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Status of marine pollution research in South Africa (1960–present)
2012
Wepener, V. | Degger, N.
The published literature on marine pollution monitoring research in South Africa from 1960 to present was evaluated. There has been a general decline in the number of papers from the 1980s and this can be linked to the absence of a marine pollution monitoring programme in South Africa. General trends observed were that contaminant exposure monitoring of metals predominates the research conducted to date. Monitoring results indicate that there has been a general decrease in metal concentrations in South African coastal waters and concentrations of metals and most organics in mussels are lower than in other industrialised nations. This is reflected in the general pristine nature and high biodiversity of the South African coastline. The establishment of a national marine pollution monitoring framework would stimulate marine pollution research.
Mostrar más [+] Menos [-]The effects of oil exposure and weathering on black-needle rush (Juncus roemerianus) marshes along the Gulf of Mexico
2012
Oil exposure has been shown to be detrimental to several salt marsh plants however little information is available for Juncus roemerianus. Thirty-two mesocosms were established with J. roemerianus sod and replicate marshes were exposed to Louisiana sweet crude oil to test oil dose (6, 12, and 24Lm⁻²) and weathering (oil weathered for 0days, 3days, and 3weeks). Juncus were monitored following oil exposure for culm survival, photosynthetic rates, and C-assimilation rates. Oil dosage had a significant effect among wetlands with low-dose (6Lm⁻²) mesocosms having higher culm survival, photosynthetic rates, and C-assimilation rates than medium or high dose wetlands (12 or 24Lm⁻²). Oil weathering did not elicit significant differences between treated wetlands however full strength wetlands (un-weathered oil) consistently had the lowest culm survivorship, photosynthetic rates, and C-assimilation rates. From our results, J. roemerianus marshes may be very susceptible to oil exposure.
Mostrar más [+] Menos [-]Effect of sewage nutrients on algal production, biomass and pigments in tropical tidal creeks
2012
Burford, M.A. | Revill, A.T. | Smith, J. | Clementson, L.
Microalgal blooms can result from anthropogenic nutrient loadings in coastal ecosystems. However, differentiating sources of nutrients remains a challenge. The response of phytoplankton and benthic microalgae (BMA) to nutrient loads was compared across tropical tidal creeks with and without secondary treated sewage. Primary productivity in the water column was limited by nitrogen availability in absence of sewage, with nitrogen saturation in the presence of sewage. Phytoplankton primary productivity rates and chlorophyll a concentrations increased in response to sewage, and there was a greater response than for BMA. There was no change in algal pigment proportions within the phytoplankton or BMA communities. Concentrations of the sewage marker, coprostanol, were higher near sewage discharge points decreasing downstream, correlating with a decline in nutrient concentrations. This suggests that sewage was the main source of nitrogen and phosphorus. This study highlights the scale and type of response of algal communities to sewage nutrients.
Mostrar más [+] Menos [-]Prevalence and diversity of norovirus genogroups I and II in Hong Kong marine waters and detection by real-time PCR
2012
Yang, Ning | Qi, Huizhou | Wong, Minnie Man Lai | Wu, Rudolf Shiu Sun | Kong, Richard Yuen Chong
Marine waters from six sites around Hong Kong with varying levels of sewage pollution were examined for noroviruses (NoVs) by PCR cloning and sequencing of a highly-variable N-terminal region of the VP1 capsid gene, at the ORF1-ORF2 junction of NoV. Phylogenetic analysis of genogroups GI- and GII-specific PCR clones obtained from different marine sites indicated that human NoV GI.1 and GII.4 strains are the most prevalent genotypes circulating in Hong Kong waters. GI- and GII-specific TaqMan-based real-time PCR assays targeting the ORF1-ORF2 junction of NoVs were used to quantify NoV particles in marine water samples in parallel with total Escherichia coli counts which were enumerated on TBX medium. No correlation of any significance between NoV and E. coli counts was observed which highlighted the inadequacy in using E. coli as a fecal indicator to predict the level of NoVs in marine waters to protect public health.
Mostrar más [+] Menos [-]Biofiltration of fishpond effluents and accumulation of N-compounds (phycobiliproteins and mycosporine-like amino acids) versus C-compounds (polysaccharides) in Hydropuntia cornea (Rhodophyta)
2012
The biofiltration capacity, biomass-yield and accumulation of N- and C-compounds of Hydropuntia cornea were analyzed. Algae were grown in different conditions for 28d: outdoor and indoor, with or without fishpond effluents. N-uptake efficiency of these effluents was higher than 95% after 7d both outdoors and indoors. N-enriched conditions reduced the extent of photoinhibition and increased the maximal quantum yield in H. cornea. The biomass-yield was higher in outdoor grown-algae after 7d and decreased independently of the treatment after 28d. N, acid polysaccharide (AP) and mycosporine-like amino acid (MAA)-yields decreased throughout the experiment in all conditions. The highest MAA-yield was observed in fishpond effluent outdoor-grown algae, indicating a positive effect of increased radiation on MAA accumulation. However, APs were higher under N-depleted conditions. The use of MAAs as UV-screening and antioxidants, and the use of AP as immunostimulants are discussed.
Mostrar más [+] Menos [-]Nanoporous polystyrene fibers for oil spill cleanup
2012
Lin, Jinyou | Shang, Yanwei | Ding, Bin | Yang, Jianmao | Yu, Jianyong | Al-Deyab, Salem S.
