Drainage Water Samples Research Articles

ASSESSMENT OF POTENTIAL RADIATION HAZARD OF THE FORMER URANIUM FACILITIES FOR THE POPULATION OF THE ISTIKLOL CITY OF THE REPUBLIC OF TADZHIKISTAN

The article presents the results of alpha, gamma spectrometric analyzes of samples, dosimetry, radon monitoring of the estimated areas in the Istiklol city. It has been established that the specific activity of radionuclides for uranium and radium in the tailing materials are in the range: 1405 – 2140, 5935 – 9843 Bq / kg, respectively. Based on the results of the monitoring of gamma radiation and radon volume activity at Istiklol city sites, it has been established that gamma radiation ambient equivalent dose rate varies from 0.52 to 1.78 μSv / h, and radon volume activity in air ranges from 20 and 45 Bq / m3. It is shown that the radon concentration in the air above the surface of tailings is not high. However, the exhalation of radon from the soil surface of all the tailings dumps examined is above the standard (1 Bq / (m2·s). The results of measurements of radon volume activity in the air of residential buildings and facilities located on the territory of Istiklol city have shown that the value of radon volume activity is within the limits of 44 – 195 Bq / m3. A high value of radon volume activity is noted in the former dilapidated plant (1319 Bq / m3). Gamma and alpha spectrometric studies revealed that the average values of the activity concentration of uranium and radium in the soils for tailings and the pit are for 234U – 65365 Bq / kg, for 238U – 50295 Bq / kg, and for 226Ra – 3800 Bq / kg. To estimate the doses of population irradiation via the water pathway were taken the average values of the volumetric activity of 234U, 238U, 226Ra in the waters. Maximum values of volumetric activity of radionuclides were observed in samples of drainage water, Bq / m3: 234U – 530000, 238U – 390000, 226Ra – 185. To calculate the contributions of various radiation factors to an additional annual dose of irradiation, the population was divided into four hypothetical groups. The time duration of stay of various hypothetical population groups in the areas of potential irradiation, radiation dose due to water use from contaminated water sources and additional factors in Istiklol were taken into account.The main contributor to the additional radiation dose received by hypothetical population groups is external irradiation during the stay on the territory of the FBR and tailing dumps, and internal irradiation due to the use of contaminated water.

The Effect of Ball Diameter on Performance of Wet Scrubber with PVC Balls-Mesh Packing Material

Toxic pollutants and harmful flue gases resulting from combustion of fossil fuels in several industries are adversely effecting human and his environment. Packed towers, especially with wire mesh type mist eliminator pads are widely used to entrap these flue gas emissions before they enter into the atmosphere. But clogging of pads during the operation became a big problem which needs replacement with new one every time. The present work motivation is to develop and test, a exhaust fume-wet scrubber with new (PVC) balls-mesh replacing traditional packing material in which the spherical surfaces are going to make only point contact between them. Water (PH Value = 8.7) and lime water (PH Value = 12.3) sprinkled finely in modified air cooler body with 72 nozzles of 1mm in diameter and re-circulated for 100 minutes to purify stationary four stroke diesel engine exhaust. The diameter of the balls used, are varied such as 10cm, 5cm and 2.5cms and drain water samples, for every 20 minutes are collected to check PH values.

Net Acidity Titration and Water Quality Results for Acid Mine Drainage Water Samples from Morris Creek

The Morris Creek Watershed Association maintains a passive limestone-bed treatment for acid mine drainage entering Morris Creek near Montgomery, WV. Water was collected and analyzed from 14 sites in the Upper and Lower Main Stem treatment areas. Analyses included net acidity and standard water quality tests: pH, turbidity, temperature, total dissolved solids, biochemical oxygen demand, phosphates, total nitrates, and dissolved oxygen (Water Quality with Vernier, 2007), as well as total flow measurements. The net acidity or “hot acidity” titration is a measure of the highest acidity the water will reach due to dissolved components that undergo redox reactions to produce acidity. Water samples are acidified, boiled with hydrogen peroxide, and titrated with base according a standard method (Standard Methods for the Examination of Water and Wastewater, 2012), This study shows that the results for net acidity are correlated with the water quality tests for biochemical oxygen demand and dissolved solids, while net acidity is inversely correlated with the fecal coliform count, dissolved oxygen, and overall water quality index. A general decrease in net acidity was found as the water progressed through the two treatment areas. This study demonstrates the utility of the net acidity titration analysis of water samples and the water quality tests that are most relevant to the titration. Related and future work includes the determination of dissolved iron, manganese and other metals by atomic absorption analysis.

