Maximum Permissible Limit Research Articles

Heavy metals in wastewater and fish collected from waste stabilization pond and human health risks in southwestern Ethiopia

IntroductionThis study aimed to measure the concentration of toxic heavy metals in wastewater samples and Nile tilapia (Oreochromis niloticus) species inhabiting wastewater (waste stabilization ponds) and evaluate their safety as a food source in southwestern Ethiopia. For this purpose, toxic metals like lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in wastewater samples and fish tissues (muscle, gill, and liver) were independently examined.MethodsA laboratory-based cross-sectional study was performed to ascertain the levels of Pb, Cd, As, and Hg in the fish tissues of O. niloticus and wastewater samples. Heavy metal levels were analyzed by microplasma atomic emission spectrometry (Agilent 4210 MP-AES) and hydrogen-generated atomic absorption spectrometry (HGAAS, novAA 400P, Germany).ResultsHeavy metal concentrations were measured in the following decreasing order (µg L−1): Cd > Pb > As > Hg in facultative and maturation ponds, with Cd (27.66 µg L−1) having the highest concentration and Hg (0.349 µg L−1) having the lowest concentration. Among the heavy metals detected in the wastewater samples, Hg showed a statistically significant difference between the sampling points (p = 0.023). The maximum metal concentration was measured for Pb (0.35 mg kg−1) and Cd (0.24 mg kg−1) in the muscle tissue of O. niloticus. The value of arsenic (0.02 mg kg−1) detected in fish edible muscles exceeded the FAO/WHO maximum permissible limit (MPL = 0.01) for human consumption. The carcinogenic and non-carcinogenic health risks of consuming fish due to trace metals were relatively low and posed fewer potential threats to human health. According to this finding, children were more susceptible to heavy metal exposure than adults.ConclusionDue to the high quantities of these harmful heavy metals, wastewater from oxidation ponds should not be used for fishing to avoid bioaccumulation. The target carcinogenic risk (TR) and target hazard quotient (THQ) indicated that all heavy metals were below the safe threshold. This research will provide a baseline for monitoring trace metals in various edible aquatic creatures and for future research in artificial habitats and regulatory considerations.

A selective and sensitive mercury sensor for drinking water based on fluorescence quenching of pure rhodamine B

The escalating threat of industrial pollutants, particularly heavy metals, in water sources poses a significant risk to global populations. Among these heavy metals, mercury stands out as a severe contaminant with detrimental health implications. This paper introduces a novel and efficient method for the selective detection of mercury ions in drinking water, employing laser-induced fluorescence with pure rhodamine B as the sensing probe. The method achieves a low detection limit of 7 ppb, closely approaching the World Health Organization’s maximum permissible limit. The simplicity of the procedure, coupled with the use of pure rhodamine B, distinguishes this approach from others relying on complex chemical procedures and derivatives of rhodamine B. The sensing mechanism involves the fluorescence quenching of rhodamine B due to complex formation with tetraiodomercurate. Noteworthy is the method’s selectivity, demonstrated by its resistance to interference from common ions present in water (e.g. Magnesium, calcium, sodium, and potassium), ensuring accurate detection of mercury ions. Extensive testing with tap water samples, considering potential interference, validates the robustness of the sensor, with recovery percentages of 99.25% and 109.2%. In summary, this study contributes a practical solution to the critical challenge of mercury detection in drinking water, addressing issues of sensitivity, selectivity, and on-site applicability. The proposed method holds promise for widespread implementation, enhancing efforts to safeguard public health and ensure the safety of water resources.

