US Environmental Protection Agency Research Articles

PUBLIC HEALTH RISK FROM CONTAMINATION OF DRINKING WATER WITH CARCINOGENIC CHEMICALS IN CENTRALIZED WATER SUPPLY SYSTEMS

The paper presents the results of assessing the carcinogenic risk to public health from consuming drinking water contaminated with priority chemicals at the level of their hygienic standards. A comparative analysis of SanPiN 1.2.3685-21 “Hygienic Standards and Requirements for Ensuring the Safety and (or) Harmlessness of Environmental Factors for Humans” and repealed SanPiN 2.1.4.1074-01 “Drinking Water and Water Supply to Populated Areas. Drinking Water. Hygienic Requirements for Water Quality of Centralized Drinking Water Supply Systems. Quality Control” valid since March 01, 2021, is carried out. Maximum allowable concentrations of carcinogenic chemical substances and values of slope factors and risk potential factors have been analyzed. A comparative analysis of SanPiN 1.2.3685-21 that is currently in force and the US EPA “2018 Edition of the Drinking Water Standards and Health Advisories Tables” has been conducted. The average daily intake doses of each studied substance in drinking water at the level of maximum permissible concentrations were determined. It has been found that, despite the tightening of standards for some substances, the content of many carcinogens in water at the maximum allowable concentrations or below can lead to high values of potential carcinogenic risk, and a list of activities is needed to complement the current standards regarding the quality of water.

Assessment of the Physicochemical and Bacteriological Content of Some Drinking Water Sources in Jos South LGA in Northern Senatorial District of Plateau State Nigeria

Drinking water is hardly found 100% pure in nature due to human activities and other natural factors. Many diseases in developing countries are caused by drinking contaminated water. Water samples collected were analyzed by automated instrumental methods prescribed by standard methods for the analysis of water and wastewater and the United State Environmental Protection Agency (USEPA). The results showed SO42- range from ND to 60.00mg/L; pH 5.27 to 6.79; NO3- 1.19-11,64 mg/L; PO42- 10.12 to 352.00mg/L; Cd range from 0.011± 0.00 to 0.032 ± 0.00mg/L; Ni, from ND to 0.04 mg/L; Cr, ND to 0.686 ± 0.07mg/L; Pb ND to 0.34 ± 0.01mg/L, total bacteria count TaBC, 1.5 x 104 to 8.5 x 104 CFU/mL in the samples used. The calculated average daily intake (ADI) for Cd, Ni, Cr and Pb were within acceptable limits while the hazard quotients (HQ) for all the metals were >1, signifying that the population would experience non-cancer risks due to exposure to these metals in drinking water. The bacteriological study of the water samples also revealed that the water samples were all polluted with bacteria and coliforms. From the foregoing, these drinking water sources, therefore require treatment before consumption to minimize or avoid the incidences of water-related diseases.

(Invited) Next Generation Electrified Membrane Technology for Simultaneous Wastewater Treatment and Production of Nitrogen Fertilizer

