Bioaccumulation Of Heavy Metals Research Articles

Bioaccumulation and Potential Risk Assessment of Heavy Metals in Tropical Bamboo Plantations of Dendrocalamus brandisii under Two Cultivation Patterns in Yunnan, China

Heavy metal (HM) pollution nowadays is a hot issue concerning global ecological and food safety. As one of the most important woody bamboos for edible shoots in Southeast Asia and southwest China, Dendrocalamus brandisii usually occurs in red soil with a high HM geological background. However, the bioaccumulation process and possible risks of HMs in their cultivation area remain unclear. In this study, a comprehensive risk assessment of HM pollution was conducted in the main cultivation area of D. brandisii under two cultivation patterns in Yunnan, China. The results revealed that moderate to heavy HM pollution existed in the soil of the study area, while bamboo shoots displayed either no pollution or weak contamination. The “large-area intensive afforestation” cultivation pattern can better control HM pollution in soil and shoots than the “small-scale farmer management” pattern. Strong and complex correlations among HMs were unveiled in both soil and shoot samples. The Cr content of 39% of the shoot samples exceeded China’s national standards. Cu and Zn were the two most easily accumulated HMs in shoots, with BCF of 0.1235 and 0.1101, respectively. Bioaccumulations of As and Cd were positively correlated with their concentrations in soil. Furthermore, the positive matrix factorization model (PMF) identified three main sources of soil HMs, i.e., Pb and Zn from traffic emissions accounting for 30%; Ni, Mn, and Cr from pedogenic parent material making up 35.4%; and As from mining and metallurgical activities accounting for 34.6%. Monte Carlo simulations suggested the probability of total noncarcinogenic risk for children from bamboo shoots was 24.82% and that As in the soil was the primary element of health risk to children (HQc = 13.94%). These findings emphasize the urgent need to control and mitigate HM pollution from the identified sources and may contribute to the sustainable cultivation of D. brandisii and food safety in Yunnan and similar tropical areas with high HM contents.

Bioaccumulation Capacity of Onion (Allium cepa L.) Tested with Heavy Metals in Biofortification.

On a worldwide scale, A. cepa is among the most commonly consumed vegetables. In Europe, the leading onion producers are Russia, the Netherlands, Spain, Poland and Germany. In this study, the bioaccumulation of heavy metals (Cr, Cu, Zn, Ni, Fe, Mn, Co, Sr, Cd and Pb) by Allium cepa L. plants was followed under hydroponic conditions. The heavy metals were applied at six concentrations (0, 25, 50, 100, 200 and 400 mg L-1) over three weeks. The quantitative analysis of selected heavy metals in plant tissues (bulbs, roots and assimilation leaves) was performed using atomic absorption spectrometry with flame atomization (F-AAS). The accumulation of metal ions was strongly dependent on their concentrations in the solution and the analyzed parts of plants. The highest accumulation of metal ions was confirmed for the roots and ranged from 8.48 to 5912.34 µg g-1 DW (dry weight). All parts of A. cepa were characterized by the high accumulation of Mn2+. The lowest accumulation was confirmed for Co2+ in the roots, Pb2+ in the assimilation leaves and Cu2+ in the bulbs of onion. Moreover, the study showed that the highest concentrations of heavy metals decreased the growth of bulbs and even caused them to die off. In contrast, lower concentrations of some elements stimulated plant development.

Distribution and accumulation of Cadmium in different trophic levels affecting Serangium japonicum, the predatory beetle of whitefly Bemisia tabaci, biologically, physiologically and genetically: An experimental study

