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1.
The effect of the water soluble oil dispersant Corexit 9527 was tested on larvae from several species of sea urchins and marine fishes. Severe effects in fertilization and development were registered often resulting in pathological larvae and rapid cytolysis. The combination of Corexit 9527 with oil was found to be even more dangerous to the embryo than Corexit or oil alone.  相似文献   

2.
This work investigated effects of three model oil dispersants (Corexit EC9527A, Corexit EC9500A and SPC1000) on settling of fine sediment particles and particle-facilitated distribution and transport of oil components in sediment-seawater systems. All three dispersants enhanced settling of sediment particles. The nonionic surfactants (Tween 80 and Tween 85) play key roles in promoting particle aggregation. Yet, the effects varied with environmental factors (pH, salinity, DOM, and temperature). Strongest dispersant effect was observed at neutral or alkaline pH and in salinity range of 0–3.5 wt%. The presence of water accommodated oil and dispersed oil accelerated settling of the particles. Total petroleum hydrocarbons in the sediment phase were increased from 6.9% to 90.1% in the presence of Corexit EC9527A, and from 11.4% to 86.7% for PAHs. The information is useful for understanding roles of oil dispersants in formation of oil-sediment aggregates and in sediment-facilitated transport of oil and PAHs in marine eco-systems.  相似文献   

3.
There continues to be reluctance in some jurisdictions to use chemical dispersants as a viable countermeasure for accidental oil spills. One argument used by some opponents to dispersant use is that “chemical dispersants do not work effectively in cold water”. To address this issue, the U.S. Minerals Management Service (MMS) funded and conducted two series of large-scale dispersant experiments in very cold water at Ohmsett - The National Oil Spill Response Test Facility, located in Leonardo, New Jersey in February-March 2006 and January-March 2007. Alaska North Slope, Endicott, Northstar and Pt. McIntyre crude oils and Corexit 9500 and Corexit 9527 dispersants were used in the two test series. The crude oils were tested both when fresh and after weathering. Results demonstrated that both Corexit 9500 and Corexit 9527 dispersants were 85-99% effective in dispersing the fresh and weathered crude oils tested at cold temperatures. The MMS expects that results from these test series will assist government regulators and responders in making science based decisions on the use of dispersants as a response tool for oil spills in the Arctic.  相似文献   

4.
The effects of three hydrocarbon dispersant agents (Corexit 9527, Hydrogamosol LT and OSR LT 126) on the bacterial flora of the marine environment are analysed in 20-square-metre basins filled with lagoon seawater.Four months after the first treatment, oil slicks were no longer visible, whereas the appearance of the untreated reference slick had hardly changed. The treatment of 10-litre crude-oil slicks causes an appreciable and long lasting increase in the bacterial population.  相似文献   

5.
Over a three-year period (1995–1998), we studied short-term effects of dispersant use and a bioremediation strategy in two consecutive field trials in sub-tropical Australian mangroves. In each case, weathered oil was applied, and a large spill simulated, in mature Rhizophora stylosa trees around 4–9 m tall. In the first trial, we used Gippsland light crude oil with or without dispersant, Corexit 9527. In the second, a bioremediation strategy followed application of Gippsland oil or Bunker C fuel oil. Bioremediation involved forced aeration with supplemental application of nutrients. Dispersant use had an overall positive benefit shown as reduced tree mortality. By contrast, there was no apparent reduction in mortality of trees with bioremediation. However, one year after oiling, leaf densities of surviving trees were greater in bioremediation plots than in controls, and less in oil-only plots. These and other results have been incorporated into spill response management strategies in Australia.  相似文献   

6.
The toxic effects of crude oil, the dispersant, Corexit 7664, and mixtures of these on the respiration and mortality of two species of bivalve have been examined. A light Arabian crude is most toxic to one, Corexit is most toxic to the other. The susceptibility to oil of the mussel Brachidontes is also reflected in a significant depression of respiration rate at sub-lethal concentrations.  相似文献   

