Metal Concentrations Research Articles

Evaluation of Heavy Metal Concentration in Different Organs of Labeo rohita in Water and Sediment of Marala Ravi Link Canal (MRL) and Upper Chenab Canal (UCC) of Chenab River, Pakistan, and Their Health Implications

Evaluation of Heavy Metal Concentration in Different Organs of Labeo rohita in Water and Sediment of Marala Ravi Link Canal (MRL) and Upper Chenab Canal (UCC) of Chenab River, Pakistan, and Their Health Implications

Assessment of produced water from oil and gas field Gujar Khan, Punjab, Pakistan

This study was conducted to analyze the physiochemical and heavy metal concentrations in produced water of Missa Kaswal Oil field Gujar khan, Punjab, Pakistan. Produced water samples were collected from various locations points and analyzed for various parameters by using standard operation procedures. According to Pakistan Environmental Protection Agency, pH, temperature was noted with in permissible limit, total dissolved solids, chlorides, fluorides and oil and grease concentrations were found very high. The concentration of chloride and oil and grease were found several times higher as compared to Pak-EPA. Heavy metals results of the research samples are compared with Pakistan Environmental Protection Agency. From the results it was found that nickel (Ni), lead (Pb), manganese (Mn), zinc (Zn) and arsenic (As0 were within the permissible limits while chromium (Cr) concentration was observed in produced water above the permissible limits. So overall study concluded that wastewater which is released from oil and gas sector is highly polluted. So, it is strongly recommended that Pakistan Environmental Protection Agency should regular check and monitor that wastewater before releasing into the environment.

Determination of Heavy Metal Concentrations at Ewu-Elepe, Ikorodu Dumpsite, Lagos, Nigeria

Heavy metal contamination of soil at dumpsites poses risks and hazards to humans and the ecosystems through inhalation of dust particles or dermal contact with the contaminated soil. Dumpsites are usually located at the outskirts of residential areas, but due to population increase in the urban centers as result of rural-urban movement which has become living habitats without considering the health implications. Thus, Ewu-Elepe dumpsite, located on the outskirts of Ikorodu, Lagos may pose a serious threat to residents of this area due to the improper disposal and ineffective management of waste at the dumpsite also, due to the metalic health issue recorded in this area. Therefore, this study was designed to determine the Heavy Metal Concentrations (HMC) and identify the type of Key Environmental Indicators (KEIs) responsible for the heavy metal contamination at the dumpsite. The Principal Component Analysis (PCA), Nemerow Integrated Pollution Index (NIPI), and Pollution Index (PI) procedures were adopted. The Akaike Information Criteria (AIC) was employed to determine the best KEI responsible for the presence of a particular heavy metal on the dumpsite. The Heavy Metals (HMs) found on the dumpsite were Zinc, Copper, Lead, Cadmium, Calcium, Manganese, and Iron. The identified KEIs on the dumpsite were: potential Hydrogen (pH), Electrical Conductivity (EC), Total Organic Carbon (TOC), Total Nitrogen (TN), Phosphorous (P), and Carbon Exchange Capacity (CEC). The AIC at 5% showed that the most significant KEI responsible for Zn was EC with the least value (16.21), pH for Pb (26.70), P for Ca (20.71), TOC for Cu (24.61) and Mn (81.09), TN for Cd (44.97), and CEC for Fe (41.04). The PCA and NIPI estimates for the heavy metals across the 20 sample points were (1760.57, 3.00); (1825.85, 2.30); (1330.80, 2.60); (1644.68, 2.40); (1602.57, 9.70); (1469.93, 2.40); (1379.85, 3.20); (1872.82, 2.40); (1859.30, 8.40); (1397.56, 2.30); (1995.32, 4.70); (1518.62, 3.10); (1565.33, 1.80); (1332.29, 5.10); (1748.59, 2.50); (1664.70, 3.90); (1792.24, 4.10); (1801.79, 2.30); (1801.18, 2.30); (1743.27, 2.00), respectively, implying that the dumpsite was highly concentrated in HMs. Copper, lead, cadmium, calcium, manganese, and iron highly polluted Ewu-Elepe dumpsite with potential hydrogen, electrical conductivity, total organic carbon, total nitrogen, phosphorous, and carbon exchange capacity as the key environmental indicators for the heavy metals.

