Levels Of Metal Contamination Research Articles

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.

Human health risk assessment due to consumption of dried fish in Chennai, Tamil Nadu, India: a baseline report.

The current study sought to determine the levels of radioactivity and heavy metal contamination in 22 dried fish samples collected in Chennai, Tamil Nadu. The study found that there were substantial heavy metals concentrations for Pb, Mn, Cr, Co, and Cd. The concentration of heavy metal Pb being alarmingly high (32.85 to 42.09mg/kg), followed by Cd (2.18mg/kg to 3.51mg/kg) than the permissible limit of WHO (2.17mg/kg) for Pb and (0.05mg/kg) for Cd. In terms of radioactivity, the gross alpha activity in the dried fish samples ranged 6.25 ± 0.12 to 48.21 ± 0.11 Bg/kg with an average of 20.35 Bg/kg and with a gross beta activity from 6.48 ± 0.02 to 479.47 ± 0.65 Bg/kg, for an average of 136.83 Bg/kg. The study found that the internal radiation dose that people receive upon consuming the fish species Sphyraena obtusata, Rachycentron canadum, Lepidocephalichthys thermalis, Synodontidae, Carangoides malabaricus, Sardina pilchardus, Scomberomorus commerson, Sillago sihama, Gerres subfasciatus, and Amblypharyngodon mola is above the ICRP-recommended limit of less than 1mSv/year. Annual gonadal dose equivalent (AGDE) and total excessive lifetime cancer risk (ELCR) ranged 0.488 µSv year-1 and 0.004 µSv year-1 respectively, the values of AGDE being higher than the global average value. The findings of the study indicate that the analyzed dried fish samples are contaminated with Pb and Cd, which shall pose cancer risk to the consumers as a result.

Trace metals distribution along sediment profiles from the Doce River Continental Shelf (DRCS) 3 years after the biggest environmental disaster in Brazil, the collapse of the Fundão Dam

The Doce river adjacent continental Shelf (DRCS) was evaluated regarding sediment quality three years after the biggest environmental disaster in Brazil, the rupture of the Fundão Dam, that released 39 million cubic meters in the Doce river basin. Five sediment cores were sampled in the shelf, two at the south of the river mouth (T3, T4), two at the north (T6, T7) and one in front of it (T13). Analyses of sedimentary variables (grain size, organic matter and carbonates), trace and major metals occurred in the first 30 cm of each core. The presence of the tailings along the cores was investigated through an Iron Mineralogical Set (IMS). Results of the geoccumulation index (Igeo) revealed sediment enrichment with Fe, Mn, Zn, Cu, Pb, Ni, Cr reaching class 6 of contamination in every core. The contamination index (mCd) revealed high contamination levels by trace and major metals, for T3, T4, T6 and T13. Sediment Quality Guideline Quotient (SQG-Q), revealed moderate impact for all the cores, regarding the potential observation of adverse biological effects. The presence of the tailings along the cores T4, T6, T7 and T13 was confirmed through the IMS. Core T13 showed the presence of the tailings all along its extension, characterizing a depocenter of this material in front of the river mouth. IMS has proved to be a good proxy to identify presence of the tailings and revealed the trend of transport of this material towards north in DRCS. Despite the prevailing accumulation of the tailings in the north and in front of the river mouth, higher levels of metal contamination were registered in the south suggesting contamination originated from anthropogenic activities previous to the rupture of the dam.

Deciphering the dynamics of metal and antibiotic resistome profiles under different metal(loid) contamination levels

Metal(loid) contaminations pose considerable threats to ecological security and public health, yet little is known about the dynamics of metal resistance genes (MRGs) and antibiotic resistance genes (ARGs) under different metal(loid) contamination levels. Here, we provided a systematic investigation of MRGs and ARGs in three zones (Zones I, II, and III) with different metal(loid) contamination levels across an abandoned sewage reservoir. More diverse MRGs and ARGs were detected from the high-contaminated Zone I and the moderate-contaminated Zone II, while the abundant MGEs (mobile genetic elements) potentially enhanced the horizontal gene transfer potential and the resistome diversity in Zone I. Particularly, resistome hosts represented by Thiobacillus, Ramlibacter, and Dyella were prevalent in Zone II, promoting the vertical gene transfer of MRGs and ARGs. The highest health risk of ARGs was predicted for Zone I (about 7.58% and 0.48% of ARGs classified into Rank I and Rank II, respectively), followed by Zone II (2.11% and 0%) and Zone III (0% and 0%). However, the ARGs co-occurring with MRGs might exhibit low proportions and low health risks (all were Rank IV) in the three zones. Overall, these findings uncovered the dynamic responses of resistomes and their hosts to different metal(loid) contamination levels, contributing to formulating accurate management and bioremediation countermeasures for various metal(loid) contaminated environments.

