Adsorption of Toxic Metals and Control of Mosquitos-borne Disease by Lysinibacillus sphaericus:Dual Benefits for Health and Environment

Objective Assessment of the bacterium L. sphaericus as a dual-action candidate for biological control of mosquito-borne diseases and bioremediation of toxic metals. Methods Larvae of the mosquito, C quinquefasciatus, were first evaluated for metal tolerance and then exposed to 5 ppm cadmium, chromium, arsenic, and lead in assays together with seven strains of L. sphaericus. A probit regression analysis was used to estimate the LCso of Cd, Cr, As, and Pb to C. quinquefosciatus. An analysis of covariance and multifactorial ANOVA examined the metal biosorption and larvicidal properties of the seven strains of L. sphaericus. Results We found that L. sphaericus adsorbed the toxic metal ions and was toxic against mosquito larvae. The L. sphoericus strain 111（3）7 resulted in a larvae mortality of over 80% for all the tested metals. This strain also exhibited the capacity to adsorb 76% of arsenic, 32% of lead, 25% of chromium, and 7% of cadmium. Conclusion This study found combined metal adsorption and larval toxicity associated with three strains of L. sphaericus [111（3）7, OT4b.31, and CBAM5]. This suggests that a combination of these strains shows strong dual potential for biological control of mosquitos in heavy metal-contaminated areas and remediate the heavy metal contamination as well.

Treatment of tunnel wash waters-experiments with organic sorbent materials. PartⅡ: Removal of toxic metals

In the first part of the article, the column and the bag experiments concerning removal of polycyclic aromatic hydrocarbons (PAHs) and nonpolar oil (NPO) from tunnel wash waters using organic sorbent materials have been described. This part presents the results of removal of toxic metals. The metals of concern (Al, As, Cd, Cr, Cu, Fe, Pb, Mo, Ni, and Zn) were selected based on the priority toxicant pollutants defined in surface water quality criteria. Concentrations of these metals in the collected effluent...

Risk assessment and binding mechanisms of potentially toxic metals in sediments from different water levels in a coastal wetland

The excessive accumulation of potentially toxic metals(Pb and Cd)in coastal wetlands is among the main factors threateningwetland ecosystems.However,the effects ofwater table depth(WTD)on the risk and binding mechanisms of potentially toxic metals in sediments remain unclear.Here,sediments from different WTD obtained from a typical coastal wetland were evaluated using a newly developed strategy based on chemical extraction methods coupled with high-resolution spectroscopy.Our findings indicated that the WTD of the coastal wetland fluctuates frequently and the average enrichment factor for Pb was categorized as minor,whereas Cd enrichment was categorized as moderate.High-resolution spectroscopy techniques also demonstrated that organic functional groups and partly inorganic compounds(e.g.,Fe-O/Si-O)played a vital role in the binding of Pb and Cd to surface sediments.Additionally,mineral components rather than organic groups were mainly bound to thesemetals in the bottom sediments.Collectively,our findings provide key insights into the potential health effects and binding characteristics of potentially toxic metals in sediments,as well as their dynamic behavior under varying sediment depths at a microscale.

Toxic metals and metalloids:Uptake,transport,detoxification,phytoremediation,and crop improvement for safer food

Agricultural soils are under threat of toxic metal/metalloid contamination from anthropogenic activities,leading to excessive accumulation of arsenic(As),cadmium(Cd),lead(Pb),and mercury(Hg)in food crops that poses significant risks to human health.Understanding how these toxic metals and their methylated species are taken up,translocated,and detoxified is prerequisite to developing strategies to limit their accumulation for safer food.Toxic metals are taken up and transported across different cellular compart-ments and plant tissues via various transporters for essential or beneficial nutrients,e.g.As by phosphate and silicon transporters,and Cd by manganese(Mn),zinc(Zn),and iron(Fe)transporters.These transport processes are subjected to interactions with nutrients and the regulation at the transcriptional and post-translational levels.Complexation with thiol-rich compounds,such as phytochelatins,and sequestration in the vacuoles are the common mechanisms for detoxification and for limiting their translocation.A num-ber of genes involved in toxic metal uptake,transport,and detoxification have been identified,offering tar-gets for genetic manipulation via gene editing or transgenic technologies.Natural variations in toxic metal accumulation exist within crop germplasm,and some of the quantitative trait loci underlying these variations have been cloned,paving the way for marker-assisted breeding of low metal accumulation crops.Using plants to extract and remove toxic metals from soil is also possible,but this phytoremediation approach requires metal hyperaccumulation for efficiency.Knowledge gaps and future research needs are also discussed.

