High Metal Accumulation Research Articles

Using Bioindicators to Assess Heavy Metal Contamination in Surface Waters and Public Health Impacts

Objective: This study aims to explore the use of bioindicators for assessing metal contamination in surface waters and its effects on public health. Theoretical Framework: The persistence and variation of heavy metal contamination in the Ave River Basin over 15 years underscore the need for ongoing monitoring and intervention. The detection of elevated levels of chromium, cadmium, lead, and zinc in aquatic mosses highlights the continuing impact of industrial activities, particularly metal coating facilities, on the river's ecosystem. Method: In the study area, the Ave River and some of its tributaries, a monitoring programme of twelve sampling points was defined in two campaigns and eight metallic ions were determined in the laboratory by atomic absorption spectrophotometry (Cd, Pb, Cu, Cr, Fe, Hg, Ni and Zn). Results and Discussion: The highest metal accumulation in mosses was observed for iron (Fe), whereas the lowest accumulation was found for mercury (Hg) during Campaign II. The order of metal accumulation in the moss samples, from highest to lowest, was Fe > Zn > Cu > Cr > Ni > Pb > Cd > Hg. The Metal Pollution Index (MPI) revealed changes in contamination levels between campaigns. Research Implications: The contamination patterns suggest the influence of industrial activities, particularly metal coating facilities. Monitoring and mitigation efforts are necessary to address persistent heavy metal pollution in the Ave River Basin. Originality/Value: The results of this research will contribute to a better understanding of the sources and loads of pollutants discharged and responsible for the contaminants. This can be used to discourage potential polluters and better manage the basin's water resources and possible risks to human health.

Influence of biochar amendment on removal of heavy metal from soils using phytoremediation by Catharanthus roseus L. and Chrysopogon zizanioides L.

Advances in sustainable toxic heavy metal treatment technologies are crucial to meet our needs for safer land to develop an urban resilient future. The heavy metals bioaccumulate in the food chain due to their persistence in the soil, which poses a serious challenge to its removal and control. Utilisation of hyperaccumulators to reduce the mobility, accumulation and toxic impact of heavy metals is a promising and ecologically safe technique. Amendments such as biochar and chelates have been shown to enhance the phytoremediation efficiency. However, the potential soil improvement is influenced by the properties of the amendment, plant and metal heterogeneities. In this study, an organic sugarcane bagasse biochar amendment for the 60-day pot experiment using Catharanthus roseus L. (NT) and Chrysopogon zizanioides L. (VT) in a heavy metal-contaminated soil was applied. The influence of biochar on the phytoremediation of lead (Pb), zinc (Zn) and cadmium (Cd) from the soil was explored. The plant survival rate enhanced to 100% with biochar amendment, and the biomass increased from 5.83 to 15g in Zn-contaminated samples. Nutrients such as potassium concentration are directly correlated to the amendment rates, whereas phosphate decreases beyond the 2% biochar amendment rate in both plants. High heavy metal accumulation capacities with improved growth with biochar indicate the sustainability of the process. The translocation factor (TF) > 1 for Zn in NT represents the phytoextraction efficiencies whereas VT indicates high BCF values in the range of 0.5-3.53 for the amended Zn-contaminated soils. The findings indicate that the amendment rate of 2% improves nutrient cycling, plant biomass and heavy metal removal efficiencies. The insights from this study establish that the synergy between biochar amendment and the selected medicinal plants improved the phytoremediation efficiency.