Heavy Metals and Hydrocarbon Level in Nile Tilapia (Oreochromis niloticus), Mullet Fish (Liza falcipinus) and Crab (Callinectes amnicola) from Crude Oil Contaminated Jetty Rivers in Port Harcourt, Nigeria

In this study, the level of polycyclic aromatic hydrocarbons and heavy metals (Pb, Cr, Zn, Cd, Cu, Fe and Mn) contamination were determined in Nile tilapia, Mullet fish and Crab collected from crude oil polluted rivers (Abuloma and Woji Jetty). Average individual PAHs concentration ranged from 0.0001mgkg-1 to 11.22±0.02mgkg-1 in Nile tilapia, 0.0001mgkg-1 to 13.43±0.17mgkg-1 in mullet fish and 0.0001mgkg-1 to 12.23±0.06mgkg-1 in crab. Benzo[a]pyrene (a carcinogenic PAH) concentrations detected in fish and seafood in this study exceeded the acceptable limit set by the European Commission (0.002mgkg-1) for fish considered safe for human consumption. The levels of Pb and Cr in fish and seafood were found to have remarkably higher concentrations which exceeded the acceptable levels (FAO/WHO) in food sources for human consumptionand that of Cd, Fe, Zn, Cu and Mn were lower. Results from this study revealed high levels of PAHs and heavy metals in seafood samples from all study locations. These high PAHs levels in these commonly consumed seafoods from the rivers question their safety for human consumption.

Environmental contamination characteristics of heavy metals from abandoned lead–zinc mine tailings in China

China holds large-scale lead–zinc mineral resources; however, mining activities often cause severe contamination by heavy metals. This study systemically assessed contamination by eight heavy metals (Cu, Zn, Cd, Pb, Cr, Hg, Ni, and As) in mine tailings, soil, and groundwater from 27 contaminated sites across China. Regarding mine tailings, 1% of the mine tailing samples were hazardous waste and 20% were class II non-hazardous waste. Regarding soil, Zn and Pb showed the highest mean concentrations, at 5574.67 mg/kg and 2034.88 mg/kg, respectively. The indexes of geo-accumulation (Igeo) of eight heavy metals ranged from −3.62 to 7.67, while Zn, Pb, and Cd showed the highest environmental risk levels as the priority pollutants. The contamination levels of these heavy metals in groundwater were generally in the order of Zn>As>Pb>Ni>Cd>Cu>Hg>Cr. In this study, 20% of the soil and 10% of the groundwater samples exceeded the corresponding quality limits. The content of heavy metals in soil, groundwater, and mine tailing were positively correlated, demonstrating the main pollution source and transport paths. The pollution levels of heavy metals in soil and groundwater were listed in the foremost and moderate positions compared with similar sites from other countries, respectively. These results may help determine the pollution levels of lead–zinc mining regions and direct the remediation activities of target sites to support the environmental management of abandoned mining and tailing waste in China.

Spatiotemporal characterization of heavy metal and antibiotics in the Pearl River Basin and pollutants removal assessment using invasive species-derived biochars

