Adaptive biochemical and physiological responses of Eriobotrya japonica to fluoride air pollution.

The biochemical and physiological effects of fluoride were investigated in loquat trees (Eriobotrya japonica) grown in the vicinity of a phosphate fertilizer plant in Tunisia. Photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were assessed; along with photosynthetic pigments, lipid peroxidation, electrolytic leakage (EL) and total phenolic contents in foliage and roots of trees at different distances from the phosphate fertilizer plant. All assessed parameters showed significant discrepancies in comparison with unpolluted sites. Obtained results showed high oxidative stress indices including H2O2, lipid peroxidation, and EL, SOD, CAT and GPx activities and proline contents in leaves and roots at the polluted sites as compared to control. In contrast, leaf Pn, Gs, E and photosynthetic pigment contents were low as compared to the control. These results indicate that even though antioxidant responses increased near the factory, adverse effects on physiology were pronounced.

Estrogenic compounds in Tunisian urban sewage treatment plant: occurrence, removal and ecotoxicological impact of sewage discharge and sludge disposal.

The occurrence, fate and ecotoxicological assessment of selected estrogenic compounds were investigated at Tunisian urban sewage treatment plant. The influents, effluents, as well as primary, secondary and dehydrated sludge, were sampled and analyzed for the target estrogens to evaluate their fate. All target compounds were detected in both sewage and sludge with mean concentrations from 0.062 to 0.993 µg L-1 and from 11.8 to 792.9 µg kg-1dry weight, respectively. A wide range of removal efficiencies during the treatment processes were observed, from 6.3 % for estrone to 76.8 % for estriol. Ecotoxicological risk assessment revealed that the highest ecotoxicological risk in sewage effluent and dehydrated sludge was due to 17ß-estradiol with a risk quotient (RQ) of 4.6 and 181.9, respectively, and 17α-ethinylestradiol with RQ of 9.8 and 14.85, respectively. Ecotoxicological risk after sewage discharge and sludge disposal was limited to the presence of 17ß-estradiol in dehydrated-sludge amended soil with RQ of 1.38. Further control of estrogenic hormones in sewage effluent and sludge is essential before their discharge and application in order to prevent their introduction into the natural environment.

Electrochemical treatment of olive mill wastewater: treatment extent and effluent phenolic compounds monitoring using some uncommon analytical tools.

Problems related with industrials effluents can be divided in two parts: (1) their toxicity associated to their chemical content which should be removed before discharging the wastewater into the receptor media; (2) and the second part is linked to the difficulties of pollution characterisation and monitoring caused by the complexity of these matrixes. This investigation deals with these two aspects, an electrochemical treatment method of an olive mill wastewater (OMW) under platinized expanded titanium electrodes using a modified Grignard reactor for toxicity removal as well as the exploration of the use of some specific analytical tools to monitor effluent phenolic compounds elimination. The results showed that electrochemical oxidation is able to remove/mitigate the OMW pollution. Indeed, 87% of OMW color was removed and all aromatic compounds were disappeared from the solution by anodic oxidation. Moreover, 55% of the chemical oxygen demand (COD) and the total organic carbon (TOC) were reduced. On the other hand, UV-Visible spectrophotometry, Gaz chromatography/mass spectrometry, cyclic voltammetry and 13C Nuclear Magnetic Resonance (NMR) showed that the used treatment seems efficaciously to eliminate phenolic compounds from OMW. It was concluded that electrochemical oxidation in a modified Grignard reactor is a promising process for the destruction of all phenolic compounds present in OMW. Among the monitoring analytical tools applied, cyclic voltammetry and 13C NMR a re among th e techniques that are introduced for thefirst time to control the advancement of the OMW treatment and gave a close insight on polyphenols disappearance.

Benthic foraminiferal assemblages as pollution proxies in the northern coast of Gabes Gulf, Tunisia.

A study of chemical and sedimentological parameters integrated with benthic foraminifera investigation was conducted along the northern coast of Gabes Gulf. Thirty-two samples were studied and a total of 68 benthic foraminiferal species were identified. Heavy metals enrichment factors and total hydrocarbon concentrations showed both metal and petrogenic pollution related mainly to phosphogypsum, sewage, and fishing activities. Statistical analysis (bivariate correlation and hierarchical cluster analysis) show a possible control of these pollutants on density, diversity, as well as the taxonomic composition of the benthic foraminiferal assemblages. The extent to which the population was found less dense and less diversified corresponded to the degree to which the sediment was contaminated. In these contaminated sites, an increase in relative abundance of opportunistic species such Ammonia tepida and Haynesina germanica was found. Far from pollution, foraminiferal assemblages are dominated by species characteristic of Mediterranean shallow water (Ammonia beccarii, Ammonia parkinsoniana, Elphidium crispum, Elphidium williamsoni, Elphidium advenum, Peneroplis planatus, Peneroplis pertesus).