7.
Accidental oil spills from ships or rigs and inputs of effluent such as production formation water (PFW) are key perceived threats to tropical biota from industry activities. Scleractinian corals are an important functional component of tropical reefs and the abundance, diversity and resilience of coral communities can be used as an indicator of ecosystem health. In this paper, we report the effects of petroleum products, including water accommodated fractions (WAF) of crude oil, PFW and dispersant (Corexit 9527), on fertilization and larval metamorphosis of the widespread scleractinian coral, Acropora millepora (Ehrenberg, 1834) in laboratory-based assays. At 20% v/v PFW fertilization was inhibited by 25%. This concentration was equivalent 0.0721 mg l−1 total hydrocarbon (THC). In contrast, larval metamorphosis was more sensitive to this effluent, with 98% metamorphosis inhibited at the same concentration. Crude oil WAF did not inhibit fertilization of gametes until dispersant was introduced. Dispersed oil was slightly more toxic to fertilization than dispersant alone, suggesting toxicity to that event may be additive. The minimum concentration of dispersed oil which inhibited fertilization was 0.0325 mg l−1 THC. Larval metamorphosis was more sensitive than fertilization to crude oil. Although crude oil and dispersant inhibited larval metamorphosis individually, this toxicity was magnified when larvae were exposed to combinations of both. Crude oil inhibited metamorphosis at 0.0824 mg l−1 THC and at 0.0325 mg l−1 THC when dispersed in 10% v/v (dispersant/oil). Management of petroleum-related risks to spawning corals should consider not only the occurrence of the annual coral spawning event, but also the subsequent 1–3-week period during which most larval metamorphosis and recruitment occur.  相似文献   

8.
Excitation-emission matrix spectroscopy (EEMS) was used to characterize the ultra violet fluorescence fingerprints of eight crude oils (with a 14,470-fold range of dynamic viscosity) in seawater. When the chemical dispersant Corexit 9500 was mixed with the oils prior to their dispersion in seawater, the fingerprints of each oil changed primarily as an increase in fluorescence over an emission band centered on 445 nm. In order to simplify the wealth of information available in the excitation-emission matrix spectra (EEMs), two ratios were calculated. A 66-90% decrease in the slope ratio was observed with the addition of Corexit. When the slope ratios were reduced in complexity to intensity ratios, similar trends were apparent. As a result either of the ratios could be used as a simple and rapid means of identifying and monitoring chemically dispersed oil in the open ocean.  相似文献   

9.
The effectiveness of chemical dispersants (Corexit 9500 and SPC 1000) on heavy fuel oil (IFO180 as test oil) has been evaluated under different wave conditions in a flow-through wave tank. The dispersant effectiveness was determined by measuring oil concentrations and droplet size distributions. An analysis of covariance (ANCOVA) model indicated that wave type and temperature significantly (p < 0.05) affected the dynamic dispersant effectiveness (DDE). At higher temperatures (16 °C), the test IFO180 was effectively dispersed under breaking waves with a DDE of 90% and 50% for Corexit 9500 and SPC 1000, respectively. The dispersion was ineffective under breaking waves at lower temperature (10 °C), and under regular wave conditions at all temperatures (10-17 °C), with DDE < 15%. Effective chemical dispersion was associated with formation of smaller droplets (with volumetric mean diameters or VMD ? 200 μm), whereas ineffective dispersion produced large oil droplets (with VMD ? 400 μm).  相似文献   

10.
Our study examined the effects of Corexit 9500 and sediment on microbial mineralization of specific aliphatic and aromatic hydrocarbons found in crude oil. We also measured gross mineralization of crude oil, dispersed crude oil and dispersant by a marine microbial consortium in the absence of sediment. When provided as carbon sources, our consortium mineralized Corexit 9500 the most rapidly, followed by fresh oil, and finally weathered oil or dispersed oil. However, mineralization in short term assays favored particular components of crude oil (2-methyl-naphthalene > dodecane > phenanthrene > hexadecane > pyrene) and was not affected by addition of nutrients or sediment (high sand, low organic carbon). Adding dispersant inhibited hexadecane and phenanthrene mineralization but did not affect dodecane and 2-methyl-naphthalene mineralization. Thus, the effect of dispersant on biodegradation of a specific hydrocarbon was not predictable by class. The results were consistent for both high and low oiling experiments and for both fresh and weathered oil. Overall, our results indicate that environmental use of Corexit 9500 could result in either increases or decreases in the toxicity of residual oil through selective microbial mineralization of hydrocarbons.  相似文献   

11.
Laboratory experiments were initiated to study the biodegradability of oil after dispersants were applied. Two experiments were conducted, one at 20 degrees C and the other at 5 degrees C. In both experiments, only the dispersed oil fraction was investigated. Each experiment required treatment flasks containing 3.5% artificial seawater and crude oil previously dispersed by either Corexit 9500 or JD2000 at a dispersant-to-oil ratio of 1:25. Two different concentrations of dispersed oil were prepared, the dispersed oil then transferred to shake flasks, which were inoculated with a bacterial culture and shaken on a rotary shaker at 200 rpm for several weeks. Periodically, triplicate flasks were removed and sacrificed to determine the residual oil concentration remaining at that time. Oil compositional analysis was performed by gas chromatography/mass spectrometry (GC/MS) to quantify the biodegradability. Dispersed oil biodegraded rapidly at 20 degrees C and less rapidly at 5 degrees C, in line with the hypothesis that the ultimate fate of dispersed oil in the sea is rapid loss by biodegradation.  相似文献   

