EPA Method Research Articles

Total and Polyaromatic Hydrocarbons in Water, Sediment, Fin and Shellfishes from Badagry Creek and Ologe Lagoon, Lagos, Nigeria

The concentrations of eleven (11) polyaromatic hydrocarbons (PAHs) and total hydrocarbons (THC) were investigated in the water, sediment, Chrysichthys nigrodigitatus and Macrobrachium macrobrachion from Badagry Creek and Ologe Lagoon in Lagos, Nigeria using EPA and Gas Chromatography (GC) methods. All the samples(except water measured in mg/l) were measured in μg/g. PAHs were not significantly different(p>0.05)across the two stations and were within WHO recommended limit.The highest concentration of THC from Badagry Creek was recorded in M. macrobrachion (219.565±171.891 μg/g) and this value exceeded WHO recommended limit. Similarly, the highest THC (211.565±127.923 μg/g) recorded in M .macrobrachion at Ologe Lagoon was above WHO limit. The study has shown that the polyaromatic hydrocarbons were below the risk level, which indicated no risk status from the consumption of the fish species studied. However, C. nigrodigitatus and M. macrobrachion studied from these water bodies are highly contaminated with THC. Therefore, persistent monitoring and strict adherence to responsible waste discharge should be upheld by all industries near these waters in order to avoid deleterious effects on the biota as well as ensuring safety of the consumers.

Experimental Analysis of Soil and Mandarin Orange Plants Treated with Heavy Metals Found in Oilfield-Produced Wastewater

Despite a declining trend, California remains a significant oil-producing state. For every barrel of crude oil, an average of 15 barrels of oilfield produced water (OPW) is generated, some of which is used to boost freshwater sources for crop irrigation in the agriculturally important Central Valley. OPW is known to contain salts, metals, hydrocarbons, alkylphenols, naturally radioactive materials, biocides, and other compounds from drilling and production processes. Less is known about the potential uptake and accumulation of these compounds in crops and soil irrigated with OPW. In this study, 23 potted mandarin orange plants were irrigated two to three times weekly (depending on season) with water containing three different concentrations of the known OPW heavy metals barium, chromium, lead, and silver. Seven sets of samples of soil and leaves and 11 fruits were collected and processed using microwave-assisted digestion (EPA Method 3051A). Processed samples were analyzed using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Analysis of variance (ANOVA) and covariance (ANCOVA) coupled with Tukey’s honest significant difference test were used to examine the effects of metal concentrations in the irrigation water and number of watering days, respectively, on the metal concentrations in the soil, leaf, and fruit samples. Accumulation of barium in soil and leaves was strongly positively associated with sample and number of watering days, increasing nearly 2000-fold. Lead also showed an upward trend, increasing up to 560-fold over the baseline level. Total chromium showed an increase in the soil that tapered off, but less consistent results in the leaves and fruit. The silver results were more volatile, but also indicated at least some level of accumulation in the tested media. The smallest absolute accumulation was observed for chromium. Concentrations in the fruit were highest in the peel, followed by pith and juice. Accumulation of all heavy metals was generally highest in the soil and plants that received the highest irrigation water concentration. Considering the potential for adverse human health effects associated with ingesting soluble barium contained in food and drinking water, and to a lesser extent chromium and lead, the study signals that it is important to conduct further research into the accessibility and bioavailability of the tested heavy metals in the soil and whether they pose risks to consumers.

Strain, disinfectant, concentration, and contact time quantitatively impact disinfectant efficacy

BackgroundTransmission of healthcare-associated infections caused by antibiotic- and multi-drug resistant (MDR) pathogens (e.g. Methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa) are a major concern in patient care facilities. Disinfectant usage is critical to control and prevent pathogen transmission, yet the relationships among strain, disinfectant type, contact time, and concentration are not well-characterized. We hypothesized that there would be significant differences in disinfectant efficacy among clinically relevant strains under off-label disinfectant conditions, but there would be less no differences among at registered label use concentrations and contact times. The purpose of this study was to quantify the effect of disinfectant concentration and contact time on the bactericidal efficacy of clinically relevant strains of S. aureus and P. aeruginosa.MethodsAccelerated hydrogen peroxide (AHP), quaternary ammonium compounds (Quat), and sodium hypochlorite were tested at label and reduced contact times and concentrations against four MDR P. aeruginosa strains and four MRSA strains. Quantitative EPA method MB-25-02 was used to measure disinfectant efficacy reported as log10 reduction.ResultsBoth off-label disinfectant concentrations and contact times significantly affected efficacy of all disinfectants tested. Bactericidal efficacy varied among MRSA and P. aeruginosa strains.ConclusionsThe quantitative disinfectant efficacy method used highlights the inter-strain variability that exists within a bacterial species. It also underscores the need for a disinfectant validation method that takes these variances into account.

