USEPA Criteria Research Articles

Assessment of heavy metal and other chemical pollution in Lake Tana along urban peripheries, Ethiopia

Abstract This study investigates the heavy metals (HMs) and other constituents in Lake Tana around the Gulf of Bahir Dar City. The water sample was collected from areas receiving drainage water and a reference sample was collected from areas away from the urban impact, both during dry and wet seasons. Pollution sources and levels were determined using pollution indices and GIS spatial analyses. All in situ parameters were in the recommended range of the USEPA aquatic and WHO drinking water guidelines. The level of dissolved P was recorded between 0.03 and 0.9 mg/l and the level of N-NO3 ranged from 0.05 to 1.01 mg/l indicating that the limits were above USEPA aquatic criteria. The HMs varied from 0.08 to 2.85 mg/l for Cu, 0.10 to 1.60 mg/l for Fe, 0.04 to 0.22 mg/l for Cr, and Mn was below detection. Cr and Fe were above the aquatic and drinking water guideline limit. Spatially, pollution was more significant in areas receiving drainage. Also, except Cu and Fe, other parameters were higher in the rainy season indicating storm runoff pollution. The overall pollution indices of water quality status, such as water quality index 63, heavy metal pollution index 3.1, and nutrient pollution index 4.7, indicated the quality level of water to be alarming. Therefore, comprehensive regulatory and waste management practices are needed.

Prediction of acute fish toxicity (AFT) and fish embryo toxicity (FET) tests by cytotoxicity assays using liver and embryo zebrafish cell lines (ZFL and ZEM2S)

Fish cell-based assays represent potential alternative methods to vertebrates' use in ecotoxicology. In this study, we evaluated the cytotoxicity of thirteen chemicals, chosen from OECD guidelines 236 and 249, in two zebrafish cell lines (ZEM2S and ZFL). We aimed to investigate whether the IC50 values obtained by viability assays (alamar blue, MTT, CFDA-AM, and neutral red) can predict the LC50 values of Acute Fish Toxicity (AFT) test and Fish Embryo Toxicity (FET) test. There was no significant difference between the values obtained by the different viability assays. ZFL strongly correlated with AFT and FET tests (R2AFT = 0.73–0.90; R2FET48h = 0.79–0.90; R2FET96h = 0.76–0.87), while ZEM2S correlated better with the FET test (48h) (R2 = 0.70–0.86) and weakly with AFT and FET tests (96h) (R2AFT = 0.68–0.74 and R2FET96h = 0.62–0.64). The predicted LC50 values allowed the correct categorization of the chemicals in 76.9% (AFT test) – 90.9% (FET test) using ZFL and in 30.7% (AFT test) – 63.6% (FET test) using ZEM2S considering the US EPA criterion for classifying acute aquatic toxicity. ZFL is a promising cell line to be used in alternative methods to adult fish and fish embryos in ecotoxicity assessments, and the method performed in 96-well plates is advantageous in promoting high-throughput cytotoxicity assessment.

Physicochemical properties of wastewater effluents from selected wastewater treatment plants

The majority of garbage that is dumped into the environment is the consequence of industrial activity, and this waste contains toxic and dangerous substances that have properties. Untreated industrial effluents have repeatedly affected the environment and human health. Additionally, the aim of this review is to determine if water treatment conforms to DWAF and USEPA criteria and to evaluate specific wastewater treatment facilities. Additionally, the effluent from companies was assessed after being collected utilizing composite sampling methods. The findings recognized pH, rivers, and industrial activities. This is a warning sign that the water is unsafe, demonstrating that industrial effluents are contributing to a reduction in river water quality. Receiving water near numerous food-processing facilities showed significant reductions after effluent discharge. As a result, when developing mitigation strategies, governments should consider this. Some of these strategies are enforcing the pollution laws that are already in place; setting up treatment facilities; turning industrial waste into biogas; educating the public; starting programs; and passing laws.