Mobility of toxic metals in sediments: Assessing methods and controlling factors

Metals and metalloids（termed as metals in this article）are important constituent elements of the earth＇s crust.A number of metals,if present in excess,are toxic to organisms and therefore they are usually defined as toxic metals.

Effects of Glomus mosseae on the toxicity of heavy metals to Vicia faba

A glasshouse pot experiment was conducted to investigate effects of the arbuscular mycorrhizal fungus Glomus mosseae on the growth of Vicia faba and toxicity induced by heavy metals （HMs） （Cu, Zn, Pb and Cd） in a field soil contaminated by a mixture of these metals. There was also uninoculation treatment （NM） simultaneously. Mycorrhizal （GM） plants have significantly increased growth and tolerance to toxicity induced by heavy metals compared with NM plants. P uptake was significantly increased in GM plants. Mycorrhizal symbiosis reduced the transportation of HMs fi＇om root to shoot by immobilizing HMs in the mycorrhizal, shown by increasing the ratios of HMs from root to shoot. Oxidative stress, which can induce DNA damage, is an important mechanism of heavy metal toxicity. GM treatment decreased oxidative stress by intricating antioxidative systems such as peroxidases and non-enzymic systems including soluble protein. The DNA damage induced by heavy metals was detected using comet assay, which showed DNA damage in the plants was decreased by the GM treatment.

Toxic chemistry of heavy metals on hochrysis galbana (parke)in inshore water

Effects of heavy metals on Isochrysis galbana (Parke ) were studied in our laboratory. The research focused on toxic effects of metals on algal cells, effects of water-soluble and lipid-soluble organic ligands on metal toxicity and processes of metal uptake by cells. Interactions between two metals and the mechanisms involved were also studied in detail. Finally, some relationships between toxicity and chemical property of metals were revealed.

Assessment of Heavy Metal Exposure in Soils of Ihwrekreka Communities, Delta State, Nigeria

Crude oil pollution in the Niger Delta, perpetrated by both local communities and industrial actors, has brought about soil pollution with its consequent ecological, human health and food challenges. The purpose of this research was to examine the concentration and distribution of heavy metals in soil from communities contaminated by crude oil in Niger Delta, and to evaluate the potential health risks to residents from exposure to these contaminants. To achieve this, soil samples were collected from the Ihwrekreka community and analyzed for heavy metal content using inductively coupled plasma mass spectrometry (ICP-MS). The analytical results in mg/kg revealed a significant metals pollution level derived from the oil spill in the soil ranging from 4.85 - 17,078 (Cu), 1.01 - 16.1 (Cd), 0.22 - 36.8 (Cr), 8.28 - 40.9 (Ni), 7.51 - 6474 (Pb), and 8.84 - 12,851 (Zn) respectively. Most of the metals were above the permissible limits of World Health Organization, with Cu, Zn, and Pb as the most contaminating metals. Lead was found to be the main contributor to the hazard index (HI) values for both children and adults in the study area, with its concentration exceeding the permitted limits set by the WHO and the EC. The hazard index (HI) values of Pb, Cu, Zn, Cd, Ni, and Cr were significantly higher than 1. These findings suggest that the release of heavy metals from an oil-contaminated site may pose a risk to human health and the environment.