Emission and health risk assessment of volatile organic compounds in various processes of a petroleum refinery in the Pearl River Delta, China

The process-specific emission of volatile organic compounds (VOCs) from a petroleum refinery in the Pearl River Delta, China was monitored to assess the health risk from VOCs to workers of this refinery. Over 60 VOCs were detected in the air samples collected from various sites in the refining, basic chemical, and wastewater treatment areas of the refinery using gas chromatography-mass spectrometry/flame ionization detection. The health risks of VOCs to the refinery workers were assessed using US Environmental Protection Agency (US EPA) and American Conference of Governmental Industrial Hygienists (ACGIH) methods. Monte Carlo simulation and sensitivity analysis were implemented to assess the uncertainty of the health risk estimation. The emission results showed that C5-C6 alkanes, including 2-methylpentane (17.6%), 2,3-dimethylbutane (15.4%) and 3-methylpentane (7.7%), were the major VOCs in the refining area. p-Diethylbenzene (9.3%), 2-methylpentane (8.1%) and m-diethylbenzene (6.8%) were dominant in the basic chemical area, and 2-methylpentane (20.9%), 2,3-dimethylbutane (11.4%) and 3-methylpentane (6.5%) were the most abundant in the wastewater treatment area. For the non-cancer risk estimated using the US EPA method, the total hazard ratio in the basic chemical area was the highest (3.1 × 103), owing to the highest level of total concentration of VOCs. For the cancer risk, the total cancer risks were very high, ranging from 2.93 × 10−3 (in the wastewater treatment area) to 1.1 × 10−2 (in the basic chemical area), suggesting a definite risk. Using the ACGIH method, the total occupational exposure cancer risks of VOCs in the basic chemical area were the highest, being much higher than those of refining and wastewater treatment areas. Among the areas, the total occupational exposure risks in the basic chemical and refining areas were >1, which suggested a cancer threat to workers in these areas. Sensitivity analysis suggested that improving the accuracy of VOC concentrations themselves in future research would advance the health risk assessment.

Editor's perspective – Per‐ and polyfluorinated substances pose substantial challenges to remediation practitioners

Editor's perspective – Per‐ and polyfluorinated substances pose substantial challenges to remediation practitioners

Analysis of 40 conventional and emerging disinfection by-products in fresh-cut produce wash water by modified EPA methods

Chlorine sanitizers used in washing fresh and fresh-cut produce can lead to generation of disinfection by-products (DBPs) that are harmful to human health. Monitoring of DBPs is necessary to protect food safety but comprehensive analytical methods have been lacking. This study has optimized three U.S. Environmental Protection Agency methods for drinking water DBPs to improve their performance for produce wash water. The method development encompasses 40 conventional and emerging DBPs. Good recoveries (60–130%) were achieved for most DBPs in deionized water and in lettuce, strawberry and cabbage wash water. The method detection limits are in the range of 0.06–0.58 μg/L for most DBPs and 10–24 ng/L for nitrosamines in produce wash water. Preliminary results revealed the formation of many DBPs when produce is washed with chlorine. The optimized analytical methods by this study effectively reduce matrix interference and can serve as useful tools for future research on food DBPs.

Mercury emissions monitoring in a coal-fired power plant by using the EPA method 30B based on a calcium-based sorbent trap