Cadmium (Cd) is a heavy metal that is of great concern in agroecosystems due to its toxicity to plants, herbivores, carnivores, and human beings. The current study evaluated the allocation and bioaccumulation of Cd from soil to cotton plants, cotton plants to herbivore pests, and herbivorous pests to a natural enemy predator. When soil was spiked with 100 mg/kg Cd, results demonstrated that cotton roots accumulated more Cd than the stems and leaves. The bioaccumulation of Cd was less in 4th instar larvae, pupa, and adults of Serangium japonicum than in Bemisia tabaci adults. The bioaccumulation in S. japonicum elongated the immature development period and reduced adult longevity, oviposition days, fertility, and total pre-oviposition duration. The net reproduction of S. japonicum was also reduced, as was female mature weight and feeding potential; as a result, Cd exposure could reduce the future population size compared to uncontaminated populations. There was decreased activity of the antioxidant enzymes (SOD, CAT, and POD) and energy-conserving lipids (glycogen, triglyceride, and total cholesterol) in Cd-contaminated S. japonicum compared to controls. The detoxifying enzyme activity of GST and P450 increased while AChE activity did not change. The qRT-PCR research showed that SOD1, CAT, POD, glycogen, and triglyceride gene expression was higher than in controls, whereas detoxification gene expression did not change. Our results indicate that Cd exposure has a physiological trade-off between its adverse effects on life history traits and elevated detoxification and antioxidation of S. japonicum, which could result from gene expression alteration. Further studies are needed to assess whether Cd exposure causes irreversible DNA damage in S. japonicum.

Heavy metal bioaccumulation and risk assessment in fishery resources from the Gulf of Thailand

The muscle tissues of 19 fish species, two crab species, and one shrimp species collected from the Gulf of Thailand (GoT) were analyzed to determine the levels of heavy metals, including Cu, Zn, Fe, Mn, Ni, Pb, Cd, and Hg. The results revealed that the mean concentrations of the heavy metals, in descending order, were Zn > Cu > Fe > Cd > Hg > Mn > Pb > Ni. Among the examined metals, zinc was found to be the most prevalent in fish tissues. Based on the risk assessment indices, the estimated average daily doses (ADD) of the heavy metals were found to be below the provisional tolerable daily intake (PTDI) recommended by the joint Committee of the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) on food contaminants. The results of the target cancer risk analysis revealed no related cancer risk from the consumption of the fishes considered for the study. However, the target hazard quotient (THQ) values exceeded the threshold of 1 (THQ > 1) specifically for mercury in Gymnothorax spp. and Terapon spp. Furthermore, the calculated hazard index (HI) values for fish muscles were all below 1, indicating that there is no significant health risk for humans at the current consumption rates, except in Terapon species for both normal and habitual consumers. Notably, habitual consumers of Gymnothorax species showed the highest HI value (>1), suggesting potential long-term effects on human health when consuming larger quantities of these fishes.

Cassava (Manihot esculenta) Yield, Nutrition, and Heavy Metal Bioaccumulation Responses to Circular Economy-Based Innovations in a Mining-Degraded Landscape

Mining operations in Ghana's Forest-Savannah Transition Zone have caused widespread land degradation, jeopardizing ecosystems, food security, and agroecological sustainability. In response, we conducted an experiment to evaluate the effects of biochar and poultry litter amendments on cassava (Manihot esculenta) growth, nutritional quality, and heavy metal accumulation at an illegal mining-degraded site in the Amansie Central District of Ashanti, Ghana. The experiment included five treatments: biochar (10 ton/ha), poultry manure (10 ton/ha), a biochar-poultry manure mix (1:1 ratio, 10 ton/ha each), and two control groups (degraded and forest sites). The combined biochar and poultry manure treatment yielded the highest cassava stover biomass (22.9 ton/ha) during the first year. Nutritional characteristics of cassava such as %carbohydrate, %protein and %total ash tubers were influenced by treatment amendments. Additionally, biochar and poultry manure reduced the accumulation of Arsenic (As) by 168.9% and Lead (Pb) by 149.8% in cassava compared with galamsey soil control. This study showcases a circular economy-based approach that employs locally available resources to restore mining-degraded landscapes and enhance regenerative agricultural practices, reducing waste, bioaccumulation of heavy metals and improving carbon sequestration. Promoting the use of biochar and poultry manure amendments for ecological restoration in mining-degraded areas can contribute to sustainable land use, food security, and livelihoods. Policymakers should consider these strategies to align with global and national development goals while improving food systems and ecosystem services. Future research should explore the long-term impacts of cassava cultivation on amended mining sites and assess the potential of these amendments for agroecological enhancement and heavy metal immobilization.