Toxic metal enrichment characteristics and sources of arid urban surface soil in Yinchuan City, China

To investigate the environmental quality of the urban surface soil in Yinchuan City, the capital of Ningxia Hui Autonomous Region （Ningxia）, China, we sampled surface soil and measured the concentrations of 8 toxic metals （Pb, Cr, Cu, Zn, Co, Bi, Ni and V） using X-ray fluorescence spectrometry. The enrichment characteristics and sources of these toxic metals in the soil were analyzed by the enrichment factor （EF） and multivariate statistical analysis. The results showed that the mean concentrations of these toxic metals in the soil samples were 25.0, 109.1, 16.8, 26.0, 37.2, 2.7, 25.3 and 59.9 mg/kg for Pb, Cr, Cu, Zn, Co, Bi, Ni and V, respectively, which were 1.2, 1.8, 0.8, 0.4, 3.2, 8.7, 0.7 and 0.8 times of the corresponding background values of Ningxia soil, respectively. The variations of Pb, Zn, Co, Bi and Ni concentrations in the surface soil of Yinchuan were larger than those of the other metals. Our results also showed that the toxic metals investigated in the soil had different enrichment levels. Both Co and Bi were significantly enriched, whereas Cr was only moderately enriched in the soil. There was a deficiency or minimal enrichment of the other toxic metals in the soil. Source analysis results based on the concentration, enrichment characteristics and multivariate statistical analysis indicated that Cr, V and Ni originated from a combination of fossil fuel combustion, traffic pollution and natural occurrence. Pb, Cu and Zn were predominantly derived from natural and traffic sources, while Co and Bi primarily originated from construction sources.

Variations in Toxic Metal Levels of Two Fish Species, Pomatomus saltatrix and Dicentrarchus labrax, and Risk Estimation for Children

The concentrations of five toxic metals were monthly determined in two fish species,obtained from fish markets in Turkey during 2010—2011.For the determinations,AAS and ICP-AES were used.The obtained lead concentrations for all studied Pomatomus saltatrix(mean 635μg·kg-1)and Dicentrarchus labrax(mean 463μg·kg-1)samples were found to be significantly higher than the maximum allowances concentration(MAC)of 300μg·kg-1.Mean chromium(324μg·kg-1)and Cu(940μg·kg-1)concentrations in Pomatomus saltatrix were higher than in Dicentrarchus labrax(268μg Cr·kg-1 and 600μg Cu·kg-1)while Ni in Pomatomus saltatrix(216μg·kg-1)was lower in Dicentrarchus labrax(291μg·kg-1).The estimated non-carcinogenic and carcinogenic health risks by the Target Hazard Quotient and target carcinogenic risk indicate that there are no sytemic effects,and the risk of developing cancer over a human lifetime is between 2~9in 1 000 000.

Potentially toxic metal concentration,spatial distribution,and health risk assessment in drinking groundwater resources of southeast Iran

In this study, the concentration and spatial distribution of potentially toxic metals(PTMs), including arsenic(As), cadmium(Cd), chromium(Cr), lead(Pb), copper(Cu), iron(Fe), manganese(Mn), and magnesium(Mg) in 23 wells and drinking groundwater distribution networks of Rafsanjan, located in southeast Iran were evaluated. Moreover, the assessment of carcinogenic and non-carcinogenic risks was estimated by Monte Carlo simulation(MCS). The results showed that the concentrations of As and Pb in more than 99% and 23.46% of the study area, respectively, were higher than the maximum concentration level(10 μg/L). The mean concentration of other metals, including Cd, Cr, Cu, Fe, Mg, and Mn in all drinking water resources was within the WHO standard level. The mean hazard quotient(HQ) for As in the age group of children was 9.246 and adults 2.972, indicating high non-carcinogenic risk of As in the study area. The lifetime cancer risk(LTCR) of As was 1.36 E-3 for adults and 1.52 E-2 for children, indicating high non-carcinogenic risk of As. The level of HQ and LTCR for Pb in both age groups was in the acceptable range. The results of sensitivity analysis showed that the most effective variables were pollutant concentration and body weight(BW), respectively. Finally, it can be concluded that exposure to PTMs, especially As through drinking water in the study area can have significant effects on people’s health living in the area;therefore, it is necessary to treat and remove As from groundwater resources before drinking or using for domestic purpose.