Health Risk of Heavy Metals in Drinking Water Sources of Water-Carrying Lakes Affected by Retreating Polder: A Case Study of Luoma Lake

Heavy metal pollution is a critical issue affecting the safety of drinking water sources. However, the impact of human activities on heavy metal risk levels in water-carrying lakes remains unclear. This study aims to explore the risk mechanisms of heavy metals in Luoma Lake, an important water-carrying lake for the South-to-North Water Diversion Project. We explored the spatial and temporal differences in the distribution of heavy metals in Lake Luoma using methods such as the heavy metal pollution index (HPI) and assessed the risk variations using a health assessment model. The results indicated that heavy metal concentrations in water-carrying lakes generally decreased during the dry season, with Mn and Zn levels decreasing by 89.3% and 56.2%, respectively. The comprehensive score of HPI decreased by 13.16% following the retreating polder compared to the control area (Non-retreating polder area). Furthermore, the HPI at the drinking water intake was lower, which is closely associated with the elevated dissolved oxygen (DO) and oxidation–reduction potential (ORP) resulting from water diversion. The annual average health risk across the entire lake was not significant, with higher levels observed in the control area. The annual non-carcinogenic risk levels of Mn, Ni, Cu, Zn, and Pb range from 10−13 to 10−9, which are considered negligible risk levels. Notably, the carcinogenic risk posed by arsenic (As) through the drinking pathway reached 10−5 a−1, exceeding the maximum levels recommended by certain organizations. These findings provide a critical foundation for managing heavy metals in water-carrying drinking water sources.

Biochar Derived from Sewage Sludge: The Impact of Pyrolysis Temperature on Chemical Properties and Agronomic Potential

The rising volume of sewage sludge from urbanization poses substantial environmental and public health concerns, underscoring the urgency for the implementation of effective waste management strategies. The objective of this study was to evaluate the influence of pyrolysis temperature on the chemical composition and agronomic potential of biochar derived from sewage sludge. The pyrolysis process was conducted at temperatures ranging from 400 °C to 800 °C, and the resulting biochar was analyzed for pH, electrical conductivity, metal content, and carbon fractions. Additionally, phytotoxicity tests were conducted to assess the impact of the biochar on plant germination. The findings indicated that elevated pyrolysis temperatures resulted in an elevated alkalinity, electrical conductivity, and concentration of alkali metals in the biochar. Conversely, these processes resulted in a reduction in total organic carbon content and an increase in heavy metal content, which may limit the potential for biochar to be used in agricultural applications. The phytotoxicity tests indicated that the biochar produced at lower temperatures (400 °C) exhibited positive effects on plant growth when administered at doses of 5 and 10 t·ha−1. Conversely, the biochar produced at higher temperatures (800 °C) demonstrated significant toxicity. The findings indicate that the pyrolysis temperature is a critical factor in determining the suitability of biochar for agricultural applications. The production of biochar at lower temperatures may offer agronomic benefits, whereas the use of higher temperatures increases stability but is associated with the risk of higher heavy metal concentrations.

Evaluation of Heavy Metal Concentration in Sediments of Rupingazi River, Kenya

Heavy metal concentration (Cu, Zn, Fe, Mn, Ni) was evaluated in sediment samples of Rupingazi river during the wet and dry seasons. In this study, the sediment samples were collected from twenty sampling points along the river. The heavy metal levels were evaluated using Atomic Absorption Spectrphotometer.The obtained data was analyzed using one-way analysis of variance. The range of the concentration of copper was found to be 4.68- 12.69 mg/kg for the wet season and 0.98-24.10mg/kg for the dry season. The mean values of the concentration of iron was found to be 1422-6145.33 mg/kg for the wet season and 1254-5866.67 mg/kg for the dry season. The range of the concentration of Nickel was found to be 0.72- 30.73 mg/kg for the wet season and 2.63-12.48 mg/kg for the dry season. Concentration of manganese was found to be 48.03-411.20 mg/kg for the wet season and 6.15-248.35 mg/kg for the dry season Zinc concentration was found to be 26.29-167.10 mg/kg for the wet season and 4.82-28.39 mg/kg for the dry season. The Zinc, Manganese, Nickel Iron and Copper levels were not beyond the USEPA recommended limits.