Formation and health risk assessment of trihalomethanes in coastal wells impacted by seawater intrusion

The formation of trihalomethanes (THMs) in coastal wells impacted by seawater intrusion (SWI) is relatively understudied. Coastal wells, unlike typical groundwater sources, frequently exhibit elevated levels of chloride and bromide ions, potentially influencing the formation and speciation of THMs. The current study investigated the THM formation in coastal well water from a location affected by SWI. Samples were chlorinated with 2.5 mg L−1 and 5 mg L−1 chlorine doses to replicate field conditions. The THM concentration in the samples exceeded the maximum permissible limit for drinking water. The well with the highest chloride-to-bromide (Cl/Br) ratio (Cl/Br = 645) exhibited the highest total THM concentration (503.2 μg L−1). Samples with high bromide concentration had more brominated THMs over the 5-day reaction period. The bromine substitution factors for wells after 24 h with a chlorine dose of 2.5 mg L−1 were 1.89, 2.21, and 2.78, corresponding to bromide concentrations of 0.098, 0.109, and 1.275 mM, respectively. The average cancer risk associated with the well water was estimated to be 20.9 × 10−06 through dermal contact and 6.84 × 10−04 through inhalation. The study area had an estimated average cancer risk of 705 cases per million population. The study area's common diseases and cancer incidence data for the past four decades indicated a decreasing trend for waterborne diseases and a steep increase in cancers. While several factors may contribute to increasing cancer cases, our study highlights chlorinated coastal well water as an additional potential cancer risk agent.

Determination of the WQI Index to Evaluate the Water Quality of the Monjas River located in Quito

The study of water quality is important over time because it is an essential element for human beings, it has been vital for their survival, territorial expansion, and socioeconomic development. The water of the Monjas river present contamination issues, mainly due to human activities such as agriculture, animal husbandry, and gray water discharges that alter their chemical, biological, and physical properties. The purpose of this research is to evaluate whether the water conditions are suitable for agricultural use, applying the Water Quality Index (WQI) methodology, which requires a study in the laboratory for fecal coliforms, dissolved oxygen, pH, biological demand for oxygen, nitrates, phosphates, dissolved solids, turbidity, and temperature. Samples were taken at six sampling points along the riverbed. Results were compared with the parameters described by TULSMA (Texto Unificado de la Legislación Secundaria de Ministerio de Ambiente), and FAO (The Food and Agriculture Organization of the United Nations) environmental regulations. Higher values were obtained for fecal coliforms, and biochemical oxygen demand that exceeded the maximum permissible limits with respect to the rest of the parameters examined. In this study, the WQI ranged from 26 to 50, classifying the water quality of the Monjas river as unsuitable. It implies that it is not appropriate for agricultural use due to the contamination that it could cause to the crops. The main reasons for this could rely on the presence of fecal matter of human, and animal origin, fertilizers, pesticides, and household waste.

Metal(loid) contamination in Bangladesh: a comprehensive synthesis in different landscapes with ecological and health implications.

Elevated metal(loid) concentrations in soil and foodstuffs is a significant global issue for many densely populated countries like Bangladesh, necessitating reliable estimation for sustainable management. Therefore, a comprehensive data synthesis from the published literature might help to provide a wholistic view of metal(loid) contamination in different areas in Bangladesh. This study provided a clearer view of metal(loid) contamination status and their associated ecological and health risks in different land use and ecosystems in Bangladesh. Comprehensive analyses were performed on data gathered from 143 published articles using multiple statistical techniques including meta-analysis. Considering the potential loading of metal(loid), the data were summarized under various groups, including coastal, rural, urban and industrial regions. Also, the concentrations of seven metal(loid)s, e.g., cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), and arsenic (As) in soil, sediment, cereal, vegetable, fruit, surface water and groundwater were included. Results showed that the relative concentrations of metal(loid)s in comparison to the maximum permissible limit (MPL) were mostly less than one, although they varied significantly for locations and individual metal(loid). However, the normalized cumulative relative concentrations over the MPL for all seven metal(loid)s across different environmental samples were 4.75, 2.97, 1.51 and 2.79 for coastal, industrial, rural and urban areas, respectively, which wasdue to the higher concentration of Cd, Cr and Cu. Similar to the metal(loid) concentrations, the average of cumulative median non-cancer risks for all metal(loid)s was in the order of industrial (6.46) > urban (4.05) > rural (3.83) > coastal (2.41). This research outcome will provide a foundation for future research on metal(loid)s and will help in pertinent policy-making by the relevant authorities in Bangladesh.

