Уточнить поиск
Результаты 2491-2500 из 8,010
Trophic assessment in South American Atlantic coastal lagoons: Linking water, sediment and diatom indicators Полный текст
2021
Tudurí, Adriana | Becoña, Laura Perez | Venturini, Natalia | Rodríguez-Gallego, Lorena | Garciá-Rodríguez, Felipe | González Arratia, Leticia | Lescano, Carolina | Costa, Soledad | del Puerto, Laura | Bergamino, Leandro
Within two coastal shallow lagoons, trophic state was assessed by integrating water and sediment chemical indicators such as the TRIX and the benthic biopolymeric carbon (BPC) trophic indicator, altogether with biological environmental indicators (diatom species characterization). Spatial and temporal behavior of TRIX and BPC indices suggest that water column trophic indicators reflect rather short-term variations in water quality changes, while benthic trophic indicators rather reflect consistent long-term trends which make them useful as enduring indicators of eutrophication. Canonical Correspondence Analysis (CCA) showed that both sediment and transitional water trophic state indices increased eutrophic conditions with a decreasing salinity and increasing total nutrients. Diatom species associated with elevated eutrophic condition such as Staurosirella martyi, Staurosira breviestriata, Amphora copulata, Amphora veneta, Nitzschia sp., and Bacillaria paradoxa, showed a positive correlation with both trophic indices. We highlight the need for considering sediment eutrophication indicators towards in monitoring programmes within shallow coastal lagoons.
Показать больше [+] Меньше [-]Occurrence and size distribution of microplastics in mudflat sediments of the Cowichan-Koksilah Estuary, Canada: A baseline for plastic particles contamination in an anthropogenic-influenced estuary Полный текст
2021
Alava, Juan José | Kazmiruk, Tamara N. | Antwood | Schuerholz, Goetz | Heath, Bill | Flemming, Scott A. | Bendell, Leah | Drever, Mark C.
Documenting the prevalence of microplastics in marine-coastal ecosystems serves as a first step towards understanding their impacts and risks presented to higher trophic levels. Estuaries exist at the interface between freshwater and marine systems, and provide habitats for a diverse suite of species, including shellfish, fish, and birds. We provide baseline values for estuarine mudflats using sediment samples collected at Cowichan-Koksilah Estuary in British Columbia, Canada, a biologically-rich estuary. The estuary also contains a marine shipping terminal, forestry log sort area, and input of contaminants from nearby residential and agricultural areas. Microplastics, both fragments and fibers, occurred in 93% (13/14) of sediment samples. A mean of 6.8 microfibers/kg dw (range: 0–12 microfibers/kg dw) and 7.9 microfragments/kg (range: 0–19 fragments/kg dw) occurred in individual samples, and counts of fibers and fragments were strongly correlated (r = 0.78, p = 0.008, n = 14). The abundance of microplastics tended to be higher on the north side of the estuary that receives greater inputs from upland sources relative to the south side. Size distributions of microplastic fragments and fibers were similar to sediment grain size distribution with size categories 0.063 to 0.25 mm and 0.25 to 0.6 mm being the most common for plastics and sediment, indicating the occurrence of microplastics likely followed existing depositional processes within the estuary. Microplastics in sediments were composed of a variety of polymers, including high density polyethylene (HDPE), Nylon 6/6 (polyhexamethylene adipamide), and polyethylene terephthalate-PETE (poly(1,4-cyclohexylene dimethylene terephthalate)). This study indicates that microplastics occur throughout most of the Cowichan-Koksilah Estuary, and future studies should focus on the exposure risk and potential for bioaccumulation for wildlife species that feed on the surface of intertidal mudflats.
Показать больше [+] Меньше [-]Localized effects of offshore aquaculture on water quality in a tropical sea Полный текст
2021
Dunne, Aislinn | Carvalho, Susana | Morán, Xosé Anxelu G. | Calleja, Maria Ll | Jones, Burton
Localized effects of offshore aquaculture on water quality in a tropical sea Полный текст
2021
Dunne, Aislinn | Carvalho, Susana | Morán, Xosé Anxelu G. | Calleja, Maria Ll | Jones, Burton
Aquaculture production has increased steadily in many tropical countries over the past few decades, although impact assessments have been frequently neglected. We investigated the impacts of an offshore barramundi fish farm on water quality in the southern-central Red Sea, a traditionally understudied tropical, oligotrophic, and semi-enclosed basin. Inorganic nutrients, particulate matter, chlorophyll-a, and heterotrophic bacteria were measured periodically over 8 months around the farm. Water down-current from the farm had, on average, more heterotrophic bacteria and chlorophyll-a than up-current (11% and 34% higher, respectively). Ratios of dissolved inorganic nitrogen:phosphorus down-current from the farm were lower than ratios up-current (mean 9.8 vs 16.0, respectively). Phosphate, inorganic nitrogen, and particulate matter showed patterns of enrichment associated with the farm after a fish feeding event. Strategies such as feed optimization and considering hydrodynamics in site selection may improve water quality for future fish farms in Saudi Arabia and other tropical countries.