A novel calcium-based sorbent was synthesized from calcium acetate and mesoporous silica through chemical impregnation method. The Brunauer-Emmett-Teller (BET) and scanning electron microscope (SEM) analysis revealed that the sorbent possessed a good surface structure as the calcium salt decomposed to calcium oxide (CaO) through multiple calcination steps. The mercury adsorption performance of the sorbent was investigated in a fixed bed system, the results showed that the sorbent has an obvious penetration behavior for gaseous element mercury (Hg0(g)) while completely adsorbed reactive gaseous mercury (Hg2+(g)) under the pure nitrogen and simulated flue gas atmosphere. On-site sampling test of the calcium-based sorbent traps was ultimately conducted on a 600 MW coal-fired power plant. The Ontario Hydra Method (OHM) was chosen as the reference method to evaluate the accuracy of the sorbent traps sampling results. The measured data obtained by sorbent traps was well consistent with OHM under the selected operational load and all the sorbent traps passed the QA/QC criteria, show that the sorbent traps performed with almost the same accuracy as OHM. The mercury emission and removal characteristics across the existing air pollution control devices (APCDs) were reported based on the sorbent traps sampling results. With the help of SCR for the Hg0 oxidation, ESP for the removal of Hg2+ and Hgp, and the good water solubility of Hg2+ in WFGD, the combination of SCR + ESP + WFGD achieved an excellent mercury removal efficiency with the value of 88.54%. The final mercury emissions from the exhaust were 3.75 μg/m3 and meet the emission requirements of China.

Distribution and health risk assessment of natural fluoride of drinking groundwater resources of Isfahan, Iran, using GIS.

Fluoride (F) contamination in groundwater can be problematic to human health. This study evaluated the concentration of fluoride in groundwater resources of Isfahan Province, the central plateau of Iran, and its related health issues to the inhabitant populations. For this purpose, 573 drinking groundwater samples were analyzed in 2016 by using the spectrophotometric method. Non-carcinogenic health risks due to F exposure through consumption of drinking water were assessed using the US EPA method. In addition, the associated zoning maps of the obtained results were presented using geographic information system (GIS). The results indicated that F content in drinking water ranged from 0.02 to 2.8mg/L. The F contents were less than 0.50mg/L in 63% of the drinking groundwater samples, 0.51-1.5mg/L in 33.15%, and higher than 1.5mg/L in 3.85% (Iran and World Health Organization guidelines) of the drinking groundwater samples. The F levels in the west and the south groundwater resources of the study areas were lower than 0.5mg/L, which is within the recommended values for controlling dental caries (0.50-1.0mg/L). Therefore, these places require more attention and more research is needed to increase F intake for health benefit. The HQ index for children, teens and male and female adults had health hazards (HQ > 1) in 51, 17, 28, and 18 of samples, respectively. Groundwater resources having a risk of more than one were located in the counties of Nayin, Natanz, and Ardestan. So, in these areas, there are potential risks of dental fluorosis. The most vulnerable groups were children. The F levels must be reduced in this region to decrease endemic fluorosis.

Bioaccessibility of heavy metals in the seaweed Caulerpa racemosa var. corynephora: Human health risk from consumption

ABSTRACTThis study reports the total and bioaccessible concentrations of heavy metals (Mn, Fe, Cu, Zn, Cd and Pb) in the seaweed Caulerpa racemosa var. corynephora collected from local markets along the Andaman coast of Krabi Province, Thailand. Microwave-assisted acid digestion (EPA Method 3052) was used for sample preparation prior to total metal analysis. The in vitro Unified Bioaccessibility Method (UBM) was applied to assess the bioaccessibility of the metals in the seaweed samples. The total, gastric phase, and residual fraction concentration were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The total amounts found in the seaweed samples, in ascending order were Cd < Pb < Cu < Zn < Mn < Fe with the mean concentrations of 0.89, 0.97, 17.4, 59.0, 63.4, and 450 mg/kg dry weight, respectively. High bioaccessibility percentages for Mn (71.8–85.3%) were observed alongside moderate bioaccessibility percentages for Cu (44.3–56.3%), Zn (37.7–47.4%), and Cd (41.8–46.7%), a low bioaccessibility percentage for Pb (22.3–32.0%), and a very low bioaccessibility percentage for Fe (11.5–16.5%). A quality control procedure was implemented which involved the analysis of a certified reference material (Seaweed NMIJ CRM 7405-a) for total metals and a mass-balance approach for the assessment of the in vitro bioaccessibility method.