Effects of Organic Manure on Wheat Yield and Accumulation of Heavy Metals in a Soil—Wheat System

The application of organic manure is an effective way to develop sustainable agriculture. However, the application of organic manure may be associated with a potential risk of heavy metal pollution for soil and crops. In this study, the effects of organic cow manure (T1) (as base fertilizer), organic pig manure (T2) (as base fertilizer) and chemical fertilizer (T3) on winter wheat grain yields, grain quality, heavy metal concentrations and heavy metal bioconcentration factors (BCFs) in a soil–wheat system were studied from November 2021 to June 2023. The results showed that the winter wheat grain yields in the T1 and T2 treatments were lower than those in the T3 treatment by 2.57–38.0% and 10.5–25%, respectively. There were no significant differences in quality indexes of winter wheat grain among different fertilizer treatments. The concentrations of heavy metals in topsoil and winter wheat were 0.12–76.11 μg/g and 0.01–43.25 μg/g, respectively. The BCFs of heavy mental in the soil–wheat grain system was 0–2.92. In general, there were no significant differences in heavy metals’ concentrations in topsoil and wheat grain among different fertilizer treatments. In summary, compared with chemical fertilizer, the short-term application of organic manures had no significant effect on heavy metals concentrations in topsoil and wheat.

Health Risk Assessment of Residents' Exposure to Air Pollutants around the Sinpyeong-Jangrim Industrial Complex in Busan.

In this study, we aimed to evaluate the health effects of heavy metals and volatile organic compounds (VOCs) in fine particulate matter (PM2.5) in the air around the Sinpyeong-Jangrim Industrial Complex, Busan, and the necessity of reduction measures. We measured the concentrations of heavy metals and VOCs in PM2.5 in five areas with dense population around the Sinpyeong-Jangrim Industrial Complex. A health risk assessment was conducted, and the spatial risk distribution for the entire Saha-gu area was predicted using inverse distance weighting (IDW). Our results indicated that the carcinogens benzene, As, and Cr6+, and the non-carcinogen m,p-xylene, have the potential to adversely affect health. In particular, As was found to have the potential to express health effects at all measurement points. Additionally, based on the IDW results, the minimum values of benzene, arsenic, and m,p-xylene exceeded the threshold level, potentially affecting the health of residents across the entire Saha-gu area. In contrast, Cr6+ could potentially impact health only in some parts of Saha-gu as only its maximum value exceeded the threshold level. We demonstrated the importance of reducing air pollutant emissions from general industrial complexes. Our results will be useful in establishing more systematic mitigation measures to protect the health of residents near the Sinpyeong-Jangrim Industrial Complex and developing air pollutant management systems.

Exploring the temporal toxicity signature: A baseline evaluation of the heavy metal concentration in estuarine core sediments in the coastal region of cauvery delta, bay of bengal.

Globally, the concentration of heavy metals and sediment toxicity analysis are significant liabilities to aquatic environments. This scrutiny outlines the sediment textures, heavy metals and toxicity status associated with environmental pollution indices in the core sediment of the Cauvery and Vettar estuaries, East coast of India. The impact of rapid industrialization, urbanization, harbour activities and agricultural activities influences on the twain estuary is a significant concern to designate the environment. The contamination status of the sediments affects the potential biodiversity, ecological risks and human health. A total of two core sediments were recovered from the Cauvery and Vettar estuaries in March 2023 to decipher the environmental pollution status. Meticulous observation of the textural studies underscores the prevalence of sand content in Cauvery, and Vettar sediments consist of predominate clay content and minor silt contents. Furthermore, the organic matter is augmented in the Vettar River due to the higher input of waste disposal, seaweeds and algae due to the surrounding landmass. Twain core sediments argue that heavy metal concentration is decreasing in order as Fe > Zn > Ni > Pb > Cu > Cr by using portable X-ray fluorescence (pXRF) spectrometry. Remarkable results of environmental pollution indices such as Igeo, Ef, Cf, Cd and mCd state very highly polluted, extreme enrichments, high contamination and very high degree of contamination. Furthermore, the potential ecological risk indices such as PLI, SQGs, and PERI argue polluted, medium to high toxicity and moderate adverse ecological risk to the estuarine regions. Statistical analysis of the heavy metal affirms the enrichment of Fe metals may derive from lithogenic and/or anthropogenic influences, and the other studied metals such as Cu, Ni, Zn, Pb and Cr may be influenced by the anthropogenic activities in the aspect of point and non-point pollution sources. This could result from both estuaries undergoing higher pollution, in which the Vettar estuary is a considerable environmental risk zone compared to the Cauvery river due to the impact of industrial effluents and rapid urbanization activities. This finding underscores the urgent need for enhanced estuarine sediment quality study and comprehensive assessment of sediment toxicity, regulating the beneficial acumen for the government to follow the suitable remediation on the embellish policy of river and marine environments.