Influence of soil physicochemical properties, particle size fractions and mineralogy on the leaching potentials of arsenic and antimony in abandoned mine soils

At abandoned mine sites, arsenic (As)- and antimony (Sb)-enriched soils are often disposed of through onsite burial or capping. In highly weathered mine sites, the mobility of As and Sb is typically controlled by iron (Fe)(III)/Fe(II) phases; thus, the suitability of such disposal methods and appropriate testing techniques are questionable. In the present study, leaching potentials of As and Sb were examined using the toxicity characteristic leaching procedure (TCLP), waste extraction test (WET), and WET-extended procedure (WET-EXT) at three abandoned mine site soils in Australia. The leached concentration of As regularly exceeded USEPA criteria (5 mg L−1). The highest leached concentrations of As and Sb were observed in the finest particle size fraction (< 0.053 mm) by WET-EXT (1 040 mg L−1 for As and 21.10 mg L−1 for Sb) followed by WET (800 mg L−1 for As and 20.90 mg L−1 for Sb). The TCLP method resulted in the lowest concentrations of leached As (0.000 9 mg L−1) and Sb (0.000 3 mg L−1). Crystalline and amorphous As-bearing Fe oxides were the main phases in the soils studied. However, the best correlations of leached As determined by TCLP (0.832), WET (0.944), and WET-EXT (0.961) were found with the non-specifically sorbed (NS1) As fraction. The mineralogical and sequential extraction data clearly indicate the dominant role of Fe geochemistry in controlling leachability of As and Sb. The TCLP method was unlikely to be suitable for assessing leachability, as it exhibited no relationship with leachable Fe and substantially lower leached As and Sb than the other two methods. Given the high to extremely high leachable As and Sb concentrations, most of the soil samples would not be recommended for placement in capping works, old shafts, or reduction systems (e.g., collection in drainage basins).

Soil washing of arsenic from mixed contaminated abandoned mine soils and fate of arsenic after washing

Arsenic contamination in abandoned soils is a global concern which warrants an effective method of remediation. In this study, two organic acids and one biodegradable chelating agent were used to treat arsenic (As) contaminated abandoned mine soils. The concentration of As was 19,100 and 75,350 (mg/kg) for Webbs Consols (WC) and Mole River (MR) samples, respectively. X-ray diffraction and scanning electron microscopy confirmed that tooeleite, arsenopyrite, scorodite and quartz were the major minerals in these soils. A major portion of the As was composed of amorphous and crystalline oxides of Fe and Al determined by sequential extraction. Among the three washing reagents (oxalic acid, citric acid and EDDS) oxalic acid showed the best performance for extracting As. Based on the batch experiment, 0.5 M oxalic acid and 3 h of washing was the most efficient treatment to extract As and other trace elements. Extraction of As, Fe, and Pb was 70, 55, and 48% respectively for WC, while 68, 45 and 63% respectively for MR soil. Oxalic acid extracted 75 and 83% of As and Fe, respectively from tooeleite. Leachability and bioaccessibility of As and Fe in the treated soil was reduced due to washing. However, bioaccessibility and leachability of Pb in soil and Fe and As in tooeleite increased in washed samples. Though the leachability and bioaccessibility of As and Fe in soil was reduced in the treated soil, As still exceeded the USEPA criteria (5 mg/L) which is needed to successfully remediate soil by washing. Soil washing and subsequent solidification/stabilization could be an alternative option to remediate extremely contaminated abandoned mine soil.

LAND DEMARCATION AND DESIGNING OF WASTE TRANSFER STATION USING GIS TECHNIQUE FOR LAHORE CITY, PAKISTAN

Rapid population growth and high rate of urbanization make municipal solid waste management a challenging task for municipalities. Lack of sufficient infrastructural facilities worsen this challenging situation. To curb this, transfer stations, which are facilities located close to residential areas and are used to receive and hold waste temporarily until it is transported to distant landfills. It reduces waste transportation cost and provide a place for waste segregation. In Lahore open transfer station is built near river Ravi and residential areas which is creating air and land pollution. This study is carryout to select the suitable location for waste transfer station in Lahore that meets the USEPA criteria. Buffer command of Arc GIS is used for site selection. Best suitable sites selected for Lahore in this analysis are UC Sultanki and UC Chandrai where more buffers are joint during buffer analysis. Furthermore, cost estimation for the construction and operation of both waste transfer stations are done.