Application of passive sorbent tube and canister samplers for volatile organic compounds at refinery fenceline locations in Whiting, Indiana

ABSTRACTSelect volatile organic compounds (VOCs) in ambient air were measured at four fenceline sites at a petroleum refinery in Whiting, IN, using modified EPA Method 325 A/B with passive tubes and EPA Compendium Method TO-15 with canister samplers. One-week, time-integrated samplers were deployed for 8 weeks with tubes and canister samplers deployed in duplicate. Good precision was obtained from the duplicate tubes (<7%) and duplicate canisters (≤10%) for BTEX, perchloroethylene, and styrene. The tubes yielded statistically significantly higher concentrations than canisters for benzene, toluene, ethylbenzene, and m,p-xylene. However, all differences were estimated to be <0.1 ppbv. No concentration differences among the four Whiting sites were found for any of the VOCs.Implications: Recently enacted EPA Methods 325A/B use passive-diffusive tube samplers to measure benzene at refinery fenceline locations. This pilot study presents VOC data applying a modified version of EPA Method 325 A/B and its comparison to EPA Compendium Method TO-15 canister samplers at four refinery fenceline sites. The findings from this study provide additional confidence in application of the tube method at refineries to ascertain VOC source influence since tube and canister samplers were comparable and good precision was obtained from duplicate sampling for both methods. No overall difference in these reported VOC concentrations was found between Whiting sites for tubes or canisters.

X-ray Fluorescence Analysis of Antimony Content in Extruded Polyethylene Terephthalate Food Packaging Below the Infinite Thickness

Consumer and environmental groups have increasing concern about heavy metal contaminants and residual catalysts in plastics inducing negative human and environmental impacts. Regulations of heavy metals in food-contact plastics seek to reduce these risks by establishing maximum allowable threshold levels. However, traditional quantification methods of heavy metal concentrations, e.g., inductively coupled plasma (ICP) and atomic absorption spectroscopy, are time-consuming and expensive. X-ray fluorescence (XRF) techniques provide a rapid, non-destructive method for monitoring heavy metals, but the sample must be of sufficient thickness for accurate XRF analysis. This study developed a correction factor equation enabling rapid, accurate XRF measurements of antimony concentration in thin plastic samples at thicknesses common for food packaging applications by measuring XRF concentration as a function of thickness and establishing correlations with the measured ICP concentration. This correction factor approach yielded antimony concentrations from XRF measurements for 94% of the challenge samples tested within the acceptability metric stated in EPA Method 6200. The approach described herein enables rapid, cost-effective screening and regulatory compliance for safety and environmental impact benefiting consumers, manufacturers, and the environment.

A new tool for the evaluation of the analytical procedure: Green Analytical Procedure Index

A new means for assessing analytical protocols relating to green analytical chemistry attributes has been developed. The new tool, called GAPI (Green Analytical Procedure Index), evaluates the green character of an entire analytical methodology, from sample collection to final determination, and was created using such tools as the National Environmental Methods Index (NEMI) or Analytical Eco-Scale to provide not only general but also qualitative information. In GAPI, a specific symbol with five pentagrams can be used to evaluate and quantify the environmental impact involved in each step of an analytical methodology, mainly from green through yellow to red depicting low, medium to high impact, respectively. The proposed tool was used to evaluate analytical procedures applied in the determination of biogenic amines in wine samples, and polycyclic aromatic hydrocarbon determination by EPA methods. GAPI tool not only provides an immediately perceptible perspective to the user/reader but also offers exhaustive information on evaluated procedures.

Soil-Transmitted Helminths in Top Soils Used for Horticultural Purposes in Cape Coast, Ghana.

This paper investigated the concentrations of eggs of three helminths (roundworm, hookworm, and whipworm) in the so-called black soils used for domestic and urban landscaping, home gardening and as growth medium for potted plants and pot experiments. The black soils are largely collected from active or abandoned waste dumpsites and fallowed or vegetated idle sites in the urban fringe or rural areas. Users buy black soils from dealers. Samples of black soils used for various purposes and at different places were collected for analysis of helminth eggs. The Modified EPA Method, which combines flotation and sedimentation, was used to isolate the eggs. The results show that these black soils have substantial loads of helminth eggs, with roundworm being dominant, followed by hookworm. Mean concentrations of helminth eggs were 2.45 (roundworm), 1.38 (hookworm), and 0.25 (whipworm) g−1 soil, respectively. The helminth egg loads also declined with duration of use of the black soils. It is concluded that black soils used for horticultural purposes in Ghana can be a potential source of helminth infestation. Therefore, treatment of black soils, regulation of black soil market and use, and development of growth media industry should be important components of helminth control strategy.

