Toxic Metals (Al, Cd, Pb) and Trace Element (B, Ba, Co, Cu, Cr, Fe, Li, Mn, Mo, Ni, Sr, V, Zn) Levels in Sarpa Salpa from the North-Eastern Atlantic Ocean Region

Heavy metals contamination of seafood from the crude oil-impacted Niger Delta Region of Nigeria: A systematic review and meta-analysis

This study aims at computing the pooled mean estimate (PME) and health risks of heavy metals in seafood obtained from the Niger Delta Region of Nigeria (NDRN), using data from existing literatures. Pubmed, Scopus and Google Scholar were searched to retrieve articles that investigated the heavy metal contents of edible seafood from the NDRN. Search hits were screened against predetermined criteria following which relevant data were extracted from eligible articles. The PME for each metal was computed by performing a maximum likelihood random effect model meta-analysis using the R Studio Software. Outcome from the meta-analysis involving 58 studies and a total of 2983 seafood samples revealed the following PMEs (mg/kg dry wt seafood) for the investigated heavy metals: As (0.777), Cd (0.985), Co (4.039), Cr (2.26), Cu (11.45), Fe (143.39), Hg (0.0058), Mn (13.56), Ni (5.26), Pb (4.35), and Zn (29.32). The health risk assessment suggests that seafood from this region poses considerable carcinogenic and non-carcinogenic risks to human consumers. Our finding calls for urgent actions aimed at identifying and eliminating point sources of heavy metals pollution of the NDRN marine environment. Inhabitants of NDRN are encouraged to reduce seafood consumption while diversifying their protein sources to include non-seafood options.

Distribution patterns of six metals and their influencing factors in M4 seamount seawater of the Western Pacific

Metals are crucial to the stability of marine ecosystems, and it is important to analyze their spatial heterogeneity. This study examined the distribution and influencing factors of six metals such as manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu) and cadmium (Cd) in M4 seamount of the Western Pacific. The results showed that the factors affecting the distribution of metals are complex. The concentration ranges of Mn, Fe, Co, Ni, Cu, and Cd in the M4 seamount were 0-0.05, 0-0.44, 0-0.0014, 0-0.082, 0.12-0.16, and 0-0.013 μg/L, respectively, roughly equivalent to those of other open seas, however, there were also some differences. Specifically, the distribution of ferromanganese nodules and Co-rich crusts, resulted in a significant increase in the concentration of metals such as Mn, Fe, and Co in the bottom. This study will significantly contribute to our understanding of the spatial heterogeneity of metals in seamount areas.

Trace elements in Foodstuffs from the Mediterranean Basin-Occurrence, Risk Assessment, Regulations, and Prevention strategies: A review

Trace elements (TEs) are chemical compounds that naturally occur in the earth's crust and in living organisms at low concentrations. Anthropogenic activities can significantly increase the level of TEs in the environment and finally enter the food chain. Toxic TEs like cadmium, lead, arsenic, and mercury have no positive role in a biological system and can cause harmful effects on human health. Ingestion of contaminated food is a typical route of TEs intake by humans. Recent data about the occurrence of TEs in food available in the Mediterranean countries are considered in this review. Analytical methods are also discussed. Furthermore, a discussion of existing international agency regulations will be given. The risk associated with the dietary intake of TEs was estimated by considering consumer exposure and threshold values such as Benchmark dose lower confidence limit and provisional tolerable weekly intake established by the European Food Safety Authority and the Joint FAO/WHO Expert Committee on Food Additives, respectively. Finally, several remediation approaches to minimize TE contamination in foodstuffs were discussed including chemical, biological, biotechnological, and nanotechnological methods. The results of this study proved the occurrence of TEs contamination at high levels in vegetables and fish from some Mediterranean countries. Lead and cadmium are more abundant in foodstuffs than other toxic trace elements. Geographical variations in TE contamination of food crops clearly appear, with a greater risk in developing countries. There is still a need for the regular monitoring of these toxic element levels in food items to ensure consumer protection.