Enhanced water stability and catalytic activity of Fe-based metal–organic frameworks with co-ligands for 2,4-dichlorophenol degradation

Fe-based metal–organic frameworks (MOFs) have good photocatalytic performance, environmental friendliness, low cost, and abundance. However, their applications are limited by low water stability, particularly in the presence of light irradiation and oxidizing agents. In this study, we present a MIL-53(Fe)-based MOF using 1,4-naphthalene dicarboxylic (1,4-NDC) and 1,4-benzenedicarboxylic (H2BDC) acid co-ligands, denoted MIL-53(Fe)-Nx, where Nx represents the ratio of 1,4-NDC. This MOF exhibits high water stability and good photocatalytic activity because of the hydrophobicity of naphthalene. The removal and mineralization rates for 100 mg/L 2,4-dichlorophenol reached 100% and 22%, respectively, within 60 min. After three cycles of use, the Fe leached into the solution from the catalysts was significantly lower than the maximum permissible limit indicated in the European Union standard. Of note, 1,4-NDC can be used to make a rigid MOF, thereby improving the crystallinity, porosity, and hydrophobicity of the resultant materials. It also significantly reduced the bandgap energy and improved the charge separation efficiency of the catalysts. This study provides a route to enhance the water stability of Fe-based MOFs via a mixed-ligand strategy to expand their applications in pollutant control.

Seasonal Variability of Water Quality for Human Consumption in the Tilacancha Conduction System, Amazonas, Peru

This study evaluated the seasonal variability of water quality in the Tilacancha River, the water source that supplies Chachapoyas, and the rural communities of Levanto and San Isidro del Maino of Perú. Eighteen physical, chemical, and microbiological water parameters were evaluated at five sampling points in two seasons (rainy and dry). To determine water quality, the results obtained for the parameters evaluated were compared with the Maximum Permissible Limits (MPL) established in the Regulation on Water Quality for Human Consumption (DS Nº 031-2010-SA), approved by the Environmental Health Directorate of the Ministry of Health. In addition, a Pearson correlation was performed to estimate the correlation between the variables evaluated. The results showed that microbiological parameters exceeded the MPLs in both periods evaluated, such as the case of total coliforms (44 MPN.100 mL-1), fecal coliforms (25 MPN.100 mL-1), and E. coli (5.45 MPN.100 mL-1), these microbiological parameters reported a positive correlation with turbidity, temperature, total dissolved solids, and flow rate. In addition, aluminum (Al) and manganese (Mn) exceeded the MPL in the rainy (0.26 mg Al.L-1) and dry (1.41 mg.Mn-1.L-1) seasons, respectively. The results indicated that the water of the Tilacancha River is not suitable for human consumption. Therefore, it must be treated in drinking water treatment plants to be used as drinking water.

Evaluación de la calidad del agua subterránea para uso agrícola en Balzar, provincia del Guayas, Ecuador

Water is a natural and vital resource for living beings and ecosystems. Groundwater is of great importance for human consumption and agricultural activities, but over the years, it has become an increasingly scarce resource. The objective of this research was to evaluate the quality of groundwater extracted from wells used for crop irrigation in Balzar, province the Guayas, Ecuador. Four treatments and three repetitions were used; groundwater extracted from three wells plus a distilled water core. Physical, chemical, microbiological analyzes and a toxicity test with dark incubation were carried out on seeds of radish (Raphanus sativus), cocoa (Theobroma cacao) and corn (Zea mays). Turbidity exceeded permitted levels under TULSMA regulations and bicarbonate and chlorine levels exceeded the permitted limit. The microbiological analysis reflected fecal coliform values above 1000 UFC.100 mL-1 of water, indicating the presence of contaminants in the water sources. Phytotoxicity tests carried out with radish seeds showed a stimulation of radicle growth in well one and mild toxicity in wells two and three. For cocoa and corn seeds, moderate and mild toxicity was evident, respectively in the three wells. Although the maximum permissible limits were exceeded in some variables, the water from the three wells can be used for irrigation; however, there is a need to take measures to improve the quality of the water in these wells.