Recovery and repurposing of wastewater nitrogen such as nitrate (NO3 −) and nitrite (NO2 −) receive increasing attention as the current approaches of biological nitrogen removal or conversion into nitrogen gas (N2) renders high energy footprints. This study reported the first electrified membrane upcycling of NO3 − into NH3 that further converted into ammonia sulfate (NH4SO4), a liquid fertilizer readily for use. Paired electrolysis was used to couple simultaneous cathodic and anodic electrochemical half-reactions to enable nitrate reduction and eliminate the external acid/base consumption. Under a partial current density of 63.8±4.4 mA·cm−2 on a cathodic membrane made of a mixed-valence copper oxide and a polytetrafluoroethylene (PTFE) hydrophobic substrate, a recovery rate and energy consumption of 3100±91 g-(NH4)2SO4·m−2·d−1 and 21.8±3.8 kWh·kg−1-(NH4)2SO4 were achieved with the synthetic feed solution (150 mM NO3 −) flowing into the cathode chamber and the produced NH3 migrating across the cathodic membrane into a trap and anode chambers filled with the flowing 0.5 M Na2SO4 solution. 99.9% NO3 − was removed in the feed after 5 h operation with a NH3 recovery rate of 99.5%. This electrified membrane process was demonstrated to achieve comparable performances of synergistic nitrate decontamination and nutrient recovery using real nitrate wastewater with durable catalytic activity and stability. Specifically, the required electricity cost for converting 10 to 100 mM NO3 − to (NH4)2SO4 was $675 to $408 ton−1, respectively. The obtained (NH4)2SO4 may be sold as fertilizer at a price of 533 $·ton−1 (according to USDA) and further offset the cost of the NO3 − removal.According to the International Fertilizer Association, in 2018 the U.S. ranked second in nitrogen production, representing 11.6% of global production. However, it still requires the importation of nitrogen fertilizer, to fully meet the national demand. The US Environmental Protection Agency reports that in 2013, ~38 kg of nitrogen per acre per year was used for fertilization, and in 2016, 94 million acres of corn were planted in the US, representing ~40% of US fertilizer demand. Roughly, this equates to ~8.9 billion kg of nitrogen per year needed to meet total US fertilization demand. The nitrogen available in drinking water sources is roughly 65 million kg per year, and the nitrogen available in wastewater sources is roughly 2.4 billion kg per year. Thus, by fully recovering the nitrogen from wastewater 34.3% of the US nitrogen fertilizer requirement could be met. This could also further mitigate the increase in nitrogen fertilizer prices due to blocked nitrogen fertilizer imports and even free the US from nitrogen fertilizer imports. According to U.S. Department of Agriculture, the average U.S. farm price of sulfate of ammonium fertilizers is $533 per ton. Even leaving aside the revenue generated by the treatment of nitrogen-containing sewage, the market size of nitrogen fertilizer produced through sewage is as high as $12.8 billion.

Acute Toxicity of Copper to Three Species of Pacific Salmon Fry in Water with Low Hardness and Low Dissolved Organic Carbon.

Proposed development of a mine within Alaska's Bristol Bay watershed (USA) has raised concerns about the potential impact of copper (Cu) on Pacific salmon (Oncorhynchus spp.). We conducted 96-h flow-through bioassays using low-hardness and low dissolved organic carbon water to determine the acute lethal toxicity of Cu to sockeye (Oncorhynchus nerka), Chinook (Oncorhynchus tshawytscha), and coho salmon (Oncorhynchus kisutch) fry. We aimed to determine Cu toxicity under field-relevant water quality conditions and to assess three methods of calculating ambient Cu criteria: the biotic ligand model (BLM), a multiple linear regression model endorsed by the US Environmental Protection Agency, and the hardness-based model currently used by the State of Alaska. The criteria generated by all models were below 20% lethal Cu concentrations by factors ranging from 2.2 to 54.3, indicating that all criteria would be protective against mortality. The multiple linear regression-based criteria were the most conservative and were comparable to BLM-based criteria. The median lethal concentrations (LC50s) for sockeye, Chinook, and coho were 35.2, 23.9, and 6.3 µg Cu/L, respectively. We also used the BLM to predict LC50s for each species. Model predictions differed from empirical LC50s by factors of 0.7 for sockeye and Chinook salmon, and 1.1 for coho salmon. These differences fell within the acceptable range of ±2, indicating the model's accuracy. We calculated critical lethal Cu accumulation values for each species to account for differing water chemistry in each bioassay; the present study revealed that coho salmon were most sensitive to Cu, followed by sockeye and Chinook salmon. Our findings underscore the importance of considering site- and species-specific factors when modeling Cu toxicity. The empirical data we present may enhance Cu risk assessments for Pacific salmon. Environ Toxicol Chem 2023;42:2440-2452. © 2023 SETAC.

An Integrated Assessment of Phthalic Acid Esters and Phenolic Compounds as Priority Concern Pollutants in Raw and Conventionally Treated Water in Plateau State, Nigeria