Novel effective mosquito larvicide DL-methionine: Lack of toxicity to non-target aquatic organisms

Mosquito larvicides are an effective tool for reducing numbers of adult females that bite and potentially spread pathogenic organisms. Methionine, an essential amino acid in humans, has been previously demonstrated to be a highly effective larvicide against four (4) mosquito species in three (3) genera, Anopheles, Culex and Aedes. The aim of the present study was to determine the potential impact on non-target aquatic organisms of methionine applied as a mosquito larvicide. DL-methionine concentrations ranging from 0.06% to 1.00% were used; wherein the highest concentration of 1.00% would result in 100% mortality within 48 h in mosquitoes. Acute toxicity assays were conducted in accordance with the US Environmental Protection Agency (US EPA) guidelines for the water flea (Daphnia magna Straus; Cladocera: Daphniidae) and the fathead minnow (Pimephales promelas Rafinesque; Cypriniformes: Cyprinidae). Water fleas and fish were placed directly into the solutions in glass containers and tanks for 48-hours and 96-hours, respectively. When applied within the above-mentioned range of effective mosquito larvicide concentrations, DL-methionine meets US EPA criteria as a "practically non-toxic" pesticide for both species. These results suggest that methionine is a viable alternative to current mosquito larvicide options, which are typically classified as moderately to highly toxic and may be a valuable addition to a mosquito integrated pest management program.

Assessement of Water Quality and Risk of Polyaromatic Hydrocarbons in Lungfish (&amp;lt;i&amp;gt;Protopterus annectens&amp;lt;/i&amp;gt;) from Freshwaters of Ogba/Egbema/Ndoni, Rivers State, Nigeria

Water quality and health risk of polycyclic aromatic hydrocarbons in <i>P. annectens</i> from freshwaters of Egi, Egbema, and Omoku communities, in Ogba/Egbema/Ndoni local government area of Rivers State, Nigeria were examined. The PAHs were checked using gas chromatography coupled with flame ionization detector (GCFID), while the physicochemical parameters were done using standard methods. Summary of the results from the three communities indicates that TDS (Total Dissolved Solids) mean value was 98.1±16.88 mg/l, TSS (Total Suspended Solid) had an average value of 68.5±10.29 mg/l, turbidity and pH had averages of 1.6±0.011 Unit (NTU) and 7.4±1.05 respectively. The concentrations of tPAHs were 4.415±1.34 µg/kg, 4.634±0.59 µg/kg, and 4.859±0.69 µg/kg for Egi, Egbema, and Omoku communities. The major PAHs were Nap, Acn, and BbF. The cancer risk for children was 2.1E-3, 2.3E-3, and 9.5E-5 for Egi, Egbema, and Omoku while that for adults were 7.1E-4, 5.7E-4, and 2.6E-4 for Egi, Egbema, and Omoku respectively. The cPAHs with the most risk index were DbA, BaA, BaP, and BkF respectively. The risk indexes were higher than the USEPA criterion of 10^-6, indicating contamination of the fish species. It is recommended that monitoring of effluent should be done often and consumption of fish from polluted water sites should be avoided.

Distribution and ecological- and health-risk assessment of heavy metals in the seawater of the southeast coast of India

The objective of the present study was to conduct an ecological and health risk assessment of heavy metals in the seawater of the southeast coast of India. The distribution profile of heavy metals in the surface seawater was Fe (79.60 ± 21.57 μg/L) > Zn (9.31 ± 1.33 μg/L) > Cu (5.19 ± 2.00 μg/L) > Ni (2.45 ± 0.76 μg/L) > Mn (1.20 ± 1.00 μg/L) > U (0.44 ± 0.23 μg/L) > Pb (0.36 ± 0.06 μg/L) > Cr (0.31 ± 0.57 μg/L) > Cd (0.11 ± 0.05 μg/L) > Co (0.07 ± 0.20 μg/L). Cu level for most of the samples exceeded the USEPA criteria for acute CMC (criterion maximum concentration) and chronic CCC (criterion continuous concentration). Other studied metals, Cd, Cr, Pb, and Ni, remained below the acute CMC and chronic CCC guidelines. The seawater pollution index (Iwp) of Cr, Ni, Zn, Cd, and Pb complied with the category–I seawater (<1, unpolluted). The ERI values (0.46–3.99) of the seawater of the studied coast mostly fell under the ecologically low risk category with respect to heavy metals. Dermal Hazard index values were orders of magnitude lower than one, indicating no potential health concern due to dermal exposure.