The impact of corrosion on marine vapour recovery systems by VOC generated from ships

Marine emissions of Volatile Organic Compounds (VOCs) have received much attention because the International Maritime Organization (IMO) requires the installation of vapour emission control systems for the loading of crude oils or petroleum products onto ships. It was recently recognised that significant corrosion occurs inside these vapour emission control systems, which can cause severe clogging issues. In this study, we analysed the chemical composition of drain water sampled from currently operating systems to investigate the primary causes of corrosion in vapour recovery systems. Immersion and electrochemical tests were conducted under simulated conditions with various real drain water samples, and the impact of corrosion on the marine vapour recovery system was carefully investigated. Moreover, corrosion tests on alternative materials were conducted to begin identifying appropriate substitutes. Thermodynamic calculations showed the effects of environmental factors on the production of condensed sulphuric acid from VOC gas. A model of sulphuric acid formation and accumulation by the characteristics of VOC from crude oil and flue gas is suggested.

The Impact of Deforestation on the Quality of Drainage Water in the &#381elezná Model Area

The article is focused on the changes in soil characteristics caused by the drainage of agricultural soils in the Czech Republic. The basis of the research was to compare current state with the state before drainage using available historical data. To resolve the subject of the research, two smaller study areas with different soil uses were chosen. The Haklovy Dvory area is an arable land that is intensively used. The other area is used mainly for grazing (extensively) and it is called ?elezna study area. In many cases, historical data regarding the quality of surface water and groundwater (well water) in the two areas is readily available; therefore, the same approach was taken for monitoring the current quality of drainage water. Several chemical indicators were measured in the water: pH, alkalinity-acidity, overall hardness, concentration of selected cations (magnesium, calcium, potassium, ammonia), concentration of bicarbonates, nitrates, nitrites, sulphates, phosphates, chlorides and the electrical conductivity of the water. During the entire course of the monitoring, no serious water pollution was found in ?elezna study area (with the exception of one sample point). In case of the intensively managed Haklovy Dvory study area, a significant pollution in all drainage water samples was confirmed. We can safely formulate a hypothesis that the drainage water quality is related to the type of agriculture procedure practiced on the land. Mainly the intensive type of agriculture, because of the use of fertilizers, has a negative impact on drainage water quality, and subsequently on the quality of surface watercourses.

Soil quality changes due to flood irrigation in agricultural fields along the Rio Grande in western Texas

Growing populations demand more food, putting more pressure on soil productivity and sustainability around the world. In western Texas along the Rio Grande Valley, the low natural rainfall requires frequent irrigations for sustaining agriculture. To investigate the impacts of irrigation on soil quality, we collected and modelled geochemical data (major elements and nutrients) on irrigation water, soil pore water, drainage water, and soil samples, and monitored soil moisture, temperature, and electrical conductivity with sensors from two pecan, one cotton, and one alfalfa fields in western Texas.This study showed that flood irrigation with both surface (Rio Grande river) and ground waters significantly increased the root-zone salinity, soil sodicity, and nutrient leaching from soils to the underlying aquifers and Rio Grande river from agricultural fields of the arid southwest. The water used for irrigation was high in total dissolved solids (>500 ppm generally), dominated by Na+, Cl−, Ca2+ and SO42−. After flood irrigation, infiltrating water dissolved salts such as gypsum that have accumulated in the soils due to previous irrigations, or/and mixed existing concentrated soil waters, and approached saturation with respect to these evaporite minerals. Soil water was supersaturated with respect to carbonates as pedogenic calcite precipitated out and reached concentrations of ∼10 wt% of total soil mass. This suggested that pedogenic carbonate is an important carbon reservoir and precipitation kinetics and controls of such secondary calcite need further investigation for the irrigated agricultural fields in arid regions of the world.Chemistry of agricultural return flow samples collected from drainage ditches was similar to that of irrigation water, suggesting that most of the irrigation water had taken a shallow and short flowpath through the fields to drains. Between irrigation events, soil water became more concentrated as water was lost through evapotranspiration that led to precipitation of evaporite salts. As a result, sodicity and salinity of soils, especially clayey soils, frequently exceeded the tolerance levels of major crops grown in the region. Here in these fine-textured soils, combination of high evapotranspiration rates, intensive irrigation with water of elevated salinity, and limited infiltration stunted crop growth, decreased soil porosity and permeability, led to poor aeration, and accelerated salt buildup via a positive feedback mechanism.During initial irrigation where soils were saturated, soil water also percolated and recharged to underlying aquifers, and thus salts, nutrients, and trace metals from agricultural practices (i.e., application of fertilizers, irrigation, soil amendments, and pesticide) could be mobilized to shallow groundwaters. This implied that chemistry of Rio Grande river, groundwater, and soil was closely linked. Thus the sustainability of agriculture depended on appropriate water, soil and crop management practices.

