Extent Of Heavy Metal Contamination Research Articles

Assessment of soils for heavy metals by atomic absorption spectrometry (Zn, Pb, Cd, Cu)

The authors studied the sources of soil contamination with heavy metals and their impact on the environment and human health. The research analysed the content of acid-soluble forms of heavy metals in soils on the territory of Sunzha, the Republic of Ingushetia, The Russian Federation near 589 km of the Federal Highway ‘Kavkaz’. According to the results, authors determined the extent of heavy metal contamination in the locations under study.

Synthesis of biochar-ZnAl-layered double hydroxide composite for effective heavy metal adsorption: Exploring mechanisms and structural transformations

Rapid industrialization has increased the extent of heavy metal contamination in water sources, demanding effective wastewater treatment methods. To mitigate this issue, adsorption techniques play a crucial role in wastewater treatment. Layered double hydroxides (LDHs) are commonly employed in such processes; however, they exhibit limitations in effectively adsorbing contaminants. Here, biochar (BC) was incorporated into LDHs using a simple hydrothermal method and subsequently used for Cd2+ and Pb2+ adsorption. Additionally, the physicochemical characteristics of BC and ZnAl-LDH-BC were assessed utilizing various instruments. The obtained ZnAl-LDH-BC400 and ZnAl-LDH-BC600 had surface areas of 52.55 and 102.56 m²/g, respectively, several times greater than those of the original BC. Adsorption performance was investigated using different kinetic and isothermal models. The Langmuir–Freundlich and pseudo-second-order kinetic models demonstrated the adsorption of single-layer chemicals. Furthermore, the highest observed adsorption capacities for Cd2+ and Pb2+ were 99.8 mg g−1 and 128.4 mg g−1, respectively, when using ZnAl-LDH–BC600. In contrast, BC600 demonstrated adsorption capacities of 42.1 mg g−1 for Cd2+ and 51.7 mg g−1 for Pb2+. Cd2+ and Pb2+ adsorption by ZnAl-LDH-BC was primarily governed by surface precipitation and cation exchange processes. These findings highlight the mechanisms underlying the removal of heavy metals using ZnAl-LDH-BC and provide valuable theoretical and applied insights into the management of agricultural waste and control of water pollution.

Poisoned for gold: Assessing the spatial extent of heavy metal contamination within the Tutua-Bura-Angoben Shelter Belt Forest Reserve in Ghana

The Tutua-Bura-Angoben Shelter Belt project in Ghana, aimed at combating desertification and land degradation, faces an unexpected threat from heavy metal contamination. This study investigates the levels and spatial distribution of arsenic (As), lead (Pb), copper (Cu), and zinc (Zn) within the forest reserve, focusing on the implications for environmental health and sustainable development goals (SDGs). Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), 195 soil samples from the forest reserve were analyzed for heavy metal concentrations. The results reveal significant contamination, with arsenic levels ranging from 3.19 to 138.63 ppm, and an alarming 26 % of the reserve exceeding the 20 ppm threshold for arsenic. Copper, lead, and zinc showed lower contamination levels, with mean concentrations of 13.83 ppm, 7.63 ppm, and 27.53 ppm, respectively. Spatial interpolation using kriging in ArcGIS highlighted localized hotspots of arsenic contamination, primarily influenced by nearby Artisanal Small-Scale Gold Mining (ASGM) activities. The study underscores the urgent need for targeted environmental management strategies, including stricter waste management protocols, sustainable mining practices, and community engagement to mitigate the contamination risks and preserve the ecological integrity of the Tutua-Bura-Angoben Shelter Belt.

Heavy Metals (Hg and As) Concentration in Mining Endowed Enclaves in Ghana

Levels of heavy metals in mining areas differ from region to region depending on the level of operations and activities engaged at the mining site. The study assessed the extent of heavy metals contamination in the available water and sediments in mining endowed enclaves in Ghana. A total of forty-eight (48) samples, 24 each of water and sediments samples were taken. At each mining site, 4 samples each of water and sediments samples were taken and studied. Water and sediment samples were taken to the laboratory to determine level of mercury and arsenic. For the sediments, the average levels of Hg ranged from 0.057-0.145ppm and that of As levels in the soil sediments ranged from 0.084-0.087ppm. The average levels of Hg in water samples ranged from 0.010-0.086ppm and that of As levels in the water samples ranged from 0.004-0.008ppm. There were significance differences (p<0.05) in the levels of Hg and As of the various mining sites for the water and the sediments. All the samples (water and sediments) taken from the various mining sites had Hg above the recommended levels whereas As for samples were below the recommended levels. There should be enforcement of more stringent water and land monitoring and pollution scheme through Environmental Protection Agency (EPA) and the Minerals Commission.

