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"De Mora, S. J"
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Tributyltin : case study of an environmental contaminant
This authoritative volume reviews the environmental chemistry and toxicological effects of a marine pollutant of exceptional potency, tributyltin (TBT), and outlines the international response to control TBT.
Book
The Effects of UV Radiation in the Marine Environment
This book, first published in 2000, provides a comprehensive review of UV radiation effects in the marine environment. A multidisciplinary approach is adopted to discuss all aspects from a physical, chemical and biological perspective. The book begins by describing the attenuation of UV radiation in the atmosphere and sea water, outlining the photochemical reactions involved and highlighting the role that such chemistry can play in influencing the biogeochemical cycling of various elements. The deleterious consequences of such radiation on organisms and strategies adopted to mitigate these harmful repercussions are discussed. The organisms considered range from virus and bacteria through phytoplankton and zooplankton to fish and mammals. The book is aimed at researchers and graduate students in photobiology, photochemistry and environmental science. It will also be useful as a supplementary text for courses in oceanography, climatology and ecology.
eBook
Tributyltin
This authoritative volume reviews the environmental chemistry and toxicological effects of a marine pollutant of exceptional potency, tributyltin (TBT), and outlines the international response to control TBT. TBT compounds have been widely utilized in marine anti-fouling paint formulations to obtain increased fuel efficiencies and long lifetimes for maritime vessels and structures. However, its extreme toxicity has resulted in numerous adverse biological effects, and its persistence ensures that such problems are likely to continue. A wide variety of disciplines are brought together to illustrate the general principles, pathways and problems involved in identifying and quantifying an environmental toxin, elucidating deleterious biological consequences, and the legal framework that can invoke mitigation via regulation. This text not only has wide appeal for undergraduate courses in environmental science, chemistry and marine ecology, but also forms a valuable sourcebook for environmental planners and serves as a 'successful' case study for undergraduate courses in environmental law, planning and science.
eBook
Dimethylsulfoxide (DMSO) and related sulfur compounds in the Saguenay Fjord, Quebec
The biogeochemical cycling of dimethylated sulfur compounds was investigated in the Saguenay Fjord during June 1996, just prior to the flooding in the catchment area. Dimethylated sulfur compounds, namely dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide (DMSO), were determined at six sites. In comparison with other coastal environments, including the Gulf of St. Lawrence, DMS (0-1.8 nmol·L
-1
, average <0.2 nmol·L
-1
) and DMSP (0-23 nmol·L
-1
, average <0.8 nmol·L
-1
) concentrations were relatively low because the brackish waters were poor in algal abundance and dominated by species not noted as major DMS and DMSP producers. Similarly, dissolved DMSO levels (<0.016 nmol·L
-1
) were low due to the limited availability of its DMS precursor and the shallow photic zone. Particulate DMSO was measured (0-110 nmol·L
-1
, average ~8 nmol·L
-1
) and occasionally exceeded particulate DMSP concentrations (0.016-140 nmol·L
-1
, average ~3.5 nmol·L
-1
). Given the low dissolved DMSO concentrations, the presence of particulate DMSO provides evidence for its direct biosynthesis by phytoplankton.
Journal Article
Influence of phytoplankton taxonomic profile on the distribution of dimethylsulfide and dimethylsulfoniopropionate in the northwest Atlantic
Distributions of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) were surveyed in surface waters of the NW Atlantic in May 1998, a few weeks after the spring bloom. A triangular transect extending from Nova Scotia to Bermuda and northeast toward Newfoundland encompassed 4 major oceanic biogeochemical provinces: Northwest Atlantic Continental Shelves (NWCS), Gulf Stream (GFST), North Atlantic Subtropical Gyre (NAST) and the North Atlantic Drift (NADR). Surface concentrations of DMS and DMSP were highest in the NADR, with peaks up to 8.9 nM DMS, 44.1 nM dissolved DMSP (DMSPd) and 240 nM particulate DMSP (DMSPp). The phytoplankton assemblage throughout the study area was dominated by dinoflagellates and prymnesiophytes. Statistically significant correlations were observed between the abundance of dinoflagellates and prymnesiophytes and the concentrations of DMS and DMSP along the transect. Size-fractionation of DMSPprevealed the 2 to 11 μm fraction to be the most important contributor to total DMSP (mean 72%, range 27% to 91% of total). In the region of the highest DMS(P) concentrations, the phytoplankton assemblage was dominated by prymnesiophytes and dinoflagellates, withChrysochromulinaspp. andGyrodinium flagellarebeing the most abundant. The abundance of these taxa showed a marked correlation with total DMSPpand with the 2 to 11 μm size fraction of DMSP in which these cells are found. This plankton assemblage was observed both early and late in the transect, which may indicate that it is a persistent feature along the northern side of the Gulf Stream at this time of year. Sea-air flux of DMS was calculated based on 2 different models. The results showed peaks in flux corresponding to the peaks in DMS concentration in surface water. Pooling and averaging the values for each biogeochemical province reveals DMS concentrations lower than the average values of an existing global DMS database for the same regions and times.