Health risk assessment of heavy metal pollution in groundwater of a karst basin,SW China

To investigate the presence of metal elements and assess their health risk for the populace in the Nandong Underground River Basin(NURB),we conducted an analysis of eleven common heavy metals in the water body.A Health risk assessment(HRA)model was employed to analyze 84 water samples from the NURB.The detection results revealed the following order of heavy metals concentrations:Fe>Al>Mn>Zn>As>Cd>Pb>Cr>Ni>Cu>Hg.Correlation analysis indicated a certain similarity in material source and migration transformation among these eleven metal elements.Our study identified that the health risks for local residents exposed to metal elements in the water of NURB primarily stem from carcinogenic risk(10^(−6)–10^(−4)a^(−1))through the drinking water pathway.Moreover,the health risk of heavy metal exposure for children through drinking water was notably higher than for adults.The maximum health risks of Cr in both underground and surface water exceeded the recommendation standard(5.0×10^(−5)a^(−1))from ICRP,surpassing the values recommended by the Swedish Environmental Protection Agency,the Dutch Ministry of Construction and Environment and the British Royal Society(5.0×10^(−6)a^(−1)).The results of the health risk assessment indicate that Cr in the water of NURB is the primary source of carcinogenic risk for local residents,followed by Cd and As.Consequently,it is imperative to control these three carcinogenic metals when the water was used as drinking water resource.

Distribution of Selected Toxic Elements in Water Phases of River Ogbere, Ibadan, Nigeria

Rivers in Nigeria are faced with increasing contamination of both solid and liquid wastes that enter the surrounding water bodies, and some of these are toxic pollutants that settle onto the riverbed (the ultimate sink of contaminants in the aquatic environment). These toxic pollutants are released into the aquatic environments and inadvertently pose serious public health risks and hazards. This study aims to assess the level of potentially toxic element in River Ogbere water in the city of Ibadan. A total of 12 surface water samples collected from River Ogbere in Ibadan during the dry and wet season of 2019 was analysed for pH, EC, Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Cadmium (Cd), Chromium (Cr), Lead (Pb) and Nickel (Ni). The pH was found in the alkaline range (7.40 - 7.83) while the conductance was obtained in the range of 236.67 - 353.3 μs/cm in both seasons. Fe, Mn, Zn, Cu, Cr, Pb, and Ni were detected in all the samples in the range 0.10 - 5.44 mg/L, 3.20 - 5.03 mg/L, 0.12 - 1.27 mg/L, 0.03 - 0.51 mg/L, 0.03 - 0.68 mg/L, 0.01 - 0.75 mg/L and 0.01 - 0.03 mg/L in both seasons respectively, whereas Cd was detected only in 75% of the samples (0.00 - 0.07 mg/L). Overall seasonal variation was significant for Fe, Mn, Pb, Cd, and Cr. The maximum mean concentration of Fe (5.44 mg/L), Mn (5.03 mg/L), Zn (1.27 mg/L), Cu (0.68 mg/L), Pb (0.75 mg/L) and Ni (0.03 mg/L) were all observed during the dry season. The heavy metals also varied with the change of sampling locations. The dominance of these toxic element in the surface water of River Ogbere followed the sequence: Mn > Fe > Zn > Cu > Cr > Pb > Ni > Cd. The anthropogenic activities around the study area were observed to have increased the influx of toxic metals at both upstream and downstream sections of the river. In view of the high human activities along the river, River Ogbere appeared to have been polluted visibly. The constant water quality monitoring and development of River Ogbere safety plans is recommended.

Insights into the Roles of Melatonin in Alleviating Heavy Metal Toxicity in Crop Plants

Alleviating heavy metal pollution in farmland soil,and heavy metal toxicity in plants is the focus of global agricultural environmental research.Melatonin is a kind of indoleamine compound that wide exists in organisms;it is currently known as an endogenous free radical scavenger with the strongest antioxidant effect.As a new plant growth regulator and signaling molecule,melatonin plays an important role in plant resistance to biotic or abiotic stress.Recent studies indicate that melatonin can effectively alleviate heavy metal toxicity in crop plants,which provides a new strategy to minimize heavy metal pollution in crop plants.This study summarizes the research progress on the role of melatonin in alleviating heavy metal toxicity in crop plants and the related physiological and ecological mechanisms such as reducing the concentration of heavy metals in the rhizosphere,fixing and regionally isolating of heavy metals,maintaining the mineral element balance,enhancing the antioxidant defense system and interacting with hormonal signaling.Furthermore,future prospects for the mechanism of melatonin in regulating heavy metal toxicity,the pathway regulating synthesis and catabolism,and the interaction mechanism of melatonin signaling and other phytohormones are presented in this paper,with the goal of providing a theoretical basis for controlling heavy metal ion accumulation in crop plants grown in contaminated soil.

