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Boundary layers between different environmental compartments represent critical interfaces for biological, chemical and physical processes. The sea-surface microlayer (uppermost 1-1000 microm layer) forms the boundary layer interface between the atmosphere and ocean. Environmental processes are controlled by the SML, and it is known to play a key role in the global distribution of anthropogenic pollutants. Due to its unique chemical composition, the upper organic film of the SML represents both a sink and a source for a range of pollutants including chlorinated hydrocarbons, organotin compounds, petroleum hydrocarbons, polycyclic aromatic hydrocarbons (PAH) and heavy metals. These pollutants can be enriched in the SML by up to 500 times relative to concentrations occurring in the underlying bulk water column. The SML is also a unique ecosystem, serving as an important habitat for fish eggs and larvae. Concentration ranges and enrichment factors of pollutants in the SML in different areas of the world's oceans have been critically reviewed, together with available toxicity data for marine biota found within the SML. Overall, the SML is highly contaminated in many urban and industrialized areas of the world, resulting in severe ecotoxicological impacts. Such impacts may lead to drastic effects on the marine food web and to fishery recruitment in coastal waters. Studies of the toxicity of fish eggs and larvae exposed to the SML contaminants have shown that the SML in polluted areas leads to significantly higher rates of mortality and abnormality of fish embryos and larvae. 相似文献
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Microplastics have been recently identified as marine pollutants of significant concern due to their persistence, ubiquity and potential to act as vectors for the transfer and exposure of persistent organic pollutants to marine organisms. This study documents, for the first time, the presence and abundance of microplastics (>1.6 microm) in Singapore's coastal environment. An optimized sampling protocol for the collection and analysis of microplastics was developed, and beach sediments and seawater (surface microlayer and subsurface layer) samples were collected from nine different locations around the coastline. Low density microplastics were separated from sediments by flotation and polymer types were identified using Fourier transform infrared (FTIR) spectrometry. Synthetic polymer microplastics identified in beach sediments included polyethylene, polypropylene, polystyrene, nylon, polyvinyl alcohol and acrylonitrile butadiene styrene. Microplastics were detected in samples from four out of seven beach environments, with the greatest quantity found in sediments from two popular beaches in the eastern part of Singapore. Polyethylene, polypropylene and polystyrene microplastics were also found in the surface microlayer (50-60 microm) and subsurface layer (1m) of coastal waters. The presence of microplastics in sediments and seawater is likely due to on-going waste disposal practices from industries and recreational activities, and discharge from shipping. 相似文献
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Use of slow-release fertilizer and biopolymers for stimulating hydrocarbon biodegradation in oil-contaminated beach sediments 总被引：4，自引：0，他引：4
Nutrient concentration and hydrocarbon bioavailability are key factors affecting biodegradation rates of oil in contaminated beach sediments. The effect of a slow-release fertilizer, Osmocote, as well as two biopolymers, chitin and chitosan, on the bioremediation of oil-spiked beach sediments was investigated using an open irrigation system over a 56-day period under laboratory conditions. Osmocote was effective in sustaining a high level of nutrients in leached sediments, as well as elevated levels of microbial activity and rates of hydrocarbon biodegradation. Chitin was more biodegradable than chitosan and gradually released nitrogen into the sediment. The addition of chitin or chitosan to the Osmocote amended sediments enhanced biodegradation rates of the alkanes relative to the presence of Osmocote alone, where chitosan was more effective than chitin due to its greater oil sorption capacity. Furthermore, chitosan significantly enhanced the biodegradation rates of all target polycyclic aromatic hydrocarbons. 相似文献
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In this paper, we use a scanning electron microscope (SEM) coupled with X‐ray spectroscopy and electron back‐scattered diffraction patterns to examine firn in cores retrieved by the United States International Trans‐Antarctic Scientific Expedition. From grain boundary grooves we were able to see where the previously existing snow crystals were joined, and can determine grain sizes. From the SEM images, the porosity and the surface area per unit volume of the pores were measured. Finally, we have shown that we can determine the microchemistry of impurities in firn and demonstrated that we can determine the orientations of the firn crystals. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Heavy metal contamination in mangrove habitats of Singapore 总被引：1，自引：0，他引：1