Показать больше [+] Меньше [-]Localized effects of offshore aquaculture on water quality in a tropical sea Полный текст
2021
Dunne, Aislinn | Carvalho, Susana | Morán, Xosé Ánxelu Gutiérrez | Calleja, María Ll. | Jones, Burton
Aquaculture production has increased steadily in many tropical countries over the past few decades, although impact assessments have been frequently neglected. We investigated the impacts of an offshore barramundi fish farm on water quality in the southern-central Red Sea, a traditionally understudied tropical, oligotrophic, and semi-enclosed basin. Inorganic nutrients, particulate matter, chlorophyll-a, and heterotrophic bacteria were measured periodically over 8 months around the farm. Water down-current from the farm had, on average, more heterotrophic bacteria and chlorophyll-a than up-current (11% and 34% higher, respectively). Ratios of dissolved inorganic nitrogen:phosphorus down-current from the farm were lower than ratios up-current (mean 9.8 vs 16.0, respectively). Phosphate, inorganic nitrogen, and particulate matter showed patterns of enrichment associated with the farm after a fish feeding event. Strategies such as feed optimization and considering hydrodynamics in site selection may improve water quality for future fish farms in Saudi Arabia and other tropical countries. | SI
Показать больше [+] Меньше [-]Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in Pacific salmon from the Kamchatka Peninsula and Sakhalin Island, Northwest Pacific Полный текст
2021
Donets, Maksim M. | Tsygankov, Vasiliy Yu | Gumovskiy, Alexandr N. | Gumovskaya, Yulia P. | Boyarova, Margarita D. | Busarova, Olesya Yu | Litvinenko, Anna V. | Khristoforova, Nadezhda K.
The purpose of the present study was to determine levels of POPs (dieldrin, endrin, HCH isomers, DDT metabolites, and PCB congeners) in organs of chum (Oncorhynchus keta), pink (O. gorbuscha), sockeye (O. nerka), masu (O. masou), and Chinook salmon (O. tshawytscha), and to identify the patterns of toxicants' distribution in organisms and the environment of the northwestern Pacific. Principal component factor analysis showed that all the salmon species typically exhibit relationships between the PCB congeners and are characterized by a similar pattern of entry of PCBs 101, 118, and 153. The OCPs levels in the organs of Pacific salmon are decreasing from 2012 to 2018, which suggests the elimination of these toxicants from the northwestern Pacific Ocean.
Показать больше [+] Меньше [-]Microparticles and microplastics contamination in African table salts Полный текст
2021
Fadare, Oluniyi O. | Okoffo, Elvis D. | Olasehinde, Emmanuel F.
The presence of micro/plastic particles has been reported in various seafood products. However, information on microplastics contamination in salts from African continent is very limited. This study analysed 23 brands of table salts from 8 African countries for microplastics using microscopic/spectroscopic techniques. South Africa showed the highest microplastics concentration (0–1.33 ± 0.32 particles/kg), Nigeria, Cameroun, and Ghana (0–0.33 ± 0.38 particles/kg each); characterized as polyvinyl acetate, polypropylene, and polyethylene. Other countries have no detectable microplastics at 0.3 μm filter pore size. To our best knowledge, this is the first study to characterize micro-fibres/plastics in table salts across African countries, confirming that it is an emission source of micro-fibres/plastics into the human food chain, highlighting the overarching need to understand their effects on human health.
Показать больше [+] Меньше [-]Spatial and environmental characteristics of colloidal trace Cu in the surface water of the Yellow River Estuary, China Полный текст
2021
Lu, Yuxi | Pan, Dawei | Yang, Tingting | Wang, Chenchen
Dynamic variations in chemical composition and size distribution of dissolved copper (Cu) along the river-sea interface in the Yellow River Estuary (China) were investigated. On average, ~64% and ~8% of bulk dissolved Cu (<0.45 μm) were partitioned in the <1 kDa fraction and 1–100 kDa, respectively. The other 28% were in the 100 kDa–0.45 μm colloids, which indicates that this fraction may dominate the overall morphology of colloidal Cu. The <3 kDa Cu fraction was susceptible to environmental parameters and the >3 kDa fraction was related to the behavior of dissolved organic carbon. 1–100 kDa Cu migrated more violently than >100 kDa Cu and tended to be a stable polymer, with stability increasing towards the sea. The source of <1 kDa Cu was complex and may be supplemented by the decomposition of small molecular colloids and the addition of the sediments or particles ligands.