Environmental quality assessment of the fish farms' impact in the Monastir Bay (eastern of Tunisia, Central Mediterranean): a benthic foraminiferal perspective.

Offshore fish farms have been active inside the Monastir Bay, Hammemet Gulf for over 10 years, but their environmental impact is still unknown. This study focuses on the evaluation of the fish farming activity impact in the Monastir Bay as revealed by geochemical and benthic foraminiferal data. Samples were collected around three fish cages at different water depths. Total organic carbon (TOC) and total phosphate (TP) in the sediment show higher values beneath the fish cages and decrease proportionally with distance from the cages. Living foraminiferal assemblages around fish farms are dominated by stress-tolerant species with higher abundances of Ammonia tepida, Rosalina bradyi, Elphidium crispum, and Peneroplis planatus. On the basis of our results, A. tepida and Quinqueloculina seminula are confirmed to be tolerant to elevated nutriment content, while Ammonia parkinsoniana seems to be more sensitive to organic enrichment. We also test the Foram-AMBI that is revealed to be a very promising tool by which evaluating the ecological quality status of marine sediment. The results of the present study confirm the suitability of living benthic foraminifera as bioindicators of organic enrichment induced by aquaculture activities.

Assessment of organic and metallic contamination in the surface sediment of Monastir Bay (Eastern Tunisia): Spatial distribution, potential sources, and ecological risk assessment.

To investigate the current environment status in Monastir Bay (Tunisia), surface sediments from 32 stations were assessed for heavy metal and organic matter concentrations, and the results were compared with values of natural metal content, marine sediment quality standards, and other results concerning sediments from other Mediterranean coasts. The study of their spatial distributions refined by complementary approaches, including potential ecological risks determined through the enrichment factor, geo-accumulation index, contamination factor, potential ecological risk index, pollution load index, and principal component analysis, showed a significant impact of multiple anthropogenic sources. Moderate pollution of sediments, particularly by Ni and Cu, was also observed. Moreover, TOC values showed that the northern part of Monastir Bay is characterized by high levels of sediment organic matter because of the presence of fish farm cage. This baseline study can be used to establish background values for future sediment surveys.

A newly isolated strain of Serratia sp. from an oil spillage site of Assam shows excellent bioremediation potential.

A hydrocarbon-degrading strain was isolated from a petroleum oil-contaminated site which was identified on the basis of 16S rDNA gene sequencing as a member of the genus Serratia. The isolate reduced surface tension of petroleum oil supplemented medium by 48.35% with respect to control after 7 days of treatment. Fluorescence microscopy revealed that its chemotaxis was towards hydrocarbon. The isolate degraded 87.54 and 85.48% of diesel and kerosene in liquid culture, respectively, after 28 day incubation at 37 ± 2 °C. The ex situ pilot scale bioremediation experiment in which artificially contaminated soil (10 and 20% v/w kerosene) was treated for 7 days showed a germination rate of Vigna radiate seeds of 52% and 72%, respectively. Interestingly, a germination rate of 31% was obtained with the heavily contaminated soil samples collected from the oil spillage site after 20 days of bioremediation treatment. The presence of υCH3 (asymmetric stretching), υC=C (stretch), and υC-C (stretch) in the crude biosurfactant produced by the isolate was revealed by FTIR analysis, and emulsification index (E 24) was found 60 and 56.6%, respectively, against diesel and kerosene oil. The non-cytotoxicity nature of the biosurfactant also supports its potential application in field trial.

Biochemical and physiological responses of halophilic nanophytoplankton (Dunaliella salina) from exposure to xeno-estrogen 17α-ethinylestradiol.

The environmental impacts of various pollutants on the entire levels of organisms are under investigation. Among these pollutants, endocrine-disrupting compounds (EDCs) present a serious hazard, even though the environmental significance of these compounds remains basically unknown. To drop some light on this field, we assessed the effects of a 11-day exposure of 17α-ethinylestradiol (EE2) on the growth, metabolic content, antioxidant response, oxidative stress, and genetic damage of Dunaliella salina, isolated from Tunisian biotopes. The results showed that at 10 ng L-1, EE2 could stimulate the growth of D. salina and increase its cellular content of photosynthetic pigments and metabolites; however, it did not significantly increase the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) or the level of malondialdehyde (MDA) and hydrogen peroxide (H2O2). In contrast, exposure to high levels of EE2 concentrations significantly inhibited the growth of D. salina (P < 0.05), decreased the cellular content of photosynthetic pigments, increased the cellular content of all of the metabolites and the SOD activity, and inhibited CAT and GPx activities. Nevertheless, the balance between oxidant and antioxidant enzymes was disrupted because H2O2 content along with MDA content simultaneously increased. Contrary to expected results, DNA damage (strand breaks) decreased after the exposure of algae to EE2. The results of this study suggest that EE2 toxicity could result in environmental impacts with consequences on the whole aquatic community. Graphical abstract.