Comprehensive human health risk assessment of heavy metal contamination in urban soils: insights from selected metropolitan zones

Introduction: This study aims to assess the extent of heavy metal contamination in urban soils in sixteen selected cities of Pakistan, encompassing the elements cadmium (Cd), lead (Pb), cobalt (Co), zinc (Zn), chromium (Cr), nickel (Ni), manganese (Mn), iron (Fe), and copper (Cu).Methods: The data utilized for this study was collected from online literature during the period 2005 to 2019. This study investigated potential threats to human health through a comprehensive analysis, considering standards such as Enrichment Factors (EF), Geo-accumulation Indices (Igeo), and Human Health Risk Assessment (HHRA).Results: Geo-accumulation Index results indicated varied risk intensities, with Cu, Pb, Co, Mn, and Fe exhibiting “no pollution” levels, while other elements show “moderate to extremely contaminated” values. EF analysis provided evidence of heavy metal presence, revealing a spectrum from “no pollution” to “moderate to extremely high pollution” for Cd, Zn, Cr, Ni, and Cu. The health risk assessment identified both carcinogenic and non-carcinogenic dangers for adults and children.Discussion: These findings highlighted the substantial contribution of identified sources such as industrial processes, vehicular emissions, sewage sludge, urban flooding, and the production and use of metallic materials that have elevated heavy metal levels in the urban soils. This established the link between urban industrial zones, human health, and long-term economic sustainability. This study provides essential guidance for decision makers to develop effective strategies for soil remediation, enhanced industrial practices, and regulatory measures to address heavy metal contamination in urban areas, ensuring the wellbeing and sustainable environmental quality management in cities.

Study of the Level of Lead and Zinc in Five Species of Fish in Tigris River

The research was carried out in the Tigris River, specifically in two distinct areas, namely Tikrit and Samarra within the Salah al-Din province, during the period of May 1, 2022, to January 9, 2021. The selection of these two stations was made with the intention of collecting fish samples for the purpose of assessing the presence of heavy element contamination in the fish population. This study was conducted at the laboratories of the Department of Food Sciences in the College of Agriculture, and the Department of Chemical Engineering in the College of Engineering at the University of Tikrit. The objective of the study was to assess the extent of heavy metal contamination, specifically lead and zinc, in various parts of fish including meat, liver, gills, and intestines. The study focused on five species of fish commonly found in the Tigris River, namely Zori, Nile tilapia, Aspius vorax, Silurus triostegus, and Carrasobarbus luteus. Additionally, the study encompassed two regions, Tikrit and Samarra, located in Salah al-Din province. The bi-interaction recorded a significant difference in the lead element, the highest value of which was (5.14 PPM) in the Nile tilapia muscles, and the lowest value (0.001 PPM) in the Nile tilapia gills, where the bi-interaction between the type of fish and the location was not recorded in the zinc element in the Samarra location, it reached the highest level The zinc element in the average of the sample type was (37.17 PPM) in the liver of the studied fish, and the lowest value was (8.82 PPM) in the intestines of the studied fish.

Application of Co3O4 nanocrystal/rGO for simultaneous electrochemical detection of cadmium and lead in environmental waters