Assessment of trace element occurrence in Nile Tilapia from the Rosetta branch of the River Nile, Egypt: Implications for human health risk via lifetime consumption

River pollution can harm human health through direct contact, drinking water, and the consumption of contaminated fish and irrigated agricultural products. Surface water and Nile tilapia (Oreochromis niloticus) samples were collected monthly from July 2022 to June 2023 at three sites (El-Rahawy, Sabal, and Tala) along the Rosetta Nile branch in Egypt to monitor the presence of eight trace elements. The potential human health risks from consuming contaminated fish were also assessed. Iron and manganese were consistently detected in all water samples across most seasons and locations, with concentrations generally below the WHO permissible levels. All 72 analyzed fish muscle samples were found to contain trace elements. The mean concentrations of metals in the fish muscle samples, in descending order, were: iron > zinc > copper > manganese > tin > antimony > lead > mercury. Significant spatial and seasonal variations were observed in both water and fish samples. El-Rahawy was identified as the most contaminated site, with summer exhibiting the highest contamination rate compared to other seasons. Fish samples collected from El-Rahawy demonstrated the highest bioconcentration factor (BCF) values for most elements, particularly mercury, lead, iron, manganese, and antimony. Target hazard quotient (THQ) calculations for the trace elements in Nile tilapia muscles revealed that all trace elements, except antimony, had THQ values below 1, suggesting that consuming Nile tilapia from these sites is unlikely to cause adverse health effects. However, THQ values for antimony exceeded the threshold of 1, indicating a potential health risk for consumers. Although the detected trace elements in the fish were below the permissible toxicity limits, some could pose a future threat to human health, necessitating further studies, ongoing monitoring, and preventive measures.

Seasonal fluctuations of heavy metal accumulation and gastrointestinal helminth induce oxidative stress and histological lesions in resident catfish Clarias gariepinus

The exposure of the African catfish (Clarias gariepinus) to various environmental contaminants leads to physiological and histological alterations. Therefore, the study aimed to assess the impact of seasonal variations of ecological contaminants as external stressors and internal stressors via helminth infections on oxidative stress and histopathology in resident C. gariepinus at EL-Salam Canal, Egypt. Seasonal water and sediment samples were collected to assess physicochemical parameters and heavy metals. The length, weight, and sex were recorded for each fish sample. The gastrointestinal tract was dissected from the visceral cavity, and the helminths were extracted and identified using SEM photos based on their morphological characteristics. The parasitic dominance in the gastrointestinal helminths was calculated. The heavy metal concentrations, bioaccumulation (BAF), and biosedimentation (BSF) factors were considered in the muscles and intestine. Specimens of muscles and intestines were removed to determine oxidative status. In addition, pieces of skin, muscles, stomachs, and intestines were subjected to light microscopy to determine the alterations. The calcium, magnesium, and potassium levels were within safe limits. Sulfate levels consistently remained below the maximum permissible thresholds throughout the seasons. Among the heavy metals examined, the highest accumulation was found in the intestinal tissues of C. gariepinus, while muscle tissues showed lower levels. The variability in metal concentrations across water, sediment, muscles, and intestines underscores the different capacities of these environments to accumulate heavy metals. The elevated metal levels in fish tissues raise concerns about potential health risks for humans who consume contaminated fish, highlighting significant bioaccumulation within the food chain. The result indicated that Cu in the sediment samples was associated with parasite abundance. The dual stress from environmental pollutants and parasitic infections exacerbates oxidative stress and causes notable histopathological changes in the tissues of the catfish. These results highlight the intricate interplay between external and internal stressors, emphasizing the need for continuous monitoring and management of aquatic ecosystems to safeguard the health of resident fish populations. It provides insight into how these factors affect fish health.