Role of nanohybrid NiO–Fe3O4 in enhancing the adsorptive performance of activated carbon synthesized from Yemeni-Khat leave in removal of Pb (II) and Hg (II) from aquatic systems

Over years, existence of toxic chemical heavy metal in aquatic systems has motivated more research studies toward the preparation of effective stable solid adsorbents for the removal of toxic chemical pollutants. Therefore, in the current research study, activated carbon adsorbent (AC) was synthesized from Yemeni khat (catha edulis) leaves which are considered as waste accumulated on waste disposal areas in Yemen. KOH (2.0 N) was used as a chemical activator to produce the AC material which was subsequently heated at 400 °C. A simple co-precipitation method was used to chemically modify AC with varying weight ratios of NiO-Fe₃O₄ NPs (5, 15, and 25 wt %). The modified AC was used to remove toxic Pb(II) and Hg(II) ions from aquatic systems. Numerous techniques, which included x-ray diffraction (XRD), Fourier transforms infrared (FTIR), field emission scanning electron microscope (FE-SEM), and N₂ adsorption/desorption isotherms, were used to confirm the morphology of AC and 5, 15, and 25 wt% NiO-Fe₃O₄/AC samples. The study findings demonstrated that, NiO-Fe₃O₄ nanoparticles improved the adsorption efficiency for toxic Pb(II) and Hg (II) ions. The AC adsorbent attained maximum removal efficiencies of 88.95% and 87.56% for Pb (II) and Hg (II) ions, respectively. In contrast, 15-NF/AC NC sample successfully attained the highest removal efficiencies of 100% for pb(II) and 99.71% for Hg(II). According to the experimental findings, the prepared NF/AC adsorbents were effective and they can be used as inexpensive and stable solid nanoadsorbents in water treatment.

From Mangrove to Fork: Metal Presence in the Guayas Estuary (Ecuador) and Commercial Mangrove Crabs

Mangrove wetlands provide essential ecosystem services such as coastal protection and fisheries. Metal pollution due to industrial and agricultural activities represents an issue of growing concern for the Guayas River Basin and related mangroves in Ecuador. Fisheries and the related human consumption of mangrove crabs are in need of scientific support. In order to protect human health and aid river management, we analyzed several elements in the Guayas Estuary. Zn, Cu, Ni, Cr, As, Pb, Cd, and Hg accumulation were assessed in different compartments of the commercial red mangrove crab Ucides occidentalis (hepatopancreas, carapax, and white meat) and the environment (sediment, leaves, and water), sampled at fifteen sites over five stations. Consistent spatial distribution of metals in the Guayas estuary was found. Nickel levels in the sediment warn for ecological caution. The presence of As in the crabs generated potential concerns on the consumers' health, and a maximum intake of eight crabs per month for adults is advised. The research outcomes are of global importance for at least nine Sustainable Development Goals (SDGs). The results presented can support raising awareness about the ongoing contamination of food and their related ecosystems and the corresponding consequences for environmental and human health worldwide.

Determination of Heavy Metals in Groundwater Around Al-Buraihi Sewage Station in Taiz City, Yemen

BACKGROUND

In recent years, mitigation of groundwater contamination resulting from the limited availability of freshwater for domestic use has become an important issue. The presence of heavy metals in water could have adverse effects on both plant and animal life.

OBJECTIVES

The main objective of the present study was to determine possible heavy metal contamination in groundwater around Al-Buraihi sewage station in Taiz, Yemen and to understand possible sources of contamination and their relationships with groundwater.

METHODS

Wastewater samples were collected from a wastewater stabilization pond from Al-Buraihi sewage station and borewell water samples were collected from the vicinity. The presence of heavy metals was quantified using inductively coupled plasma-optical emission spectrometry (ICP-OES). Pearson correlation test was performed to understand the relationship between wastewater and groundwater samples.

RESULTS

Physical variables including pH, electrical conductivity (EC), dissolved oxygen (DO) and temperature and elements such as silver (Ag), arsenic (As), aluminum (Al), barium (Ba), boron (B), cadmium (Cd), chromium (Cr), iron (Fe), molybdenum, nickel (Ni), selenium (Se) and zinc (Zn) exceeded the permissible limits recommended by international standards in wastewater samples.

CONCLUSIONS

Treated sewage wastewater in the study area is not suitable for irrigation as the elements/heavy metals are accumulated in soil and plants and may be accumulated in humans and animals through bio-accumulation. In addition, these heavy metals reach the water table and aquifers through percolation, thereby polluting groundwater.

COMPETING INTERESTS

The authors declare no competing financial interests.