خيارات البحث
النتائج 2411 - 2420 من 8,010
Identifying microplastic litter with Laser Induced Breakdown Spectroscopy: A first approach النص الكامل
2021
Sommer, C. | Schneider, L.M. | Nguyen, J. | Prume, J.A. | Lautze, K. | Koch, M.
The broad diversity of microplastic litter requires a selection of analytical techniques to reliably determine the particle's chemical composition. This study demonstrates that Laser Induced Breakdown Spectroscopy (LIBS) can identify microplastic particles based on their spectral fingerprints. By studying the spectral features of polymer reference spectra, microplastic litter can be distinguished from non-plastic materials. The results show that LIBS can be used as a fast in-situ technique for pre-characterization of the microparticle's material and is a possible tool for environmental studies on microplastics.
اظهر المزيد [+] اقل [-]Soil eutrophication in seabird colonies affects cell wall composition: Implications for the conservation of rare plant species النص الكامل
2021
Otero, X.L. | Fernández-Balado, C. | Ferreira, T.O. | Pérez-Alberti, A. | Revilla, G.
Seabird colonies exert a strong influence on coastal ecosystems, increasing soil nitrogen bioavailability and modifying plant communities. Previous studies have evidenced that increased N in soils leads to changes in plant cell wall composition; however, this effect has not been assessed in seabird colonies. The main objective of this study was to determine the influence of seabird colonies on nitrogen, cellulose and lignin content in cell walls. For this purpose, analyses were performed on droppings, soils and three native plant species (Armeria pubigera, Armeria pungens and Corema album) growing in yellow-legged gull colonies. The results showed that N excreted by yellow-legged gull is assimilated by plants, increases N content in plant tissues and reduces cellulose and lignin synthesis, therefore potentially altering plant resistance against phytoparasites.
اظهر المزيد [+] اقل [-]Analysis of persistent organochlorine pesticides in shellfish and their risk assessment from aquafarms in Taiwan النص الكامل
2021
Wang, Jiann-Hsiung | Chang, Chung-Pei | Chang, Chia-Chia | Wang, Zhaomin | Lin, Chuen-Fu | Lin, Jen-Wei | Lin, Wei-Li | Liao, Huei-Jyuan | Kao, Chen-Yung | Fan, Pei-Shan | Yang, Wei-Cheng | Chang, Geng-Ruei
In Taiwan, freshwater clams (Corbicula fluminea) and hard clams (Meretrix lusoria) are the most frequently raised shellfish in land-based pond aquaculture, but research on the accumulation of organochlorine pesticides (OCPs) in these shellfish is limited. We detected the levels of 14 OCPs in 62 shellfish from Taiwanese aquafarms by performing gas chromatography–tandem mass spectrometry. OCP residues were detected in 4.84% of the samples including readings of 0.04 mg/kg chlordane (in a freshwater clam), 0.03 mg/g p,p′-DDE (in a freshwater clam), and 0.02 mg/g p,p′-DDE (in a hard clam). However, the associated estimated daily intake values were less than the acceptable daily intake levels of chlordane and p,p′-DDE Therefore, the consumption of these shellfish presents no immediate health risks. Our findings contribute to food safety and serve as a reference for OCP screenings for aquatic shellfish.
اظهر المزيد [+] اقل [-]Filling in the knowledge gap: Observing MacroPlastic litter in South Africa's rivers النص الكامل
2021
Moss, Kerry | Allen, Deonie | González-Fernández, Daniel | Allen, Steve
Only 12% of the world's published plastic research includes references to Africa despite it being a significant contributor to the global plastic waste and mismanagement problem (~88.5% of Africa's plastic waste is mismanaged). Ocean plastics are transported from land by rivers to the sea. However, source contextualization is complex. Many African rivers predominantly run alongside human settlements that host informal waste dumpsites. In this study a simple cost effective, easily deployed, consistent and replicable survey methodology was employed. The study quantified macroplastic in three rivers discharging into Algoa Bay, South Africa. The results indicated that industrial Swartkops and metropolitan Baakens Rivers both illustrate moderate plastic pollution (>3000 plastic particles/day), with the relatively natural Sundays River to showing minimal evidence of river macro plastic (<100 plastic particles/day). The types of plastic were noted using the RIMMEL app (premier African implementation), enabling proportional comparison of different plastic litter types to be completed.
