O. F. X. Donard

Fluorescence spectroscopy of coastal and marine waters

Abstract Fluorescence measurements were performed on a large variety of water samples collected in different estuaries and oceans over the world. Spectra were recorded with a high-sensitivity spectrofluorometer without preconcentration of the samples. Qualitative and quantitative parameters of fluorescence were determined on fully corrected emission, excitation and synchronous fluorescence spectra. Critical conditions required to record the corrected fluorescence spectra of open marine water are emphasized. General results show that with an adequate excitation wavelength (313 nm) the fluorescence signature can be used to differentiate water masses. The variation of the emission wavelength maxima for excitation ranging from 250 to 410 nm give strong evidence that as far as the humic substances themselves are concerned, the fluorescence spectra of the natural water samples we investigated contain at least two distinctive classes of fluorophores. Synchronous spectra as well as all other fluorescence results we have obtained can be accounted for on the basis of a model which includes both the existence of these two classes of fluorophores in different proportions and variations in nature and the distribution of the fluorophores within each class.

Trace element speciation for environment, food and health.

Trace Elemant Speciation for Environment, Food and Health , Trace Elemant Speciation for Environment, Food and Health , کتابخانه دیجیتال جندی شاپور اهواز

Contribution of the Rhoˆne River to organic carbon inputs to the northwestern Mediterranean Sea

Abstract Particulate and dissolved organic carbon were determined in coastal waters of the Gulf of Lions, during several cruises from 1986. The input by the Rhoˆne River and its seasonal variability are studied and new data are given concerning the contribution to the Mediterranean Sea. Fluorescence measurements show the limited influence on the open sea of surface particulate matter, but suggest a bottom transport during which diagenetic evolution can occur. The remobilization of dissolved organic matter is also stressed.

Anthropogenic vs. lithogenic origins of trace elements (As, Cd, Pb, Rb, Sb, Sc, Sn, Zn) in water column particles: northwestern Mediterranean Sea

Abstract The distribution of heavy metal was analyzed in water column particles collected in autumn (October 1985) and spring (March 1986) by two series of sediment traps from a mooring located in the northeastern Mediterranean Sea continental slope. Four traps were set, at 50, 100, 300, 600 m depths on the mooring in 645 m deep water in the Lacaze-Duthier canyon. The total metal concentrations were determined by ICP-MS. Results show that Rb and Sc contents display typical shale values. As, Cd, Pb, Sb, Zn (normalized to Sc) display high enrichment factors (up to 50) over shale compositions. Distinctive temporal variability as well as the respective contributions of local (Tet, Aude) and remote (Rhone) rivers and Sahara-derived aerosols have been identified. Fluxes of most elements observed in the upper 100 m can be attributed to atmospheric fluxes. In the deepest traps (300 and 600 m) these fluxes are, however, mostly dominated by riverine particles advected from the continental shelf. Most of the trace-element enrichments are more likely to be related to the anthropogenic input rather than to biological cycling. Isotopic composition of lead determined by ICP-MS enabled to evaluate that the proportion of anthropogenic lead derived from European gasoline consumption ranged between 50 and 100%.

Spectral identification and behaviour of dissolved organic fluorescent material during estuarine mixing processes

Abstract In most estuaries, a linear relationship between fluorescence intensity and salinity has been frequently reported. Accordingly, it is commonly accepted that the dissolved organic matter in an estuary is essentially conservative and is not substantially modified by dilution with sea water. In this paper we have tried to verify whether other fluorescent parameters, namely the position of the fluorescence maximum and the apparent fluorescence efficiency (A.Fl.E.), whose variations were measured during estuarine mixing of waters in different European estuaries are consistent with this conclusion. Field observations and laboratory simulation experiments show that upon mixing with sea water, an important blue shift (≅ 40 nm) of the fluorescence emission spectra as well a non-conservative evolution of the A.Fl.E. are observed in estuarine waters. These phenomena have been explained by a complex combination of processes involving mainly, the mixing of fresh water and marine water fluorophores having different fluorescence properties, but also, the loss of high molecular weight fluorescent matter from fresh waters possibly removed by flocculation.