Rivers play essential roles in human civilization, while anthropogenic activities have deteriorated their resilience and functionalities. Combating contamination is one of the priorities for building the river's resilience and providing safe water and habitats for livelihoods, wildlife preservation, and food production. We collected 174 water and sediment samples from the upstream to the estuary of the Pearl River (PR), characterized the heavy metal and antibiotics contamination levels, and analyzed the spatiotemporal distribution by compiling historical datasets extracted from published research papers and governmental documents. We also assessed the feasibility of removing PR water heavy metals and antibiotics using biochars derived from two invasive plants, Bidens pilosa L. and Lantana camara. According to our findings, heavy metals and antibiotics in water and sediment increased towards the downstream region of the Pearl River Delta (PRD). The water and sediment samples obtained from the Dongguan and Shenzhen regions exhibited the most elevated levels of heavy metals, whereas the samples from the Huizhou region demonstrated the highest levels of antibiotics. Compared with previously published PRD sediment heavy metals (1976–2011) and antibiotics contamination data (2006–2017), we found that some heavy metals and all measured antibiotics contents in sediment substantially reduced (80–100%). Cu, Zn, Cr, and As significantly polluted the sediment in PRD. Shenzhen had the highest Index of geo-accumulation (Igeo) for Cu, Zn, and Cr, while Zhaoqing had the highest Igeo for As. The dominant antibiotics were Ciprofloxacin, Doxycycline, Norfloxacin, Ofloxacin, Oxytetracycline, and Tetracycline. Invasive plant-derived biochars showed high antibiotic removal capacity but failed to reduce most PR water heavy metals since these invasive plants are potential heavy metal hyperaccumulators. The spatial distribution of heavy metal and antibiotics concentration/content in water and sediment samples is primarily affected by anthropogenic activities such as industrialization, aquaculture, pharmaceutical, and agricultural practice. Our study provides insights into the extensive freshwater watersheds' decontamination and green policymaking.

Heavy metals contamination in sediments of Bharalu river, Guwahati, Assam, India: A tributary of river Brahmaputra.

This study aimed to assess heavy metals in the surface sediments of the Bharalu river, India. Metal concentrations ranged from 6.65-54.6 mg/kg for Ni, 25.2-250.0 mg/kg for Zn, 83.3-139.1 mg/kg for Pb, and 11940.0-31250.0 mg/kg for Fe. The level of metal contamination was assessed using sediment quality guidelines, geo-accumulation index (Igeo), enrichment factor (EF), pollution Load Index (PLI),Nemerow's pollution index (PIN), and potential ecological risk index. Pb exceeded the sediment quality guidelines at all sites indicating a potential threat to the river ecosystem. (Igeo) and EF also showed moderate to severe enrichment for Pb. Potential ecological risk (RI) showed low risk in the sediments, and Pb is the major contributor to ecological risk. Overall, pollution indices revealed comparably higher contamination of the sediments in the downstream sites than in the upstream site. PCA and correlation matrix analysis indicated both anthropogenic and natural origins for metals. Among anthropogenic sources, urban discharges and waste dumping could be mainly attributed to metal contamination in the river sediments. These findings may aid in developing future river management methods explicitly aimed at tackling heavy metal pollution to prevent further damage to the river ecosystem.

Assessment of Heavy Metal Contamination Levels in Market Gardening Soils Used to Grow Onions (Allium Cepa) in the City of Abéché (Eastern Chad)

The main objective of this study was to assess the level of metal contamination of the soils used in the cultivation of onions in the city of Abéché. Thus, 04 plots were carried out and monitored for a period of five years (05 years). Two traditional plots were chosen in the Arkou site; and two control plots were carried out in the Bagarine site. Soil samples were taken annually (2016 to 2020) after harvesting on a thickness of 0 and 20 cm. In each plot, thirteen (13) samples were taken. After quartering, one (01) representative sample from each plot was retained. The samples were analyzed by optical emission spectrometry at the Food Quality Control Center Laboratory (FQCCL) in Ndjamena. The determination of heavy metal concentrations revealed relatively low levels for Ni, Zn, Cu, Cr and Fe. These levels are generally lower than the reference values ​​for all the plots. Geoaccumulation indices (Igeo) and Contamination factor (Cf) revealed pollution indices. Pb and Cd show contaminations in traditional plots. The correlations (P < 0.05) observed in our study area are positive and significant. This study shows that the use of chemical inputs are sources of soil contamination by heavy metals. Int. J. Appl. Sci. Biotechnol. Vol 11(1): 42-53.

