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

Abstract

. 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. Environmental Monitoring and Assessment, Springer Verlag (Germany), 2012, 185, pp.2139-2155. 10.1007/s10661-012-2695-9. hal-00827412 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 Abstract The restoration of an uncontrolled phosphogypsum landfill was investigated for its effects on the seasonal distribution of phytoplankton, ciliates, and copepods. Sampling was carried out monthly from September 2007 to August 2008 at four ponds of increasing salinity (A1, 41 psu; A5, 46 psu; A16, 67 psu; and C31, 77 psu) in the Sfax solar saltern (southeastern Tunisia). Physicochemical and biological analyses were carried out using standard methods. Results showed drastic reduction of phosphate input and greater diversity of phytoplankton, ciliates, and copepods than before restoration. Pennate diatoms and new ciliates, considered bio-indicators of less-stressed marine ecosystems, proliferated in the A1 pond for the first time after restoration. Copepods appeared to feed on a wide range of prey. Economically, removal of the 1.7 million m 3 of phosphate improved the quality of the site's salt production, enabling the salt company to receive the quality ISO 9001 accreditation.

Spring phytoplankton variability along a south coast of Sfax at the water-sediment interface (Tunisia, Eastern Mediterranean Sea)

“…The positive relationship between chlorophyll-a, salinity, suspended matter and total phosphate in G1. Forms of N-nutrients (NO 3 -, NO 2 -, NH 4 + and N/P ratio) linked to Cyanobacteriae abundance (G2). Low concentration of orthophosphate was correlated to phytoplankton groups such as Dinophyceae, Bacillariophyceae, Euglenophyceae and Dictyochophyceae (G3).…”

“…Low concentration of orthophosphate was correlated to phytoplankton groups such as Dinophyceae, Bacillariophyceae, Euglenophyceae and Dictyochophyceae (G3). G4 comprised of temperature, pH, TN and Si(OH) 4 . In spring 2011, the PCA plots illustrated that, in G1 selected, microorganism's diversity (Bacillariophyceae, Dinophyceae, Cyanobacteriae and Euglenophyceae) was linked to chlorophyll -a, salinity, suspended matter and ammonium.…”

“…In spring 2011, the PCA plots illustrated that, in G1 selected, microorganism's diversity (Bacillariophyceae, Dinophyceae, Cyanobacteriae and Euglenophyceae) was linked to chlorophyll -a, salinity, suspended matter and ammonium. G2 and G4 formed by physico-chemical variables [pH, NO 3 -, NO 2 -, total N and N/P ratio (G2) Temperature, total P and Si(OH) 4 (G4)]. The presence of Dictyochophyceae in G3 was associated with high orthophosphate concentration (Figure 4).…”

“…Sfax is characterized by a dry climate and by the hot southerly wind [2]. The south coast of Sfax is marked by salt extraction ponds from solar saltern located over an area of about 1 500 hectare (COTUSAL, a company) and, especially, by an uncontrolled dumpsite of phosphate treatment from the plant for producing phosphoric acid (SIAPE, Tunisian phosphate industry) [3][4][5]. Its southern coastal area is subject to degradation of water quality [2].…”

“…The coastal area has been subjected to an increase in industrial and human activities; the population development and anthropogenic pollution have resulted in degradation of water quality and marine sediments [6,7], growing eutrophication [3,4], green tides caused by coastal Ulva rigida replacing the Posidonia oceanica seagrass beds [8], and thus degrading benthic habitats [9].…”