Phthalate acid esters (PAEs) and phenolic compounds (PCs) exist in water bodies due to the discharge of polluted wastewater from industrial, agricultural and domestic activities into water bodies. They also occur as a result of natural phenomena. These compounds are known to be toxic and inflict both severe and long?lasting effects on both humans and animals. They act as carcinogens and cause damage to the red blood cells and the liver, even at low concentrations. For this cause, this research was carried out to assess these compounds as priority concern pollutants in raw and conventionally treated water (CTW) in Plateau State, Nigeria. Raw and treated water samples were collected from Pankshin, Shendam and Jos dams. A combination of High Performance Liquid Chromatography tandem mass spectrometry was used to analyze the two categories of pollutants. The results obtained showed that almost all the PAEs were above the given permissible limit (PL) as given by the United States Environmental Protection Agency. The PCs were however below the given PL. it was discovered that out of the 12 PAEs and PCs detected, only 3 (1 PCs and 2 PAEs) were still detected in the CTW samples, proving that the method of treatment considerably reduced the concentrations of the pollutants. However, the reoccurrence of some of the contaminants proved the method of treatment was not completely effective. It was then recommended that other sophisticated method be utilized.

Comparative assessment of water quality classification techniques in the largest north-western river of Cambodia (Sangker River-Tonle Sap Basin)

The lack of adequate and good water quality is one of the serious issues that most developing countries are facing, yet environmental monitoring programs are not efficiently protecting ecosystem health. Here, we aimed to assess the suitability of different water quality assessment frameworks in order to define the most suitable method, especially for data-scarce environments, to quantify river ecosystem health. The study was conducted in the largest north-western river of Cambodia, the Sangker River in the Tonle Sap Lake (TSL) basin (UNESCO Biosphere Reserve). Five water quality assessment methods were selected for the study: Basic & Single Prati indices, Mekong River Commission water quality index (MRC-WQI), French water quality assessment system (SEQ-EAU) and US Environmental Protection Agency (US-EPA) framework. Overall, a physico-chemical gradient of water quality was observed along the river course. The river head was defined by high levels of dissolved oxygen (DO), low nutrients and chloride, while the middle course was marked by a gradual decrease of DO and increased concentration of nutrients up to the TSL floodplains. This degradation was explained by multiple impacts from human activities, e.g. domestic wastes, livestock, crop farming, causing simultaneous eutrophication and oxygen depletion along the river course. Despite those multiple pressures, the Sangker river health status was scored as fairly good reflecting the current situation of the river. So far, we found a convergence of the five water quality assessment methods; however, SEQ-EAU and Basic Prati seemed to be less suitable for tropical river health assessment. The study defined the US-EPA assessment method as the most suitable technique to quantify the Sangker river health. This method could potentially be used to monitor river ecosystem health in data-scarce environments. This would help overcome environmental monitoring challenges in developing countries faced by rapid global environmental changes.

Assessing the quality of sewage sludge: CASE study of the Kumasi wastewater treatment plant

Agricultural application is the primary method of recycling sewage sludge. It is an alternative for recycling this residue, providing nutrients and organic matter to crops and soil. However, sewage treatment and management issues may impact its quality. The main objective of the research was to determine the quality of sewage sludge generated at the Kumasi Wastewater Treatment Plant (KWTP). Understanding the effects of using sludge on soil and plants is critical. To overcome this constraint, the soil microbial biomass was used to quantify the growth of microorganisms. The levels of potentially toxic elements in the sludge using atomic absorption spectrometry (AAS) are based on US EPA part 503 regulations for the disposal and management of biosolids. This study found that trace metal concentrations in the biosolids were lower than the referenced background standards threshold. Although the microbial biomass, nutrients and bacteria levels were within the accepted values for their possible use as soil fertilizer. The ecological risk index (135.10) indicated that the level of arsenic was high in the sludge. The salinity in the sludge was low, with electrical conductivity (EC) being high (60.80–436.00 μS/cm) and pH decreasing with age (6.73–7.69). The sludge produced at KWTP is of good quality and meets international standards with only a high concentration of As. This can be used for soil amendment when As is reduced in the sludge.

