Heavy metals contamination of rainwater is a function of the adsorbed metals present in the particulates of the atmosphere in which the rain was formed from and rainwater chemistry is an alternative way of monitoring urban air pollution for predominant metal species. Three distinct sampling sites (residential, industrial and commercial) were investigated in the south western part of Nigeria for one year. After acid digestion, quantification was done using a double-beam Atomic Absorption Spectrophotometer (AAS). The obtained results showed that heavy metals were predominantly present as free metal ion in the commercial and industrial areas but Mn and As mainly occurred in the suspended fraction. Residential area presented major fractions as bound to organic complexes except Cu and Cd which were principally available as suspended fraction. The health risks associated with the intake of the studied rainwaters indicated susceptibility to possible carcinogens upon consumption due to total RI > 10-4. Ecological risk assessment equally shown a very high level of ecological risks related with the metals due to RI ˃ 600. Sequel upon this, there is need for better sensitization of the citizenry to the sources and control of these pollutants.

Two fly ashes from municipal solid waste incineration were selected to study their heavy metal leaching behavior. The main purpose of this research is to investigate the characteristics of fly ashes and compare the leaching of heavy metals in different leaching environment. pH and acid neutralization capacity analysis showed that fly ashes were highly alkaline. Fly ashes also contained a variety of heavy metals including Pb, Cu, Cr, Zn, Cd and Ni etc. Leaching studies showed that the alkalinity of fly ashes raised the pH of leaching solution from acidic to basic. Ni, Cu and Zn were strongly bound to ashes and manifested low leaching. In contrast, Cr and Cd had high mobility but their leaching was inhibited by the low solubility of carbonate Cr and Cd. Pb was highly leachable in the alkaline environment with concentration in the leaching solution reached as high as 9.74 mg/L. In addition, the presence of EDTA in the environment also increased leaching. Pb concentration was raised to 16.63 mg/L. This could be attributed to the chelating capacity of EDTA which means that the presence of organics in natural environment should be taken into consideration.

Benin’s waterways are affected by several forms of pollution that are linked in particular to anthropic activities. This study aims to detect the presence of antibiotic residues, the frequency of antibiotic resistant bacteria and the levels of heavy metals in Benin’s waterways. 160 surface water samples from streams in Benin were collected. They were filtered by the membrane filtration method, then incubated on different media. The isolated bacterial species were identified by API 20E gallery and specific biochemical tests. After detection of the resistance profile of the latter, the antibiotic residues were quantified in the samples by the ELISA technique on plate and the physicochemical analyses were performed by Multi 3630 IDS SET KS2 multimeter. Finally, heavy metal levels were detected by the MERCK test kit method specific to each metal. The bacterial species mostly identified were Klebsiella pneumoniae (56.59%), Klebsiella spp. (18.68%), Enterobacter spp. (12.63%). The most abundant resistance of bacterial strains was to amoxicillin + clavulanic acid (92%), followed by metronidazole (86%). Metronidazole was the antibiotic with the highest residue concentration in the samples (6.578 to 6.829 µg/L), followed by ciprofloxacin (2.142 to 9.299 µg/L). Benin streams contain heavy metals such as mercury (0.454±0.129 µg/L), lead (0.040±0.50 mg/L), zinc (6.120±16.017 mg/L), nickel (0.155±0.233 mg/L) and cadmium (0.154±0.132 mg/L). The analysis of the physico-chemical parameters showed that, apart from electrical conductivity, all parameters comply with Beninese and World Health Organization standards. Actions must be taken to clean up these rivers to preserve the integrity of aquatic ecosystems in Benin.

Environmental pollution has become and increasing concern due to growing risk to human health. Soil pollution is an aspect of environmental pollution that has received comparatively less attention than water pollution. However, considering direct effects of contaminants transmission through ingestion to the human body, it can lead to greater risks for human health. Arsenic is a highly prevalent environmental pollutant, and considerable number of people worldwide suffer from constant exposure to it. While there are several ways to manage and remediate contaminated soils, phytoremediation has been paid special attention due to its higher social acceptability and lower cost. Nevertheless, this approach faces challenges, including effectively handling significant quantities of contaminated biomass, managing it appropriately, and selecting suitable plant species for the remediation process. In this regard, numerous endeavors have been undertaken to tackle these obstacles like strategies encompass the utilization of amendments, adept management of biomass, and the implementation of hybrid remediation approaches. This study aims to review prior research on mechanisms, challenges, and enhanced phytoremediation of arsenic-contaminated soils, encompassing reduction of contaminated biomass after phytoremediation.