Sensing of cadmium (Cd) and lead (Pb) in environmental samples is crucial for identifying potential health risks associated with exposure to these heavy metals as well as understanding the extent of heavy metal contamination in different environments and its impact on the ecosystem. The present study elucidates the development of a novel electrochemical sensor that can detect Cd (II) and Pb (II) ions simultaneously. This sensor is fabricated using reduced graphene oxide (rGO) and cobalt oxide nanocrystals (Co3O4 nanocrystals/rGO). The characterization of Co3O4 nanocrystals/rGO was done by using various analytical techniques. The incorporation of cobalt oxide nanocrystals with intense absorption properties results in an amplification of the electrochemical current generated on the surface of the sensor by heavy metals. This, when coupled with the unique properties of the GO layer, enables the identification of trace levels of Cd (II) and Pb (II) in the surrounding environment. The electrochemical testing parameters were meticulously optimized to obtain high sensitivity and selectivity. The Co3O4 nanocrystals/rGO sensor exhibited exceptional performance in detecting Cd (II) and Pb (II) within a concentration range of 0.1–450 ppb. Notably, the limits of detection (LOD) for Pb (II) and Cd (II) were found to be highly impressive at 0.034 ppb and 0.062 ppb, respectively. The Co3O4 nanocrystals/rGO sensor integrated with the SWASV method displayed notable resistance to interference and exhibited consistent reproducibility and stability. Therefore, the suggested sensor has the potential to serve as a technique for detecting both ions in aqueous samples using SWASV analysis.

Assessment of heavy metal pollution of drinking water sources and staple food cultivars around artisanal mining site in Igade-Mashegu, Niger State, Nigeria

Ecotoxicological studies have been carried out on the precarious effects of heavy metal pollution and exposure attributed to anthropogenic practices such as mining, industrial and agricultural activities, which poses serious health challenges. This study investigated ten (10) heavy metals namely As, Cd, Co, Cr, Cu, Fe, Hg, Ni, Pb and Zn in one hundred and fifteen samples from water sources and staple food cultivars around Igade mining site in Mashegu Local Government Area of Niger State, North-Central Nigeria, using Atomic Absorption Spectrophotometer (AAS). The result revealed the concentrations of heavy metals in staple food cultivars consumed at Igade to be within the recommended maximum levels as stipulated by WHO/FAO, but As2+ and Cd2+ were higher in legumes (1.510 ± 0.169 mg/kg) and vegetables (1.666 ± 0.154 mg/kg); and cereals (0.328 ± 0.012 mg/kg) and tubers (0.421 ± 0.176 mg/kg) respectively. This implies that the artisanal mining contributed to the exogenous bioaccumulation of these metals in staple food cultivars following the pattern: Fe > Zn > Cu > As > Pb > Cr > Cd > Hg which could accumulate and destroy vital organs thereby affecting human health upon consumption. Also, the mean concentration of the heavy metals in various water sources at Igade mining site decreased in the order Zn > Fe > Cr > Cu > As > Hg > Pb > Cd > Ni. Levels of As, Hg, Pb, Fe, and partly Cr in water sources were observed to be higher than the WHO and NSDWQ recommended standards for drinking water. Thus, their continuous consumption poses potential health risk to inhabitants, and therefore, there is need for the provision of safe alternative water sources; proper sensitization and monitoring of the mining activities to curb health risks and the extent of heavy metal contamination.

Ecological Risk Assessment and Source Contributions of Heavy Metals in the Sediment of the Chan Thnal Reservoir, Kampong Speu, Cambodia

Metal contamination from farming, inadequate wastewater treatment, and poor disposal of municipal garbage are major threats to public health. This research aimed to (1) assess the extent of heavy metal contamination in sediment samples, (2) describe the distribution of heavy metals by locating likely pollution sources using a positive matrix factorization (PMF) model, and (3) quantify the potential ecological consequences associated with these metals at six different places around the Chan Thnal Reservoir. The findings indicated steady degradation and suggested moderate to high metal contamination. Fe > Zn > Cr > Cu > Pb > Co > As > Mn > Cd was the trend of metal concentrations in the sediment. Various soil pollution indices showed that most of the studied sediment samples were clean, moderately clean, or slightly contaminated. However, Co and Cd reached high-risk conditions posing a severe problem to the local population living in and around the Chan Thnal Reservoir. Principal component analysis (PCA) was used to estimate primary factors in PMF analysis. It was found that the contamination of As, Cu, Zn, Cd, and Pb originated from agricultural and traffic vehicle sources; however, Zn, Fe, Mn, Cr, and Cu were derived from natural sources (e.g., atmospheric deposition and compost amendment). Furthermore, Fe, Cd, Mn, Co, Pb, and Cr were generated from urban and industrial sources (metal coatings, plastic burning, wastewater irrigation, and sewage sludge). Accordingly, this research improves our knowledge of the prevalence of heavy metal pollution in agroecosystems, which may be used to foresee and mitigate the risks of heavy metal exposure to humans and other organisms.

