Elevated levels of metals and organic pollutants in fish and clams in the Cape Fear River watershed

Biomagnification of mercury in an estuarine food web

Methylmercury is a toxin of local, regional, and global concern, with estuarine habitats possessing ecological characteristics that support conversion of inorganic mercury into this methylated form. We monitored Hg concentrations in species within the food web of the lower Cape Fear River (CFR) estuary in 2018-2020. Samples were analyzed for Hg concentrations and nitrogen isotopes (a measure of trophic level), and we found a positive relationship within this food web each year (p < 0.0001), indicating biomagnification is occurring. The highest Hg concentrations were among the upper trophic level species (Royal Terns, 4.300 ppm). While the Hg concentrations we documented are below assumed thresholds for toxic effects, we found spikes in Hg concentrations after Hurricane Florence in 2018 and with other disturbances to the CFR that resuspended bottom sediments. Continued monitoring is needed to understand the cause of annual variations, health implications, and conservation needs.

Differential exposure to drinking water contaminants in North Carolina: Evidence from structural topic modeling and water quality data

To better understand water security of communities in North Carolina, this research uses structural topic modeling (STM) and geographic mapping to identify the main topics and pollutant categories being researched and the areas exposed to drinking water contaminants. The textual data derived from the journal article abstracts that examined water pollution in North Carolina is from 1964 to present. The STM analysis of textual data is paired with socio-demographic data from the 2015-2019 American Community Survey (ACS) 5-year estimates and water pollution data from North Carolina state agencies. The STM findings show that the most discussed topics relate to runoff management, wastewater from concentrated agricultural feeding operations, emerging contaminants, land development, and health impacts as a result of water contamination. The article discusses how the topics especially threaten groundwater resources used by community water systems and private wells. Those communities served by private wells are predominantly low-income and minority populations. As a result, threats to groundwater supplies exacerbate existing issues of environmental justice in North Carolina, especially in the Coastal Plains Region. The STM findings revealed that several key threats to safe drinking water are less covered by academic literature, such as poultry concentrated agricultural feeding operations and climate impacts, which may increase disparities in water access in North Carolina.

Cadmium exposure in living organisms: A short review

Cadmium (Cd) is a toxic heavy metal that accumulates in living systems. Exposure can occur occupationally or environmentally. Workers within the electroplating, battery production, and pigment industries are at the highest risk for exposure and have been reported to have increased levels of Cd in their blood and urine. Environmental exposure can be the result of anthropogenic activities or smoking. Cd has a long half-life and bio accumulates in plants, invertebrates, and vertebrates. The toxic effects following exposure include growth retardation and organ system toxicity, with kidney and liver toxicity most reported with in higher organisms. At the molecular level, Cd leads to the production of reactive oxygen species, DNA damage, and inhibition of DNA repair. This article gives a brief overview of the correlations between exposure to cadmium occupationally and environmentally and levels measured in blood and urine. It also examines the bioaccumulation of cadmium in aquatic invertebrates and vertebrates indicating that accumulation varies not only by location but also within and between various species.

Limited Influence of Urban Stormwater Runoff on Salt Marsh Platform and Marsh Creek Oxygen Dynamics in Coastal Georgia

Oxygen concentrations and oxygen utilization rates were monitored continuously for 23 months on marsh platforms and in small tidal creeks at two sites in coastal Georgia, USA, that receive urban stormwater runoff via an extensive network of drainage canals. These data were compared to nearby control sites that receive no significant surface runoff. Overall, rainfall and runoff per se were not associated with differences in the oxygen dynamics among the different locations. Because of the large tidal range and long tidal excursions in coastal Georgia, localized inputs of stormwater runoff are rapidly mixed with large volumes of ambient water. Oxygen concentrations in tidal creeks and on flooded marsh platforms were driven primarily by balances of respiration and photosynthesis in the surrounding regional network of marshes and open estuarine waters. Local respiration, while measurable, was of relatively minor importance in determining oxygen concentrations in tidal floodwaters. Water residence time on the marshes could explain differences in oxygen concentration between the runoff-influenced and control sites.

Health risk assessment of hazardous metals for population via consumption of seafood from Ogoniland, Rivers State, Nigeria; a case study of Kaa, B-Dere, and Bodo City

This study was designed to investigate the human health risk through consumption of seafood from contaminated sites in Kaa, B-Dere, and Bodo City all in Ogoniland. The potential non-carcinogenic health risk for consumers were investigated by assessing the estimated daily intake and target hazard quotients for Cr, Cd, Zn, Pb, Mn, and Fe while carcinogenic health effect from Cr, Cd, and Pb was also estimated. The estimated daily intake from seafood consumption was below the threshold values for Cr, Mn, and Zn while they exceeded the threshold for Cd, Pb, and Fe. The target hazard quotients for Zn and Cr were below 1. Target hazard quotients values for Cd, Pb, Mn, and Fe were greater than 1 except for Fe level in Liza falcipinis from Kaa. Furthermore, estimation of carcinogenic risk for Cr in all samples under study exceeded the accepted risk level of 10E-4. Also, Cd carcinogenic risk level for L. falcipinis and Callinectes pallidus collected from B-Dere and C. pallidus collected from Bodo City was 1.1E-3 which also exceeded the accepted risk level of 10E-4 for Cd. Estimation of carcinogenic risk for Pb was within the acceptable range of 10E-4. Consumers of seafood from these sites in Ogoniland may be exposed to metal pollution.

