RESUMEN
Devon Great Consols (DGC) is a region in south west England where extensive mining for Cu, Sn and As took place in the nineteenth century. Because of its historical and geological significance, DGC has protected status and is part of the Cornwall and West Devon Mining Landscape UNESCO World Heritage Site. Recently, the region was opened up to the public with the construction or redevelopment of various trails, tracks and facilities for walking, cycling and field visits. We used portable x-ray fluorescence spectrometry to measure, in situ, the concentrations of As in soils and dusts in areas that are accessible to the public. Concentrations ranged from about 140 to 75,000 µg g-1 (n = 98), and in all but one case exceeded a Category 4 Screening Level for park-type soil of 179 µg g-1. Samples returned to the laboratory and fractionated to <63 µm were subjected to an in vitro assessment of both oral and inhalable bioaccessibility, with concentrations ranging from <10 to 25,500 µg g-1 and dependent on the precise nature and origin of the sample and the physiological fluid applied. Concentrations of As in PM10 collected along various transects of the region averaged over 30 ng m-3 compared with a typical concentration in UK air of <1 ng m-3. Calculations using default EPA and CLEA estimates and that factor in for bioaccessibility suggest a 6-h visit to the region results in exposure to As well in excess of that of minimum risk. The overall risk is exacerbated for frequent visitors to the region and for workers employed at the site. Based on our observations, we recommend that the remodelling or repurposing of historical mine sites require more stringent management and mitigation measures.
Asunto(s)
Arsénico/análisis , Contaminantes del Suelo/análisis , Inglaterra , Monitoreo del Ambiente , Humanos , Minería , UNESCORESUMEN
The term "Unresolved Complex Mixture" (UCM) has been used extensively for decades to describe a gas chromatographic characteristic indicative of the presence of fossil fuel hydrocarbons (mainly petroleum hydrocarbons) in hydrocarbons isolated from aquatic samples. We chronicle the origin of the term. While it is still a useful characteristic for screening samples, more modern higher resolution two dimensional gas chromatography and gas chromatography coupled with advanced mass spectrometry techniques (Time-of-Flight or Fourier Transform-Ion Cyclotron Resonance) should be employed for analyses of petroleum contaminated samples. This will facilitate advances in understanding of the origins, fates and effects of petroleum compounds in aquatic environments.
Asunto(s)
Monitoreo del Ambiente/métodos , Combustibles Fósiles/análisis , Hidrocarburos/análisis , Contaminación por Petróleo/análisis , Contaminantes Químicos del Agua/análisis , Cromatografía de Gases , Terminología como Asunto , Contaminantes Químicos del Agua/clasificaciónRESUMEN
The unresolved complex mixture (UCM) frequently dominates organic extracts isolated from estuarine and coastal sediments in the vicinity of industrial centers. Despite an obvious link to a petroleum source, speculation exists that biogenic sources also contribute to the UCM. To determine the source of the UCM to these environments, natural abundance radiocarbon (Δ(14)C) and stable carbon (δ(13)C) isotopic composition of the UCM solvent-extracted from coastal sediments, road dust, and urban atmospheric particulate in the United States was measured. Extracts of UCM and separate saturate and aromatic fractions from all samples are predominantly (>90%) fossil-derived and hence have a petroleum source. Even the polar fraction of the UCM, which has a Δ(14)C composition reflecting contributions from recently photosynthesized carbon (-665), is composed of ~66% fossil carbon indicating the presence of petroleum residues that have been transformed into more polar derivatives. The δ(13)C of the UCM had consistent values (-27.65 ± 0.51; n = 16) for all but one sample, indicating a common origin of the UCM. We conclude that in coastal areas dominated by human activities whole fractions of the UCM, as well as separate saturate, aromatic, and polar fractions, are principally derived from petroleum sources.
Asunto(s)
Mezclas Complejas/análisis , Monitoreo del Ambiente , Combustibles Fósiles/análisis , Sedimentos Geológicos/análisis , Contaminantes Químicos del Agua/análisis , Bahías/análisis , Isótopos de Carbono/análisis , Monitoreo del Ambiente/métodos , EstuariosRESUMEN
Sediment cores were taken at three locations in Narragansett Bay, Rhode Island, USA in 1997 and analyzed for a variety of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlordanes, linear alkyl benzenes (LABs), benzotriazoles (BZTs) and dichlorodiphenyltrichloroethanes (DDTs) and metabolites. The distributions of these chemicals at Apponaug Cove and in the Seekonk River indicate that there was a disturbance in the depositional environment relative to cores collected at these locations in 1986 demonstrating the potential for buried contaminants to be remobilized in the environment even after a period of burial. Sharp breaks in the concentration of several organic markers with known dates of introduction were successfully used to determine the sedimentation rate at Quonset Point. Both the Quonset Point and Seekonk River cores had subsurface maximums for DDTs, PCBs, PAHs and BZTs, which are consistent with expected inputs to the environment. The Apponaug Cove core showed an increase of most contaminants at the surface indicating a recent event in which more contaminated sediments were deposited at that location.