Cuong DT Bayen S Wurl O Subramanian K Wong KK Sivasothi N Obbard JP 《Marine pollution bulletin》2005,50(12):1732-1738
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Chlorinated pesticides and PCBs in the sea-surface microlayer and seawater samples of Singapore 总被引：1，自引：0，他引：1
Sea-surface microlayer (SML) and seawater samples collected from Singapore's coastal marine environment were analyzed for selected chlorinated pesticides and polychlorinated biphenyls (PCBs). The SML is a potential site of enrichment of persistent organic pollutants (POPs) compared to the underlying water column. The concentration ranges of SigmaHCH, SigmaDDT and SigmaPCB in subsurface (1 m depth) seawater were 0.4-27.2 ng/l (mean 4.0 ng/l), 0.01-0.6 ng/l (mean 0.1 ng/l) and 0.05-1.8 ng/l (mean 0.5 ng/l) respectively. In the SML, the concentration ranges of SigmaHCH, SigmaDDT and SigmaPCB were 0.6-64.6 ng/l (mean 9.9 ng/l), 0.01-0.7 ng/l (mean 0.2 ng/l) and 0.07-12.4 ng/l (mean 1.3 ng/l) respectively. High spatial and temporal distribution was observed for all POPs measured. However, overall levels measured in the SML were lower than levels reported in the literature for SML samples from temperate coastal regions-possibly due to loss of semi-volatile compounds in the tropical climate of Singapore. Atmospheric wet deposition during the monsoon season may be an important source of POPs to the SML. This study provides the first scientific data on POP concentrations and enrichment factors in the SML for Southeast Asia. 相似文献
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Atmospheric wet deposition of PAHs to the sea-surface microlayer 总被引：1，自引：1，他引：0
Sea-surface microlayer (SML) and subsurface seawater samples (SSW) collected from Singapore's coastal environment were analyzed for 14 polycyclic aromatic hydrocarbons (PAHs) in the dissolved (DP) and suspended particulate phase (SPM). Samples were collected prior to and after rainfall events to ascertain the contribution of wet atmospheric deposition of PAH enrichment to the SML. The concentration ranges of summation operatorPAHs in the SML before rain and after wet deposition were 2.6-46.2 ngL(-1) and 4.3-278.0 ngL(-1), respectively, for the DP and 3.8-31.4 ngL(-1) and 12.8-1280 ngL(-1), respectively, for the SPM. Load factors (i.e. concentration after wet deposition relative to before wet deposition) of the atmospheric wet deposition for DP and SPM ranged from 1.4 to 42.9 and 1.2 to 337, respectively. This study provides the first data on PAH concentration, enrichment (i.e. concentration of PAHs in SML relative to subsurface water) and load factors in the SML before and after wet deposition to the ocean surface. 相似文献
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A 95-day field trial on the bioremediation of oil in beach sediment using Osmocote and chitosan was conducted on an inter-tidal foreshore in Singapore. Osmocote was the key factor in enhancing nutrient levels in sediments, the metabolic activity of the indigenous microbial biomass, and the biodegradation of aliphatics and polycyclic aromatic hydrocarbons (PAHs) with ring number of 2 and 3. In contrast, chitosan did not enhance these parameters in the presence of Osmocote. However, the addition of chitosan to Osmocote amended sediments significantly enhanced biodegradation of recalcitrant 4–6-ring PAHs. This is most likely due to the high oil adsorbancy capacity of chitosan, which enhances the bioavailability of high ring number PAHs to the microbial biomass. 相似文献
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Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured in the dissolved and suspended particulate phase in the sea-surface microlayer (SML) and subsurface water (SSW) collected from Hong Kong's coastal environment. The concentration ranges (pg/L) for summation sigmaHCHs, summation sigmaDDTs and summation sigmaPCBs in the SSW dissolved phase (DP i.e. sum of truly dissolved and colloidal phase) were 409-940 (mean 602), 774-5583 (mean 1908) and 266-433 (mean 278), respectively. The concentration ranges (pg/L) for summation sigmaHCHs, summation sigmaDDTs and summation sigmaPCBs in SSW suspended particulate matter (SPM) were <5-85 (mean 59), 358-1369 (mean 787) and 85.6-273 (mean 172), respectively. The enrichment factor of PCBs and OCPs in the SML varied between 1.1 and 4.5 for the DP, and 0.4-8.2 for the SPM. The distribution of contaminants between DP and SPM in both the SML and SSW indicates that particulate matter plays an important role in the distribution and fate of DDTs and PCBs, but not for HCH isomers. The Pearl River Estuary is likely to be a major source of contaminants transported to Hong Kong. 相似文献
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