Ecotoxicity of trace elements to chicken GALLUS gallus domesticus exposed to a gradient of polymetallic-polluted sites.

Mining activity may cause heavy metal accumulation, which threatens human and animal health by their long-term persistence in the environment. This study aims to assess the impact of polymetallic pollution on chicken (Gallus domesticus) from old lead mining sites in northeast of Tunisia: Jebel Ressas (JR). Samples of soil and chickens were collected from five sites being ranked along a gradient of heavy metal contamination. Heavy metal loads were evaluated in soil samples and in chicken liver and kidney. Biochemical evaluation of oxidative stress parameters termed as Catalase (CAT), Glutathione-S-Transferase (GST), and Malondialdehydes (MDA) accumulation was monitored. Metallothionein protein level was assessed as a specific response to heavy metals. DNA alteration was achieved using MNi frequency in the investigated tissues. Finally, the evaluation of gene expression levels of CAT, GST, mt1, mt4, P53, bcl2, caspase3 and DNA-ligase was performed. Our data showed the highest loads of Cd, Cu, Zn and Pb in tissues of animals from site 3, being more pronounced in kidney. Biochemical data suggested a significant increase in antioxidant enzymes activities in all sites respect to control except in site 3 were CAT and GST were inhibited. DNA alteration was observed in all tissues being very pronounced in animals from site 3. Overall, transcriptomic data showed that genes involved in apoptosis were up-regulated in animals exposed to the most contaminated soils. Our data suggest that chicken and selected biomarkers offer a suitable model for biomonitoring assessment of heavy metals transfer through the food web in mining sites. Finally, the obtained results of heavy metals accumulation and related alterations should be carefully considered in view of the controversial relationship between distribution and toxicology of contaminants in exposed organisms

Biochar amendment alleviates heavy metal phytotoxicity of Medicago sativa grown in polymetallic contaminated soil: Evaluation of metal uptake, plant response and soil properties

Air pollution and soil contamination have caused major environmental damage in the industrial complex of Gabes. This study aimed to evaluate the abilities of biochar to modify soil properties and assess the adaptation of alfalfa (Medicago sativa L.) plants in contaminated soils from the Gabes Region. The experiment was executed with soil samples from three sites (S1, S2 and S3) located at different distances from the industrial zone of Gabes. Additionally, a control soil was included for comparison. Pot experiments were performed under controlled conditions, with or without biochar. After 60 days, the accumulation of heavy metals in plants (roots, shoots and nodules) was determined. Moreover, oxidative stress biomarkers, such as malondialdehyde (MDA) content, glutathione-S-transferase (GST) and catalase (CAT), were evaluated. Soil microbiological properties, including bacterial functional diversity and fluorescein diacetate hydrolytic (FDA) activity, were analyzed, along with soil chemical properties. Our results revealed that biochar supplementation can improve microbial functions and cation-exchange capacity (CEC), thereby increasing the availability of nutrients to plants. Interestingly, the application of biochar resulted in decreased concentrations of copper (Cu) and zinc (Zn) in plants, which may be attributed to a reduction in their bioavailability in the soil. The accumulation of heavy metals in alfalfa organs was positively correlated with the levels of MDA and antioxidant enzymes in both leaves and roots. In this study, the addition of biochar reduced the antioxidant mechanisms of alfalfa and mitigated the negative effects of metals, resulting in a positive impact on growth and chlorophyll content. Our data highlights the beneficial effects of biochar on enhancing crop productivity and remediating contaminated soil

Biochar application mitigates salt stress on maize plant: Study of the agronomic parameters, photosynthetic activities and biochemical attributes

Climate change had caused many threats soil ecosystem, among them, soil salinity. Thus several strategies are suggested to mitigate this issue. In this context, biochar is known as a potent amendment able to alleviate the salt stress on the crops. Thus, the aim of the present investigation is to assess the impact of two salt levels (C1: 1.25 and C2: 2.5 g l−1) and two biochar rates (B1:50 g kg−1; B2: 100 g kg−1) on the agronomic, biochemical and physiological responses of maize plants (Zea mays L.). Our results revealed firstly an increase in maize biomass under salinity stress and in presence of 50g of biochar, indicating the important role of biochar in mitigating salt toxicity. Also, B1 biochar rate attenuated salt-induced oxidative stress by increasing glutathion-S-transferase (GST) and catalase (CAT) activities. Also, biochar increased chlorophyll b (Chlb) in plants treated with salt water. Overall, it can be concluded that biochar may be a useful strategy to reduce the harmful effects of salinity. However, biochar rates must be carefully used in saline soils to ameliorate plant development and reduce the toxicity of salt stress