Asunto(s)
Monitoreo del Ambiente/estadística & datos numéricos , Contaminantes Ambientales/análisis , Sedimentos Geológicos/análisis , Hidrocarburos/análisis , Cromatografía de Gases y Espectrometría de Masas , Geografía , Rhode IslandRESUMEN
Polychlorinated biphenyls (PCBs) were evaluated in 41 surface sediments collected from Narragansett Bay, RI in 1997-1998. Highest concentrations of total PCBs (1760 ng/g) were in rivers at the head of the bay and the values decreased southward toward the mouth of the bay, with elevated concentrations in some of the coves. The PCB levels in approximately 43% of the samples exceeded the effects range median (ERM) guideline [Environ. Manage. 19 (1995) 81] indicating possible adverse biological effects at these stations. Principal component analysis (PCA) of the surface sediment PCBs separated the Taunton River samples from the rest of the samples. This result suggests that this river has a different PCB composition and sources than the other areas investigated. It also showed that this river has a limited influence on other bay stations as the adjacent samples downstream did not have the same chemical signature. Congener ratios derived from the PCA were useful in distinguishing stations that had different sources of PCBs than the bulk of the bay sediments. Although Aroclor 1268 and 1270 accounted for <1% of all PCB production, their major components, CB206 and CB209, account for 3-6% of the CBs in most bay samples. This may reflect more local use of these Aroclor mixtures and/or be indicative of their relative stability, compared to less chlorinated mixtures. Using linear alkyl benzenes (LABs) as a marker for sewage derived PCBs suggested that up to 95% of the PCBs at the most contaminated sites in the Seekonk, Providence, and Taunton Rivers were sewage derived. This analysis also showed that there is a high background level (167 ng/g) of PCBs in the Seekonk and Providence River, while the Taunton River had a relatively low background level (23.7 ng/g). At the furthest stations south in the Providence River, the sewage derived PCBs only accounted for 23% of the total which suggests that PCB associated with sewage particles are rapidly deposited and are therefore not the most significant source of these compounds to the lower reaches of Narragansett Bay.
Asunto(s)
Monitoreo del Ambiente/estadística & datos numéricos , Sedimentos Geológicos/análisis , Bifenilos Policlorados/análisis , Contaminantes Químicos del Agua/análisis , Arocloros/análisis , Cromatografía de Gases , Cromatografía de Gases y Espectrometría de Masas , Análisis de Componente Principal , Rhode Island , Ríos , Agua de MarRESUMEN
Tributyltin (TBT) was detected in all 24 surface sediment (top 2 cm) samples collected from Coddington Cove, Newport, RI. TBT surface sediment concentrations ranged from 32 to 372 ng Sn/g with a mean concentration of 146 ng Sn/g. Analyses of selected core sections detected TBT in at least the top 18 cm at all 7 stations where cores were collected. No consistent TBT concentration trends with depth for these cores suggest mixing is an important process in the sediment column. In one core (station 28), TBT was found in the 76-86 cm section at a concentration of 141 ng Sn/g; thus sediments are a significant sink for TBT. However, sediment mixing processes can enhance releases of bioavailable TBT. Mussels, clams and fish from Coddington Cove contain TBT at concentrations ranging from 9.2 to 977 ng Sn/g. TBT concentrations in lobsters were below the detection limit (<6 ng Sn/g). Based on available screening criteria, TBT concentrations in Coddington Cove sediment is likely to be having an adverse effect on the biota at some locations.
Asunto(s)
Contaminantes Ambientales/análisis , Metalurgia , Moluscocidas/análisis , Compuestos de Trialquiltina/análisis , Animales , Disponibilidad Biológica , Monitoreo del Ambiente/métodos , Sedimentos Geológicos/química , Rhode Island , Mariscos/análisisRESUMEN
Polycyclic aromatic hydrocarbons (PAHs) were measured in 41 surface sediments from Narragansett Bay, RI. All the analytes generally decrease down bay from the Seekonk, Providence and Taunton Rivers at the head of the bay. Total PAHs ranged from 0.569 to 216 microg/g with 27% exceeding the effects range median (ERM) of 44.8 microg/g and 73% of the stations exceeding the effects range low (ERL) of 4.02 microg/g (Long et al., 1995). Based on principal component analysis, the major source of the contaminants in Narragansett Bay was the Providence River while the coves and Taunton River/Mt. Hope Bay appeared to only have a limited influence on the open bay. PAH source ratios indicate that creosote and/or coal may be the most significant contributor of pyrogenic high molecular weight PAHs in Narragansett Bay, along with significant contributions from diesel exhaust.