خيارات البحث
النتائج 2291 - 2300 من 6,535
Anthropoquinas: First description of plastics and other man-made materials in recently formed coastal sedimentary rocks in the southern hemisphere
2020
Fernandino, Gerson | Elliff, Carla I. | Francischini, Heitor | Dentzien-Dias, Paula
Plastic, as a “flagship species”, represents how deeply humans impact the environment. Although scarce, the presence of plastic and other anthropogenic materials in rocks has already been reported in the literature, however, so far, not in the Southern Hemisphere. Thus, the objective of the present study was to report and describe samples of sedimentary rocks containing anthropogenic items cemented with biogenic and siliciclastic material – anthropoquinas – and to discuss implications to the establishment of the Anthropocene and geodiversity conservation. Six samples of anthropoquinas were evaluated, presenting different technofossils (metal bottle caps, ship nail, plastic earring and plastic fragment) and composition (lithic and biogenic fragments). Energy Dispersive X-ray Spectroscopy was conducted on two samples, reflecting differences regarding their genesis. The description of these rocks is concerning and reflects how deeply human behavior influences various natural compartments. Therefore, studies on the effects of marine litter on geodiversity are strongly encouraged.
اظهر المزيد [+] اقل [-]Understanding the effects of coastal defence structures on marine biota: The role of substrate composition and roughness in structuring sessile, macro- and meiofaunal communities
2020
Sedano, F. | Navarro-Barranco, C. | Guerra-García, J.M. | Espinosa, F.
The increasing deployment of artificial structures into the marine environment is creating new hard substrates that differ from natural ones in physical and biological aspects. However, studies of macrofaunal and meiofaunal communities associated with artificial structures are very limited. Seawalls, cubes, acropods and rip-raps in Algeciras Bay (southern Spain) were each compared with the nearest natural hard substrate and their community structure was related to substrate roughness, composition, carbonates content, crystallinity and age, using db-RDA. The results showed clear differences between substrates for the three community levels (sessile, macro- and meiofauna). Overall, rip-raps were the most similar to natural substrates. Under similar environmental conditions, substrate roughness, composition (only for sessile) and age of the structures seemed to play important roles in structuring those communities. They especially affected the sessile community, initiating strong cascading effects that were detectable at high taxonomic level in the associated fauna.
اظهر المزيد [+] اقل [-]Spatio-temporal distribution of plastic and microplastic debris in the surface water of the Bohai Sea, China
2020
Zhang, Weiwei | Zhang, Shoufeng | Zhao, Qian | Qu, Ling | Ma, Deyi | Wang, Juying
As an emerging marine environmental issue, marine plastic debris pollution has attracted worldwide attention. Studies have covered more and more areas of the world's oceans. To further understand the sources and variation of marine plastic debris in the surface water of the Bohai Sea, in this study, plastic debris was collected during the four seasons of 2016–2017. The results showed the mean density of plastic debris over these seasons was 0.49 ± 0.18 particles/m³. Macro-, meso-, and micro- plastics accounted for 5%, 26%, and 69% of the total number of plastic debris, respectively. The density of the microplastics was 0.35 ± 0.13 particles/m³. The highest density was found in spring, followed by summer and winter, and the lowest in autumn. High distribution densities were observed in the Liaodong Bay and the Bohai Strait, which were attributed to the dynamics of the rim current, terrain, and fishery activities.Riverine input, dynamics of the rim current, terrain, and fishery activities contribute to the variations in marine plastic debris in the surface water of the Bohai Sea.