Detection of Cryptosporidium spp. oocysts and Giardia spp. cysts in surface water destined for public supply in the state of Goiás, Brazil

ABSTRACT The protozoa Cryptosporidium spp. and Giardia spp. are etiological agents responsible for the transmission of gastroenteritis, mainly due to the consumption of contaminated water. Their (oo)cysts are resistant to adverse environmental conditions, as well as to most conventional water treatment processes. Thus, the objective of this work was to evaluate the occurrence of (oo)cysts of these protozoans in surface water collected for human consumption in the state of Goiás, Brazil. Fifteen samples of raw water were collected to assess the occurrence of (oo)cysts of the protozoa using the Membrane Filtration method, in addition to turbidity and pH analyses. Recovery rates in tests with ultrapure water reached the USEPA (2012) criteria for Giardia (78.1% ± 0%) and for Cryptosporidium (60.6% ± 32.6%); however, recovery in raw water was lower due to turbidity. All samples (n = 15) were positive for Cryptosporidium spp. oocysts, with a maximum concentration of 250 oocysts/L, demonstrating that these protozoa are disseminated in the aquatic environment of the state of Goiás and pose a risk to public health. Due to the use of water sources for public consumption, it is recommended that public authorities and sanitation companies act to preserve and maintain water courses, carry out periodic monitoring of treatment plants that supply the Cerrado, Santana and São Manoel streams and improve existing treatment technologies. The results did not allow to infer whether animal load and grazing area promote an increase in contamination of the lotic aquatic systems.

Performances of stabilization/solidification process of acid mine drainage passive treatment residues: Assessment of the environmental and mechanical behaviors

Residues from passive treatment of acid mine drainage (AMD) have variable chemical stability and could regenerate contaminated drainage. Stabilization/solidification (S/S) can prevent contaminant leaching. Residues were collected from a tri-step AMD field passive treatment system, operated for 6 years at the reclaimed Lorraine mine site, Quebec, Canada. General Use Portland cement (GU), blended binders based on GU with pozzolanic additives (ground-granulated blast-furnace slag; GGBFS and fly ash type C; FAC) were used as hydraulic binders, in proportions (w/w %) of 100GU, 20GU/80GGBFS, and 50GU/50FAC, respectively. Residues were mixed with wood ash (35%) and sand (25%), while reference samples (100% sand) were also prepared. Prior to S/S, raw materials were characterized. The S/S effectiveness was assessed mineralogically and mechanically (unconfined compressive strength; UCS). Environmental behavior assessment (static vs semi-dynamic leaching tests) was also performed. UCS results showed that strength increase with age. At 56 days, GU- (1.3 MPa) and GU/GGBFS (0.7 MPa) satisfied Quebec's strength requirements for landfill disposal (0.7 MPa), but not GU/FAC (0.6 MPa), while all samples satisfied USEPA criteria (0.35 MPa). The semi-dynamic test showed that all elements can be immobilized successfully in GU- and GU/GGBFS. The GU binder had the best stabilizing performance. Based on USEPA requirements, S/S using GU, GGBFS, and FAC can be also considered for contaminant immobilization in AMD passive treatment residues. Finally, the comparison between replicates using Student's t-test indicated good reproducibility of S/S treatment.

Erkenez Çayı‘nda (Kahramanmaraş) Süt Ürünleri, Boya ve Tekstil Fabrikası Atık Sularından Kaynaklanan Ağır Metal Kirliliğinin Belirlenmesi

Endüstriler atık sularının kompozisyonunun çeşitliliği nedeniyle sucul ekosistemler üzerinde kirlilik kaynağı olarak önemli bir etkiye sahiptir. Bu çalışmada, Kahramanmaraş ili Organize Sanayi Bölgesi‘nde faaliyet gösteren süt ürünleri fabrikası, boya fabrikası ve tekstil fabrikası atık sularının Erkenez Çayı‘nda meydana getirdiği ağır metal kirliliğinin belirlenmesi amaçlanmıştır. Bu amaç doğrultusunda süt ürünleri fabrikası, boya fabrikası ve tekstil fabrikası atık sularında ve bu atık suların Erkenez Çayı‘na karıştığı bölgede bazı ağır metallerin (Fe, Cu, Zn, Cr, Ni, Cd, As ve Hg) mevsimsel olarak konsantrasyonları belirlenmiştir. Bütün istasyonlarda ağır metallerin mevsimsel değişimi dikkate alındığında genel olarak elementlerin en düşük konsantrasyonları kış mevsiminde, en yüksek konsantrasyonları ise yaz mevsiminde tespit edilmiştir. Süt ürünleri, boya ve tekstil fabrikası atık sularının ağır metal içerikleri karşılaştırıldığında en yüksek değerler tekstil fabrikası atık sularında bulunmuştur. İstasyonlar göz önüne alındığında USEPA ve su kalite kriterlerine göre süt ürünleri, boya ve tekstil fabrikası atık suları ile bu atık suların Erkenez Çayı‘na karıştığı bölgenin çok kirli olduğu belirlenmiştir. Bu sonuçlar dikkate alındığında bu fabrikaların atık sularının Erkenez Çayı‘nda ciddi bir ağır metal kirliliğine neden olduğu açıkça görülmektedir.