Treatment of Diesel-Contaminated Soil by Bioaugmented Composting with Bacteria from the Larva Tenebrio Molitor

In this study, soil composting and bioaugmentation processes were combined to remediate diesel-contaminated soil. Deciduous corn flour, wheat bran, and sawdust were used as co-substrates for soil composting. In addition, consortia of bacteria from the inner tract of the Tenebrio molitor larva were isolated and selected for the bioaugmentation of the composting reactors. It was observed that the isolated inoculum enhanced the treatment and combined with deciduous corn flour, a higher efficiency (87%) and a better removal rate (9.10% diesel removed/week) were registered. In soils with a concentration of 11,796 mg diesel/kg, this combined treatment reduced, in 10 weeks, the pollutant to values below the maximum permissible limits in soils stated by Mexican regulations.

Level of Heavy Metals and Potential Ecological Risks in Irrigated Horticultural Farms in the Vicinity of Lake Ziway, Central Ethiopian Rift Valley Region.

Research on heavy metal pollution in horticultural farms located around lakes in the Central Ethiopian Rift Valley Region has focused on measuring the levels of heavy metals and their health implications. However, the ecological risks of horticultural farms contaminated with heavy metals in this region have not been studied. The current study addresses this gap by providing information on the degree of heavy metal contamination and the ecological risk associated with horticultural farms around Lake Ziway, using various pollution indices. An inductively coupled plasma optical emission spectrometer (ICP-OES) was used to measure the concentrations of nine heavy metals (As, Cd, Co, Cu, Cr, Ni, Pb, Hg, and Zn) in a total of 30 composite soil and irrigation water samples, each consisting of a mix of six subsamples. The results indicated that the mean concentrations of Hg, Cd, Pb, and Zn in soils collected from all the sampling sites exceeded the FAO/WHO maximum permissible limit (MPL). The values of both the contamination factor (CF) and contamination degree (Cd) of the heavy metals ranged from 0.04 to 2.66 and 2.81 to 6.14, respectively, indicating a low to medium level of contamination for both indices. The pollution load index (PLI) values of 0.451, 0.449, and 0.157 for sites 2, 1, and 3, respectively, indicate "unpolluted" to "moderately polluted" levels of heavy metal pollution. However, the ecological risk indices (ERIs) at sites 2 and 1 (158.92 and 141, respectively) showed a potentially high ecological risk due to soil pollution. Therefore, close monitoring and early intervention mechanisms must be in place to control pollution in the study area.

Water Quality Assessment Using the Water Quality Index, and Geographic Information Systems in Nador Canal, Morocco

In recent decades, water pollution has emerged as a significant concern, posing a threat to both humans and natural ecosystems. This study aimed to assess the spatial variations in water quality in the Nador Canal, Morocco using the water quality index combined with multivariate statistical techniques and geographic information systems (GIS). The parameters examined were then compared to the maximum permissible limit values recommended by Moroccan surface water standards and the World Health Organization. The results indicated that the WQI of Nador Canal is generally suitable for irrigation and unsuitable for drinking. It indicated that the quality of surface water in the Nador Canal is affected by organic pollutants, and this is evidenced by low levels of dissolved oxygen, the levels of elements were high, especially chlorine and sodium, in addition to a high concentration of ammonia, nitrate, and phosphate in some of the stations studied. Principal component analysis (PCA) results revealed that PC1–PC3 collectively accounted for 73% of the variation in surface water quality within the study area. The cluster analysis also proves that the water quality is relatively polluted. Potential contributing factors to surface water pollution include changes in the hydrological regime, household waste discharges, and agricultural activities. These findings furnish essential insights into water quality, particularly its suitability for irrigation, and contribute to enhancing the water quality management system of the Nador Canal in the Gharb region of Morocco.