اظهر المزيد [+] اقل [-]Seasonal variations, potential bioavailability, and ecological risk of phosphorus species in the coastal sediments of the Makran النص الكامل
2021
Kor, Kamalodin | Ershadifar, Hamid | Ghazilou, Amir | Koochaknejad, Emad
Eutrophication and algal blooms occur frequently in coastal waters of the Makran, for which phosphorus is an important driving factor. Therefore, in this study, sequential extraction procedure was used to evaluate abundance of five phosphorus chemical species. Total phosphorus (TP) concentration ranged from 672.3 to 2031.9 μg/g in pre-monsoon and 771.7 to 2095.7 μg/g in post-monsoon. More than 87% of TP was inorganic P and contribution of organic phosphorus was low. Potential bioavailable P (PBAP) comprised of 52.1 and 35.5% of TP in the pre and post-monsoon, respectively. Average phosphorus pollution index was higher than one in all stations and seasons, implying that sediments in the study area are polluted by phosphorus and are under eutrophication risk. Thus, in the future, foregoing information will be important for assessment of phosphorus loading and pollution in the Makran.
اظهر المزيد [+] اقل [-]A new paradigm for estimating the prevalence of plastic litter in the marine environment النص الكامل
2021
Kylili, Kyriaki | Artusi, Alessandro | Hadjistassou, Constantinos
The intelligent method proposed herein is formulated on a deep learning technique which can identify, localise and map the shape of plastic debris in the marine environment. Utilising images depicting plastic litter from six beaches in Cyprus, the developed tool pointed to a plastic litter density of 0.035 items/m². Extrapolated to the entire shorelines of the island, the intelligent approach estimated about 66,000 plastic articles weighting a total of ≈1000 kg. Besides deducing the plastic litter density, the dimensions of all documented plastic litter were determined with the aid of the OpenCV Contours image processing tool. Results revealed that the dominant object length ranged between 10 and 30 cm which is in agreement with the length of common plastic litter often spoiling these coastlines. Concluding, only in-situ visual scan sample surveys and no manual collection means were used to predict the density and the dimensions of the plastic litter.
اظهر المزيد [+] اقل [-]Coastline in-situ burning of oil spills in the Arctic. Studies of the environmental impacts on the littoral zone community النص الكامل
2021
Wegeberg, Susse | Fritt-Rasmussen, Janne | Geertz-Hansen, Ole | Wiktor, Jozef | Bogø-Wilms, Lonnie | Larsen, Morten Birch | Renvald, Lars | Gustavson, Kim
In-situ burning (ISB) has been an oil combat technique studied since the 1950s. However, burning of the oil on the sea surface along the coastline, coastline ISB (cISB), is novel and was tested for the first time in the Arctic along a rocky coast in the summer 2017. A light crude oil was burned and effects of the cISB operation on the littoral zone communities investigated. The impact on macroalgal vegetation and associated fauna was analysed in three littoral zone levels. The analyses revealed limited effects on the littoral community, and that variation between sample plots and years in macroalgal biomass and coverage, as well as fauna biomass and abundance was higher than the impact from cISB. Therefore, it is concluded that cISB in the Arctic along a rocky shore may be an oil spill response option with relatively low environmental side effects for the specific oil type used.