Comparison and modeling of leachate transportation dominated by the field permeability with an anisotropic characteristic based on a large-scale field trial study

Permeability significantly affects leachate transportation. Yet, there often exists a gap for its measurements between laboratory and the field. To predict the fate and transport of heavy metals from IBA leaching, a large-scale field trial study was performed using a big column (d × h = 3 m × 5.5 m) packed with 1-m thickness of IBA (approx. 10.6 tons) overlaid by 4-m sand layer. The determined field permeability (kF) was compared with that achieved from the laboratory, demonstrating a large disparity as much as 4 orders of magnitude likely due to IBA self-compaction. Indeed, back calculation using Blake-Kozeny's equation unveiled that, the "effective" diameters were significantly reduced by 21-46%. kF also demonstrated an anisotropic characteristic associated with fingered flows, trapped bubbles and heterogeneous consolidation/cementation efficiencies. To quantify the effects by kF, we ran a mechanistic model to simulate the transport of 11 heavy metals under advection (dh/dx = 0.05 m/m), indicating dramatically prolonged breakthrough time from days to centuries. Interestingly, breakthrough time was comparable among various metal ions (0-16.6% of RSD), suggesting their synchronous movements. Metal flux under kF was predicted in the end to address its toxicity potential, demonstrating limited environmental impacts in presence of the USEPA criterion.

GMCs stabilized/solidified Pb/Zn contaminated soil under different curing temperature: Physical and microstructural properties

Stabilization/Solidification (S/S) has been widely used in soil remediation to both improve physical properties and immobilize extensive contaminants. GGBS (granulated ground blast furnace slag)-MgO-CaO (GMCs) was used to treat Pb/Zn contaminated soil. The physical and microstructural characteristics of stabilized/solidified contaminated soil were investigated in this study. Microstructural analysis showed that the main hydration products of GMC treated contaminated soil were C–S–H and hydrotalcite like gels (Ht), which dominated the physical strength of S/S soil. The unconfined compressive strength (UCS) and the leachability of GMC treated contaminated soil were improved with the increase in GMC proportion (5%–15%), curing time (7 days and 28 days) and temperature (5 °C, 21 °C and 45 °C) due to the enhanced hydration. The compressive strengths of the majority mixes met the US EPA criterion (0.35 MPa). The strength of S/S soils was less affected by the increase of curing temperature after a longer curing period (28 days). According to the XRD and SEM results, both Pb and Zn in S/S contaminated soil could be immobilized by the precipitation and the adsorption on the surface of calcium silicate hydrate (C–S–H). Zn can also be incorporated into the structure of C–S–H and Ht. The addition of Pb/Zn decreased the physical strength in the order of: Pb(5000 mg/kg)>Pb(10000 mg/kg)>Zn/Pb(5000 mg/kg)>Pb(20000 mg/kg).

Comparison of Mercury Contamination in Four Indonesian Watersheds Affected by Artisanal and Small-Scale Gold Mining of Varying Scale

Artisanal and small-scale gold mining (ASGM) accounts for almost half of anthropogenic mercury (Hg) emissions worldwide and causes widespread water pollution. In Indonesia, several studies have identified harmful levels of Hg in areas affected by ASGM. While most of these studies focus on mining areas with thousands of miners, water contamination in smaller ASGM areas is less understood. We evaluated Hg contamination in four ASGM areas in Central Java of varying scale (from 30 to 3000 amalgamator barrels at each area), including Jatiroto, Kebonsari, Gumelar, and Kulon Progo. At each location, we collected water samples along river transects upstream and downstream of ASGM areas during the dry season (June–July 2017). Total Hg (THg) concentrations in stream water increased by orders of magnitude from upstream to downstream of ASGM activities at Jatiroto (1.35–4730 ng/L), with smaller observed increases at the other locations. Dissolved THg concentrations exceeded USEPA criteria for aquatic life (12 ng/L) at two of the four ASGM areas. THg concentrations in tailings exceeded 150,000 ng/L. Notably, THg concentrations in stream water were not directly related to the scale of mining, with Jatiroto having the highest concentrations as second smallest mining areas of the four in this study. Downstream of the mining areas, the fraction of dissolved methyl Hg to dissolved THg reached 20%, indicating that active Hg methylation occurs in the watersheds. Further study is needed to investigate Hg transport in the wet season when rainfall and high stream discharge may mobilize contaminated sediment near mining areas.

