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11.
A literature review on trace metals and organic compounds of anthropogenic origin in the Wider Caribbean Region 总被引：2，自引：2，他引：0
About 30 studies from the published literature were reviewed to determine the pollution status regarding heavy metals and organic compounds of the Wider Caribbean Region (WCR). The literature revealed that most studies were performed in the South and Central American Caribbean Region with sparse reports on the small island states. Collectively, the most frequently analyzed heavy metals were Pb, Cu, Zn, Fe, Cd, Ni, Mn and Cr while DDT and its metabolites were the most frequently reported organic pollutants. The samples which were analyzed vary in terms of sampling schemes, parameters and analytical techniques, as well as differences in data reporting presentation (i.e. dry weight versus wet weight, sediment fraction analyzed, or % lipids). These differences make meaningful comparisons of the available data very difficult. Furthermore, there is limited data available for most of these contaminants from the majority of nations in the WCR. Therefore, any attempt to create a regional scale assessment from contaminants data available in the open literature is limited by the scarcity of available information. 相似文献
12.
Kaelin M. Cawley John Campbell Melissa Zwilling Rudolf Jaffé 《Aquatic Sciences - Research Across Boundaries》2014,76(4):611-622
Dissolved organic matter (DOM) source and composition are critical drivers of its reactivity, impact microbial food webs and influence ecosystem functions. It is believed that DOM composition and abundance represent an integrated signal derived from the surrounding watershed. Recent studies have shown that land-use may have a long-term effect on DOM composition. Methods for characterizing DOM, such as those that measure the optical properties and size of the molecules, are increasingly recognized as valuable tools for assessing DOM sources, cycling, and reactivity. In this study we measured DOM optical properties and molecular weight determinations to evaluate whether the legacy of forest disturbance alters the amount and composition of stream DOM. Differences in DOM quantity and composition due to vegetation type and to a greater extent, wetland influence, were more pronounced than effects due to disturbance. Our results suggest that excitation-emission matrix fluorescence with parallel factor analysis is a more sensitive metric of disturbance than the other methods evaluated. Analyses showed that streams draining watersheds that have been clearcut had lower dissolved organic carbon (DOC) concentrations and higher microbially-derived and protein-like fluorescence features compared to reference streams. DOM optical properties in a watershed amended with calcium, were not significantly different than reference watersheds, but had higher concentrations of DOC. Collectively these results improve our understanding of how the legacy of forest disturbances and natural landscape characteristics affect the quantity and chemical composition of DOM in headwater streams, having implications for stream water quality and carbon cycling. 相似文献
13.
Youhei?YamashitaEmail author Anouska?Panton Claire?Mahaffey Rudolf?Jaffé 《Ocean Dynamics》2011,61(5):569-579
The spatial and diurnal tidal variability of dissolved organic carbon (DOC) concentrations and the composition of dissolved
organic matter (DOM), as evaluated by high-temperature catalytic oxidation and excitation–emission matrix combined with parallel
factor analysis (EEM–PARAFAC), respectively, were determined in Liverpool Bay. EEM–PARAFAC modeling resulted in six fluorescent
components characterized as terrestrial humic-like (two), microbial humic-like (two), and protein-like (two). The spatial
distributions of DOC and the four humic-like components were negatively correlated with salinity in the high-salinity waters
observed in this study (30.41–33.75), suggesting that terrestrial DOM was conservatively distributed. The spatial patterns
of protein-like components were largely different from those of DOC, humic-like components, and chlorophyll a, suggesting that these distributions were the combined result of production and degradation in the bay in addition to river
inputs. These findings suggest that the DOM dynamics in Liverpool Bay are strongly controlled by river-dominated allochthonous
DOM inputs with some less significant contributions of autochthonous DOM within the bay. In addition, the temporal variations
of DOM associated with the diurnal tidal cycles were determined at one inshore (31.34–32.24 salinity) and one offshore (33.64–33.75
salinity) station in the bay. Negative linear relationships between salinity and DOM characteristics, i.e., DOC, humic-like,
and protein-like components, were observed at the inshore station. In contrast, no relationship was observed at the offshore
station, suggesting that the export of DOM through rivers and possibly tidal flats have a noticeable influence on DOM concentration
and composition up to a relatively elevated salinity of around 33 in Liverpool Bay. 相似文献
14.
The lead-zinc-silver bearing vein of Praz-Jean (Vallis, Switzerland) is hosted in a suite of metamorphic rocks, most likely of Palaeozoic age. Sphalerite, galena and sulfosalts (freibergite and boulangérite) are its main ore-forming minerals. The results of the microprobe investigation indicate that the silver is contained in a freibergite of the following composition (weight percent): Cu 23.0, Ag 23.0, Fe 4.9, Zn 1.9, As 1.0, Sb 26.9, S 23.0, and not in an argentian galena as it was believed. The mineral previously described as jamesonite (Pb4FeSb6S14) is in reality a boulangérite (Pb5Sb4S11). The mineralogical and metallogenetic characteristics of the freibergite of Praz-Jean are discussed in relation to those of other ore deposits in which this mineral is of interest.
Resumé Le filon de plomb-zinc-argent de Praz-Jean (Valais, Suisse), se trouve dans un encaissant composé de roches métamorphiques vraisemblablement d'âge Paléozoïque. Ses minéraux constitutifs, qui ont été étudiés en détail à la microsonde, appartiennent à une suite classique de sulfures à blende et galène dominantes, et de sulfosels (freibergite, boulangérite). L'argent du gisement n'est pas contenu dans une galène argentifère comme on le croyait auparavant, mais dans une freibergite de composition pondérale: Cu 23,0, Ag 23,0, Fe 4,9, Zn 1,9, As 1,0, Sb 26,9, S 23,0. Le minéral décrit précédemment comme jamesonite (Pb4FeSb6S14) est en réalité une boulangérite (Pb5Sb4S11). La freibergite de Praz-Jean est comparée du point de vue minéralogique et gîtologique à des freibergites d'autres gisements dans lesquels la freibergite joue un rôle important.相似文献
15.
Interactions between dissolved petroleum hydrocarbons and pure and humic acid-coated mineral surfaces in artificial seawater 总被引：7，自引：0，他引：7
The adsorption of total petroleum hydrocarbons (TPHs) on suspended particles in the marine environment is an important process affecting the fate of oils spilled in the ocean. Adsorption kinetics and adsorption isotherms of the water-soluble fraction of Fuel Oil No. 6 were performed on pure and humic acid-modified montmorillonite, alumina and kaolinite. The rates of adsorption on all sorbents are very fast and a pseudo-equilibrium is reached within 0.5 h. Linear adsorption isotherms were obtained for TPH and individual aromatic hydrocarbons on all sorbents. Higher sorption coefficients (Kd) were obtained for the humic acid-coated clays compared to the pure clays. However, a great contribution of mineral surface to overall adsorption was found on humic acid-modified particles in this study. A linear relationship between the log K and log Kow was also found for individual compounds on both pure alumina (log Km) and humic acid-coated alumina (log Koc). 相似文献