The effect of heavy metals (Cd, Cu, and Pb) on plant growth parameters and the phytoremediation capacity of corn

Heavy metal contamination is currently a major global environmental issue. Heavy metals contaminate the soils where crops and vegetables grow. Maize (Zea mays L.) is widely employed for phytoremediation because of its high biomass output and metal accumulation capacity. Depending on the plant and soil properties, some metals can be dangerous in high amounts. During our in vitro experiment, different levels of Cd, Cu, and Pb were introduced to a growth medium to allow maize plants to develop under diverse conditions. The study examined numerous growth features under certain metal stress conditions, including seed germination, plant height, biomass, and chlorophyll content, as well as the toxicity symptoms and mechanisms of the most common heavy metals. The study revealed that, while the maize plant is a good heavy metal accumulator, high heavy metal concentrations had a negative impact on several growth indicators: at 250 ppm, Cd inhibited captive seed germination by 50% and wild seed germination by 42.9%; Pb suppressed captive seed germination by 57% and wild seed germination by 42.9%; and Cu inhibited germination in both seed types by 40%. Similarly, plant height decreased in the following order: Pb (36.2%), Cd (24.8%), and Cu (9.7%) for the captive seed plant, and Pb (46.7%), Cd (28%), and Cu (13%) for the wild seed plant. Keywords: MAIZE, STRESS, TOXICITY, HEAVY METAL, POLLUTION, PHYTOREMEDIATION, BIOACCUMULATION

Влияние тяжелых металлов (Cd, Cu и Pb) на параметры роста растений и фиторемедиационную способность кукурузы

Heavy metal contamination is currently a major global environmental issue. Heavy metals contaminate the soils where crops and vegetables grow. Maize (Zea mays L.) is widely employed for phytoremediation because of its high biomass output and metal accumulation capacity. Depending on the plant and soil properties, some metals can be dangerous in high amounts. During our in vitro experiment, different levels of Cd, Cu, and Pb were introduced to a growth medium to allow maize plants to develop under diverse conditions. The study examined numerous growth features under certain metal stress conditions, including seed germination, plant height, biomass, and chlorophyll content, as well as the toxicity symptoms and mechanisms of the most common heavy metals. The study revealed that, while the maize plant is a good heavy metal accumulator, high heavy metal concentrations had a negative impact on several growth indicators: at 250 ppm, Cd inhibited captive seed germination by 50% and wild seed germination by 42.9%; Pb suppressed captive seed germination by 57% and wild seed germination by 42.9%; and Cu inhibited germination in both seed types by 40%. Similarly, plant height decreased in the following order: Pb (36.2%), Cd (24.8%), and Cu (9.7%) for the captive seed plant, and Pb (46.7%), Cd (28%), and Cu (13%) for the wild seed plant. Keywords: MAIZE, STRESS, TOXICITY, HEAVY METAL, POLLUTION, PHYTOREMEDIATION, BIOACCUMULATION

Potential of Plant Based Metallophytes for Phytoremediation in Agriculture

Metallophytes are the unique group of plants that have evolved to thrive in metal rich environments and have drawn plenty of attention. Remediating heavy metal contaminated places with plants is an effective choice due to phytoremediation, an environmentally friendly method that uses plants to mitigate the pollution. Metallophytes are ideal options for phytoremediation applications due to their inherent traits such as hyper-accumulation, efficient metal absorption and tolerance mechanisms impacting both the plant and soil. These plants absorb and translocate heavy metals, detoxifying the soil while accumulating them in tissues. This reduces metal toxicity in soil and holds potential for resources recovery. The role of metallophytes in phytoremediation is analysed in this review with particular focus given to their ways of metal absorption, translocation and detoxification. Metallophytes have high metal tolerance and accumulation capacities due to their unique physiological and biochemical adaptations including enhanced metal sequestration in vacuoles, metal chelation by phytochelatins and activation of anti-oxidant defence systems. This review also highlights the significance of metallophytes in enhancing the soil health, reducing metal bioavailability, and promoting the ecological sustainability as well as their potential for restoring contaminated ecosystems. Utilizing the unique capabilities of metallophytes obtained from plants possesses enormous possibilities to minimise the negative effects of heavy metal pollution, protect ecosystems, and promote sustainable development for future generations. Eventually, it outlines future research approaches that aim to enhance metallophytes based phytoremediation strategies, widen their implementation and include them in holistic approaches for environmental restoration and sustainable land management.