We analyzed 125 samples collected from Joypurhat district, Bangladesh, in this study. Average inorganic arsenic (IAs) content obtained from collected polished rice, tomato, potato, radish, and arum leaves 0.31 - 0.91, 0.24 - 0.61, 0.49 - 0.88, 0.40 - 0.93, and 0.30 - 0.69 mg/kg, respectively. This report summarized that almost every agronomic sample contains arsenic; the As contents remain within the permissible limit set by FAO/WHO’s guideline (1.00 mg/kg) except for the rice sample. The As concentration for the rice sample was significantly higher (0.31 - 0.91) than the prescribed limit (0.20 mg/kg). But, the As level for water (mean range, 0.10 - 0.72 mg/l), sediment (0.13 - 0.53 mg/kg), and soil samples (24.1 - 43.1 mg/kg) also significantly surpassed the permissible level. The present study is alarming for water samples, where the highest IAs concentration (0.72 mg/l) is 72 times [14 times] higher than WHO/FAO’s [Bangladesh’s] allowable limit (0.01mg/l) [0.05 mg/l]. All agronomic fields contain higher IAs (25.50 - 43.10 mg/kg) than the world standard limit (10 mg/kg). Statistical Igeo confirmed the moderate pollution of the entire agronomic field of Joypurhat except for the river’s sediment. Again, EF values ensured the anthropogenic pollution by the moderately severe enrichment of As for the 65% agronomic field and significant enrichment of As for the 35% agronomic field. Hazard estimation results revealed the privileged possibility of non-carcinogenic [carcinogenic] health hazards to regular polished rice [water] consumers. So, present study suggests that authorities should take necessary steps to prevent contamination/upcoming health risks.

Laboratory wastewater is categorized as hazardous waste that should not be released into the environment since it poses a serious threat to environmental safety. In the present study, the use of Sulphate-Reducing Bacteria (SRB) colonies in an anaerobic reactor to treat heavy metals-containing laboratory wastewater was examined. SRB was initially cultivated with the treatment of fermented compost and Postgate's medium before being attached to the laboratory-size anaerobic reactor to treat laboratory waste containing heavy metal. Within the 15 days of initial incubation under the room temperature of 28 °C, we discovered that SRB optimally grew on the medium with the composition of 5% Postgate B solution, 30% fermented compost liquid, and 5% active suspension liquid, with a total population of cell colonies was 1.2 x 105 CFU/ml. After SRB colonies from the most optimum medium were affixed to the reactor, the reactor attained 89% of lead (Pb) removal, 69.78% of iron (Fe) removal, and 48.93% of copper (Cu) removal for 15 days treatment periods. On the 21st days of treatment time, the removal efficiency increased significantly to 91.57%, 78.09%, and 83.56% of Pb, Fe, and Cu removed, respectively.

In this study, the concentrations of heavy metals were studied using atomic absorption spectroscopy of samples from the sediments of the Tigris River within the boundaries of the city of Mosul, northern Iraq, and the environmental parameters of heavy metals were calculated. The results showed that the average concentrations of Co, Cu, Cd, Pb, Zn, and Ni in (ppm) were (8.78, 30.42, 0.179, 12.04, 75.53, and 144.75), respectively, where these results were higher than the international accepted average. It indicates that the main factor in the high concentrations of heavy metals in the environment of the Tigris River in the city of Mosul is the pollution caused by human activities. The results of the environmental treatments for the studied heavy metals showed that the values of the enrichment factor (EF) were moderately contaminated with Cu, Cd, Ni, and Zn and not contaminated with Co and Pb. The value of the contamination factor (CF) for the sediments of the Tigris River in the studied areas showed that the sediments of those areas are moderately polluted with Co, Ni, and Zn metals. The degree of contamination (Cdeg) for the sediments of the study area in general ranges from low - medium pollution, the pollution load index (PLI) average of (1.03) showed that the sediments of the study area were contaminated with heavy metals. Therefore, we conclude that the environment of the Tigris River is polluted with heavy metals, but it is not at the level that causes concern at present.