12.
This study determined the limiting oil viscosity for chemical dispersion of oil spills under simulated sea conditions in the large outdoor wave tank at the US National Oil Spill Response Test Facility in New Jersey. Dispersant effectiveness tests were completed using crude oils with viscosities ranging from 67 to 40,100 cP at test temperature. Tests produced an effectiveness-viscosity curve with three phases when oil was treated with Corexit 9500 at a dispersant-to-oil ratio of 1:20. The oil viscosity that limited chemical dispersion under simulated at-sea conditions was in the range of 18,690 cP to 33,400 cP. Visual observations and measurements of oil concentrations and droplet size distributions in the water under treated and control slicks correlated well with direct measurements of effectiveness. The dispersant effectiveness versus oil viscosity relationship under simulated at sea conditions at Ohmsett was most similar to those from similar tests made using the Institut Francais du Pétrole and Exxon Dispersant Effectiveness (EXDET) test methods.  相似文献   

13.
Petroleum products discharged at the water surface are rapidly modified under the effect of physico-chemical and biological transformations, themselves closely dependent on ecological factors. The rôle of some of these, such as illumination, may be particularly significant. This report deals with the effect of this parameter on the phytotoxicity of Kuwait crude oil on the primary production of a microalga: (Phaeodactylum tricornutum) and marine plankton communities.The result of these investigations indicates that the toxicity of extracts made from a crude oil is about two to three times greater when the latter is previously subjected to illumination of sufficient intensity and duration. The incorporation of a chemical dispersant (Corexit 8666) magnifies this phenomenon. In the case of a weathered crude oil mixed in equal parts with the dispersant, illumination raises the toxicity of the extracts by a factor of about 30.  相似文献   

14.
Nitrate concentrations in streamwater of agricultural catchments often exhibit interannual variations, which are supposed to result from land‐use changes, as well as seasonal variations mainly explained by the effect of hydrological and biogeochemical cycles. In catchments on impervious bedrock, seasonal variations of nitrate concentrations in streamwater are usually characterized by higher nitrate concentrations in winter than in summer. However, intermediate or inverse cycles with higher concentrations in summer are sometimes observed. An experimental study was carried out to assess the mechanisms that determine the seasonal cycles of streamwater nitrate concentrations in intensive agricultural catchments. Temporal and spatial patterns of groundwater concentrations were investigated in two adjacent catchments located in south‐western Brittany (France), characterized by different seasonal variations of streamwater nitrate concentrations. Wells were drilled across the hillslope at depths ranging from 1·5 to 20 m. Dynamics of the water table were monitored and the groundwater nitrate and chloride concentrations were measured weekly over 2 years. Results highlighted that groundwater was partitioned into downslope domains, where denitrification induced lower nitrate concentrations than into mid‐slope and upslope domains. For one catchment, high subsurface flow with high nitrate concentrations during high water periods and active denitrification during low water periods explained the higher streamwater nitrate concentrations in winter than in summer. For the other catchment, the high contribution of groundwater with high nitrate concentrations smoothed or inverted this trend. Increasing bromide/chloride ratio and nitrate concentrations with depth argued for an effect of past agricultural pressure on this catchment. The relative contribution of flows in time and correlatively the spatial origin of waters, function of the depth and the location on the hillslope, and their chemical characteristics control seasonal cycles of streamwater nitrate concentrations and can influence their interannual trends. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

15.
为深入理解纳木错湖水及入湖河流中溶解有机碳（DOC）和总氮（TN）浓度的季节变化特征及其影响因素,于2012-2013年不同季节对纳木错2个站点及流域内21条主要入湖河流进行采样及分析,采用统计学方法初步探讨纳木错水体和21条河流DOC和TN浓度季节变化特征.结果表明,河流DOC平均浓度范围为0.763~1.537 mg/L,TN平均浓度范围为0.179~0.387 mg/L.21条入湖河流DOC浓度在春末夏初和夏季达到高值,冬季为低值,TN浓度季节变化趋势大体上与DOC浓度相反.湖泊水体DOC和TN浓度范围分别为2.42~8.08和0.237~0.517 mg/L,明显分别高于河水中的浓度.湖泊DOC浓度季节变化趋势与河流一致,而TN浓度无明显的季节性变化.河水DOC浓度的季节变化和空间差异受控于河流的补给方式,湖水DOC浓度受湖泊内部藻类等水生植物活动和河流外源输入的影响.DOC等有机质的分解是影响纳木错流域湖水和河水TN浓度的重要原因.  相似文献   