Metal accumulation capacity of raphidascaridid nematode, Hysterothylacium reliquens, infecting the king soldier bream (Argyrops spinifer)

There are several types of biological markers in the environment. The potential parasites’ ability to serve as bio-indicators of pollution in marine ecosystems was the focus of the current study. Forty samples of the king soldier bream Argyrops spinifer, were collected from the Red Sea (Jeddah, Saudi Arabia) for this study, and they were examined for parasite infections. Only 25 fish samples included one naturally occurring nematode parasite, Hysterothylacium reliquens, which had three of its life-cycle stages (adults, L3, and L4 larvae). The levels of some metals (Fe, Cu, Cd, and Pb) were detected in the parasite stages and the tissues of the fish host tissues (liver, muscle, and intestine). These metals accumulated higher in non-infected fish tissues than in infected ones. The significant parasite capability for metal accumulation rather than fish tissues was validated by bioconcentration factors. Depending on the stage of a parasite’s life, different metals were used. Larval stages are more prone to gathering essential elements (Fe and Cu). Although adults have a greater tolerance to toxic metals (Cd and Pb). The various metal absorption mechanisms were referred to as the differences between parasite stages. This proved that fish nematodes might serve as helpful bioindicators for assessing the extent of heavy metal contamination of aquatic ecosystems.

Determination of Heavy Metal Residues in Tropical Fruits near Industrial Estates in Rayong Province, Thailand: A Risk Assessment Study

This study determined the extent of heavy metal contamination of local fruit in Rayong, Thailand, an area where an industrial base is adjacent to agricultural areas. Dietary exposure to agricultural products grown in contaminated areas can cause multiple adverse effects to the human body. In order to avoid such undesirable effects, concentrations of heavy metals [arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn)] were investigated in popular tropical fruits from three districts of Rayong, namely Wang Chan, Klang and Mueang. The levels of heavy metals were determined by inductively coupled plasma-mass spectrometry (ICP-MS) and cold vapor-atomic absorption spectrometry (CV-AAS). Levels of the six heavy metals in sampled fruits (durian, jackfruit, pineapple, rambutan, long kong, and mangosteen) were in the range of 0.0004-6.7095 mg/kg; 16.7% of fruit samples exceeded maximum permissible limits of Pb. Based on health risk assessments, values of estimated daily intake (EDI) were less than those of maximum tolerable daily intake. However, for non-carcinogenic risks, high hazard index (HI) values were found in some markets while for carcinogenic risks (CRs), CR values of three fruits (durian, jackfruit, and mangosteen) exceeded acceptable levels. Therefore, long-term fruit consumption could impact health of local consumers. These results provided insight into the need for regular monitoring of heavy metal concentrations in potentially contaminated fruits and for prevention of its potential effects.

Assessing the extent of heavy metal contamination in crude oil-impacted soils in the Niger Delta, Nigeria using geochemical indicators

The study presents heavy metal (HM) [copper-Cu, chromium-Cr, nickel-Ni, vanadium-V, lead-Pb, zinc-Zn and iron-Fe] contamination in genuine crude oil-impacted soils and pristine (control) soils. HM concentrations were measured using inductively coupled plasma (ICP). Using soil Contamination factor, Enrichment factor, Pollution load index and Geo-accumulation index, the extent of heavy metal contamination in soils were determined and compared. Results of contaminated factor (CF) of Cu, Cr, Ni, and V were very high in the impacted soils whereas CF of Pb indicated considerable level of contamination. Pollution load index was greater than 1 which implies severe pollution in all the impacted soils while; the control soils indicated a pollution load index of less than 1 showing no pollution. Enrichment factor values of the impacted soils were between 0 and 1, which reveals background enrichment showing the presence of the metals above the threshold values. This may be attributed to anthropogenic sources especially oil spill contamination. The results of geo-accumulation index of Zn, Pb, and V showed considerable accumulation whereas, Fe, Cu, Cr and Ni indicated unpolluted to moderately pollution. Results of V, Ni, Pb, and Cr may be attributed to anthropogenic origin, which are in agreement with the calculated values of the enrichment factor. Results suggest the need for environmental risk assessment and/or remediation of the numerous oil spill sites for soil health and wellbeing of humans.