The development of oil sorbents with high sorption capacity, low cost, scalable fabrication, and high selectivity is of great significance for water environmental protection, especially for oil spillage on seawater. In this work, we report nanoporous polystyrene (PS) fibers prepared via a one-step electrospinning process used as oil sorbents for oil spill cleanup. The oleophilic–hydrophobic PS oil sorbent with highly porous structures shows a motor oil sorption capacity of 113.87g/g, approximately 3–4times that of natural sorbents and nonwoven polypropylene fibrous mats. Additionally, the sorbents also exhibit a relatively high sorption capacity for edible oils, such as bean oil (111.80g/g) and sunflower seed oil (96.89g/g). The oil sorption mechanism of the PS sorbent and the sorption kinetics were investigated. Our nanoporous material has great potential for use in wastewater treatment, oil accident remediation and environmental protection.
Mostrar más [+] Menos [-]Links between bacterial communities in marine sediments and trace metal geochemistry as measured by in situ DET/DGT approaches
2012
Gillan, David C. | Baeyens, Willy | Bechara, Rafeh | Billon, Gabriel | Denis, Kevin | Grosjean, Philippe | Leermakers, Martine | Lesven, Ludovic | Pede, Annelies | Sabbe, Koen | Gao, Yue
Our current view about the relationship between metals and bacteria in marine sediments might be biased because most studies only use ex situ approaches to quantify metals. The aim of the present research was to compare ex situ and in situ methods of metal measurement (DET and DGT – diffusive equilibration or diffusive gradients in thin-films) and relate the results with two commonly used microbiological variables (bacterial biomass and bacterial diversity as revealed by DGGE). No previous studies have used such in situ approaches in microbial ecology. For biomass and most of the investigated trace metals (Ag, Cd, Sn, Cr, Ni, Cu, Pb, and Al) no significant correlations were found. The exceptions were Fe, Mn, Co, and As which behave like micronutrients. For bacterial diversity, no relevant relationships were found. We conclude that in situ methods are more adapted tools for microbial ecologists but that ex situ approaches are still necessary.
Mostrar más [+] Menos [-]Monitoring of East Channel dredge areas benthic fish population and its implications
2012
Drabble, Ray
Regional annual sampling of commercial fish stocks formed a high priority for monitoring studies attendant with the granting of aggregate dredging licenses in the Eastern Channel Region (ECR) which had previously not been dredged. An assessment of 4m beam trawl sampling between 2005 and 2008 following the granting of licences in 2006 is provided. The majority of fish species have shown marked reductions in abundance since commencement of dredging. Draghead entrainment has been identified as a possible contributory cause based upon the known vulnerability of selected species (Drabble, 2012). Other environmental factors considered offer no explanation for the changes in abundance. Comparative analyses with ICES data for plaice and sole over the study period demonstrate that changes in the ECR do not result from seasonal flux in the wider populations. An alternative impact model and potential mitigation measures are suggested.
Mostrar más [+] Menos [-]Biomarker responses and genotoxicity in the mud snail (Bullacta exarata) as indicators of coastal contamination
2012
An, Li-hui | Zheng, Bing-hui | Wang, Li-jing | Zhang, Yan-Qiang | Chen, Hao | Zhao, Xing-ru | Zhang, Lei | Lei, Kun
In the present study different biomarker responses and genotoxicity were determined in wild mud snails (Bullacta exarata) collected from 3 sampling sites in Bohai Bay in northeastern China, which is a region that is under considerable anthropogenic influence. Significant spatial variability of superoxide dismutase (SOD) and metallothionein (MT)-like proteins were recorded, while glutathione transferase (GST), catalase (CAT), and vitellin-like proteins (Vn’s) were not observed. Furthermore, genomic DNA that was amplified with 4 fluorescence-labeled primer pairs showed variable genetic distances among the 3 wild mud snail populations found in Bohai Bay, which may be correlated with differences in the types of environmental genotoxicants, such as heavy metals and polycyclic aromatic hydrocarbons. This multi-biomarker approach provided an improved understanding of the potential toxicological impact of contaminated sediments on benthic organisms.
Mostrar más [+] Menos [-]Modelling the environmental behaviour of pollutants in Algeciras Bay (south Spain)
2012
Periáñez, R.
An environmental study of Algeciras Bay is carried out through numerical modelling. First, a 2D barotropic model is applied to calculate tides and mean circulation. Results of this model are used by a sediment transport model which provides suspended matter concentrations and sedimentation rates in the Bay. It includes three particle classes. An effective diffusion coefficient has been calibrated simulating temperature distribution inside the Bay. An additional validation is obtained from an independent nitrate dispersion simulation. Then heavy metal dispersion patterns are investigated using a model which includes water–sediment metal interactions and uses the outputs of the hydrodynamic and sediment transport models. The metal transport model has been applied to simulate the dispersion of Zn, Cu and Ni. Results from the hydrodynamic, sediment and metal transport models have been compared with measurements. Model results also indicate that transport inside the Bay is relatively weak. Numerical experiments have been carried out to determine flushing times for conservative and non-conservative pollutants. Flushing time is about 20days for a conservative tracer, and this value is mainly due to the M₂ residual current. Tides are not effective in removing pollutants.
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