Exploring the effects of metallic toxicity on the seed germination and initial growth of Lavandula stoechas L. and Myrtus communis L.: Towards promoting the dissemination of aromatic plants in contaminated lands

The high accumulation of heavy metals (HMs) in soils is becoming a major ecological concern worldwide that negatively impacts all living organisms. Therefore, sustainable solutions are urgently needed to withstand these challenging circumstances and to maintain natural ecosystem functionality. Among the relevant solutions is to select well-adapted plant species and embed them in revegetation operations for degraded areas. In this study, the effects of different concentrations (0, 200, 400, and 600 mg L–1) of cadmium (Cd), chromium (Cr), nickel (Ni), and lead (Pd) on the seed germination capacity and initial growth performance of two valuable aromatic plants (Lavandula stoechas L. and Myrtus communis L.) were tested. The germination of seeds was greatest in the control treatment (0 mg L–1), while amplifying HM stress restricted germination. The results obtained showed that seeds of L. stoechas were unable to germinate in the presence of high doses of Cd (400 and 600 mg L–1) and Ni (600 mg mg L–1), and subsequently featuring increasing tolerance thresholds in the following order: Pb > Cr > Ni > Cd. Regardless of the HM used, M. communis seeds germinated at all concentrations, and germination increased in the following pattern of HM resistance: Cd > Ni > Cr > Pb. Seedlings of L. stoechas displayed better resistance to Ni and Pb, while M. communis seedlings were most strongly affected by Ni. Overall, the hypocotyl was typically more susceptible to different metal elements than the radicle. The ability of seeds to effectively emerge in a broad range of HM solutions indicates that both species can further establish and propagate in contaminated soils.

Screening of Maize Varieties with High Biomass and Low Accumulation of Pb and Cd around Lead and Zinc Smelting Enterprises: Field Experiment

In the long-term production process of lead and zinc smelting enterprises, atmospheric subsidence leads to the accumulation of heavy metals in surrounding farmland, which poses a serious threat to the growth of crops and food safety. Given the knowledge that heavy metal pollution in cultivated land does not support treatment and restoration, determining how to ensure the quality and safety of agricultural products is the main problem facing the agricultural industry at present. Previous studies have mainly focused on the low accumulation of heavy metals in maize varieties, while the removal of heavy metals from soil through high biomass has been studied less. In order to identify the maize varieties that demonstrate high removal and low accumulation of heavy metals, 29 maize varieties were planted in soil contaminated with lead (Pb) and cadmium (Cd), and the growth status of the maize varieties and the absorption and transport of Pb and Cd by different tissues were studied. The results showed that heavy metals had the least effect on the growth of the Longhuangbai3, Jinqiuyu 35, Jinyi 418, and Qiuqing 88 varieties, and the content of Pb and Cd in maize varieties was in the order leaf > stem > root > grain. It was found that soil remediation and safe production can be taken into account in the results of the Qiuqing 88 (Pb, Cd), Fengdeng 2025 (Cd), and Yayu 719 (Pb, Cd) varieties. Moreover, the Xinzhongyu 801 (Cd) and Longdan 1701 (Pb) varieties demonstrated high metal accumulation in the edible part, which poses a potential risk to human health; thus, they are not recommended for local cultivation.