Heavy Metal Contamination in Oryza sativa L. at the Eastern Region of Malaysia and Its Risk Assessment.

Paddy plants tend to accumulate heavy metals from both natural and anthropogenic sources, and this poses adverse risks to human health. The objective of this study was to investigate heavy metal contamination in paddy plants in Kelantan, Malaysia, and its health risk assessment. The bioaccumulation of heavy metals was studied by means of enrichment (EF) and translocation factors (TF). The health risk assessment was performed based on USEPA guidelines. The EF for heavy metals in the studied areas was in the descending order of Cu > As > Cr > Cd > Pb. Meanwhile, Cr and Pb exhibited higher TF values from stem to grain compared with the others. The combined hazard index (HI) resulting from five heavy metals exceeded the acceptable limit (HI >1). The lifetime cancer risk, in both adult and children, was beyond the acceptable limit (10−4) and mainly resulted from exposure. The total cancer risk (CRt) due to simultaneous exposures to multiple carcinogenic elements also exceeded 10−4. In conclusion, intake of heavy metal through rice ingestion is likely to cause both non-carcinogenic and carcinogenic health risks. Further research is required to investigate the extent of heavy metal contamination in agricultural soils and, moreover, to establish human exposure as a result of rice consumption.

A Pilot Study on the Concentration of Heavy Metals in Sediments from the Lower Orange River, //Karas Region, Namibia

Global water shortage is caused not just by the physical scarcity of water, but also by gradual deterioration of the quality of water resources such as lakes, streams and rivers with heavy metals. This present study evaluated the status of Mn, Fe, Cr, Cu, Ni, As, Zn, Pb and Cd in sediments from the lower Orange River by Inductively Coupled Plasma Atomic Emission Spectrometry technique by collecting a total of eleven samples, each weighing 1 - 2 kg at the depth of 15 - 20 cm from two observations sites along the lower Orange River and applying pollution indicators such as contamination factor(CF), pollution load index(PLI), index of geo-accumulation(Igeo) and enrichment factor(EF) to assay the nature and extent of heavy metals contamination in sediments. The sequence of the total heavy metal content in descending order was Fe > Mn > Cr > As > Zn > Ni > Cu > Pb > Cd. The results of CF and Igeo showed Mn, Cd, Ni, Zn and Pb were minor sources of sediment contamination since most of the samples were unpolluted and moderately polluted by these metals. However, most sediments were moderate to considerably polluted with Cr, As and Fe suggesting that these were the major pollution sources. The value of PLI at one of the two observation sites was equivalent to the value of baseline level, while the next site indicted quality deterioration of the sediments. The EF revealed that Cr was moderately enriched and arsenic (As) significantly enriched in all the sediments, which suggested contamination due to anthropogenic intervention. Hence, it is recommended that sediment quality be evaluated on a regular basis to avoid further deterioration of the Orange River’s health, which might have detrimental repercussions for both aquatic life and local communities along the river.

Determination and probabilistic health risk assessment of heavy metals in widely consumed market basket fruits from Dhaka city Bangladesh

ABSTRACT Heavy metals contamination of fruits and vegetables is a growing concern to the public and policymakers in developing countries. This study investigated the extent of heavy metal contamination in widely consumed grape, apple, orange, banana, and pomegranate from supermarkets in Dhaka, Bangladesh, using atomic absorption spectroscopy (AAS) to assess the health risks to humans. Of the total 80% of banana and 60% of pomegranate samples, the mean lead (Pb) concentrations were 0.608 and 0.164, respectively, exceeding the maximum allowable concentration (MAC = 0.1) set by FAO/WHO and EU regulations, while the remaining fruit samples were below the limit. The Single-factor pollution index (PI) of Pb in bananas (6.08) and pomegranate (1.64) was higher than the reference value (PI>1), indicating the lower quality of fruits due to the higher amount of lead contents. The calculated incremental lifetime cancer risks (ILCRs) of cadmium (Cd) and Pb in banana, apple, grape, orange, and pomegranate for both children and i adults were exceeded the threshold limit (ILCR>10−6), which suggests that the consumption of heavy metal contaminated fruits poses potential cancer risks to the human health. In contrast, target hazard quotients (THQs) and chronic hazard index (HIs) values of all heavy metals were in the range of (THQ: 2.4 × 10−6–0.76; 6.5 × 10−7–0.20) and (HI:0.03–0.49; 0.01–0.13), respectively, for children and adults, which were below the acceptable limit (THQ<1), indicating no potential non-cancer risk for both consumer groups. These findings might help the policymakers and regulatory bodies concerned to apply control measures through monitoring the quality of locally grown or imported fruits available in supermarkets for human consumption.