Mobility indexes of Cu, Pb, and Zn in soil ecosystems with various levels of metal contamination (in Poland)

The aim of the study was to investigate and compare the soils of three groups of grassland ecosystems with varying degrees of heavy metal (Cu, Pb, and Zn) pollution as well as estimating of mobility on the basis of calculated mobility indexes (MI) expressed as a percentage of the EDTA-extracted forms of metals in their total content. A total of 55 surface soil samples were collected from various areas of Poland: urban soils, rural soils, and soils along communication routes. Heavy metal concentrations were determined in solutions after wet mineralization (using a mixture of acids) by atomic absorption spectrometry (AAS) with flame atomization. To isolate the mobile forms of metals in soils, a one-step extraction method was used with 0.05-M EDTA solution. The ranges of Cu, Pb, and Zn concentrations in soils were varied, respectively: 6.7–47.6, 61.1–563.9, and 86.4–644.5 mg·kg−1 (A); 5.7–39.8, 13.56–45.71, and 16.3–119.6 mg·kg−1 (B); and 1.0–195.8, 19.2–310.2, and 27.4–894.1 mg·kg−1 (C). The average values of mobility indexes of Cu, Pb, and Zn were at the level of 40.9, 33.5, and 22.2% (A); 23.2, 27.1, and 25.9% (B); and 37.5, 34.3, and 30.7% (C). Studies have shown that metals derived from anthropogenic sources are characterized by greater mobility compared to metals of natural origin (lithological associated with the ground). The inclusion of metal mobility indices in the environmental monitoring strategy may minimize errors in assessing the actual risk associated with the potential uptake of these metals by plants and incorporation into circulation.

Insights into the responses of fungal taxonomy and function to different metal(loid) contamination levels

Fungi possess prominent tolerance and detoxification capacities in highly metal(loid)-polluted systems, yet little is known about their responding behaviors under different contamination conditions. Here, we systematically investigated the structure and function profiles of fungal communities in an abandoned reservoir mainly contaminated by multiple metal(loid)s such as Al, Be, Cd, Co, Cr, and Cu. This abandoned reservoir consisted of three distinct zones, i.e., Zone I with the shortest deprecation time and the highest metal(loid) contamination; Zone II with the medium deprecation time and medium metal(loid) contamination; and Zone III with the longest abandonment time and the lowest metal(loid)contamination. The lowest pH and the highest contents of OM, TN, and TP were also observed for the high-contamination Zone I, followed by the moderate-contamination Zone II and the low-contamination Zone III. Fungal biodiversity was found to be robust and dominated by many endurable genera in Zone I, and notable cooperative relationships among fungal species facilitated their viability and prosperity under severe metal(loid) contaminations. Differently, the lowest biodiversity and fragile co-occurrence network were identified in Zone II. As metal(loid) contaminations reduced from Zone I to Zone III, dominant fungal functions gradually changed from undefined saprotroph guild to parasites or pathogens of plant-animal (i.e. animal pathogen, endophyte, and plant pathogen). Moreover, metal(loid)s combined with physicochemical properties jointly mediated the fungal taxonomic and functional responses to different metal(loid) contamination levels. Overall, this study not only broadens the understanding of taxonomic and functional repertoires of fungal communities under different metal(loid) contaminated conditions, but also highlights the crucial contributions of specific fungi to bioremediation and management in varying metal(loid)-polluted environments.

Heavy Metals Concentration in Sardina pilchardus (Walbaum, 1792) from the Moroccan Mediterranean Coast and Potential Human Health Risk Assessment

Due to their toxicity, long persistence, bioaccumulative nature, and biomagnification in the food chain, heavy metals pose a serious hazard. The aim of this study was to evaluate the health risks associated with the consumption of Sardina pilchardus (Walbaum, 1792) and to study the spatiotemporal dynamics of four potentially toxic metallic elements. Three hundred and sixty specimens of sardine were collected between December 2020 and October 2021 at three Mediterranean coast sites, Beni-Ensar, Ras el Ma, and El-Houceima, in the northeast region of Morocco. The toxic metallic elements were evaluated by assessing the contamination level of cadmium (Cd), mercury (Hg), lead (Pb), and arsenic (As) in the muscle, liver, and gills of sardine from the Mediterranean Moroccan coast. The results showed a significant effect of the study area, organ, and season ( p > 0.05 ) on Moroccan Mediterranean sardine heavy metal contamination levels. Regardless the location and season, the liver presents the higher concentration of the studied metals ( p < 0.05 ). The highest heavy metal concentrations of Cd (0.408 μg·g−1 wet weight (ww)), Hg (0.044 μg·g−1 ww), and As (6.74 μg·g−1 ww) were found in winter while the concentration of Pb was the highest in autumn (0.056 μg·g−1 ww). Furthermore, the lowest contamination of metal levels was found in the spring. El-Houceima region contains the highest values for Hg (0.093 μg·g−1 ww), Pb (0.018 μg·g−1 ww), and As (7.73 μg·g−1 ww). However, the highest values for Cd (0.172 μg·g−1 ww) were recorded in Beni-Ensar. Regarding the assessment of possible risks to human health, the results showed that the indices are below the established safety values in the case of estimated weekly intake, and target hazard quotient (THQ). In contrast, the carcinogenic risk index and total THQ were above the threshold limits and thus represented a potential carcinogenic risk to human health.