Recent Advancements in Mitigating Abiotic Stresses in Crops

In recent years, the progressive escalation of climate change scenarios has emerged as a significant global concern. The threat to global food security posed by abiotic stresses such as drought, salinity, waterlogging, temperature stress (heat stress, freezing, and chilling), and high heavy metal accumulation is substantial. The implementation of any of these stresses on agricultural land induces modifications in the morphological, biochemical, and physiological processes of plants, leading to diminished rates of germination, growth, photosynthesis, respiration, hormone and enzyme activity disruption, heightened oxidative stress, and ultimately, a reduction in crop productivity. It is anticipated that the frequency of these stresses will progressively escalate in the future as a result of a rise in climate change events. Therefore, it is crucial to develop productive strategies to mitigate the adverse effects of these challenges on the agriculture industry and improve crop resilience and yield. Diverse strategies have been implemented, including the development of cultivars that are resistant to climate change through the application of both conventional and modern breeding techniques. An additional application of the prospective and emerging technology of speed breeding is the acceleration of tolerance cultivar development. Additionally, plant growth regulators, osmoprotectants, nutrient and water management, planting time, seed priming, microbial seed treatment, and arbuscular mycorrhiza are regarded as effective methods for mitigating abiotic stresses. The application of biochar, kaolin, chitosan, superabsorbent, yeast extract, and seaweed extract are examples of promising and environmentally benign agronomic techniques that have been shown to mitigate the effects of abiotic stresses on crops; however, their exact mechanisms are still not yet fully understood. Hence, collaboration among researchers should be intensified to fully elucidate the mechanisms involved in the action of the emerging technologies. This review provides a comprehensive and current compilation of scientific information on emerging and current trends, along with innovative strategies to enhance agricultural productivity under abiotic stress conditions.

Unraveling Arbuscular Mycorrhizal Fungi Interactions in the Exotic Plant Nicotiana glauca Graham for Enhanced Soil Fertility and Alleviation of Metal Pollution

The harm that invasive species cause to the environment has received a lot of attention. It is therefore appropriate that the current research was undertaken to evaluate the effects of invasion by Nicotiana glauca Graham on soil fertility by looking at (i) its contribution to the mycorrhizal potential of the soil, (ii) its impact on soil richness and diversity in terms of the arbuscular mycorrhizal fungi (AMF) community (iii), and its ability to modify the physicochemical characteristics in the invaded soil, specifically cleaning up heavy metal. The current study was conducted at Al Houz plain (Marrakesh region, Morocco), in heavily infested sites by N. glauca. The spores of AMF were isolated using the wet sieving process; the isolated spores were sorted for morphological features using a binocular microscope. The plant roots were thinned and colored before microscopic observation. The most probable number method was used to assess mycorrhizal soil infectivity. Heavy metal contamination in soils was characterized using an X-ray fluorescence spectrometer, and the pollution load index (PLI) was utilized to assess and compare the level of heavy metal contamination at each station. The ability of N. glauca to reproduce was evaluated in order to support one of its invasive characteristics. The estimate indicated that each plant might produce more than three million seeds. This significant number guarantees the plant a great capacity for reproduction and invasion. The extra-significant mycorrhizal potential, which can take the form of spores, mycelium, or vesicles that can regenerate mycorrhizae, was discovered by conducting soil analysis in the rhizospheric soils of N. glauca. This research demonstrated the strong mycotrophic capability of N. glauca and the large mycorrhizal potential of soils. Between 4.85 and 305.5 mycorrhizal propagules were considered to be the most probable number (MPN) per 100 g of dry soil. Based on color, shape and size, AMF were classified into five morphotypes corresponding to five genera. The isolated taxa of AMF with the most diverse spores were Glomus, Rhizophagus, Paraglomus, Scutellospora, and Sclerocystis. The Glomus genus was found to have spores in significant quantity. Furthermore, N. glauca demonstrated a potential involvement in the phytoremediation of damaged soils, with a high pollution load index demonstrating a particularly high accumulation of heavy metals. N. glauca is a highly mycotrophic plant that can boost soil mycorrhizal propagule stock. N. glauca has also been demonstrated to be a phytoremediation plant capable of cleansing contaminated soils. As a result, N. glauca could be considered as a prospective candidate for application in phytoremediation of polluted soils.