Koncentracija teških metala u tkivu oslića Merluccius merluccius (Linnaeus, 1758) iz Oranskog zaljeva (Sredozemno more)

To evaluate the potential human health risk to hake consumers, the bioaccumulation of heavy metals (Cd, Pb, and Zn) was measured in the edible tissues of hake Merluccius merluccius (Linnaeus, 1758) caught from Oran Bay on the western Algerian Mediterranean coast. Results revealed that the average metal concentrations varied significantly among sex and in target organs. The concentrations of metal accumulation take place preferentially in the liver compared to the muscle of hake species, with the highest levels found for Zn, followed by Pb and Cd. The Estimated daily intake (EDI) of each trace metal did not exceed the tolerable daily intake (TDI). Human health risk assessment from heavy metal exposure through fish consumption from Oran Bay for adults showed no significant non-carcinogenic adverse health risk since all calculated values for Target Hazard Quotient (THQ) and Total Target Hazard Quotient (TTHQ) were <1.

Chemical profile and toxicological analysis of Pluerotus pulmonarius grown on different substrates

Mushrooms are rich sources of bioactive compounds; however, their safety for human consumption is a public health concern. This study investigated the chemical profile and toxicological effects of Pluerotus pulmonarius (mushroom) grown on three substrates (corn cob, sawdust, and palm bunch). The mushrooms were designated corn cob mushroom (CCM), sawdust mushroom (SDM), and palm bunch mushroom (PBM), respectively. The mushrooms' bioactive compounds and heavy metals were characterized using a GC-MS and ICP-AES, respectively. Acute and sub-acute tests of the mushrooms were conducted in mice fed mushroom-supplemented diets at a 1:1 (w/w) proportion. Heavy metals bioaccumulation factor (Ka) estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) were calculated. Twelve major bioactive compounds and three heavy metals (Cu, Zn, and Fe) were detected in the mushrooms. PBM-fed mice had the highest total plasma protein and GSH levels, and GPx activity, but the lowest ALT and AST activities, and LDH and urea levels. The SDM-fed mice exhibited the lowest cholesterol level in the sub-acute test, while the CCM-fed mice had the highest cholesterol in both the acute and sub-acute toxicity test. CCM-fed mice also showed the highest HDL level in both the acute and sub-acute toxicity studies. The mushrooms bio-accumulated more Zn than Fe, but their EDI were below the permissible tolerable daily intake. The mushrooms' THQ of Cu, Zn and Fe were greater than 1, except that of Cu in CCM (THQ, 0.96), but their HI values were less than 5, except in PBM (HI, 6.40). The mushroom-fed mice had a normal kidney morphology, and a mild-to-moderate portal inflammation of their liver tissues. Hence, P. pulmonarius from different substrates caused no severe toxicity in mice, but their HI for Cu, Zn, and Fe suggests a potential risk to humans.

Quantifying Bioaccumulation Factors of Food Cultivars in the Vicinity of Coal Mining: A Study in Ngwo, Akwuke, and Udi Communities, Enugu State, Nigeria

Heavy metal contamination resulting from coal mining activities poses a substantial threat to both environmental stability and human health. This study delves into the bioaccumulation factors of various food cultivars within the coal mining regions of Ngwo, Akwuke, and Udi Communities in Enugu State, Nigeria. Heavy metals, including lead, cadmium, nickel, manganese, and chromium, have been recognized as significant contaminants responsible for various detrimental health effects. The presence of these metals in the environment, particularly in soil, water, and subsequently in food crops, leads to indirect human exposure through the food chain, thereby triggering several health risks. This research focuses on assessing the levels of heavy metal bioaccumulation in food cultivars and their potential implications for human health. Samples of leafy vegetables and tubers were collected from different locations within the communities and processed following recommended methods. The digestion process involved the use of concentrated acids and subsequent analysis through Atomic Absorption Spectrophotometry (AAS) to quantify the concentration of heavy metals. Bioaccumulation factors (BAF) were determined by establishing the ratio of metal concentrations in the plants to those in water. Results indicated significant variations in bioaccumulation factors among different cultivars and study sites. For instance, the bioaccumulation of manganese and chromium in pumpkin from Akwuke was notably higher compared to Udi and Ngwo, while lead and cadmium levels were significantly higher in Udi. Similar trends were observed in scent leaf and cassava samples, suggesting differential metal accumulation based on cultivar type and geographical location. The findings underscore the concerning levels of heavy metal bioaccumulation, especially high cadmium accumulation in certain food cultivars, posing potential health hazards to communities reliant on these crops. This study emphasizes the critical need for effective environmental management strategies and water treatment practices in these regions to mitigate health risks associated with heavy metal exposure through food consumption. Keywords: Heavy metals, Bioaccumulation factors, Food cultivars, Coal mining, Environmental health, Nigeria.