Is Biofloc fish a safe alternative to conventionally cultivated fish regarding metal bioaccumulation in Bangladesh?

In this study, two types of biofloc cultivated fishes (n=10) namely Anabas testudineus and Oreochromis niloticus, used water (n=6), and commercial fish feeds (n=5) from Dhaka, Bangladesh were collected and analyzed for 11 metals.The contamination level and bioaccumulation of metals to different organs of fishes were also determined. Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) was used to quantify the concentration of metals in different samples. The concentration (ppb FW) range of metals in the fish samples are as follows, As (0.47-1.14), Cd (0.09-0.59), Co (0.03-0.33), Cr (0.82-4.60), Cu (0.001-7.01), Hg (0.96-3.37), Ni (1.01-10.8), Pb (2.10-4.40), Zn (0.12-73.1), Mn (1.64-18.0), Fe (23.1-261.5); and in the feed samples (ppb), As (1.56-1.91), Cd (0.09-0.39), Co (0.25-1.17), Cr (0.001-1.93), Cu (4.96-11.7), Hg (0.90-2.06), Ni (2.19-3.38), Pb (2.93-5.38), Zn (0.002-105.8), Mn (0.01-0.03), Fe (132.3-603.4). This study found fish feed as a source of metals in the Biofloc system as the metal pollution index value followed the order of fish feed>fish tank water>fish. However, the metal concentrations in the fish species and feeds were within the safe limits recommended by different international and national institutions. The highest bioaccumulation of metals in the fish species is found for Mn and lowest for Co. Fish tank water was found as hyperaccumulator for As, Cd, Ni, Zn, and Fe. On the other hand, fish-feed acts as an excluder considering the metal bioaccumulation from feed to fish except for Cr, Hg, and Mn. According to the findings, all fish organs have a considerable tendency to accumulate metals from their diet and tank water. However, human health risk assessment revealed no non-carcinogenic health hazard (THQ<1) and target cancer risk due to the consumption of these farmed fish. Thus, the consumption of the studied Biofloc fish is quite safe regarding metal contamination.

Heavy metal stabilization remediation in polluted soils with stabilizing materials: a review.

The remediation of soil contaminated by heavy metals has long been a concern of academics. This is due to the fact that heavy metals discharged into the environment as a result of natural and anthropogenic activities may have detrimental consequences for human health, the ecological environment, the economy, and society. Metal stabilization has received considerable attention and has shown to be a promising soil remediation option among the several techniques for the remediation of heavy metal-contaminated soils. This review discusses various stabilizing materials, including inorganic materials like clay minerals, phosphorus-containing materials, calcium silicon materials, metals, and metal oxides, as well as organic materials like manure, municipal solid waste, and biochar, for the remediation of heavy metal-contaminated soils. Through diverse remediation processes such as adsorption, complexation, precipitation, and redox reactions, these additives efficiently limit the biological effectiveness of heavy metals in soils. It should alsobe emphasizedthat the effectiveness of metal stabilization is influenced by soil pH, organic matter content, amendment type and dosage, heavy metal species and contamination level, and plant variety. Furthermore, a comprehensive overview of the methods for evaluating the effectiveness of heavy metal stabilization based on soil physicochemical properties, heavy metal morphology, and bioactivity has also been provided. At the same time, it is critical to assess the stability and timeliness of the heavy metals' long-term remedial effect. Finally, the priority should be on developing novel, efficient, environmentally friendly, and economically feasible stabilizing agents, as well as establishing a systematic assessment method and criteria for analyzingtheir long-term effects.