Surface chemistry of iron oxides formed by neutralization of acidic mine waters: Removal of trace metals

Secondary iron minerals are important in mining areas as they are natural scavengers of many contaminants. Thus, aluminium and iron oxides derived from acid mine drainage determine the fate of trace metals commonly found in mining areas. They mainly do this via sorption processes, which prevent leaching of the metals and contamination of surface and groundwater.In the present study, abiotic precipitates were obtained from samples of acid drainage water collected from an abandoned copper mine. Characterization of the precipitates revealed that schwertmannite was the dominant iron mineral phase present. Retention of Cu, Cd, Ni and Pb by natural iron precipitates was compared with retention of the same elements by synthetic analogues. The study findings indicate that the natural abiotic precipitates have a higher retention capacity than their synthetic analogues. Thermodynamic modelling was used to predict the geochemical behaviour of the trace metals in the presence of iron precipitates. Inclusion of adsorption and precipitation reactions in the models yielded a good description of the degree of attenuation of adverse effects of the trace metals. Under acidic conditions, the schwertmannite-like particles initially present in the natural precipitates evolve towards more crystalline mineral phases. This transformation process is accompanied by the release of sulphate ions into the solution and by a decrease in trace metal sequestration.

Monitoring of Foodborne Hepatitis A virus Outbreaks in the Fresh Foods

HEPATITIS A virus (HAV) is one of the most widespread foodborne pathogens and the cause of viral hepatitis. Fresh foods can be considered as a vector of transmission for HAV when contaminated by spoiled irrigation water or when prepared by infected food handlers. To improve microbiological detection and to increase insights into the contribution of fruit and vegetables to foodborne viral transmission, sensitive and standardized methods are needed. Two outlet drainage water samples from El-Mariotia and El-Gable Elasfar canals (Nile River) were collected in each month starting from March 2015 over a period of 12 months. As well as vegetables and fruit samples (lettuce, green onion and strawberry) were irrigated and washed with drainage water were also collected. Samples were extracted and concentrated for viral analysis. Strawberry and lettuce foods collected from El-Mariotia and lettuce from El-Gable Elasfar gave positive serological results by enzyme-linked immunosorbent assay (ELISA) test.Reverse transcription polymerase chain reaction (RT-PCR) was successfully used to detect the virus in strawberry and lettuce samples using HAV-specific primers, designed to amplify a 500 bp fragment covering VP1/2A gene in HAV. The VP1/2A gene was sequenced and the nucleotide sequence similarity was in the range of 95- 99.1% between HAV-Eg isolate and 30 HAV sequences retrieved from GenBank. Phylogenetic analysis revealed that HAV-Eg isolate was grouped into a clade comprising Egyptian HAV isolates sub-genotype IB. Phylogenetic tree of nucleotides sequence showed that HAV sub- genotype IB is the circulating strain.

Spatial and temporal patterns of pesticide concentrations in streamflow, drainage and runoff in a small Swedish agricultural catchment