Sustainability analysis of packaging waste management systems: A case study in the Romanian context

Packaging waste is an important waste stream being directly linked to any product or good that consumers buy, use and then discard. Beyond policies setting recycling and recovery targets and the usual waste indicators in terms of generation, collection and treatment, packaging waste should be analyzed from the sustainability perspective. For countries in which municipal solid waste management has modest performances and packaging waste is organized solely based on Extended Producer Responsibility principle, such as Romania, this type of analysis is even more significant. Starting with 2018 onwards, the legislative European framework have set stringent packaging waste recovery and recycling targets, however beyond their achievement, it is important to also check what is the mid-term impact on sustainability at the member states level. Firstly, the study investigates multiple data sources (Environmental Fund Administration-EFA, Eurostat and National Waste Management Plan) to have a complete overview on the packaging waste generation and technical performances. Secondly, the US EPA WARM methodology was selected to perform the analysis. The indicators set within the methodology are the main indicatives for the environmental impacts and the socio-economic aspects in the end of life management operations, namely: greenhouse gas emissions and energy use, together with number of full-time jobs, wages and taxes. Throughout 5 proposed scenarios, the impact of packaging waste quantities variations on the sustainability results could be observed. Irrespective of the scenario, when the overall packaging waste generated quantities are within 1.88 up to 2.14 million tons, the sustainability profile limits give results for environmental indicators within the following ranges: greenhouse gas emissions −3.75 × 106 ÷ −1.4 × 106 tons CO2e/year, energy use −2.9 × 107 ÷ −1.1 × 107 GJ/year, social indicator: 5823–14368 full time jobs and economic indicators: 328 × 106 ÷ 692 × 106 US $/year in wages and 56.7 × 106 ÷ 136.7 × 106 US $/year in taxes. Beside the overall packaging waste sustainability profiles, specific packaging waste material streams, namely polyethylene terephthalate (PET) and aluminium sustainability profiles were obtained. For the entire packaging waste system, compared with the other scenarios, the sustainability profile for the EFA scenario has indicated the lowest environmental impact and the highest positive impact for the socio-economic indicators (with 2018 registering the best results). For both PET and aluminium packaging waste systems, in the EFA scenario, 2019 has been the year with the lowest performance (highest environmental impact and lowest values for the socio-economic indicators).

Characterization of the sources and health risks of polycyclic aromatic hydrocarbons in PM2.5 and their relationship with black carbon: A case study in northern Taiwan

Polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) often coexist in PM2.5 because both form during the incomplete combustion of organic matter. These compounds are regarded as hazardous air pollutants with potential health effects, including respiratory and cardiovascular effects. In this study, to evaluate the health risks of PAHs and BC at an urban site in northern Taiwan, 16 priority PAHs and BC, identified by the United States Environmental Protection Agency, were analyzed and quantified in PM2.5 to determine their concentrations, their relationship with each other, and their likely sources. The results indicated that the mean concentrations of total PAHs and BC were 0.91 ng m−3 and 0.97 μg m−3, respectively, with a significant positive correlation between them, indicating the same emission sources. The results also indicated that fossil fuel combustion and traffic emissions were primary contributors to PAHs, with wood and biomass combustion playing a less prominent role. Among these 16 priority PAHs, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[b]fluoranthene, and indeno[1,2,3-cd]pyrene served as major carcinogenic compounds, accounting for 89.0% of the total carcinogenic toxicity. Thus, the lifetime excess cancer risk resulting from PAH exposure was estimated as 8.03 × 10−6, indicating a potential carcinogenic risk to human health at the sampling site. Overall, this study highlights the need for future mitigation policies for traffic emissions and fossil fuel combustion for reducing the local emissions of BC and co-produced PAHs in northern Taiwan.

Transparent conductive film of silver nanowires employed for SERS detection of mercury ions

Silver nanowires (Ag NWs)/glass transparent conductive film was prepared by one-step spin coating method. l-Cysteine (L-Cys) functionalized Ag NWs were employed for the surface-enhanced Raman scattering (SERS) detection, which was used to evaluate the photoelectric performance by detecting heavy metal Hg2+ ions. The L-Cys functionalized Ag NWs/glass transparent conductive film exhibits selective, rapid and sensitive detection to Hg2+. The limit of Hg2+ detection reaches 10−9 M, which is ten times lower than the maximum Hg2+ concentration in drinking water set by the US Environmental Protection Agency. Furthermore, this dual-function of transparent conductive silver sensor has high accuracy, and reliability, which provides new insights into the design of rapid and sensitive SERS detection of mercury ions, and indicates a great potential for efficient heavy metal detection.