اظهر المزيد [+] اقل [-]Leisure craft sacrificial anodes as a source of zinc and cadmium to saline waters
2020
Rees, Aldous B. | Gallagher, Anthony | Wright, Laurance A. | Wood, Jonathan | Cathery, Timothy | Harrison, Bradley | Down, Chloe | Comber, Sean
Sacrificial anodes are attached to the hulls of boats and marine structures to prevent corrosion. Their use inevitably leads to release of zinc as well as impurities in the zinc alloy such as cadmium to the saline environment. Risk assessments and source apportionment exercises require accurate assessments of the potential loads of chemicals into the environment. This research has surveyed a wide variety of zinc anodes for their composition to compare against a reported industry standard as well as using differing methodologies to determine the dissolution rate of zinc and cadmium from anodes. A zinc dissolution rate of 477 g/yr/kg of anode is proposed. Although most anodes tested had concentrations of cadmium within the prescribed limits set by the reported standard, calculated leaching rates from laboratory dissolution experiments suggested as much as 400 g per year of cadmium could leach from zinc anodes used on leisure vessels within UK waters.
اظهر المزيد [+] اقل [-]Predator prey interactions between predatory gastropod Reishia clavigera, barnacle Amphibalanusamphitriteamphitrite and mussel Brachidontesvariabilis under ocean acidification
2020
Li, F. | Mu, F.-H. | Liu, X.-S. | Xu, X. Y. | Cheung, S.G.
Since the response to ocean acidification is species specific, differences in responses between predator and prey will alter their interactions, hence affect the population dynamics of both species. Changes in predator prey interactions between a predatory muricid gastropod Reishia clavigera and its prey, the barnacle Amphibalanus amphitrite amphitrite and mussel Brachidontes variabilis under three pCO₂ levels (380, 950, and 1250 μatm) were investigated. The searching time for barnacles increased and the ability to locate them decreased at higher pCO₂ levels. The movement speed and the prey consumption rate, however, were independent of pCO₂. There was no preference towards either B. variabilis or A. amphitrite amphitrite regardless of pCO₂. Exposure experiments involving multiple generations are suggested to assess transgenerational effects of ocean acidification and the potential compensation responses before any realistic predictions on the long term changes of population dynamics of the interacting species can be made.
اظهر المزيد [+] اقل [-]Estimation of Internal Loading of Phosphorus in Freshwater Wetlands
2020
Pant, Hari K.
PURPOSE OF THE REVIEW: Freshwater wetlands are found in various climatic zones ranging from tropics to tundra, and their roles from groundwater recharge and flood control to water quality management and biodiversity protection are well recognized. Phosphorus (P) is a limiting nutrient for algal growth in freshwater systems, including wetlands. Various physico-chemical and biological characteristics of wetlands regulate cycles of nutrients such as P. Thus, estimating internal loading of P in wetlands would be crucial in the formulation of effective P management strategies in the wetland systems. This review and limnological data presented may offer needed knowledge/evidence for the effective control of P inputs in wetlands and provide insights on possible ways for interventions in controlling eutrophication and saving the ecosystem from collapse. RECENT FINDINGS: Various ways of P losses such as agriculture, urbanization, etc., to the water bodies have severely impacted water quality of wetlands by altering physical and chemical nature of the P compounds and release bound P to the water columns. Studies indicate that P sorption–desorption dynamic, mineralization, and enzymatic hydrolysis of P in freshwater wetlands’ soils/sediments are crucial in causing internal loading or sink of P in wetland systems. Thus, extensive studies on abovementioned arenas are crucial to restore natural freshwater wetlands or to increase the efficiency of constructed wetlands in retaining P. In general, researchers have elucidated significant amounts of limnological data to understand eutrophication processes in freshwater wetlands; however, studies on the interactions of P stability and hydro-climatic changes are not well understood. Such changes could significantly influence localized limnology/microenvironments and exacerbate internal P loading in freshwater wetlands; thus, studies in such direction deserve the attention of scientific communities.