Box-Behnken design for extraction optimization of crude polysaccharides from Tunisian Phormidium versicolor cyanobacteria (NCC 466): Partial characterization, in vitro antioxidant and antimicrobial activities.

In this study, response surface methodology (RSM) based on Box-Behnken design (BBD) was employed to optimize the aqueous extraction of crude polysaccharides from Tunisian cyanobacteria Phormidium versicolor (NCC 466). The optimal extraction conditions with an extraction yield of 21.56±0.92% were as follows: extraction temperature at 81.05°C, extraction time of 3.99h, and water to raw material ratio of 21.52mLg-1. Crude Phormidium versicolor polysaccharides (CPv-PS) are found to be a hetero-sulfated-anionic polysaccharides that contained carbohydrate (79.37±1.58%), protein (0.45±0.11%), uronic acids (4.37±0.19%) and sulfate (6.83±0.28%). The carbohydrate fraction was composed of arabinose, xylose, ribose, rhamnose, N-acetyl glucosamine, galactose, glucose, mannose, glucuronic acid and saccharose with corresponding mole percentages of 2.41, 14.58, 2.18, 6.23, 7.04, 28.21, 26.04, 3.02, 0.86 and 5.07, respectively. Evaluation of the antioxidant activity in vitro suggested that CPv-PS strongly scavenged radicals, prevented bleaching of ß-carotene and reduced activity. Furthermore, the CPv-PS exhibited effective antimicrobial properties.

Impact of treated urban wastewater for reuse in agriculture on crop response and soil ecotoxicity.

The scarcity of freshwater resources is a serious problem in arid regions, such as Tunisia, and marginal quality water is gradually being used in agriculture. This study aims to study the impact of treated urban wastewater for reuse in agriculture on the health of soil and food crops. The key findings are that the effluents of Sfax wastewater treatment plant (WWTP) did not meet the relevant guidelines, therefore emitting a range of organic (e.g., up to 90 mg L(-1) COD and 30 mg L(-1) BOD5) and inorganic pollutants (e.g., up to 0.5 mg L(-1) Cu and 0.1 mg L(-1) Cd) in the receiving aquatic environments. Greenhouse experiments examining the effects of wastewater reuse on food plants such as tomato, lettuce, and radish showed that the treated effluent adversely affected plant growth, photosynthesis, and antioxidant enzyme contents. However, the pollution burden and biological effects on plants were substantially reduced by using a 50 % dilution of treated sewage effluent, suggesting the potential of reusing treated effluent in agriculture so long as appropriate monitoring and control is in place.

Valorization of treated olive mill wastewater in fertigation practice.

Olive mill wastewater (OMW) brings about a major environmental problem in Tunisia as well as in the other Mediterranean countries. Its strong organic load and its toxicity due to the presence of complex phenolic compounds have dire effects when applied to soil. To overcome this difficulty, the OMW pretreatment was investigated in the present work using the Fenton oxidation reaction with zero-valent iron. Then, this pretreated wastewater was valorized in fertigation practice. The effects of the addition of different concentrations of both treated and raw OMW on soil and cropping system were investigated. The treatment by Fenton oxidation with zero-valent iron could reduce 50 % of COD and decrease 53 % of phenolic compounds. OMW application had a temporary effect on the soil pH and EC. The results showed that the evolution of soil pH and EC was related to the organic matter of the soil which depends on the spread concentrations of raw or treated OMW. After 15-day incubation period, the soil pH and EC tended to stabilize and return to the control level. Moreover, this stabilization is faster in treated OMW than that in raw OMW especially for concentrations as high as 3 and 4 %. Plants cultivated with treated OMW showed an increase in their germination. The results pointed an improvement in the stem length of plants which is almost similar to that of the control for both pea and tomato, especially for high concentrations of 3 and 4 %.

Effects of sewage sludge fertilizer on heavy metal accumulation and consequent responses of sunflower (Helianthus annuus).

