulate phase. The metal concentrations in sediment and oyster samples ranged within 0.02–148.4mgkg−1 and 0.18–1238mgkg−1 (dry W.), respectively. No anomalous values were found in the analyzed samples, except the Cu content in the oyster samples ranged within 274–1238mgkg−1. The relatively high bioconcentration factor of Cu in oyster and the longer exposure time induced the green oysters occurred within the MIH.
Show more [+] Less [-]Incidence of marine debris in seabirds feeding at different water depths
2017
Tavares, D.C. | de Moura, J.F. | Merico, A. | Siciliano, S.
Marine debris such as plastic fragments and fishing gears are accumulating in the ocean at alarming rates. This study assesses the incidence of debris in the gastrointestinal tracts of seabirds feeding at different depths and found stranded along the Brazilian coast in the period 2010–2013. More than half (55%) of the species analysed, corresponding to 16% of the total number of individuals, presented plastic particles in their gastrointestinal tracts. The incidence of debris was higher in birds feeding predominantly at intermediate (3–6m) and deep (20–100m) waters than those feeding at surface (<2m). These results suggest that studying the presence of debris in organisms mainly feeding at the ocean surface provides a limited view about the risks that this form of pollution has on marine life and highlight the ubiquitous and three-dimensional distribution of plastic in the oceans.
Show more [+] Less [-]Commercially important species associated with horse mussel (Modiolus modiolus) biogenic reefs: A priority habitat for nature conservation and fisheries benefits
2017
Kent, Flora E.A. | Mair, J. M. (James M.) | Newton, Jason | Lindenbaum, Charles | Porter, Joanne S. | Sanderson, William G.
Horse mussel reefs (Modiolus modiolus) are biodiversity hotspots afforded protection by Marine Protected Areas (MPAs) in the NE Atlantic. In this study, horse mussel reefs, cobble habitats and sandy habitats were assessed using underwater visual census and drop-down video techniques in three UK regions. Megafauna were enumerated, differences in community composition and individual species abundances were analysed. Samples of conspicuous megafauna were also collected from horse mussel reefs in Orkney for stable isotope analysis.Communities of conspicuous megafauna were different between horse mussel habitats and other habitats throughout their range. Three commercially important species: whelks (Buccinum undatum), queen scallops (Aequipecten opercularis) and spider crabs (Maja brachydactyla) were significantly more abundant (by as much as 20 times) on horse mussel reefs than elsewhere. Isotopic analysis provided insights into their trophic relationship with the horse mussel reef. Protection of M. modiolus habitat can achieve biodiversity conservation objectives whilst benefiting fisheries also.
Show more [+] Less [-]Effects of anthropogenic surfactants on the conversion of marine dissolved organic carbon and microgels
2017
Shiu, Ruei-Feng | Lee, Chon-Lin
The possible impact of three types of anthropogenic surfactants on the ability of marine dissolved organic carbon (DOC) to form self-assembled microgels was evaluated. The behavior of existing native microgels was also examined in the presence of surfactants. These results reveal that the release of surfactants even at low concentrations into the aquatic environment could effectively hinder the self-assembly of DOC polymers. The extent of the size reduction had the following order: anionic, cationic, and non-ionic. Furthermore, charged surfactants can disrupt existing native microgels, converting large assemblies into smaller particles. One possible mechanisms is that surfactants are able to enhance the stability of DOC polymers and disrupt aggregates due to their surface charges and protein-denaturing activities. These findings suggest that the ecological system is altered by anthropogenic surfactants, and provide useful information for ecological assessments of different types of surfactants and raise warnings about surfactant applications.
Show more [+] Less [-]Chlorination induced damage and recovery in marine diatoms: Assay by SYTOX® Green staining
2017
Venkatnarayanan, Srinivas | Sriyutha Murthy, P. | Nancharaiah, Yarlagadda V. | Kirubagaran, Ramalingam | Venugopalan, Vayalam P.
Phytoplankton entrained into cooling water systems of coastal power stations are subjected to acute chemical stress due to biocides (chlorine) used for biofouling control. They are subsequently released into the environment, where they may survive/recover or succumb. Experiments were conducted to evaluate the susceptibility of a centric (Chaetoceros lorenzianus) and pennate (Navicula sp.) diatom to in-plant administered concentrations of chlorine (0.2–0.5mg/L, TRO). Viability of cells exposed to chlorine was assessed by SYTOX® Green fluorimetry and was compared with other conventional end points like total cell counts, chlorophyll a content and cellular autofluorescence. Results showed a concentration-dependant reduction in viability, chlorophyll a and autofluorescence. C. lorenzianus cells were more susceptible to chlorine compared to Navicula sp. SYTOX® Green staining appears to be a sensitive method to assess chlorine-induced damages. The data show that in-use levels of chlorination can potentially impact entrained organisms; however, they can recover when returned to coastal waters.
Show more [+] Less [-]The Persistent Environmental Relevance of Soil Phosphorus Sorption Saturation
2017
Kleinman, Peter J. A.