RESIDUOS DE PLAGUICIDAS EN SUELOS DE USO AGRÍCOLA Y RIESGO DE EXPOSICIÓN EN LA MICROCUENCA LOS ZARZALES, MUNICIPIO RIVAS DÁVILA, ESTADO MÉRIDA, VENEZUELA

There is a growing concern about the presence of pesticide residues in agricultural land because they constitute an environmental risk and a source of human exposure. In this work, the presence of these residues and the risk of exposure was determined in the micro-watershed of Los Zarzales, Rivas Davila municipality, Merida, Venezuela. Soil samples were taken in the initial, middle and final stages of short cycle crops, and the active ingredients were extracted and analyzed by HPLC. The risk of exposure was estimated by calculating the dose of pesticides through non-dietary intake of contaminated soil and dust, according to the US-EPA criteria. The highest concentration and variety of compounds was recorded during the middle stage: 26 ± 7 mg/kg of total residues and 100% detection frequency, standing out among them paraquat (15 ± 7 mg/kg), carbendazim (8 ± 2 mg/kg), mancozeb (3.7 ± 0.7 mg/kg) and carbofuran (1.2 ± 0.5 mg/kg). Based on these values, the calculated daily doses were 1.5, 0.8, 0.37 and 0.12 μg/day, respectively, all of which were below the admissible daily intake established by FAO/WHO, which is used as reference. Despite of this, the total dose reached 2.8 μg/day, which is considered as a risk of exposure.

Environmental risk assessment for sustainable pesticide use in coffee production

The extensive use of pesticides in agricultural practices has been associated with human health problems and environmental contamination worldwide. Brazil is the largest consumer of pesticides in the world and Espírito Santo State stands out as the second Brazilian producer of coffee. However, there is no information about environmental impact of coffee producing at Itapemirim River Basin (IRB) region, Espírito Santo State, Brazil; hence a simple and quick method using open access softwares (AGROSCRE and ARAquá Web) to estimate surface entrainment and pesticide leaching potential was carried out. AGROSCRE evaluates the contamination risk of superficial and groundwater by Active Ingredients (AIs), using GOSS Method, GUS index and US EPA criteria, while ARAquá Web estimates AI concentrations in water resources, indicating their suitability based on water quality requirements for different uses. Regarding pesticides used in coffee plantations, there is 44.7% chance of surface water and 23.7% chance of groundwater contamination. Results showed that ametryne, cyproconazole, diuron, epoxiconazole, flutriafol, triadimenol and triazophos pose contamination risk to both surface water and groundwater in the IRB region. Of these, 10.5% of the total AIs are triazoles and fall under environmental classes II and III (Product Very/Dangerous to the Environment). The AIs ametryne, thiamethoxam, iprodione, flutriafol, triazophos, endosulfan, triadimenol, cyproconazole, diuron, pendimethalin, chlorpyrifos, copper II hydroxide, etion, epoxiconazole and paraquat dichloride, were found to be potentially toxic, presenting environmental concentrations ranging from 123.40 μg L-1 to 0.14 μg L-1, which are higher than the safety standard for potable water (0.1 μg L-1). With respect to these AIs, chlorpyrifos, ethion and triazophos showed concentrations higher than EC50 values for aquatic invertebrates and ametryne and diuron for algae. Thus, local residents and environment may be at high risk of pesticide exposure, when these AIs are used in coffee plantations next to surface water or groundwater.