16.
Embryos and juveniles of the sheepshead minnow (Cyprinodon variegatus), a saltwater fish, were exposed to ammonium jarosite, a waste product of the processing of zinc ore, during a 28-day posthatch, flow-through toxicity test. Exposure to measured ammonium jarosite concentrations ≤ 290 ppm had no significant effect on the hatching success of embryos. However, slight delays in hatching were observed in test concentrations ≥ 140 ppm. Although exposure to test concentrations ≥ 140 ppm significantly decreased the ability of juvenile fish to uncurl after hatching, juvenile mortality was significantly increased only in test concentrations ≥ 230 ppm. There was no effect on growth of juvenile fish in jarosite concentrations ≤ 230 ppm. The estimated maximum acceptable toxicant concentration (MATC), based on measured concentrations, was > 140< 230 ppm.  相似文献   

17.
This study examined the potential use of macroalgae epiphytic on mangrove aerial roots as indicators of estuarine contamination. The distribution and abundance of macroalgae was investigated in four estuaries in the vicinity of Sydney, Australia, and compared to water and sediment metal concentrations, nutrient concentrations and physicochemical parameters over four seasonal surveys. Macroalgal diversity and distribution appeared to be highly influenced by the ambient contaminant concentrations, while biomass appeared to be linked with nutrient concentrations. The distribution of the Rhodophyta species, Catenella nipae Zanardini significantly decreased as metal concentrations increased among the estuaries during all seasonal surveys. This species showed strong potential for use as a bioindicator of estuarine contamination.  相似文献   

18.
The investigation and continuous monitoring with an innovative iron oxide embedded cellulose acetate membrane (FeO/CAM) on the concentrations of biologically available phosphorus (BAP) were conducted in the Meiliang Bay of the Taihu Lake during summer in 2004. The results showed that the concentrations of dissolved (FeO-DP), particulate (FeO-PP) and total bioavailable phosphorus (FeO-P) had similar horizontal distribution. The BAP concentrations were the highest in those estuaries in the northern bay. With the decrease of the distance to the estuary or long shore, there was little difference between BAP concentrations in an open lake area. During the observation period, algal blooms occurred in most waters of the northern bay, which was reflected from the high concentrations of chlorophyll a (Chl-a). While they were not highest in the estuarine waters of those major rivers, this is the case for the BAP concentrations. The concentrations of Chl-a had a significantly positive correlation with those of bioavailable phosphorus in the open area of the Meiliang Bay. With the sediment resuspension induced by wind and wave, BAP concentrations increased in a short-term, indicating that the riverine P inputs mainly contribute to the concentrations of BAP in the estuarine water while internal P release was the major source of BAP in the open lake area. In the eutrophic shallow lake, the blooms of alga may cause pH increase and further result in internal P release. The above results showed that the new membrane of FeO/CAM can be used to monitor the concentrations of BAP and provide the scientific justifications for the control strategy of the lake eu-trophication.  相似文献   

19.
Variations in Irgarol 1051 concentrations in the UK's largest marina at Brighton were determined regularly over a period of one year. Aqueous concentrations ranged from <1 to 960 ngl(-1) with highest mean concentrations generally associated with berths for larger vessels and with the main channels. Temporally, highest concentrations were recorded in November through to January and were probably associated with maintenance of vessels in an adjacent boatyard. Elevated levels were also encountered at the beginning of the season, coinciding with the introduction of newly antifouled vessels. Increased concentrations also followed dredging, possibly through re-mobilisation of Irgarol 1051. No correlations were found between dissolved Irgarol 1051 concentrations and pH, temperature or salinity. With the exception of sporadically high concentrations recorded for water samples (probably taken in close proximity to recently antifouled vessels), concentrations rarely exceeded the no observed effect concentration for marine periphyton of 63 ngl(-1). Concentrations of Irgarol 1051 in sediments sampled from the marina ranged from <1 to 77 ngg(-1). Apparent distribution coefficients (K(d)) calculated from sedimentary and aqueous samples (collected simultaneously) are generally within the range of K(d)'s reported from laboratory experiments.  相似文献   

20.
《Marine pollution bulletin》2014,78(1-2):130-136
For heavy metals, quality standards indicating good environmental status are designed to evaluate concentrations in the whole fish body, whereas monitoring of metals is often conducted using muscle or liver tissue. As most metals accumulate at different rates in different parts of fish, data should be adjusted to reflect whole fish body concentrations; however, this requires knowledge on distribution of metal concentrations within fish. Here, concentrations of cadmium, mercury, and lead were analyzed in the liver, muscle and whole fish of herring and perch to create conversion factors for transformation of heavy metal concentrations between these tissues. Species-specific accumulation of metals between muscle, liver, and whole fish were observed. Relationships between different tissues were used to recalculate data from monitoring programs in the Baltic Sea region. Based on whole fish concentrations, environmental status for cadmium and mercury in herring improved compared to assessments based on muscle or liver concentrations alone.  相似文献   

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