No abstract

Microplastics (MPs) are regarded as a global issue due to their toxicity effects on fish and humans. Fish is a vital origin of human protein, which is necessary for body growth. Contamination of fish by MPs is a major hazard that requires special focus. After exposure to MPs alone or in combination with other pollutants, fish may experience a variety of health issues. MPs can cause tissue damage, oxidative stress, and changes in immune-related gene expression as well as antioxidant status in fish. After being exposed to MPs, fish suffer from neurotoxicity, growth retardation, and behavioral abnormalities. The consequences of MPs on human health are poorly understood. Due to the abundance of MPs in environment, exposure may occur via consumption, inhalation, and skin contact. Humans may experience oxidative stress, cytotoxicity, neurotoxicity, immune system disruption, and transfer of MPs to other tissues after being exposed to them. The toxic effects of MPs in both fish and human are still unknown. This detailed review has the potential to add to existing knowledge about the ecotoxicity effects of MPs in both fish and humans, which will be useful for the forthcoming study.

The present study was conducted to measure globally alarming of ten heavy metals (Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn and Mn) in surface water and sediment of the Old Brahmaputra River in Bangladesh. The observed order of heavy metal mean concentration in water and sediments is Al > Mn > Ni > Co > Cu > Pb > Zn > Cr > Cd > Hg in mg/l and Al > Mn > Zn > Ni > Pb > Cr > Cu > Co > Cd > Hg in mg/kg, respectively. The significant variations of Cr, Cu, Al and Ni were found in the water of all seasons (p < 0.05), while sediment showed Pb and Hg exhibited substantial changes in terms of seasons (p < 0.05). Principal component analysis and correlation matrix revealed that significant anthropogenic input of Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn and Mn in water and sediment. In case of water, very strong linear relationships exhibited in Ni versus Cu (0.911), Ni versus Al (0.910), Mn versus Co (0.882), Cr versus Al (0.877), Cu versus Cd (0.853), Ni versus Pb (0.850), Zn versus Cr (0.833), Ni versus Cd (0.828), Cu versus Cr (0.827), Al versus Cd (0.827) and Zn versus Co (0.804) at the significance level 0.05. In sediments, very strong linear relationships were noted in Zn versus Cr (0.889), Al versus Pb (0.848), Co versus Al (0.819) and Mn versus Co (0.806) at the significance level 0.05. The result discovered that water and sediment quality of the Old Brahmaputra River became contaminated due to the anthropogenic sources of industrial, domestic and irrigation discharges. This environmental monitoring and assessment research will be useful for the management and planning for the protection of this river.

The present study was carried out to assess the contamination levels of heavy metals (Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn, Mn) in surface water and sediment of the Halda River. The observed order of heavy metal concentration in water for Al > Ni > Zn > Mn > Cu > Cd > Pb > Cr > Co > Hg (mg/l) and for sediments Al > Mn > Zn > Ni > Cr > Pb > Cu > Co > Cd > Hg (mg/kg), respectively. The concentrations of Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn, and Mn in water, whereas in sediment Pb, Cu, Al, Ni, Co, Zn, and Mn were found above the permissible limit (WHO 2004; USEPA 2006; EPA 1986, 2002 and ECR 1997). Significant variations in the concentrations of Al and Ni were found in water (p < 0.05) while Cr, Cu, Pb, Co, Mn, and Ni showed substantial changes in sediment (p < 0.05). Principal component analysis (PCA) and correlation matrix revealed anthropogenic intrusions of Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn, and Mn in water and sediment. In case of water, very strong linear relationship was found in Hg vs Pb (0.941), Mn vs Zn (0.939), and Ni vs Cu (0.922) at the significance level 0.01. In sediment, very strong linear relationships were found in Mn vs Cr (0.999), Co vs Ni (0.999), Ni vs Cu (0.994), Zn vs Pb (0.993), Co vs Cu (0.992), Cu vs Cr (0.990), Mn vs Cu (0.989), Mn vs Ni (0.975), Mn vs Co (0.975), Ni vs Cr (0.974), Co vs Cr (0.972), Mn vs Pb (0.951), Cr vs Pb (0.948), Zn vs Cr (0.944), and Mn vs Zn (0.941) at the significance level 0.01 which direct that their common origin entirely from industrial effluents, municipal wastes, and agricultural activities. The study shows that seasonal water flows/water discharge (pre-monsoon, monsoon, and post-monsoon) have an impact on the mobility of metals. Elevated levels of metals were detected during monsoon in sediments (Pb, Cr, Cu, Al, Ni, Co, Zn, Mn) and post-monsoon in water (Cd, Hg, Ni, Co, Mn). The detection of high-risk metals in the Halda River may demonstrate that metals can cause significant effects on fry and fingerlings of the Gangetic carp fishery and prawn fishery (via sub-lethal and lethal effects and bioaccumulation or secondary poisoning of metals to fish and prawn).