Distribution and ecological risk of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in surface sediments from the Bizerte lagoon,Tunisia

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were determined in 18 surface sediment samples collected from Bizerte lagoon, Tunisia. The total concentrations of ten PCBs (∑PCBs) and of four OCPs (∑OCPs) in the sediments from this area ranged from 0.8 to 14.6 ng g^?1 dw (average value, 3.9 ng g^?1 dw) and from 1.1 to 14.0 ng g^?1 dw (average value, 3.3 ng g^?1 dw), respectively. Among the OCPs, the range of concentrations of dichlorodiphenyltrichloroethane and its metabolites (DDTs) and hexachlorobenzene (HCB) were 0.3–11.5 ng g^?1 dw (1.9 ng g^?1 dw) and 0.6–2.5 ng g^?1 dw (1.4 ng g^?1 dw), respectively. Compositional analyses of the POPs indicated that PCB 153, 138 and 180 were the predominant congeners accounting for 60 % of the total PCBs. In addition, p,p′-DDT was found to be the dominant DDTs, demonstrating recent inputs in the environment. Compared with some other regions of the world, the Bizerte lagoon exhibited low levels of PCBs and moderate levels of HCB and DDTs. The high ratios ΣPCBs/ΣDDTs indicated predominant industrial versus agricultural activities in this area. According to the established guidelines for sediment quality, the risk of adverse biological effects from such levels of OCPs and PCBs, as recorded at most of the study sites, was insignificant. However, the higher concentrations in stations S1 and S3 could cause biological damage.     

Risk of laryngeal and nasopharyngeal cancer associated with arsenic and cadmium in the Tunisian population

Chronic exposure to heavy metals has long been recognized as being capable of increasing head and neck cancer (HNC) incidence, such as laryngeal (LC) and nasopharyngeal (NPC), among exposed human populations. The aim of the present study was to evaluate the concentrations of arsenic (As) and cadmium (Cd) in the blood of 145 patients (LC and NPC) and 351 controls in order to establish a potential relationship between these factors and the occurrence of LC and NPC. Mean blood levels of As and Cd in patients (5.67 and 3.51 μg/L, respectively) were significantly higher than those of controls (1.57 and 0.74 μg/L, respectively). The blood levels of As and Cd were mostly significantly higher than those of controls (p?<?0.05) after controlling the other risk factors of HNC including tobacco smoking and chewing, and alcohol drinking. Cd levels in blood increase significantly with the number of occupational exposure years for patients (p?<?0.05). However, seafood was not found to be contributing as an exposure source. Among these risk factors, smoking (>30 pack years) and occupational exposure (>20 years) presented the most significant association with HNC (OR?=?10.22 and 10.38, respectively, p?<?0.001). Cd level in blood sample of cases that are occupationally exposed/tobacco users (smokers and chewers) were higher than that of non-occupationally exposed/nontobacco users (p?<?0.001). The logistic regression model illustrated that HNC (LC?+?NPC) was significantly associated with blood levels of As (OR?=?2.41, p?<?0.001) and Cd (OR?=?4.95, p?<?0.001).     

Interaction of selenium and cadmium in wheat at different salinities

Abstract

Interaction of Se up to 8?mg?kg^?1 soil and Cd at 5 and 15?mg?kg^?1 soil in wheat at different salinities was evaluated. Se concentrations in wheat shoots were progressively increased in parallel to Se in soil but decreased by addition of Cd. With increasing salinity, Cd concentrations increased and Se decreased. At low salinity, low addition of Se to the soil reduced Cd accumulation. At moderate and high salinities, only high Se amendment led to decline in Cd uptake, at the expense of reduction in biomass yield. Se at 0.5?mg?kg^?1 soil alleviated the negative effect of Cd on shoot yield.     

Sodium arsenate induce changes in fatty acids profiles and oxidative damage in kidney of rats

Six groups of rats (n?=?10 per group) were exposed to 1 and 10 mg/l of sodium arsenate for 45 and 90 days. Kidneys from treated groups exposed to arsenic showed higher levels of trans isomers of oleic and linoleic acids as trans C181n-9, trans C18:1n-11, and trans C18:2n-6 isomers. However, a significant decrease in eicosenoic (C20:1n-9) and arachidonic (C20:4n-6) acids were observed in treated rats. Moreover, the “Δ5 desaturase index” and the saturated/polyunsaturated fatty acids ratio were increased. There was a significant increase in the level of malondialdehyde at 10 mg/l of treatment and in the amount of conjugated dienes after 90 days (p?p?p?p?n-6 polyunsaturated fatty acids and leads to an increase in the trans FAs isomers. Therefore, FA-induced arsenate kidney damage could contribute to trigger kidney cancer.     

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.     