The carrying capacity of estuarine mangroves in maintaining the coastal urban environmental health of Southeast Sulawesi, Indonesia

This study aims to elucidate the carrying capacity of estuarine mangroves in Southeast Sulawesi, to maintain environmental health of its coastal cities. The concentrations of mercury (Hg), Copper (Cu), Manganese (Mn), Lead (Pb), Zinc (Zn), and Nickel (Ni) were analyzed in sediments and mangrove tissues samples from Kendari bay and Tinanggea estuaries. This was followed by the determination of translocation and bioaccumulation factors, as well as the total accumulation of heavy metals on a landscape level. The results showed that the sediment in Kendari Bay had higher heavy metal concentrations than in Tinanggea, indicating the anthropogenic impact of the highly populated city of Kendari. Moreover, the roots and stems of mangroves had higher heavy metal concentrations than the leaves. Overall, the Bioconcentration Factors (BCF) of Hg, Cu, Mn, Pb and Zn metals were >1, indicating that estuarine mangroves have a higher phytoremediation capacity for heavy metals. Estuarine mangrove biomass also enables the high accumulation of heavy metals in both Kendari bay and Tinanggea, signifying the greater phytoremediation potential of urban estuarine mangroves. Based on these findings, the study supports the conservation and management of mangroves in urban estuaries to maintain the environmental health of coastal cities.

Survey to identify the metal accumulation pathway in humans using hair and nail as biomarkers from fisherfolk population

Human hair and nail samples from Cuddalore fisherfolk populations were used as biomarkers for assessing metal concentrations in humans. Hair samples from 80 participants (47 men and 33 women) and nail samples from 40 participants (21 men and 19 women) were collected, and the concentrations of Cd, Cu, Pb, and Zn were assessed using an atomic absorption spectrophotometer (AAS). Metal data from AAS were compared with the survey questionnaire's personal and dietary parameters. Results indicate that both personal and dietary parameters may influence metal exposure; however, majority of the sources may have originated from metal-contaminated seafood. Higher metal accumulation in communities, especially those which consume seafood on a daily basis, may increase the possibility for them to get affected by metal-related diseases. Based on environmental parameters, people who live ≤500 m from industrial zones accumulate more metals. Further extensive studies with more individuals and more questionnaire parameters are needed to identify the metal accumulation pathway in humans.

Potentially Toxic Metals in the Tropical Mangrove Non-Salt Secreting Rhizophora apiculata: A Field-Based Biomonitoring Study and Phytoremediation Potentials

The present study evaluated the potentials of phytoremediation and the biomonitoring of potentially toxic metals (PTMs) (Zn, Ni, Fe, Pb, and Cu) in the mangrove leaves of Rhizophora apiculata from the tropical mangrove ecosystem in the Sepang Besar River and Lukut River, Peninsular Malaysia. Overall, the present studies concluded that (a) the levels of essential Fe, Cu, and Zn in lamina are significantly (p < 0.05) higher than in MP, (b) the levels of Pb and Ni in MP are significantly (p < 0.05) higher than in lamina, (c) the lamina has better potential as a phytoremediator of Cu, Zn, and Fe, while MP is a better potential phytoremediator of Pb and Ni, (d) lamina is a potential biomonitoring agent of potentially toxic metals based on better correlation coefficients with the surface sedimentary geochemical fractions, and (e) metal uptake in the mangrove leaves and comparative levels of metals is low with reported studies. Specifically, based on bioconcentration factors (BCF), their most obtained values were considered low (<1), suggesting that R. apiculata can be considered as a low-efficiency plant for the bioaccumulation of PTM. However, the present findings also suggested that R. apiculata may be classified as a potential phytoremediator for Zn, Cu, Pb, and Ni in the leaves, as indicated by higher metal accumulation in the MP, with BCFEFLE values > 1.0; BCFAR > 1.0 for Cu, Pb, and Ni. The mangrove leaves are potential biomonitors of PTMs since positive correlations of PTMs were found between the leaves and their habitat surface sediments. Having been identified as a potential phytoremediator and biomonitor of PTMs, the present study emphasized the possibility of establishing a framework for managing the coastal aquatic ecosystems along the mangrove ecosystems of Sepang and Lukut.