اظهر المزيد [+] اقل [-]Letter to the editor regarding the article “Taking advantage of seagrass recovery potential to develop novel and effective meadow rehabilitation methods” by Alagna et al., published in Marine Pollution Bulletin, 149: 2019 (110578)
2020
Alagna et al. (2019) suggest new transplantation methods for Posidonia oceanica (Linnaeus) Delile, inspired by its natural recovery process after disturbance due to dredging operations for gas-pipelines. They observe that P. oceanica vegetative fragments naturally settled only on loose calcareous stones deployed to fill the trenches of the gas-pipeline. No recovery was noted on dead matte, sand and large calcarenitic boulders. Following a new pilot restoration project currently ongoing in the same area, we demonstrate that natural recovery also occurs on dead matte. After examining other alternative transplantation methods for P. oceanica, the Authors suggest using their “habitat enhancement units” method for the restoration of seagrasses, not only on rocky bottom but also on sand and other bare substrate requiring general environmental restoration. Here we express disagreement on certain issues reported in the paper.
اظهر المزيد [+] اقل [-]Production, characterization, evaluation and toxicity assessment of a Bacillus cereus UCP 1615 biosurfactant for marine oil spills bioremediation
2020
Durval, Italo José B. | Mendonça, Ana Helena R. | Rocha, Igor V. | Luna, Juliana M. | Rufino, Raquel D. | Converti, A. | Sarubbo, L.A.
In this study, Bacillus cereus was cultivated in a mineral medium composed of 2% frying oil and 0.12% peptone to produce a biosurfactant. The production was scaled up from flasks to 1.2-, 3.0- and 50-L bioreactors, where surface tension achieved 28.7, 27.5 and 32 mN/m and biosurfactant concentration 4.3, 4.6 and 4.7 g/L, respectively. The biosurfactant was characterized as anionic, while nuclear magnetic resonance, thin-layer chromatography and gas chromatography analyses revealed its lipopeptide nature. Toxicity tests showed survival rates of the fish Poecilia vivipara and the bivalve Anomalocardia brasiliana higher than 90% and 55%, respectively, thus suggesting the use of this biosurfactant in marine environment depollution. Moreover, the biosurfactant stimulated the growth of autochthonous microorganisms independently of the presence of motor oil in bioassays performed in seawater. These results demonstrate that the biosurfactant is biocompatible and has potential for industrial-scale production and application to bioremediation of oil spills-polluted marine environment.
اظهر المزيد [+] اقل [-]Phytoplankton biomarkers in surface sediments from Liaodong Bay and their potential as indicators of primary productivity
2020
Xiong, Wei | Mei, Xi | Meng, Xiangjun | Chen, Huijun | Yang, Hao
This paper reported the distribution of phytoplankton biomarkers in surface sediments of Liaodong Bay, Bohai Sea. The primary productivity indicated by biomarkers is consistent with the results from modern water column phytoplankton surveys, indicating that the biomarkers can be used to reconstruct the primary productivity. The productivity in the bay mouth is higher than in the shallow coast area, indicating that the main controlling factor is the turbidity rather than terrestrial nutrients. The high primary productivity near Juhua Island is mainly related to eutrophication caused by human culture and land-based sewage discharge. The relative proportion of biomarkers showed that diatom and dinoflagellate contributed more to the coastal area and were mainly related to the competitive advantage under the condition of high nutrient salts, while a high proportion of haptophytes was found in the middle, which corresponded to the high salinity water.
اظهر المزيد [+] اقل [-]Using citizen science to investigate the spatial-temporal distribution of floating marine litter in the waters around Taiwan
2020
Chiu, Ching-Chun | Liao, Chun-Pei | Kuo, Ting-Chun | Huang, Hsiang-Wen
Marine litter is currently one of the most widespread pollutants. However, monitoring the spatial-temporal changes of floating marine litter remains challenging. In this study, with data collected by citizen scientists, we investigated the distribution and density of floating marine litter in the waters around Taiwan. With 40 volunteers surveying 978 transects in 410 cruises from December 2017 to December 2018, the overall survey area was approximately 121.26 km² (5455 km in length). We found that the mean density of floating marine litter was 90.10 ± 8.60 items/km² and that the majority was plastic (63.2%). Nearly 70% of the litter was found in 30% of the surveyed area. We also identified hotspots of floating marine litter, which are at the Northwestern and Southeastern regions of Taiwan. Our study highlights the contribution of citizen science to monitor floating marine litter and provides insight into the management of marine litter.
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