Physicochemical Studies for Risk Identification, Assessment, and Characterization of Artisanal Barite Mining in Nigeria

Over 90% of barite mining activities in Nigeria are carried out by artisanal and small-scale miners (ASMs), and up to 75% of these miners operate informally, without mining license and rights. Such mining activities endanger human lives through the uncontrolled release of toxic heavy metals and other pollutants which are major causes and consequences of severe health hazards in children and adults living close to the mining sites. This paper is in two parts. The first section assesses the extent of heavy metal contamination of Cd, Cu, Fe, Pb, Ba, and Zn in drinking water by the mine water and tailing effluents. The second section estimates heavy metals’ toxicity and exposure level and analyzes and characterizes other human health risks in tailing effluents selected from three barite mining sites in Nigeria. Inductively coupled plasma mass spectroscopy (ICP-MS) results show that the concentrations of Ba and Pb among other heavy metals are above the allowable limits for drinking water. Index of geo-accumulation (Igeo) and contamination factor (CF) for Ba, Fe, and Pb were classified as moderately to extremely polluted (based on the Igeo) and highly contaminated (based on the CF). The calculated non-carcinogenic risk for Ba is 0.87 and 0.99 for Pb. HQ/HI (health quotient/health index) for Zn, Cu, and Fe is ≤0.005. The results indicate that some precautionary measures should be taken to avert the non-carcinogenic risk of Ba and Pb. It is important that barite mining is carried out in a responsible manner, respecting local and national mining laws and global environmental standards.

Assessment of Heavy Metal Levels in Soil and Vegetables in Some Farms Around Mining Sites in Mangu Local Government Area Plateau State, Nigeria

When the mining process is not properly controlled, it can be a source of heavy metals pollution in the environment. The uptake of these heavy metals in edible parts of vegetables can be a direct source of the metals into the human food chain. This study assessed the concentrations of lead (Pb), manganese (Mn), zinc (Zn), copper (Cu), nickel (Ni) and chromium (Cr) in soil and vegetables obtained from nine (9) farms around mining sites in Mangu LGA. Concentrations of heavy metals in soil and vegetables were determined using atomic absorption spectrophotometer (AAS). The results revealed the concentrations of the heavy metals at the farms to be within the recommended maximum levels of world soils but were higher than their respective controls. This implies that the artisanal mining contributed to the increased values of these heavy metals in the environment. Also, the mean concentrations of the heavy metals at Mangu Halle mining site decreased in the order Mn &gt; Zn &gt; Cr &gt; Cu &gt; Ni &gt; Pb &gt; Cd whereas at Alogwom it decreased in the order Mn &gt; Zn &gt; Pb &gt; Cu &gt; Ni &gt; Cr &gt; Cd. The enrichment factor (EF) of the elements showed deficiency to minimum enrichment for all the heavy metals whereas the pollution index (PI) of the metals indicated very slight contamination to moderate pollution. The results of the heavy metals in the vegetables showed that the bioaccumulation of the metals followed a pattern: Zn &gt; Cu &gt; Pb &gt; Cr &gt; Cd &gt; Ni. Levels of Cd, Pb and Ni in the vegetables were observed to be higher than the recommended limit for vegetables whereas Cu, Cr and Zn exhibited lower values than recommended standards. Thus, their consumption might pose health risk to consumers and therefore there is the need for proper monitoring of the illegal mining activities to reduce health risk and the extent of heavy metals contamination.

Assessment of heavy metal pollution and exposure risk for migratory birds- A case study of Caohai wetland in Guizhou Plateau (China).