Hazard assessment of metals in invasive fish species of the Yamuna River, India in relation to bioaccumulation factor and exposure concentration for human health implications

Monitoring of heavy metals was conducted in the Yamuna River considering bioaccumulation factor, exposure concentration, and human health implications which showed contamination levels of copper (Cu), lead (Pb), nickel (Ni), and chromium (Cr) and their dispersion patterns along the river. Largest concentration of Pb in river water was 392 μg L(-1); Cu was 392 μg L(-1) at the extreme downstream, Allahabad and Ni was 146 μg L(-1) at midstream, Agra. Largest concentration of Cu was 617 μg kg(-1), Ni 1,621 μg kg(-1) at midstream while Pb was 1,214 μg kg(-1) at Allahabad in surface sediment. The bioconcentration of Cu, Pb, Ni, and Cr was observed where the largest accumulation of Pb was 2.29 μg kg(-1) in Oreochromis niloticus and 1.55 μg kg(-1) in Cyprinus carpio invaded at Allahabad while largest concentration of Ni was 174 μg kg(-1) in O. niloticus and 124 μg kg(-1) in C. carpio in the midstream of the river. The calculated values of hazard index (HI) for Pb was found more than one which indicated human health concern. Carcinogenic risk value for Ni was again high i.e., 17.02 × 10(-4) which was larger than all other metals studied. The results of this study indicated bioconcentration in fish due to their exposures to heavy metals from different routes which had human health risk implications. Thus, regular environmental monitoring of heavy metal contamination in fish is advocated for assessing food safety since health risk may be associated with the consumption of fish contaminated through exposure to a degraded environment.

Teratogenic effects and monetary cost of selenium poisoning of fish in Lake Sutton, North Carolina

Selenium pollution from coal ash wastewater was investigated in Lake Sutton, NC. This lake has been continuously used as a cooling pond for a coal-fired power plant since 1972. Historic and recent levels of contamination in fish tissues (14-105µg Se/g dry weight in liver, 24-127 in eggs, 4-23 in muscle, 7-38 in whole-body) exceeded toxic thresholds and teratogenic effects were observed in fish collected in 2013. A high proportion (28.9 percent) of juvenile Lepomis spp. exhibited spinal and craniofacial malformations that were consistent with selenium poisoning. Teratogenic Deformity Index values indicated population-level impacts on the fishery. The partially monetized cost of resultant fishery losses was calculated at over $US 8.6 million annually, and over $US 217 million for the entire period of damage, which dates back to 1987 when chemical and biological monitoring began.

Evidence of elevated levels of polychlorinated biphenyl congeners in commonly consumed fish from Eleyele Reservoir, Southwestern Nigeria

Environmental pollution of water, which is a source of cheap and affordable protein in the form of fish on which the population depends on, is of great concern globally. The present study assesses the levels of polychlorinated biphenyls (PCBs) congeners in sediments and six commonly consumed cichlid species from Eleyele Reservoir, Southwestern Nigeria. The results indicate that the concentrations of heavier PCB congeners are higher than the lighter congeners in both sediment and fish tissue. The predominant PCB congeners in the sediment samples from this site were PCBs 8, 44, 114, 101, 189, 196, 206 and 209. The concentration of PCB congeners increased with increasing molecular weight from hepta-PCB to deca-PCB in all fish species. The trend in accumulation of total PCBs in fish was as follows: Tilapia guineensis (2,531.1 ± 74.6 ng/g) > Sarotherodon galilaeus (1178.7 ± 68.5 ng/g) > Oreochromis niloticus > (891.8 ± 49.6 ng/g) > Tilapia zillii (832.8 ± 38.2 ng/g) > Hemichromis fasciatus (475.7 ± 28.5 ng/g) > Sarotherodon melanotheron (333.2 ± 26.1 ng/g). In summary, data from this study shows that the levels of PCBs in cichlid species from Eleyele Reservoir are higher than the threshold level of 0.023-0.047 ng g(-1) recommended by United States Environmental Protection Agency. Such elevated PCB levels present significant health implications for human consumers and a threat to the resident fish communities.