Assessing children’s potential exposures to harmful metals in tire crumb rubber by accelerated photodegradation weathering

Whether a tire crumb rubber (TCR) playground would expose children to potentially harmful chemicals such as heavy metals is an open question. The released metals available for pickup on the surface of TCR tiles was studied by accelerated 2-year aging of the TCRs in the NIST-SPHERE (National Institute of Standards and Technology Simulated Photodegradation via High Energy Radiant Exposure). The dermal contact was mimicked by a method of composite surface wiping from US Environmental Protection Agency throughout the weathering process. The surface release of ten most concerned harmful metals (Be, Cr, Cu, As, Se, Cd, Sb, Ba, Tl, Pb) was monitored through the course of aging. The cumulative release of Cu, As, Tl, and Sb reached potentially harmful levels at various times within 3 years, although only Cr was found at a harmful level on the surface of the tiles. Taking the cleansing effect of precipitation or periodic cleansing with rain into account, TCR playgrounds may still be safe for use.

Methodological introduction to the carbon footprint evaluation of intermodal transport

Managing logistics processes from an environmental perspective is increasingly important in international supply chains. Essential elements of global logistics are supply chains based on intermodal logistic units. The specificity of this type of shipment, which often involves several modes of transport, requires a precise definition of model boundaries and identification of specific factors determining the level of carbon footprint. This research is focused on identifying the specific emissivity level of each intermodal transport stage. The conducted study refers to the international emission evaluation guidelines gathered in the UN GHG Protocol. The carbon footprint (CF) evaluation commenced during the case study indicated the need to consider the specificity of the assigned modes of transport. Hence selected emission factors such as US DEFRA, US EPA, KOBiZE and UNFCCC were engaged for better carbon footprint evaluation related to each stage of the intermodal transport process. In the summary part, the environmental efficiency level of each mode of transport has been compared. The sea freight mode was indicated as the most efficient in terms of overall kg*eCO2 per kilometre. The study shows that intermodal maritime transport, taking into account the weight of the goods transported and the distance, is approximately 68% more efficient than road transport. However, it must be mentioned that to identify the differences comprehensively, transshipment operations must also be taken into account in each scenario. Further research steps and recommendations have been presented in the last section of this research.

US EPA orders toxicity tests on PFAS used in GenX

US EPA orders toxicity tests on PFAS used in GenX

Radon level in groundwater in Kwara State, Nigeria, and the potential radiation dose due to intake.

Abstract Radon in groundwater for domestic purposes contributes to indoor radon and at high concentration levels could be hazardous to inhabitants. Rn-222 concentrations in 101 groundwater samples from some Local Government Areas (LGAs) of Kwara State, Nigeria, were determined by AlphaGUARD portable radon monitor. The mean activity concentrations for the LGAs varied from 4.28 ± 2.29 to 14.59 ± 8.92 Bq.l−1. Radon concentrations were <100 Bq.l−1 guidance level recommended by CEC and WHO. Eighteen percent exceeded the recommended 11.1 Bq.l−1 by the United States Environmental Protection Agency. All the samples exceeded the 0.1 Bq.l−1 Maximum Permitted Level of the Standard Organization of Nigeria for radionuclide contaminant. Mean effective dose from ingestion was estimated for adults, children and infants. Inhalation dose was also estimated. The mean annual effective doses in five LGAs were higher than the 0.1 mSv reference dose level of committed effective dose from the intake of drinking water for 1 y as recommended by the ICRP. Highlights

Analysis of phthalate acid esters in butter and cheese samples using MSPE‐GC/MS method: A health risk assessment study

