细化搜索
结果 1-10 的 23
Spatial and vertical distributions of heavy metals and their potential toxicity levels in various beach sediments from high-background-radiation area, Kerala, India
2015
Suresh, G. | Ramasamy, V. | Sundarrajan, M. | Paramasivam, K.
The spatial and vertical distribution of heavy metals and the sediment characteristics of beaches in Kerala, India (the upper surface sediments and the first, second and third one-foot-thick strata) were assessed in this study. The concentrations of most of the studied metals were highest at sampling site S1 (Cochin). The measured concentrations were compared with background and toxicological reference values. The results show that definite adverse biological effects are possible at most of the sampling sites due to the high Pb levels. Three different indexes were calculated to investigate the potential toxicity level. Most of the studied metals and all calculated indexes were highest in the third foot of sediment. Multivariate statistical analyses were performed and suggested that particular heavy metals, e.g., Pb, Cd, Cr and Ni, may represent contamination from a common source. The Cd and Pb concentrations and all the calculated index values show a relationship with the content of organic matter. The results of the present study suggest the recommendation that a systematic analysis is needed to monitor heavy metal levels in the studied area.
显示更多 [+] 显示较少 [-]Sand patties provide evidence for the presence of Deepwater Horizon oil on the beaches of the West Florida Shelf
2015
McDaniel, L.D. | Basso, J. | Pulster, E. | Paul, J.H.
The ecological consequences of the Deepwater Horizon (DWH) oil spill are both long-term and pervasive. The distribution of toxicity and mutagenicity in the Gulf of Mexico suggests oil from the DWH spill could have contaminated the West Florida Shelf (WFS). We utilized polycyclic aromatic hydrocarbon (PAH) analysis to determine presence and potential origin of oil contaminants in beach sand patty samples. PAH profiles from WFS beaches were statistically significantly similar to DWH contaminated samples from the Northeast Gulf of Mexico (Gulf Shores, AL; Ft. Pickens, FL). Dioctyl sodium sulfosuccinate (DOSS), a major component of Corexit 9500 dispersant was also detected in the sediments. DOSS concentrations ranged from 1.6 to 5.5ngg−1 dry weight. Additionally, two samples from DWH oil contaminated beaches were acutely toxic and one WFS beach sediment sample was mutagenic. These observations provide support for the theory that DWH oil made its way onto beaches of the WFS.
显示更多 [+] 显示较少 [-]Fate of Deepwater Horizon oil in Alabama’s beach system: Understanding physical evolution processes based on observational data
2015
Hayworth, Joel S. | Prabakhar Clement, T. | John, Gerald F. | Yin, Fang
The impact of MC252 oil on northern Gulf of Mexico (GOM) beaches from the 2010 Deepwater Horizon (DWH) catastrophe was extensive along Alabama’s beaches. While considerable amount of cleanup has occurred along these beaches, as of August 2014, DWH oil spill residues continue to be found as surface residual balls (SRBs), and also occasionally as submerged oil mats (SOMs). Four years of field observations informing the fate and transport of DWH SRBs in Alabama’s beach system are presented here, along with a conceptual framework for describing their physical evolution processes. The observation data show that SRBs containing MC252 residues currently remain in Alabama’s beach system, although their relationship to SOMs is not fully known. Based on our field observations we conclude that small DWH SRBs are likely to persist for several years along the Alabama shoreline.
显示更多 [+] 显示较少 [-]Prevalence and diversity of extended-spectrum-β-lactamase-producing Enterobacteriaceae from marine beach waters
2015
Maravić, Ana | Skočibušić, Mirjana | Cvjetan, Svjetlana | Šamanić, Ivica | Fredotović, Željana | Puizina, Jasna
A total of 1351 Enterobacteriaceae isolates from 144 seawater samples were collected over a four-year period from three public beaches in the eastern Adriatic Sea in Croatia. Approximately 35% of the strains were multidrug-resistant. BlaESBL genes were detected in 4.2% of the isolated Enterobacteriaceae, the main species of which were Escherichia coli, Enterobacter cloacae and Klebsiella pneumoniae. BlaTEM-1+SHV-12 was the most dominant genotype, followed by blaCTX-M-15.Raoultella terrigena and E. intermedius simultaneously harboured blaTEM-1,blaSHV-11/12 and blaCTX-M-15. Isolate fingerprinting revealed that marine E. coli isolates were clonally related to CTX-M-producing strains from a regional university hospital. These results indicate that marine beach waters are reservoirs of ESBL-producing Enterobacteriaceae and thus constitute a public health problem with further potential to act as mediators in gene flow between marine coastal areas and clinical settings.
显示更多 [+] 显示较少 [-]Degradation of oil by fungi isolated from Gulf of Mexico beaches
2015
Simister, R.L. | Poutasse, C.M. | Thurston, A.M. | Reeve, J.L. | Baker, M.C. | White, H.K.
Fungi of the Ascomycota phylum were isolated from oil-soaked sand patties collected from beaches following the Deepwater Horizon oil spill. To examine their ability to degrade oil, fungal isolates were grown on oiled quartz at 20°C, 30°C and 40°C. Consistent trends in oil degradation were not related to fungal species or temperature and all isolates degraded variable quantities of oil (32–65%). Fungal isolates preferentially degraded short (<C18; 90–99%) as opposed to long (C19–C36; 7–87%) chain n-alkanes and straight chain C17- and C18-n-alkanes (91–99%) compared to their branched counterparts, pristane and phytane (70–98%). Polycyclic aromatic hydrocarbon (PAH) compounds were also degraded by the fungal isolates (42–84% total degraded), with a preference for low molecular weight over high molecular weight PAHs. Overall, these findings contribute to our understanding of the capacity of fungi to degrade oil in the coastal marine environment.