Bioaccumulation and Potential Risk Assessments of Heavy Metals in Two Varieties of Edible Vegetables (Amaranthus hybridus and Celosia argentea) around Lapite Dump Site, Akinyele Local Government Area, Ibadan, Oyo State, Nigeria

The objective of this paper was to evaluate the bioaccumulation and potential risk assessments of heavy metals in two varieties of edible vegetables (Amaranthus hybridus and Celosia argentea) around Lapite Dump Site of Akinyele Local Government Area, Ibadan, Oyo State, Nigeria using different standard analytical techniques. The mean concentrations of the heavy metals showed that Pb, Cd and Mn (3.05mg/kg, 0.67mg/kg, and 129.61mg/kg) are the metals with means higher than their respective permissible values (PL) for humans (0.3mg/kg, 0.2mg/kg, and 6.64mg/kg respectively). These three heavy metals are also the metals with the most significant contamination and pollution factor according to the calculated contamination factor and geo-accumulation index. The bioaccumulation factors showed that Mn and Zn are the heavy metals accumulated most in the plants with the leaves having high content of these metals more than the stems. Pollution load index calculated revealed that the dumpsite area has been deteriorated (PLI > 1) making activities around the area (including agriculture) and the habitants at high risk of health hazards. Consequently, planting and other human activities in this area should be discouraged while appropriate authorities should get involved in impact assessment of the environment to relocate the farms and habitants of the area to a more suitable and environmental friendly area.

Bioaccumulation and biomagnification of heavy metals in marine micro-predators

Nematodes represent >3/5 of the abundance of the world’s metazoans and usually account for nearly 90% of the total benthic fauna, playing a key ecological role in the benthic ecosystem functioning on a global scale. These small metazoans include a relevant number of microscopic predators and, in turn, are the most abundant preys of macro-megafauna and fish juveniles thus playing a key role in marine food webs. Here, using two independent approaches, we test the bioaccumulation in marine nematodes of several heavy metals present in contaminated sediments. We report here that nematodes, despite their short life cycle and small size, bioaccumulate significantly heavy metals. Bioaccumulation increases from deposit feeders and microalgal grazers to predators of microbes and other tiny metazoans. These results suggest that nematodes also contribute to their biomagnification along the food webs and can contribute to increase the transfer of contaminants from the sediments to larger organisms.

Comparative Study of Whole-Body Proximate Composition, Dressing Losses and Bioaccumulation of Heavy Metals in Muscle Tissues of Wild and Farm-Raised Labeo Rohita

The muscle tissues of wild and farm-raised rohu were analyzed for proximate composition (Crude protein, crude fat, ash, and dry matter) and uptake of heavy metals (Cd, Ni, Pb, and Cr) using the standard protocols. For this purpose, wild fish samples were collected from the Khanpur Canal, Sheikhupura, and farmed fish samples from a local fish market in Lahore. The results showed that the concentration (%) of protein (17.92±0.36), ash (06.54±0.13), and moisture (76.50±1.53), was observed to be higher in the wild when compared to protein (16.90±0.34), ash (5.07±0.10) and moisture (73.50±1.47) of farm-raised rohu. In contrast, crude fat contents were observed to be higher (4.02±0.08) in farm-raised rohu than wild (03.65±0.07). In terms of dressing losses, wild fish showed higher (26.37%) losses as compared to farm raised (25.83%). Results showed that in wild and farm fish’s muscles, the trend of the heavy metals was Pb > Cd > Ni > Cr. The findings demonstrated that in comparison to Cd, Ni, and Cr, Pb concentration (ppb) was greater in both wild (128.32.82) and farm-raised (111.42.16) rohu. When compared to wild rohu, farmed rohu showed a higher bioaccumulation tendency for Cr and Ni, but Cd and Pb showed the reverse pattern. The findings of this study suggest that fish proximate composition, dressing losses, and bioaccumulation of heavy metals are certainly impacted by the aquatic life of freshwater fish like Labeo rohita both in wild and farmed conditions and these results will be helpful for the aquaculturists as well as the local consumers of the fish.