Teratogenic Effects of Carissa spinarum and Azadirachta indica Aqueous Extracts in Mice

Carissa spinarum (mũkawa in Kikuyu, lamuriak in Maasai) and Azadirachta indica (neem, mwarubaini in Kiswahili) are widely used in African communities. C. spinarum is used as food and as treatment for gonorrhoea, cancer, and abnormal pain in pregnancy. A. indica is used as a mosquito-repellent and as treatment for malaria and dental carries. Both plants have broad biological activities including anticancer, hypoglycaemic, antinociceptive, and anti-inflammatory activity. However, data on their safety for use during pregnancy is scarce. This study aimed to determine the teratogenic effects of C. spinarum and A. indica in mice. FDA guidelines for reproduction studies were used. Pregnant mice were randomly divided into 8 groups (n=5) for the assay. Plant extracts were prepared in the doses 100, 250, and 500mg/kg body weight. Phenytoin sodium 100mg/kg body weight was used as the positive control and distilled water was used as the negative control. Treatments were administered orally and began from gestation day 6 and ended on gestation day 15. On gestation day 18, the mice were weighed and euthanized and the pups were recovered. Weights of the gravid uteri, number of pups and their body measurements, and incidences of foetal resorption were also recorded. Data were expressed as means and their standard errors and analysed using one-way ANOVA/Dunnett’s post hoc test. The significance level was set at p&lt;0.05. Heavy metal concentrations in the plant samples were determined using flame photometry and atomic absorption spectrophotometry. All doses of C. spinarum and A. indica caused significant (p&lt;0.001) weight loss and foetal resorption in the gravid mice. Reduced head sizes (microcephaly) and elongated limbs were observed in the C. spinarum 100mg/kg and A. indica 500mg/kg groups. Premature birth and high birth weights were also observed in the latter group. The plant samples were found to have high concentrations of lead, cadmium, iron, chromium, manganese, and zinc and this may have added to the teratogenicity observed. C. spinarum and A. indica exhibited significant teratogenicity and should be used with caution during pregnancy. In addition, the level of heavy metal contamination in Kenya should be assessed.

Effects of different heavy metal pollution levels on microbial community structure and risk assessment in Zn-Pb mining soils.

Heavy metal contamination in soils seriously threatens human health and aggravates the global pollution burden. In this study, we investigated the risk of heavy metal contamination in soils at a Zn-Pb mineral processing plant in Longnan, China, and the effects of different heavy metal contamination levels on diverse microbial communities. Statistical analysis showed that, except for Ni, the average content of all detected metals (Zn, Pb, As, Cu, Cd, Hg) in the soil was higher than the background value of soil in the study area, which was most seriously contaminated with Pb and As. Comparison of functional divisions showed that heavy metal soil contamination was most serious in the raw material stacking area and the production area. Interpolation analysis showed that areas closer to the wastewater discharge area had higher contents of each heavy metal and were more seriously polluted. From the point of pollution index, the risk of heavy metal soil pollution in the study area was very high (RI = 2845.24, i.e., > 600), with Cd and Hg being the most serious pollutants compared with other heavy metals. Microbial community abundance, diversity, and structure differed at different levels of heavy metal contamination. The community diversity of bacteria decreased with increasing heavy metal concentrations, while no significant change in fungi was observed. Evidence from variation redundancy analysis (RDA) and the Spearman correlation analysis showed that the leading factors affecting microbial community composition were Cu, Cd, Hg, and pH. Actinobacteria and Gemmatimonadetes at the uncontaminated level (CL) were significantly and negatively correlated with the concentrations of Cu, Zn, Cd, and Pb. Proteobacteria and Chloroflexi at the severely contaminated level (SL) were significantly correlated with pH and Hg. However, heavy metal contamination had less effect on most of the dominant fungi. In conclusion, microbial communities such as Proteobacteria, Actinobacteria, Chloroflexi, and Ascomycota showed greater tolerance to heavy metals. These results could be used as important references for the remediation of heavy metal-contaminated soils.

Harmful Effects of Different Classes of Heavy Metals in Our Beautiful Environment

Today we all take care very much about environment because it degrades day by day for several reasons; one of them is the accumulation of heavy metals which are one of the intrinsic components of this environment. The excessive accumulation of heavy metals affects all sides’ viz. air, soil, water of our beautiful environment through their adverse impacts. There are too many sources open till now for helping them to enter into the environment. This paper shows how they enter together and affects food chain, plant growth, seed germination, photosynthesis and so many. Excess accumulation of both types of heavy metals viz. essential (Zn, Cu, Fe etc) and non-essential (Pb, Hg, As etc) are responsible for disturbance of both aquatic as well as non-aquatic environment parallelly. Human beings also face slow but steady affect either direct or indirect way. So, we try to reflect how toxic level of heavy metals contamination poses a serious threat to our living environment.