A better understanding of the dominant source areas and transport pathways of pesticide losses to surface water is needed for targeting mitigation efforts in a more cost-effective way. To this end, we monitored pesticides in surface water in an agricultural catchment typical of one of the main crop production regions in Sweden. Three small sub-catchments (88–242ha) were selected for water sampling based on a high-resolution digital soil map developed from proximal sensing methods and soil sampling; one sub-catchment had a high proportion of clay soils, another was dominated by coarse sandy soils while the third comprised a mix of soil types. Samples were collected from the stream, from field drains discharging into the stream and from within-field surface runoff during spring and early summer in three consecutive years. These samples were analyzed by LC-MS/MS for 99 compounds, including most of the polar and semi-polar pesticides frequently used in Swedish agriculture. Information on pesticide applications (products, doses and timing) was obtained from annual interviews with the farmers. There were clear and consistent differences in pesticide occurrence in the stream between the three sub-catchments, with both the numbers of detected compounds and concentrations being the largest in the area with a high proportion of clay soils and with very few detections in the sandy sub-catchment. Macropore flow to drains was most likely the dominant loss pathway in the studied area. Many of the compounds that were detected in drainage and stream water samples had not been applied for several years. This suggests that despite the predominant role of fast flow pathways in determining losses to the stream, long-term storage along the transport pathways also occurs, presumably in subsoil horizons where degradation is slow.

EVALUATE THE GROUNDWATER SUITABILITY FOR IRRIGATION IN DUJAILA AREA – WASIT GOVERNORATE – MIDDLE OF IRAQ

The selected area is Dujaila project, Wasit governorate, Iraq. Twelve water samples groundwater and drainage were collected during March 2016. Total dissolved solids (TDS), pH, electrical conductivity (EC), major ions Ca2+, Mg2+, Na+, K+, Cl-, SO4 2- and HCO3-, and chemical analysis were determined. To evaluate the suitability of analyzed water for irrigation, Sodium adsorption ratio (SAR), residual sodium carbonate (RSC), sodium percent (Na%) and electrical conductivity were applied. The based on electrical conductivity classification of the analyzed water indicated that both the groundwater and drainage water are unacceptable for irrigation, except for very salt-tolerant plants (EC> 2250 μs/cm). These samples mostly have no harmful effects and no hazard in terms of RSC (RSC < 0), while for SAR, the groundwater samples have no harmful effects of sodium (SAR < 10) but it is unsatisfactory for irrigation for drainage water samples ( SAR > 26) and groundwater samples are good (Na% range from 20 to 40) to permissible (Na% > 40) in terms of Na%, while, the drainage water samples indicate doubtful class for the three samples (Na% > 60). Applying the water-sediment relationship experiments with respect to dry and wet periods show that about 2.2% – 4.8% of the TDS were librated after the drying condition which is believed to be of the water-soluble salts that exist within the sediment column.

Genetic diversity of Acinetobacter spp. adapted to heavy metal polluted environments

AbstractMultiple metallotolerant bacterial strains were isolated from soil and drainage water samples collected from three industrially heavy metals polluted areas in Slovakia. Obtained bacterial isolates were identified using MALDI-TOF mass spectrometry and bacterial isolates that belonged to the Acinetobacter genus were subjected for the further study. A. calcoaceticus was found to be prevalent species among analyzed Acinetobacter spp. strains, followed by A. lwoffii and A. johnsonii. A. calcoaceticus strains exhibited higher minimum inhibitory concentration to Mn, Zn, and Cu cations compared to A. lwoffii and A. johnsonii. On the other hand minimum inhibitory concentration to Co and Ni were identical in all Acinetobacter spp. isolates. Genetic analyses demonstrated multiple plasmids presence in A. lwoffii and A. johnsonii but not in A. calcoaceticus. Using ERIC-PCR the presence of two different genotypes of A. calcoaceticus was detected in heavy metal polluted environments in Slovakia.

Surface runoff and subsurface tile drain losses of neonicotinoids and companion herbicides at edge-of-field