Controlling phosphorus (P) loss from agricultural soils remains a priority pollution concern in much of the world. Dissolved forms of P loss are among the most difficult to manage. The concept of soil P sorption saturation, the extent to which a soil’s binding sites for P are occupied, emerged from the Netherlands in the 1990s and has broad appeal as both environmental indicator and management paradigm. For hydrologically active and connected soils, P sorption saturation is responsible for the stubborn problem of legacy P, resulting in long-term release of dissolved forms of P from soils. Short- and long-term mitigation options for elevated soil P sorption saturation do exist, all with trade-offs that require adoption of new mitigation and prevention strategies. Ultimately, better incorporation of soil P sorption saturation into both crop fertility and environmental management programs is needed to promote the sustainable management of P in agricultural production systems.
Show more [+] Less [-]Polycyclic aromatic hydrocarbons (PAHs) in traditionally harvested bivalves in northern British Columbia, Canada
2017
Thompson, Kim-Ly | Picard, Chris R. | Chan, Hing Man
Butter clams, blue mussels, and Nuttall's cockle are important traditional food of the Gitga'at First Nation in Canada. Samples were collected and analyzed for polycyclic aromatic hydrocarbon (PAH) from the Gitga'at harvest sites from 2006 to 2015 to: 1) establish baseline conditions; 2) determine the likely source; 3) understand species specific response to spills; and 4) evaluate health risk associated with consumption. Baseline lipid normalized-total PAH in mussels was 2.36 (±2.86, 95%CI) μg/g in mussels, 3.26(±4.14) μg/g in clams and 3.98 (±4.98) μg/g in cockles. PAHs varied according to proximity to point sources and became less petrogenic through time. Concentrations of PAHs were elevated in all three species following diesel spills but returned to baseline levels within 5months. However, Gitga'at harvesters avoided bivalves from spill-affected habitats for several years because of their detection of reduced quality and palatability, highlighting the importance of incorporating local knowledge into future monitoring programs.
Show more [+] Less [-]Tungsten Contamination of Soils and Sediments: Current State of Science
2017
Datta, Saugata | Vero, Sara E. | Hettiarachchi, Ganga M. | Johannesson, Karen
Tungsten (W) is commonly employed as a non-toxic alternative to lead in a broad variety of industrial and military applications. However, correlations between environmental contamination through soil, water and airborne pathways, and biological effects such as epithelial damage, bioaccumulation, and trophic mobility, have led to its classification as an “emerging contaminant.” Of particular concern are recent clusters of childhood leukemia and lung cancer in the vicinity of tungsten mines and processing facilities. High environmental tungsten availability has also been associated with altered thyroid function, cardiovascular disease, and prolonged elevation of concentrations in blood, breath, and urine. Tungsten’s use as a replacement for lead (Pb) in military munitions has resulted in leaching of tungsten into soil and into soft tissues in which bullet fragments are embedded. Despite these associations, no consensus has been reached regarding the mechanisms by which tungsten affects the human body. Particularly confounding are the issues of co-toxicity with other known contaminants such as arsenic, cobalt, and cadmium, and differences resulting from the various methods of ingestion. The present paper summarizes the current behavior of tungsten in the environment, its occurrence within the pedosphere, biosphere, and atmosphere, and discusses its potential effects on exposed biota (especially humans). In particular, knowledge gaps are identified regarding the biological mechanisms of tungsten-related disease, which urgently require further elucidation in order to develop appropriate policies and management practices for the use of this element.
Show more [+] Less [-]Characteristics and contributions of biogenic secondary organic aerosol tracers to PM2.5 in Shanghai, China
2017
Zhu, Wenfei | Luo, Lina | Cheng, Zhen | Yan, Naiqiang | Lou, Shengrong | Ma, Yongpeng
To evaluate biogenic secondary organic aerosol (BSOA) tracers from biogenic precursors, fine particles (PM2.5) were collected using filter-based high-volume samplers from spring-summer of 2015 in the central part of Shanghai, China. The results showed that the isoprene SOA tracers exhibited the highest levels (17.64 ± 9.75 ng m−3) and were always observed along with higher temperatures, which results in a higher tracer formation rate and isoprene emission strength. However, the isoprene SOA tracers showed a weak correlation with the relative humidity (p > 0.05). The isoprene SOA tracers showed remarkable correlations with the [H+] because of the enhanced formation of isoprene SOA in the acidic aerosols. On the basis of these results, 2-methylglyceric acid was determined to have weak correlations with other isoprene tracers, which indicated that it had different formation pathways from those of other isoprene SOA tracers. Cis-pinonic acid had negative correlations with other SOA tracers, indicating that it is the first product in the oxidation process. Furthermore, the isoprene-based tracers (SOCisoprene) were calculated to be 0.031–0.299 μg C m−3 (with an average of 0.114 ± 0.062 μg C m−3), which accounted for more than half of the biogenic SOA. The SOC estimation with SOA tracers (SOC tracer-based) averaged 0.155 ± 0.066 μg m−3, with a range from 0.049 to 0.309 μg m−3 during the sampling period, which amounted to 2.73% OC.
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