The present study investigates the influence of an organophosphorus pesticide, namely Dimethoate, and cadmium on biomarkers of the green alga, Spirogyra sp., in a 14-day experiment. For so doing, it has exposed Spirogyra sp. to 0.0, 100, 200, and 400 mg L-1 of Dimethoate and/or 1 mg L-1 of cadmium chloride (CdCl2) to observe a reduction in chlorophyll a and b level in Spirogyra sp., exposed to 200 and 400 mg L-1 of Dimethoate as well as algae treated with cadmium alone or in combination with Dimethoate. Levels of malondialdehyde (MDA) and total antioxidant in cells, as well as the activity of ascorbate peroxidase (APX) soar in Spirogyra sp., exposed to Dimethoate and/or cadmium (alone or simultaneously). Also Spirogyra’sexposure to cadmium and/or Dimethoate significantly increases catalase (CAT) activity. However, levels of carotenoids in Spirogyra sp., treated with both cadmium and Dimethoate, decline significantly, with no significant change found in catalase activity of Spirogyra sp., exposed to 100 and 200 mg L-1 of Dimethoate, in comparison to the control group. However, CAT activity rises significantly in Spirogyra sp., treated with 400 mg L-1 of Dimethoate. Cadmium can cause cytotoxicity in 1 mg L-1 concentration of the green algae(Spirogyra sp.). On the whole, investigating the biological and biochemical markers in Spirogyra sp., exposed to different concentrations of Dimethoate, has revealed some concentration-dependent toxicity. Furthermore, Dimethoate can synergistically increase toxicity and bioavailability of cadmium in Spirogyra sp.

The present investigation characterizes tannery effluents by determining water quality parameters and some selected trace metallic constituents in order to measure the magnitude of environmental pollution. Effluents and sediments have also been used to isolate chromium-resistant bacteria, collected from Hazaribagh area, Dhaka, claimed to be increasing Cr (VI)-enriched environments, and utilized to reduce Cr (VI). The pH, TDS, DO, and EC values of all investigated samples have been within the range of 4.35 to 9.74, 290 to 9,200 mg/L, 1.5 to 4.90 mg/L, and 587 to 19,000 µs/cm, respectively. The concentrations of trace metallic constituents have been determined by means of Atomic Absorption Spectrophotometer (AAS), giving the following ranges: Cr: 14.282 to 6,769.554 mg/L; Cd: 1.546 to 2.214 mg/L; Pb: 18.808 to 32.026 mg/L; Cu: 1.522 to 2.578 mg/L; Zn: 0.682 to 8.688 mg/L; Fe: 1.37 to 108.556 mg/L; and Mn: 3.494 to 17.17 mg/L. The order of trace metallic constituents in the effluent samples was Cr > Fe > Pb > Mn > Zn > Cd > Cu. The water quality parameters and metallic constituents’ concentration were higher than that of standard permissible limits in all the examined samples. The average number of Cr (VI)-resistant bacteria in the sediment samples with glucose (0.5%, w/v) supplementation was 2.35× 103 CFU/gm at 24h. One of the representative isolate was able to tolerate up to 400 mg/L of K2Cr2O7 as Cr (VI). The bacteria, isolated in the present study, can be used as eco-friendly biological agents for the remediation and/or detoxification of chromium (Cr) pollution from the chromium contaminated environments.

The present study has been undertaken in a laboratory scale to characterize and investigate pollution potential of textile effluents from DEPZ area in Dhaka, Bangladesh. Collected effluent samples from five different industries were analyzed for physico-chemical parameters using field kits and Standard Methods, and for metals using Flame Atomic Absorption Spectrophotometer (FAAS). The average physico-chemical parameters such as temperature, color, pH, DO, EC, BOD, COD, TS, total alkalinity and total hardness were found 52.4 ºC, 2646 PCU, 9.788, 1.492 mg/L, 7473.2 μS/cm, 157 mg/L, 508.8 mg/L, 9140.8 mg/L, 761.2 mg/L and 189.6 mg/L, respectively. The average concentrations of metal found in the textile effluents were in the order of Na (4611.762 mg/L) > Ca (9.166 mg/L) > Mg (3.578 mg/L) > Zn (0.113 mg/L) > Ni (0.0074 mg/L) > Cu (0.0032 mg/L). All the measured physico-chemical parameter values are negatively deviated but metal concentrations (except Na) are positively deviated from standard limits of wastewater discharge set by Department of Environment and US Environmental Protection Agency. In view of those characteristics, the textile industry effluents should be considered to be treated by setting eco-friendly effluent treatment plant (ETP) before directly discharging into the water bodies.

International audience | Penguins have been recently identified as useful bioindicators of mercury (Hg) transfer to food webs in the Southern Ocean over different spatial and temporal scales. Here, feather Hg concentrations were measured in adults and chicks of all the seven penguin species breeding in the southern Indian Ocean, over a large latitudinal gradient spanning Antarctic, subantarctic and subtropical sites. Hg was also measured in feathers of museum specimens of penguins collected at the same sites in the 1950s and 1970s. Our aim was to evaluate geographical and historical variation in Hg transfer to penguins, while accounting for feeding habits by using the stable isotope technique (δ13C, habitat; δ15N, diet/trophic level). Adult feather Hg concentrations in contemporary individuals ranged from 0.7 ± 0.2 to 5.9 ± 1.9 µg g-1 dw in Adélie and gentoo penguins, respectively. Inter-specific differences in Hg accumulation were strong among both adults and chicks, and mainly linked to feeding habits. Overall, penguin species that feed in Antarctic waters had lower feather Hg concentrations than those that feed in subantarctic and subtropical waters, irrespective of age class and dietary group, suggesting different Hg incorporation into food webs depending on the water mass. While accounting for feeding habits, we detected different temporal variations in feather Hg concentrations depending on species. Notably, the subantarctic gentoo and macaroni penguins had higher Hg burdens in the contemporary rather than in the historical sample, despite similar or lower trophic levels, respectively. Whereas increases in Hg deposition have been recently documented in the Southern Hemisphere, future monitoring is highly needed to confirm or not this temporal trend in penguins, especially in the context of actual changing Hg emission patterns and global warming.

International audience | Studying long-term trends of contaminants in Arctic biota is essential to better understand impacts of anthropogenic activities and climate change on the exposure of sensitive species and marine ecosystems. We concurrently measured temporal changes (2006e2014) in mercury (Hg) contamination of little auks (Alle alle; the most abundant Arctic seabird) and in their major zooplankton prey species (Calanoid copepods, Themisto libellula, Gammarus spp.). We found an increasing contamination of the food-chain in East Greenland during summer over the last decade. More specifically, bird contamination (determined by body feather analyses) has increased at a rate of 3.4% per year. Conversely, bird exposure to Hg during winter in the northwest Atlantic (determined by head feather analyses) decreased over the study period (at a rate of 1.5% per year), although winter concentrations remained consistently higher than during summer. By combining mercury levels measured in birds and zooplankton to isotopic analyses, our results demonstrate that inter-annual variations of Hg levels in little auks reflect changes in food-chain contamination, rather than a reorganization of the food web and a modification of seabird trophic ecology. They therefore underline the value of little auks, and Arctic seabirds in general, as bio-indicators of long-term changes in environmental contamination.