显示更多 [+] 显示较少 [-]To swim or not to swim? A disagreement between microbial indicators on beach water quality assessment in Hong Kong
2015
Cheung, Pui Kwan | Yuen, Ka Lai | Li, Ping Fai | Lau, Wai Hing | Chiu, Chung Man | Yuen, Suet Wai | Baker, David M.
The USEPA and the WHO now advocate the use of enterococci as indicators for marine water quality. This study investigated the outcomes for Hong Kong beach water quality assessment by comparing enterococcus measures with data from the HKEPD's monitoring programme. Six beaches were tested once every 2–3months from November 2013 to June 2014 in order to identify the most contaminated sites, followed by intensive water sampling in sites found to have the highest enterococci densities (Clear Water Bay Second and Golden) every five to six days for six sampling events over a 30-day period in 2014. The geometric means of enterococci were found to be 124 and 41cfu/100mL at Clear Water Bay Second and Golden respectively, indicating that there may be higher risks of illness associated with swimming at both beaches than previously known. Moreover, beach sediments contained higher concentrations of enterococci than water, and warrant further study.
显示更多 [+] 显示较少 [-]The amount and accumulation rate of plastic debris on marshes and beaches on the Georgia coast
2015
Lee, Richard F. | Sanders, Dorothea P.
The amount and accumulation rate of plastic debris at 20 sites along the Georgia coast were prepared using data reported by a number of volunteer organizations. The amount of plastic debris at highly visited barrier island beaches and estuarine marshes ranged from 300 to >1000kg. Relatively large amount of plastics (180–500kg) were found on less visited barrier island beaches, i.e. Blackbeard, Ossabaw and Cumberland Islands. A follow up monthly or quarterly collection study was carried out on two of the sites, a barrier beach and estuarine marsh, to determine accumulation rate in 8000m2 areas. Accumulation rates ranged from 0.18 to 1.28kg/30days–8000m2 on the barrier island beach and from 0.6 to 1.61kg/30days–8000m2 at the estuarine marsh site. The major type of plastics, e.g. bottles, food wrappers, plastic fragments, was highly variable at different seasons and sites. The authors recommend consideration of a standardization in reporting plastic debris, with respect to quantitation of debris and sample area.
显示更多 [+] 显示较少 [-]Number of bacteria decomposing organic phosphorus compounds and phosphatase activity in the sand of two marine beaches differing in the level of anthropopressure
2015
Mudryk, Z.J. | Perliński, P. | Antonowicz, J. | Robak, D.
Number of heterotrophic bacteria ability to decompose organic phosphorus compounds and the level of phosphatase activity in the sand of two marine beaches (southern coast of the Baltic Sea) differing in the level of anthropopressure were studied. The study showed that the number of bacteria and level phosphatase activity were higher in the sand of the beach subjected to stronger anthropopressure. In both studied beaches bacteria hydrolysing DNA were the most numerous (92.7–302.8CFU·g−1 d.w.). The least numerous were phytin (26.0·103CFU·g−1 d.w.) and phenolphthalein diphosphate (11.1·103CFU·g−1 d.w.) decomposing bacteria. Number of bacteria able to attack tested organic phosphorus compounds were the most numerous in dry zones (10.77–739.92CFU·g−1 d.w.) then wet zones (3.34–218.15CFU·g−1 d.w.). In both studied beaches bacteria hydrolysing organic phosphorus compounds and phosphatase activity generally were more numerous in surface sand layer. Seasonal variation in the occurrence of bacteria in both studied beaches was observed.
显示更多 [+] 显示较少 [-]Impact of sea-level rise on cross-shore sediment transport on fetch-limited barrier reef island beaches under modal and cyclonic conditions
2015
Baldock, T.E. | Golshani, A. | Atkinson, A. | Shimamoto, T. | Wu, S. | Callaghan, D.P. | Mumby, P.J.
A one-dimensional wave model is combined with an analytical sediment transport model to investigate the likely influence of sea-level rise on net cross-shore sediment transport on fetch-limited barrier reef and lagoon island beaches. The modelling considers if changes in the nearshore wave height and wave period in the lagoon induced by different water levels over the reef flat are likely to lead to net offshore or onshore movement of sediment. The results indicate that the effects of SLR on net sediment movement are highly variable and controlled by the bathymetry of the reef and lagoon. A significant range of reef-lagoon bathymetry, and notably shallow and narrow reefs, appears to lead hydrodynamic conditions and beaches that are likely to be stable or even accrete under SLR. Loss of reef structural complexity, particularly on the reef flat, increases the chance of sediment transport away from beaches and offshore.
显示更多 [+] 显示较少 [-]Surface oil footprint and trajectory of the Ixtoc-I oil spill determined from Landsat/MSS and CZCS observations
2015
Sun, Shaojie | Hu, Chuanmin | Tunnell, John W.
The Ixtoc-I oil spill occurred in 1979 in shallow waters (50m) of the Bay of Campeche, Mexico. Although it is known that a large portion of the released oil from this second largest accidental marine oil spill in history reached the surface, to date there has been no attempt to document the surface footprint and trajectory of the released oil. Our study attempts to fill this knowledge gap using remote sensing data collected by Landsat/MSS and CZCS. Both showed the same general patterns of oil trajectory to the northwest and north, nearly parallel to the coastline of the western Gulf of Mexico (GoM) with possible oil landing on Mexican and Texas beaches. Field observations at selected beaches and islands along the coast of the western and southern GoM during and after the spill confirmed these satellite-based findings, which were also used to help in planning a recent field campaign to collect sediment samples in the southern GoM.
显示更多 [+] 显示较少 [-]