Heavy metals and potential health risk assessment of Lactuca sativa and Daucus carrota from soil treated with organic manures and chemical fertilizer

The large-scale production of food crops with heavy application of chemical fertilizers in the effort to meet the astronomical increase in food demands may be counterproductive to the goal of food security. This study investigated the effect of different soil treatments on the levels of heavy metals (Cr, Cu, Fe, Ni, Pb, and Zn) in two types of vegetables Lactuca sativa (lettuce) and Daucus carrota (carrot). The potential carcinogenic and non-carcinogenic health risks from their consumption were also evaluated. Planting experiment was set up in a randomized block design, with different soil treatments of soil + cow dung (CD), soil + sewage sludge (SS), soil + chemical fertilizer (nitrogen-phosphorus-potassium (NPK)), and untreated soil (UNTRD). The vegetables were harvested at maturity, washed with distilled water, and subjected to an acid digestion process before the levels of heavy metals were measured by inductively coupled plasma spectrometry (ICP-MS). The mean concentrations of the metals in the vegetables across all treatments were below the maximum permissible limits. The pattern of heavy metal accumulation by the vegetables suggested that the lettuce from SS treatment accumulated higher concentrations of heavy metals like Cr (0.20 mg/kg), Cu (3.91 mg/kg), Ni (0.33 mg/kg), and Zn (20.44 mg/kg) than carrot, with highest concentrations of Fe (90.89 mg/kg) and Pb (0.16 mg/kg) recorded in lettuce from NPK treatment. The bioaccumulation factor (BAF) showed that lettuce, a leafy vegetable, has bioaccumulated more heavy metals than carrot, a root vegetable. The BAF was generally below the threshold value of 1 in both vegetables, except in lettuce from NPK and CD treatments and carrot from NPK treatments, with BAF values of 1.6, 1.69, and 1.39, respectively. The cancer risk assessment factors were well below the unacceptable maximum range of 10−4 suggesting that consuming these vegetables might not expose an individual to potential risk of cancer development. The hazard quotient estimations were below the threshold values of 1 for all heavy metals; however, the hazard index (HI) values of 1.27 and 1.58 for lettuce from NPK and SS treatments indicate a potential non-carcinogenic health risk to consumers from intake of all the heavy metals.

Assessment of health risks from potassium bromate and trace metals in bread consumption in Ado Ekiti, Southwest, Nigeria