HYDROCHEMICAL CHARACTERISTICS OF THE GROUNDWATERS IN PRILEP’S PART OF PELAGONIA VALLEY – REPUBLIC OF MACEDONIA

This paper presents the results of hydrochemical investigations of groundwater from the Prilep part of the Pelagonia valley - Republic of Macedonia. These investigations were carried out by analyzing 12 samples of groundwater, taken from the exploitation wells. Samples are taken once a season, during August 2013. Values of the pH were determined with the field digital pH meter, while cations are determined by inductively coupled plasma-atomic emission spectrometry (ICP – AES). For the determination of the anions are used standard EPA methods (gravimetric - TDS, volumetric - Cl-, spectrophotometric - NO3-, NO2-, NH4+ and turbidimetric - SO42- with the spectrophotometer 6715 UV / VIS, Jenway). Тhe maps with spatial distribution of the hydrochemical components were prepared using the IDW (Inwerse Distance Weighting) method for map generation (Geographic Information System software (GIS) ESRI® ArcGis™ 9.2 and its extension Geostatistical Analyst). Spatial distribution maps were constructed according to the coordinates and sample content of each analyzed sample. Samples were taken from the wells which are divided into 3 groups: wells with free level with depth up to 10 m, wells with free level with depth up to 100 m and artesian wells. The graphical methods, Piper diagram and Chadha’s diagram, were applied in order to determine the hydrochemical properties of the groundwater. The results indicate that the groundwater samples have different hydrochemical properties. Ca 2+ >Na+>Mg2+ for the cations and HCO3- >Cl- >SO42- for the anions were dominantly dissolved ions in the majority of the water samples. Generally, increased values of Ca2+, Mg2+, Na+, K+, HCO3-, K+ and Cl- occur in the groundwater from deeper artesian wells, as a result of the longer retention time of water in the underground and its interaction with the geological environment. Dominant groundwater in Prilep field, in all three types of wells, are waters from hydrocarbonate class (HCO3¯), calcium group (Ca), the first type of water. Groundwater from the shallow wells show the increasing content of K+, NO3- and PO43-which indicates water pollution from fertilization of the cultivated areas, livestock farms as well as communal wastewater. Although hydrochemical data are obtained on the basis of water samples taken only once, they provide an indicative insight into the hydrochemical composition of the water. To obtain more reliable data, taking groundwater samples from wells should be performed multiple times in different seasons.

Levels and congeners distribution of dioxins, furans and dioxin-like PCBs in buffaloes adipose tissues sampled in vivo and milk

ABSTRACTThe levels of PCDDs, PCDFs and DL-PCBs were analyzed both in milk and adipose tissues sampled “in vivo” from lactating, drying off and heifer buffaloes from a Campania farm which had been impounded by the competent authority owing to the high dioxin levels found in bulk milk. The chemical determination was carried out by HRGC-HRMS using US EPA Method 1613b. The range of WHO-TEQ values for the PCDDs/PCDFs in adipose tissues was 1.79 to 68.64 pg g−1 fat and in milk was 8.33 to 13.95 pg g−1 fat. The contamination profile for dioxins and furans was given by 1,2,3,7,8-PeCDD; 2,3,4,7,8-PeCDF; 1,2,3,6,7,8-HxCDD and 2,3,7,8-TCDD. The levels of DL-PCBs in adipose tissue varied from 1.38 to 20.13 pg g−1 fat while ranged from 8.33 to 13.95 pg g−1 fat in milk. The pattern of DL-PCBs in both matrices was dominated by congeners PCB 126 and PCB 169.

A composable module-type cyanide microfluidic sensor based on polydimethylsiloxane membrane pervaporative sampling with sodium bicarbonate internal-pressure regulation and dual fluorescence/potentiometric monitoring