Ozone and volatile organic compounds in the metropolitan area of Lima-Callao, Peru

This study analyzes ozone formation in the metropolitan area of Lima-Callao as a function of meteorological patterns and the concentrations of nitrogen oxides and reactive organic gases. The study area is located on the west coast of South America (12°S) in an upwelling region that is markedly affected by the Southeast Pacific anticyclone. The vertical stability and diurnal evolution of the mixing layer were analyzed from radiosondes launched daily during 1992–2014 and from two intensive campaigns in 2009. Vertical profiles show that during June–November, the subsidence inversion base ranges from 0.6 to 0.9 km above sea level (asl). In contrast, during December–May, subsidence inversion dissipates, leading to weak surface inversions from 0.1 to 0.6 km asl. At the surface level, compliance with the ozone standard of 51 parts per billion by volume (ppbv) is explained by the marine boundary layer effect and by strong inhibition of ozone formation due to titration with nitric oxide. Day-of-the-week variations in ozone and nitrogen oxides suggest a VOC-limited ozone-formation regime in the atmosphere of Lima. Furthermore, the pattern of C6–C12 species indicates that gasoline-powered vehicles are the main source of volatile organic compounds (VOCs), whereas the species with the greatest ozone-forming potential corresponded to the sum of the isomers m- and p-xylene. Mean benzene concentrations exceeded the standard of 0.63 ppbv, reaching 1.2 ppbv east of Lima. Nevertheless, the cancer risk associated with the inhalation of benzene was deemed acceptable, according to USEPA and WHO criteria.

Using an integrated method for the determination of environmental TCLP arsenic for sulphide-rich mine tailing remediation in Ghana, West Africa

Toxicity characteristic leaching procedure (TCLP) is a versatile short-term leaching protocol used to estimate the release of toxic metals from waste prior to disposal to a repository. This paper uses the integrated TCLP leachate data from tailings, tailings dam monitoring borehole data, and acidity ratio (AR) range of sulphide-rich ores to simulate the environmental TCLP As in tailings at the AngloGold Ashanti Obuasi mine in Ghana. The aim was to incorporate long-term leaching characteristics of tailings to minimise the risk of TCLP As test failure. The mean As concentration and pH value are 2.26 mg/l and 5.7 in TCLP leachate, 0.35 mg/l and 6.7 in monitoring boreholes, and < 0.01 mg/l and 5.7 in control boreholes, respectively. The evaluation of the TCLP As data using a one-sample t test performed at 80% confidence interval has the upper confidence limit (UCL) of 2.41 mg/l; this value which constitutes the short-term characterised environmental TCLP As is below the USEPA criterion of 5 mg/l and, therefore, qualifies the waste as safe for disposal. Alternatively, TCLP leachate, borehole and AR data were integrated to simulate the long-term environmental TCLP As of 2.40 mg/l and pH value of 5.7, and As concentration and pH value of 0.01 mg/l and 6.7 in monitoring boreholes, respectively. Such laboratory simulations of TCLP As leaching aimed at achieving 0.01 mg/l in field monitoring data would provide a more robust predictive value for environmental management decision making due to long-term considerations.

Cr, Cu, Hg and Ni release from incineration bottom ash during utilization in land reclamation – based on lab-scale batch and column leaching experiments and a modeling study

Incineration bottom ash (IBA) as potential material for land reclamation was investigated, based on leaching tests, sorption studies and simulation models. Based on batch and column leaching tests, Cr, Cu, Hg and Ni in the IBA leachates were measured as high as 510 μg/L, 20330 μg/L, 5.1 μg/L and 627 μg/L, respectively, presenting potential environmental risks. Sorption study was then performed with various concentrations of IBA leachates on sands and excavated materials. Partitioning coefficients of targeting metals were determined to be 6.5 (Cr), 18.4 (Cu), 16.6 (Hg), and 1.8 (Ni) for sands, while 17.4 (Cr), 13.6 (Cu), 67.1 (Hg), and 0.9 (Ni) for excavated materials, much lower than literature in favor of their transportation. Deterministic and Monte Carlo simulation was further performed under designated boundaries, combined with measured geotechnical parameters: density, porosity, permeability, partitioning coefficient, observed diffusivity, hydraulic gradient, etc., to quantitatively predict metals' fate during IBA land reclamation. Environmental risks were quantitatively unveiled in terms of predicted time of breakthrough for the targeting metals (comparing to US EPA criterion for maximum or continuous concentration). Sands were of little effects for all metals’ breakthrough (1 month or less) under advection, while excavated materials sufficiently retained metals from thousands up to millions of years, under diffusion or advection. Permeability next to the IBA layer as the major risk-limiting factor, dominated transport of IBA leachates into the field. The current study provides discrimination of environmental risks associated with metals and a quantitative guidance of project design for IBA utilization in land reclamation.