IntroductionBread, a staple food consumed by a large portion of the population worldwide, including Nigeria, has emerged as one of the most popular quick meal options. The excessive intake of potassium bromate and trace metals in bread has been identified as detrimental to human health due to its heightened propensity to induce cancer in human. ObjectiveThe current study assessed the exposure to potassium bromate (KBrO3) and trace metals through bread consumption, as well as the associated risks to dietary habits among Ado Ekiti, Southwest Nigeria residents. Bread varieties commonly consumed in Ado Ekiti were randomly chosen from local bakeries. These bread samples were then analyzed in the laboratory using an Atomic Absorption Spectrophotometer to determine the levels of trace metals, including lead (Pb), manganese (Mn), nickel (Ni), chromium (Cr), zinc (Zn), cadmium (Cd), and cobalt (Co), as well as potassium bromate concentrations. ResultsThe findings revealed that cobalt (Co) had the highest mean concentration (29.35±3.59 mg.kg−1), whereas lead (Pb) exhibited the lowest mean concentration (0.06±0.02 mg.kg−1). The sequence of trace metal levels was Co > Cd > Zn > Ni > Mn > Cr > Pb. All trace metal concentrations exceeded the standards set by FAO/WHO. Regarding potassium bromate content, it ranged from 0.01 mg.kg−1 to 0.06 mg.kg−1, surpassing the maximum permissible limits of 0.02 mg.kg−1 set by the Food and Drug Administration.Although the chronic hazard quotient among adults and children was low, the hazard ratio ranged from 11 to 9 among adults and from 14 to 9 among children, suggesting the potential for carcinogenic effects with repeated consumption. Based on the hazard ratios, the estimated chances of developing cancer from daily consumption of bread samples were approximately 14 in 1,000,000, 86 in 1,000,000, 71 in 1,000,000, and 40 in 1,000,000, respectively, for the adult population, and about 20 in 1,000,000, 11 in 1,000,000, 90 in 1,000,000, and 56 in 1,000,000 for the children population. ConclusionThe study showed that trace metals Pb, Mn, Ni, Cr, Zn, Cd and Co concentrations were higher than the FAO/WHO permissible limits. The concentration of potassium bromate in all the sorted bread samples exceeded the maximum acceptable limits except one. Though chronic hazard quotient among adults and children was low, the hazard ratio among the adult and children population was high, signifying possible cancer risks when continually consumed. These findings underscore the importance of stringent oversight by Nigerian regulatory authorities over using potassium bromate as an ingredient in bakeries.

Quality and safety of new types of dairy products based on cow’s and mare’s milk with vegetable additives

The modern market of dairy products is quite developed, but the issue of compliance with the quality and safety of their production remains relevant. The purpose of this paper was to study the organoleptic, physicochemical and safety indicators of combined dairy products based on mare’s and cow’s milk using herbal supplements. In the course of the research, analytical and statistical methods of information processing were used; experimental studies of raw materials and the finished combined product, namely the determination of acidity, solids, fat and protein; energy and biological values of the product were calculated. Technological processes of combined dairy products based on cow’s and mare’s milk using a vegetable origin filler were studied. Of the three prototypes of the proposed dairy products, it was determined to recommend samples No. 2 and 3. High quality indicators are observed in them, in particular, a rich taste with a pronounced taste of additional components, a pleasant smell and appearance. Also, the finished product in samples No. 2 and 3 have high safety indicators. Pathogenic and harmful microorganisms and substances were not found, acceptable microorganisms are within the maximum permissible limits. According to the research results, new dairy products are recommended using vegetable raw materials with different fat, protein, energy value, caloric content and lactose content. In the process of writing this paper, indicators of nutritional, energy value and safety of new types of dairy products based on cow and mare’s milk with vegetable additives were determined. Taking into account the research results and the materials of previous scientific papers, authors consider it promising to develop and sell dairy products based on cow’s and mare’s milk using a filler of plant origin. The advantages of the resulting product include: consumer interest in such products, high quality indicators, product safety, the possibility of using products in functional and specialized nutrition.Graphical

Analysis of the heavy metals and Escherichia coli contamination of liquid organic fertilizers in the local market, Sri Lanka

Commercially available liquid organic fertilizers have gained popularity in agriculture due to their convenience and perceived environmental benefits. However, these fertilizers are susceptible to various contaminations, including heavy metals such as lead (Pb) and cadmium (Cd), as well as bacterial contaminants like Escherichia coli (E. coli). Monitoring these contaminants helps to identify potential health risks to consumers, prevent soil and water pollution, and maintain the quality of agricultural products. Therefore, this study involved a comprehensive analysis of Pb and Cd heavy metals and E. coli bacterial contaminants in two widely used liquid organic fertilizers in the local market. The samples were digested using an open-vessel acid digestion followed by the flame atomic absorption spectroscopic (FAAS) analysis. The limit of detection (LOD), limit of quantification (LOQ), matrix effect, and spike recovery were determined. The Pb concentration of one fertilizer was 3.45 (± 0.07) mg/kg with 92% recovery whereas the other was 2.87 (± 0.08) mg/kg with 91% recovery. In contrast, the Cd concentration was 0.09 (± 0.01) mg/kg and 0.11 (± 0.01) mg/kg with percentage recoveries of 93% and 90% for two fertilizers respectively. The Pb content exceeded the maximum permissible limit of 1.0 mg/kg set by the Sri Lanka Standard (SLS 1702:2121), while Cd levels remained within the limit of 0.5 mg/kg. Polymerase chain reaction (PCR) coupled with gel electrophoresis confirmed the presence of the pathogenic O157:H7 E. coli strain in both fertilizers. Thus, the results of this study confirmed the lead (Pb) and Escherichia coli contamination in liquid organic fertilizers in the local market of Sri Lanka.

