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One of the big environmental problems in today’s world is dye-contaminated toxic waste. Peroxidase is known as highly efficient for the degradation of various pollutants, including dyes. Environmental contamination caused by the discharge of dyes into water bodies is an onerous challenge that poses both human and ecological hazards. In the current studies, biocatalysts used for enzyme decolorization (1847 Colafx Blue P3R and 621 Colafx Blue) are regarded as an eco-friendly method utilizing commonly available low-cost material lemon peels (Citruslimon peroxidase). Peroxidase was extracted in a phosphate buffer of pH 7.0 and partially purified by 20–80% ammonium sulfate precipitation technique from Citruslimon peels. The soluble enzyme was characterized in terms of kinetic and thermodynamic parameters. The values of Km and Vmax (23.16 and 204.08 μmol/ml/min) were determined, respectively. The enzyme showed maximum activity at pH 5.0 and a temperature of 55 °C. Citruslimon efficiently degraded 1847 Colafx Blue P3R and 621 Colafx Blue R dyes with maximum degradation of 83 and 99%, respectively, with an initial dye concentration of 200 ppm at pH 4 and 35 °C temperature within 5–10 min of incubation time. The effect of the redox mediator on the degradation process was examined. Results showed that the peroxidase HOBT system efficiently enhanced the degradation of dyes from water. Hence, Citruslimon peroxidase is an efficient biocatalyst for the treatment of effluents.

This study investigated mercury (Hg) contamination in the Gilgit-Baltistan, Pakistan. Water and sediment samples were collected from various sites having artisanal gold-mining along the Indus, Gilgit, and Hunza Rivers. Sediments were classified as wet sediment (WS, collected just after amalgamation), fresh dry sediment (FDS, collected after 1–2 h of amalgamation), and old dried sediment (ODS, collected after 1–2 days of amalgamation). Samples were analyzed for Hg by atomic absorption spectrophotometry with a mercury hydride system. Mercury mean concentrations were 2767 mg/kg in WS, 1917 mg/kg in FDS, and 191 mg/kg in ODS. These results revealed very high levels of Hg contamination in the WS and FDS. The Hg contamination of the spring (drinking water) did not exceed the permissible limits set by the World Health Organization (WHO) and Pakistan’s environmental protection agency (Pak-EPA); however, the stream water surpassed these limits. Therefore, the Hg levels in the drinking water was used to assess the potential human health risk via the average daily dose (ADD) and hazard quotient (HQ). The ADD values were 0.03 and 0.06 µg/kg-day and HQ value of 0.9 and 2.0 for adults and children, respectively. This level of Hg contamination level is alarming and could be hazardous in future.

Mercury (Hg) is considered as a global pollutant because of its presence in every environmental sector. This study was conducted to investigate the negative impacts of Hg on the human beings involved in gold mining along the three rivers (Gilgit, Hunza and Indus) in the northern areas of Pakistan. Biological samples such as blood, urine, hair and nails were obtained from the gold miners including men and women and extracted using standard procedure. The final extracts were analyzed for Hg and its species concentrations using atomic absorption spectrophotometer (Perkin Elmer-700) equipped with mercury hydride system (MHS-15). Total Hg concentrations in the blood, plasma, urine, hair and nails of male workers were 41 μg/L, 30.8 μg/L, 49.5 μg/L 0.64 μg/kg and 0.46 μg/kg, respectively, while in female workers were 44.4 μg/L, 36.8 μg/L, 41.5 μg/L, 1.1 μg/kg and 0.97 μg/kg, respectively. The results indicated that Hg in all (100%) samples exceeded the permissible limit set by US Environmental Protection Agency, (USEPA, 1997) and World Health Organization, (WHO, 2003). Being a highly toxic metal, Hg exposure has caused diseases in the workers such as inhalation problem, belly and neck pain, skin burn, stunted growth in children, teeth, heart, respiratory, kidney, joints and skin problems.

This study investigates the mercury (Hg) contaminations in soil and foodstuffs along the artisanal gold mining areas, Gilgit-Baltistan Province, Pakistan. For this purpose, soils were analyzed for Hg concentrations and evaluated for the enrichment/contamination using enrichment factor or contamination factors (CF). The CF values ranged from 18.9 to 153 showed multifold higher levels of Hg contamination as compared to background or reference site. Foodstuffs including vegetables, seeds or grains and fish muscles showed Hg accumulation. Results revealed that Hg concentrations in foodstuffs were higher than the critical human health value set by European Union. The Hg in foodstuffs was consumed and, therefore, evaluated for the risk assessment indices using the daily intake (DI) and health risk index (HRI) for the exposed human population both children and adults. Results of this study revealed that cumulative HRI values through foodstuffs consumption were