Bioinspired synthesis of calcium magnesium aluminate nanoparticles using aloe vera extract: A promising material for electrochemical sensors, antibacterial and environmental remediation applications

Aloe vera (Aloe barbadensis miller) leaf extract was used in green fuel-assisted microwave synthesis to prepare Calcium Magnesium Aluminate (CMA). The synthesized CMA was characterized by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR), Scanning electron microscope (SEM), Energy dispersion spectrometer (EDAX), and Transmission Electron Microscopy (TEM) analyses. X-ray diffraction confirmed the formation of Ca2Mg2Al28O46. The UV–Vis diffuse reflectance (DRS) technique was employed to investigate its absorbance spectrum, and the band gap of CMA was found to be 4.9 eV. The CMA nanoparticles were used to design a sensing electrode for creatinine, enabling the determination of its concentration in human samples and heavy metals. Acid Orange-88 dye was degraded using CMA nanoparticles as a photocatalyst under UV irradiation. After dye degradation, treated water was used to grow Vigna radiata plants to test their suitability for seedling growth. This report demonstrates that CMA photocatalysts are alternatives to semiconductor photocatalysts for the degradation of Acid Orange-88 dye under UV illumination. Escherichia coli (E. coli), Staphylococcus species, and Pseudomonas species were used as model organisms to assess the antibacterial activity of CMA NPs through a green route.

Statistical evaluation and quality analysis of water resources around quarry site in Abuja Suburban Nigeria

Water resources occupies vital position regarding the lifespan and general wellbeing humans while significant shortfalls on its reserves hinders almost all sustainable development globally. Most host communities to quarry companies without a water treatment plant are greatly affected by the use of water resources within its area. The present study highlights statistical evaluation and quality analysis of water resources around a quarry site in FCT Nigeria. The research engaged biological assay, physiological and chemical analysis to quantify contamination level of the water resources from obtained data which were also subjected to statistical analysis. The statistical tools employed are Pearson's Correlation, descriptive statistics, Levene's test for homogeneity and one–way analysis. The physiochemical analysis revealed the water resources to have high turbidity value in 58.3 % of sampled population while nitrate concentration and electrical conductivity value were very low. The bioassay revealed presence of coliform bacteria in 100 % of sampled population while thermotolerance count discovered disease-causing-pathogens in 41.7 % of sampled population. Chemical analysis revealed that Pb, Cr, Ni and As were 91.7 %, 83.3 % 100 % and 100 % above recommended permissible limits for sampled population. These results suggests that water resources in this study is unsafe and holds a health-treat with regards to the contaminations inherent in them. Statistical evaluation revealed average positive linear relationship between heavy metal concentration suggesting close relationship of contamination source. Observed strong positive linear relationship between lead and copper, nickel and chromium as well as nickel and arsenic in the scatterplot depicts same source of contamination.

Pollution Characteristics and Risk Assessment of Heavy Metals in the Soil of a Municipal Solid Waste Landfill Site

ABSTRACT With the excavation of landfill sites, the disposal and reduction of organic-rich soils with high proportions of heavy metals have become urgent issues. This study focuses on the pollution characteristics and ecological risks associated with heavy metals in the humus soil of a municipal solid waste (MSW) landfill. The results indicate that the concentrations of heavy metals in the humus soil followed the sequence of Cu > Zn > Cr > Pb > Ni > As > Cd > Hg, and Cu and Cd exhibited the highest exceedance multiples. Except for Cr, the concentrations of the heavy metals in the humus soil were higher than those in combustible components, with a strong Hg correlation. Heavy metal forms indicate varying degrees of mobility and stability; Cr, As, Hg, and Pb were stable, while Ni, Cd, Cu, and Zn showed higher mobility. The results of the principal component analysis reveal that heavy metals primarily originate from industrial and agricultural waste. Finally, the geoaccumulation index of the metals indicated that Cu, Zn, Cd, and Pb exhibited severe contamination. Most importantly, Cd posed the greatest environmental risk as it has the highest effective content, bioavailability, and mobility. This study provides a scientific foundation for mitigating heavy metal pollution in the humus soil of landfill sites.

Sorbent selection for the recovery of gallium and indium from aqueous solutions: a sustainable approach to the recovery of strategic metals from LED lamps.