This paper demonstrates a reliable and safe microfluidic sensor on the monitoring of weak-acid dissociable cyanide (WAD-CN−) from environmental waters. The sensor chip consists of three parts: a pervaporative membrane sampling module, a fluorescence labelling/detection module and a cyanide ion selective-electrode (CN−-ISE) potential detection module. Cyanide pervaporation was achieved by in situ sample acidification to produce hydrogen cyanide (HCN) through a gas-diffusing polydimethylsiloxane (PDMS, 4–5 μm thickness) membrane. HCN was recovered using a lye solution and subsequently split into two streams for the dual fluorescence/potentiometric monitoring. Dual fluorescence and CN−-ISE potential monitoring were performed by applying two indispensable treatment to the split streams with naphthalene-2,3-dicarboxaldehyde (NDA)-glycine (Gly) and total-ionic-strength-adjustment buffer solution (TISAB), respectively. The parameters in the pervaporation process and both detections were optimized. To increase the sensitivity at low concentrations, a sodium bicarbonate solution was introduced into the sample stream as a chemical pressure regulator, which maintained a constant pressure in the channel by continuously producing CO2. To prevent the loss of produced gas, the channels, except for the membrane, were coated by a polyvinylsilazane (PVSZ) polymer solution and cured. Under an HCl donor stream (0.5 mol L−1; 15 μL min−1) and a sodium hydroxide acceptor stream (0.1 mol L−1; 20 μm/min), 65.7% of transmission rate (RSD = 0.86%; n = 3 for 0.1 mg L−1 CN−) was achieved. The pervaporative sampling method effectively minimized the interferences (except organic thiols) from the environmental matrices during the detection of cyanide in both detection modules. The validity and quality of the assay were assessed in terms of the linearity 5–500 μg L−1 (R2 = 0.9992) and limit of detection (cL) 0.015 μg L−1 with the fluorescence method and those are 2.6–1000 μg L−1 (R2 = 0.998), and 1.1 μg L−1 with the CN−-ISE potentiometric detection. The cyanide levels in waste waters were determined using the standard addition method and verified using the EPA method OIA-1677. Furthermore, a microchip electrophoresis (MCE) analysis was performed to investigate the systemic errors from the mercapto-interferences of the samples. The developed microfluidic sensor was applied to monitor WAD-CN− in waste waters. The sensor is a flexible, extensible, and environmentally friendly alternative for WAD-CN− monitoring.

Identification and quantification of linear and branched isomers of perfluorooctanoic and perfluorooctane sulfonic acids in contaminated groundwater in the veneto region

Perfluoroalkylated acids (PFAAs) are ubiquitous xenobiotic substances characterized by high persistency, bioaccumulation potential and toxicity. They have generated global concern because of their widespread presence both in water and biota compartments. In the past four years, alarming levels of these pollutants have been found in both surface and groundwater collected in an area covering more than 150 square kilometers in the south-western part of the province of Vicenza (Veneto region, Italy). One of the sources of the contamination recognized by local authorities is a fluorochemicals production plant that produced PFAAs since late sixties by electrochemical fluorination involving the obtainment of a complex mixture of linear and branched isomers. Branched isomers account for a significant part of total long chain homologues (22%–35%). Because of the potential threat to public health and the absence of specific limits set for these pollutants by Directive 98/83/EC, local authorities have established the following performance limits for drinking water: 90 ng L−1 for PFOA + PFOS, (reduced to 40 ng L−1 in the most contaminated municipalities), 30 ng L−1 for PFOS and 300 ng L−1 for the sum of all other PFAAs. Given the non-negligible incidence of branched isomers, it appears very important to correctly identify and quantify their contribution to total PFAAs. A liquid chromatography-electrospray ionization tandem spectrometry LC–MS/MS method, coupled with solid phase extraction, was developed to identify and quantify 25 PFAAs including six branched isomers of PFOS and four branched isomers of PFOA. Expanded uncertainty, recovery and precision were determined and found to agree with the reference EPA method 537:2009. The quantification limit is comprised in the 1–5 ng L−1 range.

Selected persistent organic pollutants (POPs) in water of River Niger: occurrence and distribution.

This study assessed the levels and distribution of selected persistent organic pollutants (POPs) in water of River Niger. The selected POPs of interest were organochlorine pesticides (OCPs). Fifteen representative sites along River Niger: three each from Gurara River (tributary) in Niger State, Lokoja (confluence) in Kogi State, Onitsha in Anambra State, Brass and Nicolas Rivers (tributaries) in Bayelsa State were selected for sampling quarterly over a 24-month period. A total of 240 surface and bottom water samples were collected using Van Dorn water sampler in the eight quarters of 2008-2009. At the Delta locations where tidal effects take place, high- and low-tide water samples were taken as compared to surface and bottom at the River Niger locations. For sample extraction, EPA method 3510c was employed with slight modifications. Certified reference standards from Accustandards USA was used for the instrument calibration and quantification of OCPs. The extracted samples were subjected to gas chromatography (GC/ECD) for identification/quantification. And Shimadzu GCMS QP2010 was used for confirmation. Chlordane, endosulfan, endrin and DDT metabolites were very prominent in the water samples, compared to HCH, dieldrin, and isomers which occurred at lower concentrations. The sequence in the concentration of the organochlorine pesticides were ∑chlordane > ∑DDT > ∑endosulfan > ∑endrine > ∑dieldrin > ∑HCH. The highest concentration of ∑OCPs in water samples of River Niger, 1138.0 ± 246.7ng/L, with range 560.8-1629ng/L was detected at Onitsha location, while the lowest concentration, 292.6 ± 74.9, with range 181-443.0ng/L was detected at Nicolas River. Levels of OCPs in a larger percentage of the samples exceeded guidelines and therefore hold potential harmful effects on benthic fauna, fish, and man. Abstraction of water from the River for drinking water treatment should be discouraged. Because of the potential danger, this presents, continuous monitoring of the water body and if possible remediation, determination of the sources of the POPs is therefore very necessary.