With their application as seed coatings, the use of neonicotinoid insecticides increased dramatically during the last decade. They are now frequently detected in aquatic ecosystems at concentrations susceptible to harm aquatic invertebrates at individual and population levels. This study intent was to document surface runoff and subsurface tile drain losses of two common neonicotinoids (thiamethoxam and clothianidin) compared to those of companion herbicides (atrazine, glyphosate, S-metolachlor and mesotrione) at the edge of a 22.5-ha field under a corn-soybean rotation. A total of 14 surface runoff and tile drain discharge events were sampled over two years. Events and annual unit mass losses were computed using flow-weighted concentrations and total surface runoff and tile drain flow volumes. Detection frequencies close to 100% in edge-of-field surface runoff and tile drain water samples were observed for thiamethoxam and clothianidin even though only thiamethoxam had been applied in the first year. In 2014, thiamethoxam median concentrations in surface runoff and tile drain samples were respectively 0.46 and 0.16 μg/L, while respective maximum concentrations of 2.20 and 0.44 μg/L were measured in surface runoff and tile drain samples during the first post-seeding storm event. For clothianidin, median concentrations in surface runoff and tile drain samples were 0.02 and 0.01, μg/L, and respective maximum concentrations were 0.07 μg/L and 0.05 μg/L. Surface runoff and tile drain discharge were key transport mechanisms with similar contributions of 53 and 47% of measured mass losses, respectively. Even if thiamethoxam was applied at a relatively low rate and had a low mass exportation value (0.3%), the relative toxicity was one to two orders of magnitude higher than those of the other chemicals applied in 2014 and 2015. Companion herbicides, except glyphosate in tile drains, exceeded their water quality guideline during one sampling campaign after application but rapidly resumed below these limits.

Dissolved nitrous oxide (N2 O) dynamics in agricultural field drains and headwater streams in an intensive arable catchment

Indirect nitrous oxide (N2O) emissions produced by nitrogen (N) leaching into surface water and groundwater bodies are poorly understood in comparison to direct N2O emissions from soils. In this study, dissolved N2O concentrations were measured weekly in both lowland headwater streams and subsurface agricultural field drain discharges over a two-year period (2013–2015) in an intensive arable catchment, Norfolk, UK. All field drain and stream water samples were found to have dissolved N2O concentrations higher than the water–air equilibrium concentration, illustrating that all sites were acting as a net source of N2O emissions to the atmosphere. Soil texture was found to significantly influence field drain N2O dynamics, with mean concentrations from drains in clay loam soils (5.3 µg N L-1) being greater than drains in sandy loam soils (4.0 µg N L-1). Soil texture also impacted upon the relationships between field drain N2O concentrations and other water quality parameters (pH, flow rate, and nitrate (NO3) and nitrite (NO2) concentrations), highlighting possible differences in N2O production mechanisms in different soil types. Catchment antecedent moisture conditions influenced the storm event mobilisation of N2O in both field drains and streams, with the greatest concentration increases recorded during precipitation events preceded by prolonged wet conditions. N2O concentrations also varied seasonally, with the lowest mean concentrations typically occurring during the summer months (JJA). Nitrogen fertiliser application rates and different soil inversion regimes were found to have no effect on dissolved N2O concentrations, whereas higher N2O concentrations recorded in field drains under a winter cover crop compared to fallow fields revealed cover crops are an ineffective greenhouse gas emission mitigation strategy. Overall, this study highlights the complex interactions governing the dynamics of dissolved N2O concentrations in field drains and headwater streams in a lowland intensive agricultural catchment.

Scaling in railway infrastructural drainage devices: site study

Abstract In France, about 450 km of high-speed lines (HSL) are potentially subject to drain scaling problem. A HSL site affected by calcite scaling was continuously monitored for 20 months to follow the phenomenon and also to estimate the monthly calcite precipitation rate. Drain water samples were also monthly analyzed and show high calcium and sulphate concentrations. The high sulphate concentration (~6 mM) highlights the dissolution of gypsum in the drain environment. Based on the material analysis (X-ray diffraction), gypsum is present in the subballast and capping layer. Since the drain system is a multi-environments system, and based on multi-phase reactions, the study is divided into two parts: a physical one (transport of water in the system) and a chemical one (transport of the reactants in the system). The physical processes have an essential impact on the chemical precipitation processes. In the present paper, on the basis of the collected data, the physical behaviour of the experimental site (water circulation) will be presented in the first step and used in the further chemical process study. The monthly calcite precipitation rate and quantities are given as well.

Leaching of the Neonicotinoids Thiamethoxam and Imidacloprid from Sugar Beet Seed Dressings to Subsurface Tile Drains.