Показать больше [+] Меньше [-]Variation in polymer types and abundance of microplastics from two rivers and beaches in Adelaide, South Australia Полный текст
2021
Hayes, Anna | Kirkbride, K Paul | Leterme, Sophie C.
Microplastics are a major source of marine pollution and comprise of many recyclable polymers. For this study, we investigated the prevalence of microplastic polymers in an urban and non-urban setting and determined what type of plastic polymers was most common in these areas. This was conducted by extracting sediment and sand samples from 2 rivers and beaches in Adelaide, South Australia. The microplastics were extracted using density separation and were identified using Fourier-transform infrared spectroscopy. We found a significantly higher abundance of microplastics and variety of polymers in the sediment of the Patawalonga creek, compared to the less urbanised environment. Most of the microplastics found in the study were from recyclable products which highlight the lack of recycling practices undertaken by the inhabitants of that area.
Показать больше [+] Меньше [-]A Review of the Use of Psychoacoustic Indicators on Soundscape Studies Полный текст
2021
Engel, Margret Sibylle | Fiebig, André | Pfaffenbach, Carmella | Fels, Janina
This work reviews the literature of 46 peer-reviewed papers and presents the current status on the use of psychoacoustic indicators in soundscape studies. The selection of papers for a systematic review followed the PRISMA method. Afterwards, descriptive analysis and principal component analysis (PCA) were realised. For the PCA, the following parameters extracted from the papers were analysed: psychoacoustic indicator, hypothesis, statistical units, data collection method and major findings for each investigated psychoacoustic indicator. The results show an overview of the use of psychoacoustic indicators, through main hypothesis and findings for each psychoacoustic indicator i.e. the importance of statistical units, such as percentiles, to investigate the hypothesis related to the description of auditory descriptors and perceptual attributes. Another important finding is that many papers lack the specification of computation methods limiting the comparability of study results and impeding the meta-analyses.
Показать больше [+] Меньше [-]The behavioural response of European seabass (Dicentrarchus labrax) to chlorinated seawater effluents Полный текст
2021
Davis, Scott H. | Maxwell, David L. | Spence, Michael A. | Muiruri, Evalyne W. | Sheahan, Dave
Seawater chlorination is widely used for coastal, marine industries for the prevention of fouling. Using a choice chamber system, we investigated the influence of chlorinated seawater at typical concentrations occurring near chlorinated cooling water discharges, on the behaviour of juvenile seabass (Dicentrachus labrax). These studies showed that there was evidence of an effect of chlorination, with models predicting 22% fewer fish present in the chlorine dosed chamber compared to the undosed chamber in all control runs (mean number of fish in the dosed chamber in all control runs was 2.23 in comparison to 1.74 when chlorine was present). These data suggest that when food is available D. labrax will enter areas that are at mean chlorination levels of 0.04 mg l⁻¹, which are typical close to the discharge of power station cooling water but are more likely to move away once the food supply is reduced.
Показать больше [+] Меньше [-]Effects of reclamation methods and habitats on macrobenthic communities and ecological health in estuarine coastal wetlands Полный текст
2021
Huang, Yinying | Li, Yiming | Chen, Qiang | Huang, Yingying | Tian, Jiangtao | Cai, Mingqi | Huang, Youhui | Jiao, Yang | Yang, Ying | Du, Xinglin | Liu, Zhiquan | Zhao, Yunlong
This study compared the community structure of macrobenthos in bare tidal areas and vegetated regions under two reclamation patterns, fully enclosed and opened reclamation, in Yangtze wetland, China. Compared with fully enclosed reclamation areas, opened reclamation areas had higher water salinity, higher number of species and abundance, and less disturbed habitat health status. Compared with bare tidal areas, vegetated regions were more suitable for the survival of macrobenthos and its habitat health status was more stable. Salinity, pH and larger soil particle diameter were positively associated with macrobenthic diversity, while total nitrogen and total phosphorus were negatively associated. Overall, compared with fully enclosed reclamation and vegetated regions, opened reclamation and bare tidal areas had less negative effects upon macrobenthic community and habitat health. Opened reclamation is preferred for wetland reclamation, and planting indigenous plants and releasing species adapted to fresh water is beneficial to the restoration of macrobenthic communities.
Показать больше [+] Меньше [-]