Emission characteristic and transformation mechanism of hazardous trace elements in a coal-fired power plant

Coal-fired power plant is considered to be main anthropogenic emitter for emission of hazardous trace elements (HTEs), which can cause great damage on environment and human health. Emission characteristic of nine HTEs, namely Hg, Zn, Sb, Pb, Cd, As, Cr, Mn and Ba was carried out on a 320MW coal-fired power plant equipped with SCR, ESP and WFGD. US EPA method 29 was used for flue gas HTEs sampling at inlet or outlet of each APCD simultaneously. Solid or liquid samples like feed coal, ESP ash, bottom ash, fresh slurry, waste water, gypsum were collected at the same time. Scanning electron microscope, energy dispersive spectrometer and X-ray power diffraction spectrometry were adopted to characterize the physical and chemical structure characteristic of some solid samples. Results show that mass balance rate of the HTEs for each device and the system is in acceptable range. Mass amount of HTEs distributed in bottom ash and ESP ash accounts for large proportion, while little of them escapes into atmosphere (<0.05%). The mass amount of Mn and Ba in bottom ash is higher than that of other HTEs. Particulate HTEs are the main form in flue gas before ESP. ESP+WFGD has high removal efficiency for the HTEs in flue gas (99.96–99.99%), in which ESP makes a great contribution. During coal combustion, Mn and Ba enrich in bottom and fly ash equally while As, Cd, Sb, Zn, Pb and Cr will be prone to enrich in fly ash. Concentration of the HTEs in flue gas emitted to atmosphere is relatively low (3.5×10−3–4.30μg/m3) with emission factor of 0.001–1.473g/1012J. Finally, transformation mechanism of the studied HTEs during coal combustion is discussed.

Polychlorinated biphenyls (PCBs) in River Niger, Nigeria: Occurrence, distribution and composition profiles.

Contamination of rivers with persistent organic pollutants (POPs) is an issue of current global concern. Polychlorinated biphenyls (PCBs) are POPs with origin from commercial, incineration and industrial sources. Hence, there is a need for monitoring their occurrence and distribution in the environment. This study assessed the occurrence, distribution and composition profiles of PCBs in River Niger, Nigeria. Surface and bottom water samples were collected in consecutive quarters for a period of 2 years, covering the beginning and end of the rainy seasons and the dry seasons, from five locations (Gurara, Lokoja, Onitsha, Brass and Nicolas) along River Niger. A total of 240 water samples were collected using a Van Dorn water sampler. EPA method 3510c was used with slight modifications for sample preparation and analysis. The PCBs were analysed using a Hewlett Packard GC 5890 Series 11 with electron capture detection, and confirmation was made using a Shimadzu GCMS QP2010. The higher molecular weight marker PCBs (∑CB 138, 153 and 180) were more dominant than the lighter homologues (∑CB 28, 52 and 101), while commercial sources Co-PCBs (80.8 ± 61.7 to 288.3 ± 102.0 ng L-1) were more dominant than the incineration sources (34.9 ± 3.82 to 75.5 ± 65.2 ng L-1). The POPs load in River Niger water varied in both time and space. In surface water of the River Niger, ∑PCBs were higher during the rainy season, as a result of storm run-off from land-based sources. In the Brass and Nicolas Rivers during the dry season, the ∑PCBs were higher during low tide. There was no noticeable pattern during the rainy season. It may be concluded from this study that the water of River Niger is not good for human consumption or abstraction of water from the river for drinking water treatment.