Elemental composition and contaminants of saffron from different origins and geographical discrimination using chemometrics

Elements such as As, Cd, Cr and Pb are classified as contaminants of major concern for public health, due to their high degree of toxicity. Saffron is an important medicinal herbal spice used in variety of food items, pharmaceutical medicines, and cosmetics. Presence of heavy metals in saffron will increase the health risk to consumers. Also, authentication of geographical origin of saffron is an issue of utmost importance for global trading. The present study is focused on investigation of elemental contaminants in saffron and elemental composition of saffron from India (Jammu and Kashmir); Iran and Afghanistan are also explored for geographical discrimination, using Chemometrics. In total, 29 elements including Ag, Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sb, Se, Si, Sr, Ti, Tl, V and Zn were analyzed using ICP-OES. Toxic elemental contaminants including As, Cd, Pb were found below the maximum permissible limit. Using PCA, elements B, Ni, Ba, Fe, V, Si, Al, Ti, K, Na, Sr, and Zn were found as significant discriminators of geographical origin. Elemental composition of saffron may be utilized, to prevent cases of falsified geographical origin in trade.

Pollution by total suspended solids and its relationship with the liquid-solid flow of the lower basin of Usumacinta River in Tabasco, Mexico

Rivers are natural environments that collect water from basins and transport it in laminar flow to the sea. Gradual changes occur due to the erosion of the walls and the bottom of rivers and the deposition of solids that the current carries. In the Usumacinta River basin, there is a sinusoidal correlation between liquid and solid flow. The term solid flow refers to the amount of sediment in motion, gaining its name from the product between liquid flow and the concentration of suspended solids. 21 simple samples of surface water were taken from June to December 2017, in the municipalities of Tenosique, Emiliano Zapata and Jonuta, in the state of Tabasco, Mexico. The concentrations of total suspended solids exceed the maximum permissible limits of the NOM-001-SEMARNAT-1996 (Mexico), for urban public use. Moreover, according to CE-CCA-001/89 (Ecological Water Quality Criteria in Mexico), the surface water of the lower basin of the Usumacinta River is classified as polluted.

Evaluation of the phytoremediation potential of selected hydrophytes grown in wastewater. A case study in Sheikhupura, Pakistan

Water pollution is a major environmental issue and human health risk worldwide. With rapid industrialization and economic growth, water bodies are contaminated at large scale. In the current study the concentration of four heavy metals (HMs) cadmium (Cd), copper (Cu), nickel (Ni), and manganese (Mn) was measured in water, sediment, and hydrophytes (Eichhornia Crassipes, Pistia stratiotes and Lemna minor) samples collected from wastewater stream in Sheikhupura, Punjab, Pakistan. The results revealed that the concentrations of Cd (0.23 mg L-1), Cu (5.00 mg L-1), Mn (6.00 mg L-1), and Ni (3.00 mg L-1) in water samples were above the permissible limits (APL) set by the World Health Organization (WHO). However, the concentration of Cd, Cu, Mn, and Ni in sediment samples was found to be below the maximum permissible limits (BMPL) set by WHO. The WHO permissible limits for Cd, Cu, Mn, and Ni in water is 0.01, 0.02, 0.20, and 1.40 mg L-1 respectively while in sediments is 3.00, 100, 2000, and 50 mg kg-1 respectively. In addition, Mn concentration was highest among all the tested hydrophytes, water, and sediment samples. HMs contents were higher in hydrophytes as compared to water and sediment samples. In addition, all three hydrophytes were found to absorb HMs from wastewater with bioaccumulation factor ranging from 2.52 to 216. Current data revealed that Pistia stratiotes have greater potential to absorb HMs from water as compared to Eichhornia Crassipes, and Lemna minor