The aim of this study was to evaluate the level of six phthalate acid esters (PAE) and associated health risks in butter and cheese samples, using the magnetic solid‐phase extraction with gas chromatography/mass spectrometry (MSPE‐GC/MS) technique. In this study, the limit of detection (LODs), limit of quantifications (LOQs) and the recovery percentages were 0.26–1.02, 0.78–3.06 μg/kg and 98.6–102%. The results showed that in all samples, the mean total PAEs was 9.76 ± 2.39 μg/kg (in the range of 6.33–14.49 μg/kg) and the average of Bis (2‐ethylhexyl)phthalate (DEHP) was 2.9 ± 0.88 μg/kg (in the range of 1.84–4.24 μg/kg), which is lower than the standard level (EFSA set PAE standard levels between 0 and 50 μg/kg in food and US Environmental Protection Agency (EPA) set 6 μg/L for DEHP in drinking water). Moreover, the average total PAEs in all butter samples were 11.52 ± 2.03 μg/kg (in the range of 7.82–14.49 μg/kg) and the average of DEHP was 3.53 ± 0.73 μg/kg (in the range of 2.05–4.24 μg/kg) and the average total PAEs in all cheese samples were 8.00 ± 1.02 μg/kg (in the range of 6.33–9.91 μg/kg) and the average of DEHP was 2.26 ± 0.43 μg/kg (in the range of 1.84–3.04 μg/kg). The rank order of the estimated THQ (target hazard quotient) values based on the 95% percentile (in all samples) was DEHP > DBP (dibutyl phthalate) > BBP (butylbenzyl phthalate) > DEP (diethyl phthalate). The ILCR (Incremental Life Cancer Risk) assessment found that phthalates (DEHP) in dairy product samples are not of concern to humans. Finally, since the amount of these pollutants was less than the existing standards, it can be concluded that it does not pose any danger to Iranian consumers.

Pd nanoparticles anchored Co-MOF for nitrophenol reduction.

Three nitrophenols are among the 126 priority toxic pollutants identified by the US Environmental Protection Agency. Catalyzing hydrogenation is a simple way to convert these toxic nitrophenols into harmless aminophenols. Commercial PdC has excellent catalytic hydrogenation activity but has weaknesses such as high price and low reusability. Here, we fabricated a series of nano-Pd 2D Co-MOF heterostructures and filtered for optimal Co-MOF@Pd0.0012, which contain ultra-low Pd content (0.08 wt%) and recorded high catalytic efficiency for 4-nitrophenol among the reported non-single atom catalyst due to edge and size effects. The TOF value of Co-MOF@Pd0.0012 is 9800h-1, ∼206 times higher than that of PdC (Pd content, 10 wt%). Furthermore, Co-MOF@Pd0.0012 has been widely applied to catalyze the reduction of various nitrophenol substrates with higher than 99% conversion efficiency and selectivity.

Study on the occupational exposure limit of glyphosate in the air of workplace

Objective: To establish occupational exposure limits for glyphosate in workplace air. Methods: In November 2014, by searching the documents of the United States Environmental Protection Agency (EPA) on glyphosate toxicity, the toxicity data and clinical symptoms of glyphosate toxicity were collected through various literature databases, and the target organs of glyphosate toxicity were determined. A total of 5 representative production enterprises in Jiangsu Province and Shandong Province were selected for field investigation. A total of 968 people were selected as the study subjects, including 526 workers exposed to glyphosate as the contact group, and 442 off-site (such as financial, administrative, etc.) workers with enterprises as the control group. Health examination was carried out in the exposure group and the control group to observe the damage of target organs of workers with different exposure concentrations and determine the occupational exposure limit. Results: The main target organs of glyphosate are liver and kidney and its effect on cholinesterase activity. The time-weighted average concentration (TWA) of glyphosate exposure in the exposure group was <0.03~48.91 mg/m(3), and there were statistically significant differences in liver and renal function between the exposure group and the control group (P<0.05). When the concentration of glyphosate in the air was higher than 5 mg/m3, there was a statistically significant difference in the abnormal rate of renal function between the exposure group and the control group (P<0.05) . Conclusion: The study sets the occupational exposure limit of glyphosate as 5 mg/m(3). The safety of this standard conforms to the relevant requirements of toxicology and occupational disease epidemiology, and also conforms to the existing economic and technological level in my country, and is highly feasible.

Pollution level, source, and health risk assessment of PAHs in food products and environmental media in Nantong, China: A pilot case