Heavy metal contamination levels, source distribution, and risk assessment in fine sand of urban surface deposited sediments of Ekaterinburg, Russia.

Urban surface deposited sediments (USDS) are unique indicators of local pollution that pose a potential threat to the living environment and human health. Ekaterinburg is a highly populated metropolitan area in Russia with rapid urbanization and industrialization activities. In Ekaterinburg's residential areas, about 35, 12, and 16 samples are represented by green zones, roads, driveways, and sidewalks, respectively. The total concentrations of heavy metals was detected using a chemical analyzer inductively coupled plasma mass spectrometry (ICP-MS). Zn, Sn, Sb, and Pb have the highest concentrations in the green zone, while V, Fe, Co, and Cu represent the utmost values on roads. Moreover, Mn and Ni are the prevailing metals in the fine sand fraction of driveways along with sidewalks. Broadly, the high pollution in the studied zones is generated by anthropogenic activities and traffic emissions. The potential ecological risk (RI) was observed in high risk (IR > 600), even though the results of all heavy metals reveal no adverse health effects from the considered noncarcinogenic metal for adults and children by different exposure pathways except the children's exposure to Co in case of the dermal contact, where the HI values of Co for children in the studied zones are higher than the proposed level (> 1). In all urban zones, the total carcinogenic risk (TLCR) values are predicted as a high potential inhalation exposure.

Heavy metal fraction, pollution, and source-oriented risk assessment in biofilms on a river system polluted by mining activities

The Lanping Pb–Zn mine is the largest source of Pb and Zn ores in China, thus posing a great threat to local ecosystems and human health. A total of seven heavy metals (Zn, Pb, Ni, Cu, Cr, Cd, and As) in the Bijiang River near the Pb–Zn mine were measured in winter and summer to assess their spatial–temporal enrichment, ecological risk, and source-oriented health risk in periphytic biofilms. Positive matrix factorization (PMF) receptor model and clustering analysis were used to quantitatively identify pollution sources. The results of PMF were then imported into the health risk assessment to further determine the carcinogenic and noncarcinogenic risks of various pollution sources. The results indicated distinct seasonal patterns in metal concentrations, with much higher concentrations in winter. Sites near the Pb–Zn mine tailing reservoir exhibited higher metal contamination levels than other sites. A strong correlation between the enrichment factor and the levels of nonresidual fraction suggested that anthropogenic inputs were the main source of these metals. Mining industries (Cd, Zn, and Pb), natural sources (As, Ni, and Cu), and agricultural activities (Cr) were the primary sources of heavy metal pollution in biofilms, accounting for 44.43%, 33.32%, and 22.26% of the total metal accumulation, respectively. Moreover, the carcinogenic and noncarcinogenic risks via dermal contact of the studied elements in biofilms were typically acceptable. Notably, as concentration was the main factor influencing these risks in children and adults. This study provides evidence that natural epilithic periphyton may be a potential metal biomonitor in aquatic systems and provide supporting information for effective source regulation.

Evaluation of the pollution extent of heavy metals in the sediment of the Nile Delta, Mediterranean Coast, Egypt

The Nile Delta coast extends along the middle region of Egypt’s Mediterranean coast, from Port Said eastward to Alexandria westward. Six short sediment cores were collected across the Nile Delta sector to assess the pollution level of nine heavy metals: Fe, Mn, Zn, Ni, Cu, Cr, Cd, Pb, and Ba. Geochemical analysis of the core samples revealed their sediment features. The predominant sediment was Nile fine-grained sand, with fluctuations in organic matter, carbonate, and heavy metal content. They correspond mainly to an exposure scale to effluent discharges, relevant to anthropogenic factors influencing the coastal ecosystem. The applied environmental indices demonstrated that the western and middle sites of the Nile Delta are classified as unpolluted areas, while the eastern edge, represented by the Port Said core, is identified as polluted area. Variations in the metal contamination level were recognized, ranging from high contamination with Cd to considerable contamination with Cr, and moderate contamination with Zn, Ni, Cu, Mn, and Fe. Port Said site is significantly affected by the anthropogenic impact of industries and port activities. It is recommended to mitigate ecological threats and limit pollution spreading westward to prevent further degradation of the Nile Delta coast.