Ameliorative Role of Pre-Sowing Proline Treatment in Coriandrum sativum L.Seedlings under Mercury Toxicity

Heavy metal toxicity is one of the major ecosystem concerns globally in present time and is also responsible for significant threat to agronomic crops.The current work was conducted to investigate the possible ameliorative role of proline in Coriandrum sativum L.seedlings treated with mercury(Hg).The seedlings were exposed to different concentrations of Hg(0,0.1,0.3 and 0.5 mM)for 20 days.The effects of pre-sowing treatment with proline were studied on C.sativum seedlings in terms of pigment(chlorophylls,carotenoids and anthocyanins),malondialdehyde(MDA),antioxidant compound(glutathione,total phenolic compounds,ascorbic acid)and osmolytes(proline,glycine betaine).Additionally,activities of antioxidant enzymes,namely catalase(CAT),superoxide dismutase(SOD),ascorbate peroxidase(APX)and dehydroascorbate reductase(DHAR)were also studied.A strong decline of photosynthetic pigment concentrations was observed in leaves of C.sativum under Hg toxicity.Treatment of seeds with proline reduced the loss of photosynthetic pigments,counteract Hg-triggered oxidative stress,likely preserving the functionality of antioxidant apparatus under Hg stress.The increment of total polyphenols and glycine betaine also contributed in ameliorating Hg toxicity,suggesting the use of exogenous proline as a potential method to enhance the plant tolerance against heavy metal stress.

Effects of Heavy Metals on Activated Sludge Microorganism

The efforts of heavy metals on activated sludge microorganisms are reviewed. Although some heavy metals play an important role in the life of microorganism, heavy metals concentrations above toxic levels inhibit biological processes. Copper, zinc, nickel,cadmium and chromium were mostly studied because of their toxicity and widely used, regardless of single or combination. The microorganism response to these heavy metals varied with species and concentrations of metals,factors such as pH, sludge age, MLSS etc. also affect toxicity on the microorganism. The acclimation could extend the microorganism tolerance of heavy metals. The effects of heavy metals on sludge microorganisms could be described with different models, such as Sigmoidal and Monod equation. The kinetic constants are the useful indexes to estimate the heavy metals inhibition on activated sludge system. Methods to measure the toxicity and effects on microorganism community were also reviewed.

An assessment of Some Toxic, Essential Elements and Natural Radioactivity, in Most Common Fish Consumed in Jeddah-Saudi Arabia

This study has been carried out to determine the concentrations mg/Kg of the toxic elements (Al, Hg, Cd, Pb, U, Th, and As) and essential elements (K, Sn, Ca, Ni, Cu, Fe, Co, and Mn) using inductively coupled plasma optical emission spectrometer, and the radionuclides concentration levels of (238U, 226Ra, 232Th, 40K and 137Cs) using a high purity germanium spectrophotometer in ten of the most common fish samples collected from local store in Jeddah city, Saudi Arabia during 2014. The results showed that, the concentrations of the elements (Al, Hg, Pb and Cu) in all fish samples were not detected or below the detection limit. The concentrations of metals (Cd, U, Th, As, K, Sn, Ca, Ni, Fe, Co, and Mn) were below the recommended limit by the international organizations. The estimated metal dose (EDI) values for daily average consumption were lower than the recommended values by FAO/WHO, and hazard indices (HI) in fish samples were below safety levels for human consumption (HI 1), then this increase is to be of concern for fish consumer. The measured concentrations in (Bq/Kg) dry weight of natural radionuclides 238U, 226Ra, 232Th, 40K and fallout 137Cs in fish samples were calculated. The results show that the activities in fish samples were of no risk to public health. The total average annual effective dose μSv/y due to intake of 238U, 226Ra, 232Th and 40K from the ingestion of the fish samples were estimated to be 6.07 for infants (≤5 Y), 22.88 and 45.03 for children (5 - 10 Y and 10 - 15 Y) and 56.26 for adults (≥17 y), which are lower than the allowed value (1 mSv). The contribution of 137Cs is nearly negligible. This study could be useful as a baseline data for toxic, essential metals, and radiation, exposure.