Gallium and indium, metals present in light-emitting diode (LED) lighting technology, can be effectively recovered from aqueous solutions by sorption. For this purpose, carbonaceous materials, such as activated carbon, or low-cost biosorbents as beer bagasse, spent coffee grounds or peanut shells, and a low-cost zeolite as chabazite, were characterized by BET, FTIR, XRD, and SEM analysis prior use. Protonated chabazite, with high surface area (505m2/g) and a Si/Al molar ratio of 3.4, showed high sorption capacities for gallium (56mg/g) and indium (92mg/g), which is 10 to 30 times higher than those of our carbonaceous materials (T = 298K, pH < 3, dosage = 1g/L). Sorption experiments with both metals in solution showed a competitive effect between gallium and indium for the sorption sites of the chabazite, showing more affinity toward gallium than indium. Ga3+sorbed/In3+sorbed molar ratio above 2 was achieved for the same initial concentration of both metals, increasing to almost 3 when the initial gallium concentration increased, which was appropriate since gallium concentration tends to be higher in LED chips. However, the sorption capacity for both metals was always around 0.35mmol Ga + In/g. The selectivity of the chabazite was conditioned by different behavior of both metals in aqueous solution at the sorption pH (below 3.5) being the predominant species in solution Ga(OH)2+ for gallium and In3+ for indium. Sorption with protonated chabazite can be used in the treatment of spent LEDs leachate for the dual purpose of water purification and selective metal separation.

Geochemical Modeling and Quality Assessment of the Surface Waters from the Mouhoun River System, Burkina Faso: Implications of Water–Rock Interactions and Anthropogenic Activities

Major ion and heavy metal geochemistry was used to investigate the factors that control the Mouhoun River water quality in western Burkina Faso. Major cation concentrations was in the following decreasing order: Ca2+&gt; Na+&gt; K+&gt; Mg2+, reflecting silicate weathering. However, relatively high HCO3- and SO42- concentrations could be related to dissolution of calcite and sulfide minerals, respectively. The average heavy metal concentrations in the riverine system were in the following order: FeT&gt;Ag&gt;Mn&gt;Zn&gt;Pb&gt;Cu&gt;Ni&gt;AsT&gt;Cr&gt;Hg&gt;Co&gt;Cd with FeT and Ag exceeding the World Health Organization permissible limits. Concentrations of all heavy metals, except Cr, were higher in the Mouhoun system compared to the average world river concentrations. Adsorption and speciation models showed that Zn, Ag, Cd, Co, Cr and Ni are likely to remain in their free ionic forms, and thus posing serious threats to aquatic life and human health. Ag-Hg-Ni-Cd association around Poura and Tenado on the principal component plot suggested that the widespread artisanal gold mining in these areas may have contributed to these metals’ loading. In contrast, NH4+, Pb, Cu, Cr, AsT and Zn were clustered around a densely populated and industrialized Kou watershed, pointing to agricultural and industrial sources of these pollutants. Furthermore, the Kou River had the highest metal index followed by Tenado, Samendeni, Poura and Boromo. Hence, the chemistry of the Mouhoun River and its tributary appears to be mainly controlled by population density and various anthropogenic activities taking place in their drainage basins. The findings could provide avenues for sound and sustainable water resource management in a water scarce semi-arid environment.

Trophic stoichiometry of macroelements and metals in a terrestrial food web

In order to understand the transfer of macroelements and toxic metals in the terrestrial food web, barn swallows, terrestrial frogs, and insects were collected from farmlands in the Leizhou Peninsula, and analyzed for macroelements carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) and trace metals nickel (Ni), zinc (Zn), selenium (Se), copper (Cu), chromium (Cr), cadmium (Cd), lead (Pb), and mercury (Hg). The multi-element ecological stoichiometry was discussed to trace the food web flow of nutrients and toxicants. The percentage contents of C, N, P, and S were 35.43–59.91%, 6.89–12.11%, 0.49–4.66%, and 0.44–2.19%, respectively. The concentrations of Ni, Zn, Se, Cu, Cr, Cd, Pb, and Hg were 0.163–116 mg/kg, 38.7–227 mg/kg, 0.0453–3.82 mg/kg, 3.11–141 mg/kg, not detected—79.6 mg/kg, 0.0203–0.358 mg/kg, 0.148–4.57 mg/kg, and 0.00159–1.46 mg/kg, respectively. Organisms at high trophic levels had higher contents of N, P, and S, and lower contents of C. Significant correlations were observed between δ15N and ratios of C: N, C: P, C: S, N: P, N: S, and S: P, indicating selective transfer of biogenic elements for predators in the terrestrial food web. Most metals including Ni, Zn, Se, Cu, Cr, Pb, and Hg had biomagnification factors and trophic magnification factors higher than 1, because the whole body of organisms rather than tissues were used. The negative correlations between the detoxification ratios of Se: X (each toxic metal) and metal concentrations suggest potential adverse effect of metals on terrestrial organisms.