Three decades of tributyltin in the coastal environment with emphasis on Arcachon Bay, France

This account briefly reviews the fate, bioconcentration and effects of tributyltin (TBT) three decades after its introduction into the coastal environment. Data on TBT-related events that occurred in Arcachon Bay (gastropod imposex, oyster recruitment failure, oyster shell malformations, concentrations in water and sediments) are revised and reinterpreted. Historically, TBT concentrations in the waters of the open bay seldom exceeded 1 ng Sn l(-1) in the 1960s, likely surpassed the range of 100 ng Sn l(-1) from 1977 to 1981 (years when no oyster spat were collected and the local shellfish industry collapsed), and decreased to about 1 ng Sn l(-1) in the late 1980s and early 1990s following legislation in January 1982 banning TBT use. TBT pollution is discussed in relation to the green tides that have developed in Arcachon Bay since 1982.

Cryofocusing coupled to atomic absorption spectrometry for rapid and simple mercury speciation in environmental matrices

A fully automated on-line hyphenated system for mercury speciation analysis in environmental samples is presented. It provides derivatization by hydride generation or ethylation, preconcentration by cryotrapping, separation by packed column gas chromatography and detection by quartz furnace atomic absorption spectrometry. Automation of the hyphenation results in improved reproducibility of the analysis. The system has been specifically optimised for analysis of mercury compounds, but it is also potentially operative for other hydride- or ethylated derivative-forming elements, after the corresponding optimisation. Main advantages and potential limitations of the system are discussed. General procedures for the analysis of both solid (sediments, biotissues, suspended particulate matter) and liquid (sea and fresh water) samples are proposed and validated by analysis of certified reference materials. The obtained methylmercury and inorganic mercury concentrations are in agreement with the certified values. Detection limits of the method have been estimated as 0.5 ng g–1 , 3 ng g–1 , 0.1 ng l–1 for both mercury species in dry sediments, biological tissues and aqueous samples, respectively. Analysis of one sample only requires 10 min (hydride generation) or 20 min (ethylation), so that a sample throughout of 6 or 3 samples h–1, respectively, may be achieved. Results from the analysis of real samples collected in the Gironde and Scheldt estuaries (sediments, suspended particulate matter, water and biological tissues) are also provided.

High-sensitivity fluorescence spectroscopy of mediterranean waters using a conventional or a pulsed laser excitation source

Abstract Instrumental efforts have been made to record the fluorescence spectra of coastal and marine waters of the Mediterranean Sea for different excitation wavelengths without preconcentration of the samples. A fluorescence spectrophotometer, using a pulsed nitrogen laser as excitation source, was developed and spectra obtained on marine waters were compared with those obtained with a high-sensitivity commercial spectrofluorometer. Fluorescence emission spectra recorded with this high-resolution instrument, using the laser excitation source, do not show resolved structured bands. Other results obtained on a high-sensitivity fluorometer with a very low stray light level show that, on the same sample, fluorescence spectra present a difference in the position between the maximum of the emission spectra when recorded with an excitation wavelength of 313 or 370 nm. The positions of the maxima of the emission spectra also show shifts between samples collected at different locations. No difference is observed between coastal and marine waters for a 370-nm excitation wavelength. On the other hand, an important blue shift (up to 20 nm) is observed between coastal and marine samples when 313 nm is used as the excitation wavelength. These results clearly show that marine and coastal waters have different fluorescence signatures, and demonstrate that high-sensitivity fluorescence spectroscopy is a promising tool for better elucidation of the behaviour of part of the complex dissolved organic matter in the ocean.

Organotin stability during storage of marine waters and sediments

SummaryThe stability of organotin compounds in water and sediment samples during storage and pre-treatment is of paramount importance. This study presents experiments with butyltin compounds showing that the storage of filtered natural seawater in the dark at pH 2 in pyrex glass bottles is suitable to preserve the stability of tributyltin (TBT) over 4 months both at 20–25°C and 4°C. The other butyltin compounds (mono- and dibutyltin) are stable at 4°C but display some losses at 25°C. A poor recovery of butyltins in turbid water hampered the assessment of the stability on a quantitative basis: however, it could be demonstrated on a qualitative basis that the butyltin stability is uneasily achieved in water samples with high suspended matter. Finally, wet storage and freezing are found to be suitable to preserve the tributyltin stability in sediments, as well as ovendrying (at 50°C), freeze-drying and air-drying. Mono- and dibutyltin are generally subject to changes during the storage of sediments using the different methods.

Metal contamination in surface sediments of mangroves, lagoons and Southern Bay in Florianopolis Island

Total concentrations for Hg, Pb, Cd, Se, As, Sn, U, Zn, Ni, Cu, Cr, Sb, Sr, Pd and Ag were determined in surface sediments of the mangroves, lagoons and Southern Bay from Florianopolis Island in Br...