Journal Article
Production and consumption of dimethylsulfide (DMS) in North Atlantic waters
Production and consumption of dimethylsulfide (DMS) were studied in surface waters of the northwest Atlantic between latitude 32° and 45° N during May 1998. The kinetics of DMS production by the whole planktonic community were studied in short-term (3 h) experiments using additions of dissolved dimethylsulfoniopropionate (DMSPd) (0 to 3000 nM). Measurements of DMS production and DMSPdconsumption showed that the DMS production rate increased in direct proportion to the concentration of added DMSPd. This rate relationship did not saturate, suggesting acclimation of the microbial community to DMSPdconcentrations much higher than the average for bulk seawater. Longer-term experiments were performed in which DMSPdconsumption and DMS production were measured over 48 to 60 h. The DMSPdconsumption rate decreased as the concentration of DMSPddecreased during the incubations. However, the DMS production rate was initially constant for the first 36 h. When DMSPdconcentrations fell below 50 nM, DMS production stopped, even though DMSPdconsumption continued. A possible explanation is that DMSP cleavage might dominate the total DMSP consumption at high DMSPdconcentrations while DMSP demethylation and other processes dominate at low DMSPdconcentrations. DMS consumption was measured both directly and by using the DMS consumption inhibitors dimethyl disulfide (DMDS) and methyl butyl ether (MBE). DMS consumption was generally undetectable except at 1 station dominated by a dense population of the DMSP-producing phytoplanktonChrysochromulinasp. and where ambient DMS concentrations were high. This suggests that the potential for DMS consumption is highest where ambient DMS levels are elevated. Pooling results from these experiments with earlier results from more northerly waters revealed an inverse exponential relationship (r² = 0.75, p < 0.0001) between the potential rate constant and chlorophyllastanding stock across a wide area of the Northwest Atlantic. This finding is potentially useful for the development of DMS production models.
Journal Article
Tributyltin : case study of an environmental contaminant / edited by Stephen J. de Mora
This authoritative volume reviews the environmental chemistry and toxicological effects of a marine pollutant of exceptional potency, tributyltin (TBT), and outlines the international response to control TBT.
eBook
Influence of copepod grazing on concentrations of dissolved dimethylsulfoxide and related sulfur compounds in the North Water, northern Baffin Bay
The impact of copepod grazing on the biogeochemical cycling of dimethylated-sulfur compounds was investigated in the North Water polynya, northern Baffin Bay, during the period 21 April to 24 June 1998. The results show that zooplankton grazing can influence DMSOdconcentrations in addition to those of DMS and DMSPd. This study is the first to demonstrate this effect for DMSOd. Weight-specific production rates for DMSOddue to the presence of copepods in incubation experiments were 0.14 to 23 nmol mg–1dry wt (DW) d–1(median = 1.02 nmol mg–1DW d–1) and were occasionally higher than rates for the production of DMSPd. Weight-specific production rates for dimethylsulfide were 0.011 to 2 nmol mg–1DW d–1(median = 0.23 nmol mg–1DW d–1) and for DMSPd0.005 to 6.86 nmol mg–1DW d–1(median = 0.71 nmol mg–1DW d–1). In comparison, the volumetric and individual-normalized production rates for DMS and DMSPd, which were used to derive weight-specific production rates for these compounds, were similar to published results. The influence of copepod grazing on the production rates of DMS and DMSPdwas statistically significant in more than 85% of the incubation experiments conducted, but in fewer than 50% of the incubations for DMSOd. These results suggest that the impact of copepod grazing might be less important for the biogeochemical cycling of DMSO than that of DMS and DMSP. Analysis of the data indicates that grazing may influence the release of DMSO and DMSP in different ways. A secondary objective of the study was to assess the potential role of copepod grazing onin situlevel of DMS, DMSPdand DMSOdin the North Water. Weight-specific production rates were used to calculatein situproduction rates, which ranged from 0.002 to 21.7 nmol m–3d–1for DMS, from 0.001 to 85.8 nmol m–3d–1for DMSPd, and from 0.003 to 184 nmol m–3d–1for DMSOd. Comparison of these results with the average concentrations of DMS, DMSPdand DMSOdin the water column of the polynya indicates that copepod grazing was a minor mechanism in the release of these compounds in the North Water.
Journal Article
Cation Binding by Humic Substances
Humic substances are highly-abundant organic compounds formed in soils and sediments by the decay of dead plants, microbes and animals. This book focuses on the important binding properties of these compounds which regulate the chemical reactivity and bioavailability of hydrogen and metal ions in the natural environment. Topics covered include the physico-chemical properties of humic matter and interactions of protons and metal cations with weak acids and macromolecules. Experimental laboratory methods are also discussed, together with mathematical modelling. Finally the author looks at how the results of this research can be used to interpret environmental phenomena in soils, waters and sediments. This comprehensive account of cation binding by humic matter is a valuable resource for advanced undergraduate and graduate students, environmental scientists, ecologists and geochemists.
eBook
Tributyltin : case study of an environmental contaminant
This authoritative study brings together a wide variety of disciplines to illustrate the general principles in identifying and quantifying an environmental toxin, elucidating deleterious biological consequences, and the legal framework that can invoke mitigation via regulation. It has wide appeal for undergraduate courses in environmental science, chemistry, marine ecology and environmental law.
eBook