Typha latifolia resilience to high metal stress: Antioxidant response in plants from mine and flotation tailing ponds

Typha latifolia (cattail) forms natural stands in the transition zone of artificial flotation and mine tailings ponds and is contaminated with extremely high concentrations of metals. We assessed the absorption capacity of the plant, metal transfer to leaves, and the effects of elevated metal concentrations on antioxidant enzyme activities. Soil acidity, the pseudototal and available metal content of the substrate, and metal concentrations in plants were examined. The effects of elevated metal concentrations in plants on antioxidant enzyme activities (superoxide dismutase, catalase, ascorbate peroxidase, guaiacol peroxidase, glutathione reductase) were assessed. Cattails exhibited high metal accumulation levels in roots and a low transfer rate to the leaves. The effects of metal concentrations on antioxidant enzyme activities were found to depend on the type of enzyme, metal concentrations in the plant and their molar ratios, as well as on the pH of the substrate. High activities of antioxidant enzymes indicate increased generation of reactive oxygen species (ROS) and show that metal detoxification mechanisms are insufficient to restrain their toxicity. Pronounced resistance to elevated metal concentrations and high efficiency in metal phytostabilization show that cattail could be a valuable component of biological treatment systems for removing metals from multi-metal and heavily contaminated substrates in the pH range from ultra-acidic to neutral.

Examination of the Metallothionein Gene Family in Greater Duckweed Spirodela polyrhiza.

Duckweeds are aquatic plants that proliferate rapidly in a wide range of freshwaters, and they are regarded as a potential source of sustainable biomass for various applications and the cost-effective bioremediation of heavy metal pollutants. To understand the cellular and molecular basis that underlies the high metal tolerance and accumulation capacity of duckweeds, we examined the forms and transcript profiles of the metallothionein (MT) gene family in the model duckweed Spirodela polyrhiza, whose genome has been completely sequenced. Four S. polyrhiza MT-like genes were identified and annotated as SpMT2a, SpMT2b, SpMT3, and SpMT4. All except SpMT2b showed high sequence homology including the conserved cysteine residues with the previously described MTs from flowering plants. The S. polyrhiza genome appears to lack the root-specific Type 1 MT. The transcripts of SpMT2a, SpMT2b, and SpMT3 could be detected in the vegetative whole-plant tissues. The transcript abundance of SpMT2a was upregulated several-fold in response to cadmium stress, and the heterologous expression of SpMT2a conferred copper and cadmium tolerance to the metal-sensitive ∆cup1 strain of Saccharomyces cerevisiae. Based on these results, we proposed that SpMT2a may play an important role in the metal detoxification mechanism of duckweed.

Mixing tannery effluent had fertilizing effect on growth, nutrient accumulation, and photosynthetic capacity of some cucurbitaceous vegetables: A little help from foe.

Tannery effluent contains a number of organic and inorganic elements as pollutants which reduce plant growth. To overcome shortage of water, use of diluted industrial wastewater such as tannery effluent can be a viable strategy for improving crop growth and yield. A pot experiment was conducted to determine the effects of tannery effluent and its various dilutions on physiological and biochemical characteristics of five cucurbitaceous vegetables. Tannery effluent was applied 0, 25, 50, 75 and 100% to 3-week-old plants of five cucurbitaceous vegetables (Cucurbita maxima, Luffa cylindrica, Citrullus vulgaris, Cucumis melo, and Praecitrullus fistulosus) for 4weeks. Tannery effluent reduced the growth of all five cucrbitaceous vegetables. Diluted tannery effluent (25%) improved the growth of Cucurbita maxima, Citrullus vulgaris, and Cucumis melo. Moderately diluted (50%) did not affect the growth of Citrullus vulgaris and Cucumis melo. Toxic effects of tannery effluent were associated with high accumulation of heavy metals Cr, Cd, Mn, and Fe in leaves and roots. High accumulation of heavy metals in leaves reduced the accumulation of nutrients in leaves (N, P, K) and reduced photosynthetic pigments and photosynthetic rate. Changes in photosynthetic rates of all vegetable species due to tannery effluent were not associated with stomatal limitations (stomatal conductance, transpiration rate, internal CO2). Toxic effects of tannery effluent on plants also include changes in N-metabolism (amino acid and protein). However, extent of these adverse effects of tannery effluent on vegetables was species specific. It is suggested that Cucurbita maxima can be grown by supplying 25% tannery effluent, whereas Citrullus vulgaris and Cucumis melo can be grown with moderately diluted (50%) tannery effluent.