Risk assessment of four toxic heavy metals in terrestrial and aquatic ecosystems around BSCIC tannery industrial estate of Savar, Dhaka,Bangladesh.

The shifting of tannery industries from Hazaribagh to Savar adjacent to Dhaleshwari River might have inevitable adverse impacts, especially the heavy metal contamination of both terrestrial and aquatic ecosystems. The study was carried out to investigate the concentrations of four heavy metals in the soil, water, and plant samples collected from around Dhaleshwari River adjacent to the Bangladesh Small & Cottage Industries Corporation Tannery Industrial Estate, Dhaka. This study revealed that average concentrations of cadmium and chromium in soil exceeded the maximum permissible limit of World Health Organization (1996) and average concentrations of lead, cadmium, and chromium in water exceeded the maximum permissible limit of World Health Organization (2011) and Environmental Conservation Rules (1997). The average concentrations of lead, cadmium, and chromium in the roots and shoots of both Eichhornia crassipes and Cynodon dactylon exceeded the maximum permissible limit of Food and Agriculture Organization/ World Health Organization (2016). Ecological risk assessment using indices model for soil pollution indicated that soil is mostly contaminated with cadmium and chromium which can pose strong ecological risk Health risk assessment using indices model for water pollution revealed the high degree of contamination and unacceptable non-carcinogenic risk and carcinogenic risk for adults as well as children through ingestion of water. Average bioconcentration factor and bioaccumulation factor were higher in Eichhornia crassipes than Cynodon dactylon for lead, cadmium, and chromium. Average translocation factor was also higher in Eichhornia crassipes for all the metals except cadmium. It is suggested remedial and mitigation measures be instituted to control environmental degradation of the newly established Tannery Industrial Estate.

Risks to Human Health from Mercury in Gold Mining in the Coastal Region of Ecuador.

Artisanal and small-scale gold mining (ASGM) plays a crucial role in global gold production. However, the adoption of poor mining practices or the use of mercury (Hg) in gold recovery processes has generated serious environmental contamination events. The focus of this study is assessing the concentration of Hg in surface waters within the coastal region of Ecuador. The results are used to conduct a human health risk assessment applying deterministic and probabilistic methods, specifically targeting groups vulnerable to exposure in affected mining environments. Between April and June 2022, 54 water samples were collected from rivers and streams adjacent to mining areas to determine Hg levels. In the health risk assessment, exposure routes through water ingestion and dermal contact were considered for both adults and children, following the model structures outlined by the U.S. Environmental Protection Agency. The results indicate elevated Hg concentrations in two of the five provinces studied, El Oro and Esmeraldas, where at least 88% and 75% of the samples, respectively, exceeded the maximum permissible limit (MPL) set by Ecuadorian regulations for the preservation of aquatic life. Furthermore, in El Oro province, 28% of the samples exceeded the MPL established for drinking water quality. The high concentrations of Hg could be related to illegal mining activity that uses Hg for gold recovery. Regarding the human health risk assessment, risk values above the safe exposure limit were estimated. Children were identified as the most vulnerable receptor. Therefore, there is an urgent need to establish effective regulations that guarantee the protection of river users in potentially contaminated areas. Finally, it is important to continue investigating the contamination caused by human practices in the coastal region.