Biomonitoring of cadmium, chromium, nickel and arsenic in general population living near mining and active industrial areas in Southern Tunisia

The human health impact of the historic and current mining and industrial activities in Tunisia is not known. This study assessed the exposure to metals in the population of Southern Tunisia, using biomonitoring. The aim of this pilot study was to evaluate metal exposure on 350 participants living near mining and active industrial areas in the South of Tunisia. Blood specimens were analyzed for metals (Cd, Cr, As, and Ni) by Atomic Absorption Spectrometer equipped with Zeeman background correction and AS-800 auto sampler by graphite furnace and graphite tubes with integrated L'vov platform. The sample population was classified according to different age groups, sex, smoking habit, sea food and water drinking consumption, occupational exposure, amalgam fillings and place of residence. The blood As, Cd, Cr and Ni values expressed as mean?±?SD were 1.56?±?2.49, 0.74?±?1.15, 35.04?±?26.02 and 30.56?±?29.96 μg/l, respectively. Blood Cd and Ni levels in smokers were 2 and 1.2 times, respectively, higher than in non-smokers. Blood Cd levels increase significantly with age (p?=?0.002). As, Cd and Ni were significantly correlated with gender and age (p?<?0.05). Cd level in blood samples of subjects occupationally exposed was 1.3 times higher than that of non-exposed. Blood metals were not significantly affected by amalgam fillings, place of living and sea food and drinking water consumption. This first biomonitoring study of metal exposure in the South of Tunisia reveals a substantial exposure to several metals. The pathways of exposure and health significance of these findings need to be further investigated.     

Concentration of polychlorinated biphenyls and organochlorine pesticides in mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) from Bizerte Lagoon (Northern Tunisia)

Concentrations of polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) were determined in two fish species, mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax), collected from Bizerte Lagoon and the Mediterranean Sea. In all samples, PCBs were found in higher concentrations than OCPs. The highest concentrations of OCPs and PCBs were found in sea bass, and in Bizerte Lagoon. Concentrations of DDTs and PCBs detected in this study were generally comparable or slightly higher than those found in studies from other Mediterranean and non-Mediterranean regions subject to a high anthropogenic impact. ∑PCBs, ∑HCHs and HCB levels were negatively correlated with lipid content, while no such correlation was seen for ∑DDTs. A significant correlation between levels and length and between levels and weight existed only for ∑PCBs. The daily intake of PCBs and OCPs ingested by people living in Bizerte through the studied fish species was estimated and compared with those observed in other areas.     

Degradation of Acid Orange 7 by electrochemically generated (*)OH radicals in acidic aqueous medium using a boron-doped diamond or platinum anode: a mechanistic study

A comparative study of the degradation of Acid Orange 7 (AO 7) aqueous solutions in acidic medium of pH 3.0 by electro-Fenton process using Pt or boron-doped diamond (BDD) anode was reported. The oxidative degradation of AO 7 by electrochemically generated hydroxyl radicals follows a pseudo-first order kinetic with a similar rate constant with BDD or Pt anode. The absolute rate constant of the AO 7 hydroxylation reaction was determined as (1.10+/-0.04)x10(10)M(-1)s(-1) by using the competition kinetic method. The comparative study of TOC measurements during electro-Fenton treatment showed a higher mineralization rate with BDD than Pt anode at the first hours of electrolysis because of the higher oxidizing power of this anode. The electro-Fenton degradation of AO 7 was followed by monitoring the formation and evolution of aromatic intermediates which are oxidized to aliphatic carboxylic acids before mineralization (transformation to CO(2) and inorganic ions, i.e. sulphate, nitrate and ammonium). The follow-up of the solution toxicity evolution shows the formation of intermediates more toxic than AO 7 and the connection between toxicity and aromaticity. A mineralization reaction pathway of AO 7 by electro-Fenton degradation involving all the intermediates identified was proposed.     

Concentrations of organochlorine pesticides and polychlorinated biphenyls in human serum and their relation with age,gender, and BMI for the general population of Bizerte,Tunisia

Human serum samples (n?=?113) from Bizerte, northern Tunisia, collected between 2011 and 2012 were analyzed for 8 organochlorine pesticides (OCPs) including p,p′-dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB), hexachlorocyclohexane isomers, dieldrin, and heptachlor and 12 polychlorinated biphenyls (PCBs) congeners. Concentrations of these residues in serum were determined by gas chromatography with electron capture detector and total cholesterol (CHOL) and triglycerides (TG) levels were evaluated by enzymatic colorimetric method. HCB, p,p′-DDE, PCB-138, PCB-153, and PCB-180, were the most abundant organochlorine compounds (OCs) detected in >95 % of the study subjects. The mean levels of p,p′-DDE and HCB in serum were 168.8 and 49.1 ng?g^?1 lipid, respectively. The sum PCBs concentrations ranged from 37.5 to 284.6 ng?g^?1 lipid in the samples, with mean and median value of 136.1 and 123.2 ng?g^?1 lipid, respectively. The PCB profile consisted of persistent congeners, such as PCB-138, PCB-153, and PCB-180 which contributed for approximately 82.7 % to the ∑PCBs. Statistical analysis showed that most OCs correlated significantly with age, considering all samples together or with gender differentiation. The present study shows that the levels of p,p′-DDE and ∑DDTs were significantly higher in females than in males (p?<?0.05), while PCBs levels were significantly higher in male (p?<?0.05) than in females. No statistically significant association was found between body mass index and concentration of any organochlorine pesticide or PCB congeners 153, 138, 180, or ∑PCBs.     

Effects of sewage sludge fertilizer on heavy metal accumulation and consequent responses of sunflower (<Emphasis Type="Italic">Helianthus annuus</Emphasis>)

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.

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Graphical abstract Origin, fate and behavior of sewage sludge fertilizer