Increasing heavy metal pollution in wetland ecosystems around the world pose significant health risks to waterbirds, especially the endangered species. We analyzed heavy metal pollution in bird foraging area of Caohai wetland in Guizhou Plateau (China), and used an integrated exposure risk model for assessing heavy metal (Cd, Pb, Cr, Ni, Zn, Sb) exposure risk in birds from the soil, water, plants and benthic invertebrates. There is considerable variation in the extent of heavy metal contamination across the different sampling sites, and Cd and Sb are the main contaminants. The mussel Anodonta showed greater heavy metal accumulation (except for Zn) compared to the snail species C.cathayensis. The different plant species also varied in terms of amount for accumulated heavy metals. The phytophagous together with omnivorous birds were exposed to Cd, Pb, Zn and Ni through plants rather than the soil, whereas the maximum Zn exposure in the omnivorous and carnivorous birds was through consumption of benthic invertebrates. Furthermore, the phytophagous black-necked cranes (Grus nigricollis) were less risk to heavy metal exposure compared to the omnivorous bar-headed goose (Anser indicus) and carnivorous ruddy shelducks (Tadorna ferruginea). The exposure risk of Cr (8.1) was highest, followed by Pb (5.1), Zn (3.8), Sb (1.0), Cd (0.33) and Ni (0.28). The heavy metal assessment heavy metal exposure risk for migratory birds should take into account the exposure from food and soil. Our findings provide new insights into developing measures to minimize heavy metal contamination in migratory birds.

English

The status of heavy metal contamination of surface soils in two cocoa plantations of approximately 30 years in Cameroon was evaluated. The bioavailable fractions of Fe, Cu, Zn, Cd and Cr were used to assess the extent of heavy metal contamination using a selection of contamination indices. In addition, other physicochemical properties including organic matter, particle size, CEC and pH were assessed. One of the farms was dominated by sand (64.56 - 73.46% sand) in contrast to the other (2.56 to 37.51%) and the latter had a higher clay content. The order of abundance of heavy metals, as expressed by the mean values, is as follows: Fe > Cu > Zn > Cr > Cd in soils from the two areas. Contamination factors of Cu-, Zn- and Cd are considerable for clay-dominated soil. The potential ecological risk of the metals in both soils was low with the exception of Cd in the clayey soil. Results for hazard assessment showed Cu levels were within the low ISQC sediment criteria in the clay-dominated soil; possibly linked to the long-term application of Cu-fungicide. Key words: Heavy metal, contamination indices, cocoa plantation, Cameroon.

Impact of Abandoned Mining Facility Wastes on the Aquatic Ecosystem of the Mogpog River, Marinduque, Philippines.

Background.Mine waste from abandoned mining sites can cause environmental degradation and ecological imbalance to receiving water bodies. Heavy metal pollution affects local communities and may pose health risks to the general public. An abandoned mining facility in Marinduque, Philippines, situated on the of Mogpog River, continuously deposits mine wastes, which may affect the river and the health of local communities.Objectives.The aim of the present study was to examine the presence and extent of heavy metal contamination from mine wastes in the aquatic ecosystem of the Mogpog River by determining the level of heavy metal concentration in the water, sediments and biota.Methods.Four sampling sites were monitored for heavy metals (copper (Cu), arsenic (As), chromium (Cr) and sulfur (S)) pollution. Several analyses were conducted to determine the heavy metals present in the water, sediment and biota. Atomic absorption spectrophotometry was used for the analysis of Cu concentrations in water. X-ray fluorescence was used for the analysis of total heavy metals in the sediments and biota.Results.An inverse relationship with water and sediment from upstream to downstream of the river were observed. This trend shows deposition of Cu in the sediments as factored by pH. Flora gathered from the riverbanks recorded concentrations of Cu in their leaves and fruits.Conclusions.It has been difficult for the Mogpog River to regain water quality after years of mine waste deposition. Acid mine drainage occurred upstream of the river which affects the speciation of heavy metals. The potential risk of heavy metal exposure to local communities was observed due to the communities' river utilization.Participant Consent.ObtainedEthics Approval.The Office of Vice Chancellor for Research and Extension of University of the Philippines Los Baños approved the studyCompeting Interests.The authors declare no competing financial interests.