Detection of Water and Sediments Pollution of An Arid Saltern (Sfax, Tunisia) by Coupling the Distribution of Microorganisms With Hydrocarbons

Abstract

International audienceWe investigated the coupling of abundance of bacteria, phytoplankton and ciliates with hydrocarbons in the surface water and sediments of five interconnected ponds in the arid Sfax solar salterns. This study aimed at determining the potential sources of hydrocarbons and the effects of salinity gradients on microorganism metabolism. Hydrocarbon analysis was performed by gas chromatography (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS). The GC-FID allowed the detection of aliphatic hydrocarbons and n-alkanes ranging from n-C13 to n-C30. Total aliphatic hydrocarbon concentrations varied from 92.5 mg. l−1 in the first pond (having marine characteristics) to 661.1 mg. l−1 in the last pond (crystallizer) (316.8±120.1 mg. l−1) for water samples and from 26.7 to 127.8 !g. g−1 dry weight for sediment samples. The GC-MS enabled us to detect halogenated hydrocarbons (bromoalkanes and chloroalkanes) and n-alkenes. The distribution of n-alkanes indices coupled to several environmental factors suggests that a major fraction of hydrocarbons resulted from both prokaryotic (bacteria) and eukaryotic (protists) developments. A low hydrocarbon fraction might be petrogenic

Space-time variation of ciliates related to environmental factors in 15 nearshore stations of the Gulf of Gabes

“…The high salt concentration found in water samples throughout the study is the clearest evidence of the Sabkha El Meleh influence on the Karboub ecosystem (Kchaou et al, 2009). This is reflected by the presence of substantial amounts of halotolerant Hetrotrichea F. salina (9.2 % of the ciliate total abundance), in Karboub samples, a species that was also found in high abundance in the primary ponds of Sfax saltern (Elloumi et al, 2008), yet in higher salinities (range . This change in ambient salinity resulted in smaller F. salina at the Karboub station (length = 75 µm; biovolume = 44.3 µm 3 ) than in the Sfax saltern (length = 111 µm; biovolume = 108.1 µm 3 ) (Elloumi et al, 2006(Elloumi et al, , 2009b.…”

“…The seasonal distribution of the ciliate community, coupled with environmental factors along the coast of the Gulf of Gabes, is investigated at three sampling stations (Tabia, Karboub and the Port of Gabes) (Kchaou et al, 2009). However, data on large scale distribution of ciliate assemblages are lacking, except, for a study on a man-made solar saltern receiving water inputs from the Gulf of Gabes (Elloumi et al, 2006(Elloumi et al, , 2008(Elloumi et al, , 2009a.…”

Impacts of restoration of an uncontrolled phosphogypsum dumpsite on the seasonal distribution of abiotic variables, phytoplankton, copepods, and ciliates in a man-made solar saltern

“…Despite their considerable landscape and economic value, and though studies clearly indicate that the salt-production process via evaporation and precipitation is closely related to biological processes (Davis 1990(Davis , 2000, salterns are now threatened biotopes, mainly due to human interference. This is particularly true of the Sfax saltern located on the southwestern Mediterranean coast and which suffered from pollution by phosphogypsum (Rekik et al 2012) and petroleum products (Elloumi et al 2008). Indeed, the anthropogenic nutrient input in the saltern'sre ce iving pond may have impacted the development of the ponds biological communities and correlatively the quality of the salt produced (1990).…”

The effect of lake restoration by the hypolimnetic withdrawal method on the intensity of ambient odour

“…This method involves the removal of oxygen-deficient water from the lake's hypolimnion layer, which is characterized by significant fertility and the presence of methane, hydrogen sulphide and decomposable organic matter, to the receiving body, usually a river (Cooke et al, 1982;Klapper, 1991;Nürnberg, 2007;Górniak et al, 2014;Zamparas and Zacharias, 2014). Hypolimnion water pollutes the watercourse into which it is discharged, and it induces periodic changes in hydrochemical and biological conditions (Elloumi et al, 2008). Some previous studied showed that without careful management, hypolimnetic releases can degrade water quality in the receivers such as rivers with small flows (Marshall et al, 2006;Nürnberg, 2007).…”