Moringa oleifera-based diet protects against nickel-induced hepatotoxicity in rats

Multiple health-promoting effects have been attributed to the consumption of Moringa oleifera leaves,as part of diet without adequate scientific credence.This study evaluated the effect of M.oleifera-based diets on nickel（Ni）-induced hepatotoxicity in rats.Male rats assigned into six groups were given oral administration of 20 mg/kg body weight nickel sulfate in normal saline and either fed normal diet or M.oleifera-based diets for 21 days.All animals were sacrificed under anesthesia 24 hours after the last treatment.Ni exposure elevated the rat plasma activities of alanine transaminase,aspartate transaminase and alkaline phosphatase significantly.Ni exposure also raised the levels of triglyceride,total cholesterol and low-density lipoprotein cholesterol while depleting the high-density lipoprotein cholesterol concentration.Further,Ni exposure raised rat plasma malondialdehyde but depleted reduced glutathione concentrations.The histopathological presentations revealed inflammation and cellular degeneration caused by Ni exposure.We show evidence that M.oleifera-based diets protected against Ni-induced hepatotoxicity by improving the rat liver function indices,lipid profile as well as restoring cellular architecture and integrity.Study lends credence to the health-promoting value of M.oleifera as well as underscores its potential to attenuate hepatic injury.

Macro-and Microelement Contents of Fruiting Bodies of Wild-Edible Mushrooms Growing in the East Black Sea Region of Turkey

Eleven different wild-edible mushroom species growing in the Black Sea region of Turkey were analysed for their metal content. Specimens of mushrooms were gathered in Trabzon, Giresun and Ordu and analyzed for 31 minerals, four of which (Be, Sb, Te and Ti) were not detected. Whereas some minerals including Ag, As, Cd, La, Mo, Pb, Se, Y and Zr were detected in just a few mushroom species, another 18 minerals were found in all 11 species. All metal concentrations were expressed on a dry weight basis (d.w.). With regard to nutritionally important amounts of essential and trace minerals, the metal content (μg/g d.w.) of mushroom samples ranged from 21,800-39,800 for K, 2590-14,000 for P, 268-1600 for Ca, 561-1210 for Mg, 74-829 for Fe, 11.2-321 for Cu, 36.2-241 for Zn, 14.1-76.5 for Mn and 0.13-2.85 for Co. Small amounts of toxic metals such as As, Cd and Pb were found in all 11 mushroom species. L. laccata contained a large amount of As (145 μg/g d.w.). These results show that the investigated mushrooms can be a useful component for human diets because of their high content of many essential minerals and trace elements and low content of toxic metals.

Phytoremediation:A Green Technology to Remove Environmental Pollutants

Land, surface waters, and ground water worldwide, are increasingly affected by contaminations from industrial, research experiments, military, and agricultural activities either due to ignorance, lack of vision, carelessness, or high cost of waste disposal and treatment. The rapid build-up of toxic pollutants (metals, radionuclide, and organic contaminants in soil, surface water, and ground water) not only affects natural resources, but also causes major strains on ecosystems. Interest in phytoremediation as a method to solve environmental contamination has been growing rapidly in recent years. This green technology that involved “tolerant plants” has been utilized to clean up soil and ground water from heavy metals and other toxic organic compounds. Phytoremediation involves growing plants in a contaminated matrix to remove environmental contaminants by facilitating sequestration and/or degradation (detoxification) of the pollutants. Plants are unique organisms equipped with remarkable metabolic and absorption capabilities, as well as transport systems that can take up nutrients or contaminants selectively from the growth matrix, soil or water. As extensive as these benefits are, the costs of using plants along with other concerns like climatic restrictions that may limit growing of plants and slow speed in comparison with conventional methods (i.e., physical and chemical treatment) for bioremediation must be considered carefully. While the benefits of using phytoremediation to restore balance to a stressed environment seem to far outweigh the cost, the largest barrier to the advancement of phytoremediation could be the public opposition. The long-term implication of green plant technology in removing or sequestering environmental contaminations must be addressed thoroughly. As with all new technology, it is important to proceed with caution.