Use of sewage sludge, a biological residue produced from sewage treatment processes in agriculture, is an alternative disposal technique of waste. To study the usefulness of sewage sludge amendment for Helianthus annuus, a pot experiment was conducted by mixing sewage sludge at 2.5, 5, and 7.5 % (w/w) amendment ratios to the agricultural soil. Soil pH decreased whereas electrical conductivity, organic matter, total N, available P, and exchangeable Na, K, and Ca increased in soil amended with sewage sludge in comparison to unamended soil. Sewage sludge amendment led to significant increase in Pb, Ni, Cu, Cr, and Zn concentrations of soil. The increased concentration of heavy metals in soil due to sewage sludge amendment led to increases in shoot and root concentrations of Cr, Cu, Ni, and Zn in plant as compared to those grown on unamended soil. Accumulation was more in roots than shoots for most of the heavy metals. Moreover, high metal removal for the harvestable parts of the crops was recorded. Sewage sludge amendment increased root and shoot length, leaves number, biomass, and antioxidant activities of sunflower. Significant increases in the activities of antioxidant enzymes and in the glutathione, proline, and soluble sugar content in response to amendment with sewage sludge may be defense mechanisms induced in response to heavy metal stress. Graphical abstract Origin, fate and behavior of sewage sludge fertilizer.

Hydrocarbons in surface sediments from the Sfax coastal zone, (Tunisia) Mediterranean Sea.

The Semi-enclosed Mediterranean Sea records various signals of high anthropic pressures from surrounding countries and the industrialized European countries. This is particularly true for oil pollution. Although accounting for 1% of the world's ocean surface, it receives about 25% of the petroleum inputs to the ocean. To achieve a global budget we need to collect information from different parts of the Mediterranean. Particularly, we focus in this paper on the Southern Mediterranean, where data are presently very scarce. In this context, the University of Sfax has undertaken an estimation of hydrocarbon pollution along the coasts of Sfax and Gabès Gulf. Non-aromatic hydrocarbons were analysed in 8 surface sediments by FT/IR and GC/MS. Non-aromatic hydrocarbon concentrations vary in the range 310-1406 microg g(-1) sediments dry weight, which is high, compared to other Mediterranean sites. GC/MS data indicate a large group of unresolved compounds suggesting a petroleum contamination, confirmed by the identification of hopanes with predominant C29 and C30alpha,beta compounds and steranes with predominance of C27 over C28) and C29 compounds.

Effect of phosphogypsum on growth, physiology, and the antioxidative defense system in sunflower seedlings.

Phosphogypsum (PG) is the solid waste product of phosphate fertilizer production and is characterized by high concentrations of salts, heavy metals, and certain natural radionuclides. The work reported in this paper examined the influence of PG amendment on soil physicochemical proprieties, along with its potential impact on several physiological traits of sunflower seedlings grown under controlled conditions. Sunflower seedlings were grown on agricultural soil substrates amended with PG at rates of 0, 2.5, and 5 %. The pH of the soil decreased but electrical conductivity and organic matter, calcium, phosphorus, sodium, and heavy metal contents increased in proportion to PG concentration. In contrast, no variations were observed in magnesium content and small increases were recorded in potassium content. The effects of PG on sunflower growth, leaf chlorophyll content, nutritional status, osmotic regulator content, heavy metal accumulation, and antioxidative enzymes were investigated. Concentrations of trace elements in sunflower seedlings grown in PG-amended soil were considerably lower than ranges considered phytotoxic for vascular plants. The 5 % PG dose inhibited shoot extension and accumulation of biomass and caused a decline in total protein content. However, chlorophyll, lipid peroxidation, proline and sugar contents, and activities of antioxidant enzymes such as superoxide dismutase and catalase increased. Collectively, these results strongly support the hypothesis that enzymatic antioxidation capacity is an important mechanism in tolerance of PG salinity in sunflower seedlings.

Olive mill wastewater degradation by Fenton oxidation with zero-valent iron and hydrogen peroxide.

The degradation of olive mill wastewater (OMW) with hydroxyl radicals generated from zero-valent iron and hydrogen peroxide has been investigated by means of chemical oxygen demand (COD) and phenolic compounds analyses. The effects of the H2O2 dose, the pH and the organic matter concentration have been studied. The optimal experimental conditions were found to have continuous presence of iron metal, acid pH (2.0-4.0), and relatively concentrated hydrogen peroxide (9.5M). Coloration of OMW disappeared and phenolic compound decreased to 50% of initial concentration after 3h reaction time. The application of zero-valent Fe/H2O2 procedure permitted high removal efficiencies of pollutants from olive mill wastewater. The results show that zero-valent Fe/H2O2 could be considered as an effective alternative solution for the treatment of OMW or may be combined with a classical biological process to achieve high quality of effluent water.