Growth Performance and Biochemical Composition of Nile Tilapia (Oreochromis niloticus) Reared in Membrane Bioreactor Treated Wastewater

The aquaculture sector in Africa has great potential for growth; however, it faces several challenges, one of them being the scarcity of clean water. This prompts the need for water recycling. The present study was conducted to investigate the effects of rearing Nile tilapia (Oreochromis niloticus) using municipal wastewater treated with membrane bioreactor (MBR) technology. A total of 270 Nile tilapia fingerlings (0.15±0.05 g) were reared in three treatment groups in triplicate. There were 2 treatments, including; MBR treated wastewater and stabilization pond treated wastewater (maturation pond), while the municipal tap water was used as the control. The growth performance (weight and length) of the fish was monitored over a 24-week period. After the experimental period, the biochemical composition of the fish muscle was analysed using standard AOAC methods. The results showed that the highest weight gain, length gain, survival rate, and specific growth were obtained in the fish in the control followed by the MBR treatment. Additionally, the crude protein, as well as the crude fiber and dry matter, were significantly higher in the fish in the maturation ponds at 23.10%, 0.29%, and 25.35%, respectively, while the crude ash was highest in the MBR at 1.22%. Results also showed that the MBR and maturation pond treatments meet the permissible levels for BOD, COD, NH4, and NO3 for water to be used in aquaculture. The bioaccumulation of heavy metals in the fish was mainly from the feed, with copper being the highest contaminant at 1.75 mg/100 g. In conclusion, both the MBR and maturation pond treated wastewater are viable for use in the rearing of Nile tilapia without adverse effect on the growth. However, MBR treatment showed better growth performance, suggesting that it could be used to increase productivity in fish farming.

An experimental study on the effects copper and lead on the seedlings of some economically important vegetable species

Bioaccumulation of toxic heavy metals in vegetables is closely related to the problems of safety concerns as they negatively affect plants in particular those consumed by the humans. Among the food systems the vegetables are the most noticeable foods affected by environmental pollution. Vegetables can take up the metals like copper and lead and store them in excessive levels. Keeping this in view this investigation was undertaken to study the effect of copper and lead concentrations (20, 40, 80, 160, 240, 320, 640, and 1280 µM) and assess their toxic affects on germination and seedling growth at early stages of eight vegetable cultivars; kidney bean, peas, black-eyed bean, artichoke, kale, lettuce, rocket and radish. The results were evaluated by multivariate analysis of variance and Pearson correlation statistical analysis. Our results indicate that the seeds of the vegetables studied by us are generally tolerant to both copper as well lead, except higher concentration exposures which showed no improvement when applied to artichoke (for Cu 1280 µM) and lettuce seeds (Cu 1280 µM; Pb 1280 µM). An application of copper and lead ended up with a decrease in barium, calcium, iron, magnesium, manganese, sodium and zinc content in all seedlings studied. In all vegetables exposed to copper and lead a promotion in copper and lead accumulation was recorded. There was a decrease in nutrient element intake which interrupted the mineral element uptake in the seedlings.

Histopathological alteration in the liver of Sardinella longiceps as a biomarker of heavy metal pollution in aquatic ecosystem.

The discharge of heavy metals from industrial effluents into aquatic ecosystems is a major cause of serious aquatic pollution. The bioaccumulation of toxic heavy metals in aquatic species can lead to their transmission to the food chain, posing serious public health risks. Present study was done to assess heavy metal accumulation and histopathological analysis in the liver of Sardinella longiceps collected from Sassoon dock during the rainy season between 2019 to 2022. It was found that amongst studied heavy metals Cu, Cr, and Mn concentration was beyond the permissible limit of WHO and FAO guidelines. Histopathological analysis of liver tissues during the studied period showed various architectural alteration which could be due to the accumulation of heavy metals found in it.