Fungi are successful microorganisms in the bioremediation of environmental pollution. So, this study aimed to determine the potential of Trichoderma tomentosum to remediate cadmium, lead, and nickel contaminations from potato dextrose agar (PDA) and potato dextrose broth (PDB) media. Growth rates, toxicity tolerance sporulation, bio-sorption capacity, and bio-sorption efficiency of the fungus were evaluated under different concentrations of CdCl2, Pb(NO3)2, and NiCl2. The findings demonstrated that the growth rate of the fungus differed depending on concentration, metal type, and medium. More metals in PDA medium induced more inhibition on fungus growth rates; however, the rate was independent from the heavy metals concentrations in PDB medium. Cadmium was the most toxic metal tested against T. tomentosum, with a 72h LC50 of 37 ppm. It was about 3.16 and 4.24 times as toxic as nickel and lead, respectively. In the control condition, sporulation of the fungus began at 72 hours, but under the heavy metals, it began at 168, 168, and 192 hours, respectively, for Pb, Ni, and Cd. Both the bio-sorption capacity and efficacy of the fungus were significantly enhanced by an increase in metal content and the highest values were obtained at 200 ppm of the salts. The heavy metals total bio-sorption capacity order was Ni < Cd < Pb in the aqueous medium. The conclusion was that T. tomentosum has a greater potential for the biosorption of heavy metals; hence, the fungus may be employed for the bioremediation of heavy metals from polluted sites, particularly wastewater and industrial influents.

The purpose of this study was to evaluated the origin of the heavy metals amongst nuisance dust particles in Sanandaj, Khorrmabad and Andimeshk cities located in different latitudes in western Iran for the dustiest year during last decade. Samples of dust-fall particles were collected with 10 days intervals from these three cities for the duration of June 2012 to July 2013 using Deposit Gauge Method. Concentration of the heavy metals including iron, manganese, zinc, copper, arsenic, chromium, silver, nickel, lead and cadmium were measured using atomic absorption spectroscopy. The Quantification of Contamination index (QC) was applied to evaluate the origin of heavy metals among dust-fall particles collected in three stations. The results revealed that the annual mean rate of dust-fall was 1.73, 2.66 and 3.37 g/m2 per 10 days for Sanandaj, Khorramabad and Andimeshk, respectively. The highest and the lowest amount of dust-fall were obtained for July and February, respectively, while Fe had the highest concentration among the metals studied. The temperature and wind speed were found to be the most correlated meteorological parameters to dust-fall content throughout the three stations. According to QC index; Ag, Cu, Cd, As, Pb, Mn and Zn (except Pb and Mn for Andimeshk) were derived mainly from similar origins such as anthropogenic activities but the increased values of Fe, Ni, and Cr were ascribed to natural processes. Furthermore, Cu had the highest correlation with other heavy metals measured and was determined the most stable metal amongst dust-fall particles for the three studied stations.

peer reviewed | Contamination of land and aquatic ecosystems with heavy metals (HMs) is a global issue having the persistent potential to damage the quality of food and water. In the present study, Tagetes erecta L. plants were used to assess their potential to uptake HMs from wastewater. Plants were grown in soil for 20 days and then transplanted in hydroponic system containing Hoagland nutrient solution. After more than 15 days of growth, plants were then subjected to wastewater from tannery and surgical industries in different concentrations ranging from 25 to 100% in combination of citric acid (5 and 10 mM). After 6 weeks of treatment, plants were collected and segmented into roots, stem, and leaves for characterizing the morphological properties including plant height, roots length, fresh and dry mass of roots, stem, and leaves. For evaluation of the effect of wastewater on the plants, photosynthetic pigments; soluble proteins; reactive oxygen species (ROS); antioxidant enzymes SOD, POD, CAT, and APX; and metal accumulation were analyzed. Application of industrial wastewater revealed a significant effect on plant morphology under wastewater treatments. Overall growth and physiological attributes of plant decreased, and metal accumulation enhanced with increasing concentration of wastewater. Similarly, the production of ROS and antioxidant enzymes were also increased. Chlorophyll, protein content, and enzyme production enhanced with CA (5 and 10 mM) mediation; however, ROS production and EL were reduced. Metals analysis showed that the maximum accumulation of Pb was in roots, while Cr and Ni in the stem which further increased under CA mediation. Overall, the metal accumulation ability was in the order of Pb > Ni > Cr under CA.