Heavy metal changes related to land use changes in a karst area: a case study in Changshun, Guizhou Province, China

Karst areas are often characterized by fragile ecological systems, and environmental pollution has increased the pressures on people living in such regions. This study aimed to investigate the status of pollution caused by heavy metals (Pb, Cd, Hg, As, and Cu) in soils based on different land uses in Changshun County, a karst area in southwestern China. Soil samples were collected from natural forestlands (NFLs), natural brush lands (NBLs), natural pasture lands (NPLs), artificial forestlands (AFLs), artificial brush lands (ABLs), and artificial pasture lands (APLs) for evaluation. The results suggest that the soil profile characteristics of the heavy metals studied herein vary significantly among different land uses. The heavy metal concentrations in all soil samples collected from NFLs were lower than those in samples from other land uses. Forest trees can protect soil from heavy metal pollution caused by atmospheric deposition; this is especially true for Hg. In cultivated forestlands and brush lands, special attention should be devoted to Cd pollution in the soil, which may be caused by the use of fertilizers. Changing both natural and artificial pastoral lands to forestlands could benefit the local ecosystems as it may reduce Hg contamination.

Trace metal distribution in seagrass-vegetated sediments of an urbanized estuary in Queensland, Australia

Seagrasses increase sediment complexity by trapping particulates and influencing biogeochemical cycles via root oxygen loss and organic matter exudation. However, their impact on trace metal sequestration is poorly studied. We found significantly higher trace metal concentrations in seagrass sediments compared to adjacent bare sediments, correlating with total organic carbon, iron, and fine sediments. Sequential extractions showed that most trace metals were dominated by recalcitrant fractions (oxidizable and residual fractions), representing phases such as organic matter, iron sulfides, and crystalline iron oxides. Depth-dependent trends in trace metal partitioning were evident. For example, arsenic in the oxidizable fraction only weakly correlated with Fe in surface sediments (rsp = 0.55) but correlated strongly in deeper sediments (rsp = 0.87), consistent with iron sulfides being a dominant host-phase. Overall, these results suggest that the unique geochemical conditions facilitated by seagrasses play an important role in sequestering trace metals in urban estuarine sediments.

Comparative Analysis of Concentrations of Heavy Metals in Surface Water of Nafada, Ashaka and Almakashi Corridors of River Gongola, Nigeria

A study on comparative analysis of heavy metals concentrations in surface water was carried out in three selected stations: Nafada, Ashaka and Almakashi along the corridors of River Gongola in Gombe state for a period of eighteen months. The water samples were collected in triplicate from the sampling stations. Water samples were collected using sampling bottles of 250ml dipped below the water surface for water collection. Zinc, lead, copper, cadmium and manganese were determined using Atomic Absorption Spectrophotometer. The result elucidates that most of the heavy metals were found to be within the recommended ranges as compared to standard limits. The result of concentrations of heavy metals in the surface water elucidates that there was a significant difference (P&gt;0.05) among the months with respect to zinc and there was no significant difference in the concentration of lead (P&lt;0.05). The concentrations follow the order (Zn &gt;Cd&gt;Cu&gt;Mn&gt;Pb). The higher concentration of heavy metals was found in Ashaka corridors with Zinc concentration ranging between 0.99±0.01 and 0.33±0.01, Cadmium 0.88±0.02 and 0.03±0.00, Cupper 0.58±0.02 and 0.14±0.02, Manganese 0.87±0.56 and 0.17±0.01, Lead 0.28±0.36 and 0.01±0.01. The wastewater from the cement effluent factory in Ashaka might have impacted negatively on the water chemistry by elevating the levels of some heavy metals. Therefore, more intensive treatment of the factory effluents before discharging into the River Gongola is recommended.