Predisposing Factors that Promote Prevalence of Heavy Metals Assimilation and Bioaccumulation in Aquatic Medium and amongst Fishes

The degree of heavy metals assimilation and bioaccumulation in fish tissues (muscles, gills, liver, and kidneys), amongst scale-less fishes- Chrysichthys macrotis, Chrysichthys nigrodigitatus, Clarias gariepinus and Heterobranchus longifilis, -scaly fishes- Cynoglossus senegalensis, Oreochromis aureus, O. niloticus, Lutjanus fulgens, Pomadasys rogeri, and Tilapia galilea, water columns and sediments, were investigated. Heavy metals assimilation and bioaccumulation varied among organisms with or without scales, tissue types, and fish location (water column & sediments) and pollution level. Fishes with scales had lower concentrations of heavy metals than scale- less fishes. The scalier the fish, the lower the metal assimilation and bioaccumulation. As expected, trace metals were generally lower in muscles than liver, and kidney. Liver had highest followed by kidney, gills and then muscles. Fish trophic level (water column or sediments) and water pollution levels affected heavy metal concentrations. Concentrations were always more in sediments than water column or tissues. The more polluted the water, the more the assimilation and accumulation of trace metals.

Interaction and Transport Characteristics of Lead and Cadmium in Different Soil-wheat Systems

In this study, four groups of lead(Pb) and cadmium(Cd) combined treatments with different concentration ratios were set up in Hailun black soil, Xianning brown-red soil, and Changwu Heilu soil, and wheat(Zhengmai 9023) was planted for a five-month pot experiment to analyze the Pb-Cd interaction behavior on heavy metal bioaccumulation in wheat under three soil-wheat systems. The low pH brown-red soil had the highest water-soluble Cd and Pb contents with significant Pb-Cd interactions in the soil, whereas the black soil with high organic matter and Heilu soil with high calcium carbonate content exhibited lower Cd and Pb activities. Among the three soils, wheat height and dry weight showed the poorest growth performance in the Heilu soil, but the wheat height increased by 2.68-8.49 cm compared with that in the control under the Pb-Cd combined treatment, whereas Pb-Cd interaction had the least effect on wheat height and dry weight in black soil and inhibited the growth of wheat in the brown-red soil. In the transport process of Cd or Pb in wheat, Pb-Cd interaction showed quite different effects in the three soil-wheat systems. Under the 125 mg·kg-1 and 250 mg·kg-1 Pb treatments, the Pb content in wheat grain planted in brown-red soil significantly increased by 73.2% and 19.1% with the addition of Cd, respectively, and therefore there was a synergistic effect between Pb and Cd. Under the 0.3 mg·kg-1 and 0.6 mg·kg-1 Cd treatments, the Cd content in wheat grains planted in black soil decreased by 51% and 33% with the addition of Pb, respectively; therefore, there was an antagonist effect between Pb and Cd. In the Heilu soil, a synergistic effect of Cd on Pb transport in wheat leaves was only observed under high Pb treatment. Therefore, pH and organic matter content were the key factors that determined the interaction behavior of Pb and Cd. The wheat food security risk of Pb and Cd combined pollution was higher than that of single metal pollution in acidic brown-red soil and lower in high organic matter black soil, whereas the interaction of Pb and Cd had little impact on the wheat food security risk of alkaline Heilu soil.

Heavy Metal Bioaccumulation in Highly Consumed Pelagic and Benthic Fish and Associated Health Risk.

The present study investigated the levels of Manganese (Mn), Cadmium (Cd), Copper (Cu), Zinc (Zn), Lead (Pb) and Iron (Fe) in the tissues of a benthic fish (Clarias gariepinus) and a pelagic fish (Oreochromis niloticus), which are highly consumed in Ghana. The fish were collected from the Weija reservoir, which is an important source of fishery and potable water in Accra, Ghana. The results indicate heavy metal accumulation in all the tissues (gills, liver and muscles) analyzed. The bioaccumulation of all the metals was lowest in the muscles compared to the liver and gills in both species. The bioaccumulation of the metals was generally higher in the tissues of the catfish, except for Fe and Zn. Fe was higher in the gills and liver of the tilapia, and Zn was higher in the liver of the tilapia. The analysis of relationships between metal levels in the different tissues and the size of the fish showed a few significant correlations. The results also showed that all metals showed no potential health risk to consumers, as THQs and TTHQs in tilapia and catfish were less than one, and the metal levels in both species were all below the FAO/WHO maximum permissible limits.