The following study is an analysis of the pollution characteristics, dietary intake levels, and health effects of 16 polycyclic aromatic hydrocarbons (PAHs) in vegetables, fruits, and meat products in Nantong City, China. The PAHs content, pollution level, carcinogenic risk, and correlation of soil and local atmospheric environment in the crop irrigation area were determined. A total of agricultural products (n = 42), soil samples (n = 18), and air samples (n = 42) were freshly collected from selected irrigation areas in Nantong to detect the content of 16 US EPA PAHs. The total contents of PAHs in vegetables, fruits, and meat products were 16.4 − 136.5 ng/g, 86.0 − 225.1 ng/g, and 0.1 − 23.4 ng/g, respectively. Phe (32.00 −37.24%) and Pyr (27.25 −28.79%) were two PAHs with the highest pollution. The total contents of 16 PAHs in both soil and air were 31.5 − 288.2 ng/g and 1.08 − 28.85 ng/m3, respectively. The single PAHs with the highest pollution were BaP (36.48%) and Flu (21.45%). The characteristic ratio analysis method was used to trace the source of PAHs. Accordingly, PAHs in the three types of food sources primarily originated from the burning of coal, oil or biomass, and was consistent with the air or soil pollution sources. The total exposure to PAHs in vegetables, fruits, and meat products was 18.81 − 66.82 ng/d, 5.69 − 8.62 ng/d, and 0.82 − 2.45 ng/d, respectively. The lifetime incremental carcinogenic risk was 4.20 × 10−7 − 6.41 × 10−6, 1.0 × 10−7 − 7.8 × 10−7, and 1.9 × 10−8 − 2.0 × 10−7, which corresponds to a relatively low−risk level. In comparison, the total exposure of soil and air were 4.15 × 10−7 − 1.54 × 10−6 mg·kg−1·d−1 and 2.71 × 10−6 − 1.40 × 10−5 mg·kg−1·d−1, respectively, and the non−carcinogenic and carcinogenic risk of soil were 3.07 × 10−5 − 1.21 × 10−4 and 1.09 × 10−8 − 3.98 × 10−8, respectively. The carcinogenic risk of air was 8.42 × 10−6 − 4.35 × 10−5, indicating that the risk of cancer is within the acceptable range; however, it cannot be ignored.

Determining the factors controlling the chemical composition of groundwater using geochemical methods and groundwater health assessment in Qixing Town, southwest China

Abstract Studies on groundwater quality and possible hazards to human health are important for improved groundwater utilization. This study explored the chemistry of groundwater in Qixing Town and the influencing factors. Statistical evaluation, ion correlation, Entropy-Weighted Water Quality Index (EWQI) assessment, and human health risk evaluation were conducted on data derived from 25 groundwater samples. The main groundwater chemistry types were HCO3–Na and HCO3–Ca. The results of ion and geological modeling analysis indicated that major ion concentrations were mainly determined by cation exchange. The study on the variation of heavy metal concentration in groundwater with depth shows that the heavy metal content in groundwater decreases first and then increases with the increase of depth, and the EWQI suggested that groundwater was suitable for drinking. The total carcinogenic health risks for Cr and As for both adults and children were higher than the highest permissible hazard value suggested by the United States Environmental Protection Agency (USEPA). The categorization of hazardous ingestion (HI) by the USEPA indicated a negligible non-carcinogenic hazard to human health by toxic metals. The results suggest the need to increase Cr and As contamination monitoring in shallow groundwater. This study can facilitate the rational development of groundwater resources.

Synergistic effects of bacterial consortium and thermal energy on treatment of sewage by waste stabilisation pond

The low rates of biodegradation of organic pollutants in wastewater have been attributed to the daily fluctuation of temperatures, which affects microbial metabolism and activities in reactors. This work aimed to develop a method to degrade sewage pollutants using a synergistic effect of bacterial consortium and thermal energy, while a grey concrete pond served as the control. The results demonstrated that the temperature profile of ICCP showed that all through the experiment, the temperature was above 25 °C, which is a suitable temperature for mesophilic bacterial growth. A properly-stabilised effluent was achieved by the ICCP with a low biodegradation index between 0.11 and 0.14. The values of BOD (95%) and COD (74%) removal efficiencies were obtained at a 10-day retention time in ICCP, which is in accordance with standard of the United State Environmental protection Agency. Moreover, a comparison between a control and ICCP revealed that the latter emits heat energy 30% higher than the first. The temperature of 30 °C (dark) and 30.8 °C (light) produced a BOD removal > 90%. Therefore, this method could be considered to bridge the gap in daily fluctuation of temperature for enhanced biodegradation.•Designing of a thermal coated concrete pond to investigate their thermal performance during the dark and light condition•Bioremediation test for selection of mixed bacteria strain of high degradation potential used as inoculum•A detention time of 10 days under natural sunlight used for investigation for concentration balance of organic pollutant