Bibliometrics-Based: Trends in Phytoremediation of Potentially Toxic Elements in Soil

Land purity is of central importance to crop production. The accumulation of toxic elements in soil seriously affects crop safety. Phytoremediation is a widely used technology to clean soil pollution because of its low cost, simple implementation, and lack of secondary pollution. This investigation includes data from 4787 articles on phytoremediation of heavy metals in soil from the period between 2008 and 2021, acquired from Web of Science databases. VOSviewer was utilized to conduct statistical analysis of countries (regions), institutions, journals, cited literature, and keywords. According to the statistical data, the use of phytoremediation for cleaning soil with heavy metals has matured in recent years, showing a trend of rapid growth. There were also few collaborative studies on this subject between institutions, and China has the most extensive research in this field and, therefore, has the highest number of publications, followed by India and the United States. Publications from Pakistan are very in-depth and have the highest average number of citations. It was discovered that many researchers are now publishing articles on Environmental Science and Pollution Research. Chemosphere was revealed as the most influential journal, whereas The Journal of Hazardous Materials was the most cited. In-depth research on keywords such as metal enrichment, super-enrichment plants, phytoremediation, Cd, Pb, etc. have been conducted by many scientists; however, the research content for different countries was different. The review analysis revealed that in the future it will be possible to breed trees with high heavy metal accumulation, or to use transgenic plants and ornamental plants with high tolerance to prevent and control heavy metal pollution in soil. This paper aims to provide references for scholars in this field and to allow them quick access to summarized knowledge on this topic.

Eco-geological consequences of textile processing wastes: Risk assessment, elemental dissolution kinetics, and health hazard potential

Although substantial quantities of toxic wastes are generated from textile industries, the characteristics of textile processing wastes (TPWs) have yet scantily been investigated from ecological and agricultural perspectives. Here, the eco-geological consequences of TPWs are evaluated by considering three types of sludges (i.e., silk fibre sludge (SFS), dye mixed silk processing sludge (DSPS), and cotton processing wastewater sludge (CPWS)). The predominance of certain components between different wastes (e.g., fibrous substances in silk industry wastes (i.e., SFS and DSPS) and amorphous materials in cotton processing wastes (i.e., CPWS)) is accounted for by the use of different raw materials in different industries. According to the FTIR and other characterization analyses, all three types of TPWs were rich in carbonaceous compounds and nutrients (e.g., CNPK) because of their biological origin. Further, high accumulation of toxic metals (e.g., Cd, Cr, Cu, Zn, Pb, and Mn) was apparent with chemical-processing routes. The principal component analysis indicated strong relationships between certain environmental variables (e.g., moisture content and bulk density) and bioavailability of several metals (e.g., Cd, Zn, Cu, and Mn), while C levels in TPWs were tightly associated with Cr levels. According to the Visual MINTEQ model, the dissolution-precipitation dynamics of potentially toxic elements (e.g., Pb, Cr, and Zn) in TPWs are predicted to be controlled by the levels of phosphates/chlorides/sulphates in line with the textile processing steps employed in different factories. The great toxicity potential of CPWS (e.g., relative to SFS and DSPS) is recognized to pose significant metal-induced hazards to ecosystems and human health over time. Among the three TPWs, SFS could be prescribed for agricultural application after proper treatment (e.g., via valorization techniques) with the aid of its benign nature and high nutrient (Total N: 3.83%; available P: 118.6 mg kg−1) value.