اظهر المزيد [+] اقل [-]Heavy metal concentration in reef-associated surface sediments, Hare Island, Gulf of Mannar Marine Biosphere Reserve (southeast coast of India): The first report on pollution load and biological hazard assessment using geochemical normalization factors and hazard indices النص الكامل
2021
Arisekar, Ulaganathan | Shakila, Robinson Jeya | Shalini, Rajendren | Sivaraman, Balasubramanium | Jeyasekaran, Geevartnam | Asha Hema Malini, Narayanan
In this study, reef-associated surface sediment samples were collected from Hare Island in the Gulf of Mannar Marine Biosphere Reserve, Bay of Bengal and analyzed for heavy metal concentration. The sediment quality was evaluated based on the geochemical, biological, and ecological hazard indices. The mean concentration of heavy metals in the sediments ranged from 0.02 (Cd) to 26,262.87 mg/kg (Fe). Except for Cd and Hg, all other elements were found to be below the sediment quality guidelines and contamination level. The biological and ecological hazard (BEHI) revealed that most sediment samples (80%) fell under the low-risk category with 9% probability of toxicity to the marine flora and fauna. The overall contamination level of heavy metals in Hare Island suggested that the sediment could be grouped under low-risk category. Hence, this study recommends the need for a routine monitoring program in this region to maintain a clean and sustainable ecosystem in future.
اظهر المزيد [+] اقل [-]Influence of anthropogenic activities on the spatial distribution of heterotrophic, indicator and pathogenic bacteria around Andaman and Nicobar Islands النص الكامل
2021
Srinivas, T.N.R. | Sudharani, P. | Behera, Swarnaprava | Dutta, S. | Sampath Kumar, G. | Sathibabu, Y. | Geethika, G. | Swagata, C. | Pratim Kandar, P.
To examine the influence of anthropogenic activities on the marine ecosystem around the Andaman and Nicobar Islands, a study was conducted to investigate the abundance of heterotrophic, indicator and pathogenic bacteria during the monsoon season. We noticed the higher abundance of heterotrophic, indicator (Escherichia coli and Enterococcus faecalis) and pathogenic bacterial counts (Aeromonas hydrophila, Enterobacter aerogens, Escherichia coli strain O157:H7, Shigella dysenteriae and Vibrio parahaemolyticus) near the 10ᵒ channel, which is the principal route to reach Andaman mainland. Most of the stations are offshore (chosen to cover shipping tracks) at a distance ranging from 41 to 266 km from the coast. The nearest station to the coast was at 21 km away. Apart from those mentioned above, several other pathogenic bacteria were also detected such as Klebsiella pneumoniae, Salmonella paratyphi, Vibrio cholera and Vibrio vulnificus but they are sparsely detected at few stations only.
اظهر المزيد [+] اقل [-]Temporal evolution of imposex and butyltin contamination in Gemophos viverratus from São Vicente (Cabo Verde) - a countercurrent trend on the world scenario النص الكامل
2021
Gomes, Diana M. | Galante-Oliveira, Susana | Almeida, Corrine | Abreu, Fiamma E.L. | Castro, Ítalo Braga | Fillmann, Gilberto | Barroso, Carlos M.
Organotin (OT) based Antifouling Systems (AFS) were globally banned by the AFS Convention since 2008, but the Republic of Cabo Verde did not ratify this Convention, nor did it develop a national legislation to control OT-AFS. Gemophos viverratus imposex and butyltin tissue contamination were assessed around the São Vicente Island (Cabo Verde) in 2019 and compared with the data available from 2012. The vas deferens sequence index (VDSI), the relative penis length (RPL), the percentage of females with imposex (%I) and the percentage of sterilized females (%S) in 2019 ranged from 0 to 4.0, 0–84.4%, 0–100% and 0–5.1%, respectively, whilst TBT reached maximum values of ≈30 ng TBT-Sn g⁻¹ dw in the whelk tissues. These values are very similar to those registered in 2012, which indicates that TBT pollution has not decreased over the years, in contrast to the declining trend observed worldwide.
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