Potential of Purslane (Portulaca oleracea L.) in Phytoremediation: A Study on the Bioaccumulation and Bio-Transfer of Cadmium, Nickel, and Copper in Contaminated Soils

As industrial and agricultural activities intensify and technology rapidly advances, soil pollution has escalated to alarming levels. The increasing contamination of agricultural areas and the crops cultivated therein has emerged as a significant contemporary issue. Phytoremediation, the use of plants to remove pollutants, is a promising method for mitigating soil heavy metal contamination. 
 This study investigates the bioaccumulation capacity of purslane (Portulaca oleracea L.), a potential phytoremediator, in soils artificially contaminated with cadmium (Cd), nickel (Ni), and copper (Cu). Purslane was cultivated under controlled conditions with varying doses of Cd, Ni, and Cu. After 55 days, the plants were harvested and analysed for heavy metal concentrations in their roots, stems, and leaves. Results demonstrated a direct correlation between environmental heavy metal concentration and plant heavy metal content, with the most significant accumulation occurring in the roots. Leaf chlorophyll content was adversely affected by increased Cd, Ni, and Cu applications. The highest Cu, Ni, and Cd contents were found in the roots at 140 mg kg-1 Cu, 80 mg kg-1 Ni, and 20 mg kg-1 Cd applications, respectively. The bio-transfer coefficient (BTC), a measure of heavy metal transport from the root region to the leaves, was calculated. The BTC values ranged from 0.84-1.09 for Cu, 0.39-0.84 for Ni, and >1 for Cd at the Control and 5 mg Cd kg-1 treatments. 
 These findings suggest that purslane has potential for phytoremediation of heavy metal-contaminated soils, although the bioaccumulation and bio-transfer of heavy metals are dependent on the specific metal and its concentration in the soil. The study also highlights the potential risks associated with the consumption of plants grown in heavy metal-contaminated soils, as heavy metals can accumulate in different plant tissues, potentially entering the food chain.

Role of amino acid functional group in alga-amino acid-Zn ternary complexes

The bioaccumulation of heavy metals (HMs) at the water-algal interface determines their threat degree to aquatic ecosystem. Amino acids (AAs), as predominant components of dissolved organic matter (DOM), play pivotal roles in shaping the speciation of HMs in water and their subsequent accumulation by algae. However, the diverse nature of amino acid poses a challenge in generalizing the underlying mechanisms. This study explores four amino acids (asparagine, aspartic acid, glycine, lysine), each possessing distinct amino and carboxyl groups, and investigates their impact on zinc (Zn) bioaccumulation through batch experiments. Upon the introduction of AAs, the adsorption process obeyed the pseudo-second-order kinetic adsorption model demonstrating chemisorption (R2 >0.99), and it affected Zn externalization (up to 3.994 mmol g-1). This phenomenon followed a two-step model, indicating multilayer adsorption. The study proposed that the protonated amino group of AA could serve as a link between Zn-AA complex and microalgae. Amino acids adsorbed onto the surface of microalgae via protonated amino groups did not occupy the Zn-binding sites, instead, they furnished additional functional groups. This differs from the previous results of organic acids containing only carboxyl functional groups as DOM. Multiple linear regression equations and correlation analyses were used to explain the effects of amino and carboxyl morphology on microalgae accumulation of Zn. The equation showed that the leading model terms explain 75.8% of the accumulation amount variance. This study enhances our understanding of the effects of functional group-different DOM on the accumulation of heavy metals in microalgae, offering insights for future research and prediction.

WITHDRAWN: Heavy metal bioaccumulation, stable isotope ratios, and human health risks of fishes from urban rivers in Haikou City, China

WITHDRAWN: Heavy metal bioaccumulation, stable isotope ratios, and human health risks of fishes from urban rivers in Haikou City, China