High accumulation of metals and metalloids in the liver of the blue tilapia (Oreochromis aureus) during a massive mortality event induced by a mine tailing spill.

In this study, the concentration of six metal(loid)s was examined in the fish Oreochromis aureus collected from El Comedero dam during a massive mortality event induced by a mine tailing spill. A major spill (~ 300,000 m3) of waste was released into the San Lorenzo River System following a rupture in the tailing dam of a mining plant in NW Mexico; consequently, the discharged material flowed into El Comedero dam. The accumulation of metal(oid)s in the tissues of O. aureus showed higher levels in the liver than in the guts and muscle. Concentrations in the liver were high (As, 1.1-1063; Cd, 8.9-392; Cu, 372-59,129; Hg, 0.46-19.79; Se, 8.7-748; and Zn, 116-820μgg-1), revealing that these fish were exposed to high concentrations of these elements. The mortality of fish could have resulted from the combined effect of the six analyzed metal(loid)s, as well as other residues present in mine tailings.

Accumulation pattern and risk assessment of potentially toxic elements in selected wastewater-irrigated soils and plants in Vehari, Pakistan

There are scarce data about the accumulation pattern and risk assessment of potentially toxic elements (PTEs) in soil and associated potential ecological risks, especially in less-developed countries. This study aims to assess the pollution levels and potential ecological risks of PTEs (As, Cr, Cd, Cu, Ni, Mn, Pb and Zn) in wastewater-irrigated arable soils and different edible-grown plants in selected areas of Vehari, Pakistan. The results revealed that the values of PTEs in soil samples were higher than their respective limit values by 20% for As, 87% for Cd, 15% for Cu, 2% for Cr, 83% for Mn, 98% for Fe, and 7% for Zn. The values of soil risk indices such as the potential ecological risk (PERI >380 for all samples), pollution load index (PLI >4 for 94% of studied samples), and degree of contamination (Dc > 24 for all samples) showed severe soil contamination in the study area. Some vegetables exhibited a high metal accumulation index (e.g., 8.1 for onion), signifying potential associated health hazards. Thus, long-term wastewater irrigation has led to severe soil contamination, which can pose potential ecological risks via PTE accumulation in crops, particularly Cd. Therefore, to ensure food safety, frequent wastewater irrigation practices need to be minimized and managed in the study area.

Metal Removal Kinetics, Bio-Accumulation and Plant Response to Nutrient Availability in Floating Treatment Wetland for Stormwater Treatment

Floating treatment wetland (FTW) is a recent innovation to remove nutrients from stormwater, but little is known about its effectiveness for metal removal. This study aims to test the hypothesis that the metal removal performance of FTWs will be affected by nutrient (NH3-N, NO3-N, and PO4-P) availability in stormwater. Two experiments were carried out in nutrient-deficient tap water, and two experiments were carried out in nutrient-rich lake water using four native Australian plants, namely Carex fascicularis, Juncus kraussii, Eleocharis acuta, and Baumea preissii. Up to 81% Cu and 44.9% Zn removal were achieved by the plants in 16 days in tap water. A reduction in Cu and Zn removal of 28.4–57.3% and 1.0–19.7%, respectively, was observed in lake water compared with tap water for the same duration. The kinetic analysis also confirmed that plant metal uptake rates slowed down in lake water (0.018–0.088 L/mg/day for Cu and 0.005–0.018 L/mg/day for Zn) compared to tap water (0.586–0.825 L/mg/day for Cu and 0.025–0.052 L/mg/day for Zn). A plant tissue analysis revealed that E. acuta and B. preissii bioaccumulated more than 1000 mg/kg of both metals in their tissue, indicating high metal accumulation capacities. To overcome the slower metal uptake rate problem due to nutrient availability, future studies can investigate multi-species plantations with nutrient stripping plants and metal hyper-accumulator plants.