Pesticide transport from seed dressings toward subsurface tile drains is still poorly understood. We monitored the neonicotinoid insecticides imidacloprid and thiamethoxam from sugar beet seed dressings in flow-proportional drainage water samples, together with spray applications of bromide and the herbicide S-metolachlor in spring and the fungicides epoxiconazole and kresoxim-methyl in summer. Event-driven, high first concentration maxima up to 2830 and 1290 ng/L for thiamethoxam and imidacloprid, respectively, were followed by an extended period of tailing and suggested preferential flow. Nevertheless, mass recoveries declined in agreement with the degradation and sorption properties collated in the groundwater ubiquity score, following the order bromide (4.9%), thiamethoxam (1.2%), imidacloprid (0.48%), kresoxim-methyl acid (0.17%), S-metolachlor (0.032%), epoxiconazole (0.013%), and kresoxim-methyl (0.003%), and indicated increased leaching from seed dressings compared to spray applications. Measured concentrations and mass recoveries indicate that subsurface tile drains contribute to surface water contamination with neonicotinoids from seed dressings.

Environmental assessment of drainage water impacts on water quality and eutrophication level of Lake Idku, Egypt

Lake Idku, northern Egypt, receives large quantities of drainage water from four main discharging drains. Ecological and biological status of Lake Idku has been monitored during (autumn 2012 to summer 2013) to examine the lake water quality and eutrophication level in response to the quality as well as the source of the discharging water. Discrete water samples were collected from the lake body and the drains. Chemical analyses revealed an excessive nutrient load goes into the lake. A range of 1.4–10.6 mg nitrites/L was determined for drain waters, however a sudden increase was observed in lake and drain water samples of up to 84 and 74.5 mg/L, respectively. Reactive silicate ranged between 2.9 and 4.8 mg/L; while inorganic phosphate fluctuated between 0.2 and 0.43 mg/L. Transparency varied from 45 cm to 134 cm with better light conditions at drain sites. Biological results indicated a hyper-eutrophic status for the lake with a range of chlorophyll-a varied from a minimum of 39.9 μg/L (at Idku Drains) and a maximum of 104.2 μg/L (at El-Khairy drain). Phytoplankton community structure revealed higher abundance at lake sites compared with the drains. Maximum phytoplankton density was detected during summer with the dominance of Bacilariophyceae (e.g. Cyclotella meneghiniana, Cyclotella comate, Melosira varians) followed by Chlorophycean taxon (e.g. Scenedesmus dimorphus, S. bijuga and Crucigenia tetrapedia). Five indices were applied to evaluate the water quality of the lake. Diversity Index (DI) indicated slight to light pollution along all sites; while Sapropic Index (SI) indicated slight pollution with acceptable oxygen conditions and an availability of sensitive species. Palmer Index (PI) gave a strong evidence of high organic pollution at some sites in the lake, while Generic Diatom Index (GDI) revealed that levels of pollution varied from average to strong. Trophic Index (TI), suggest that there are an obvious signs of eutrophication in the lake.

Microbial communities in dairy processing environment floor-drains are dominated by product-associated bacteria and yeasts

Floor-drains in food production environments harbour diverse microbes and can be contamination sources. To prevent cross-contamination with spoilage organisms or pathogens, sanitation protocols are regularly applied in food processing facilities. Along with product-associated samples, floor-drain water serves as an important indicator in hygiene monitoring in food processing facilities. However, knowledge about the microbial communities in floor-drains is still low. In this study, the microbial communities in floor-drain water and biofilm samples from an Austrian dairy plant were analysed and revealed that floor-drain microbial communities are dominated by product-associated microbes. DNA was extracted of drain water and drain biofilm samples from three different areas (n = 6) of an Austrian cheese production facility. To characterise the bacterial and eukaryotic communities, 16S rRNA gene pyrosequencing as well as cloning and sequencing of 18S rRNA genes were used. Floor-drain communities were dominated by product-associated bacterial (e.g. Lactobacillus kefiranofaciens, Streptococcus thermophilus) and eukaryotic phylotypes (e.g. Debaryomyces hansenii, Saccharomyces unisporus). In addition, putative drain water-derived phylotypes (e.g. Psychrilyobacter atlanticus, Cobetia marina) and ciliates were identified.

Priority Polycyclic Aromatic Hydrocarbons (PAHs): Distribution, Possible Sources and Toxicity Equivalency in Urban Drains

Wastewater from urban areas constitutes one of the major sources of pollutants contributed to aquatic ecosystem. This study was carried out to elucidate the occurrence and possible source of US Environmental Protection Agency identified 16 priority polycyclic aromatic hydrocarbons (PAHs) in water and sediments from the urban wastewater drains in Delhi, India. A total 60 samples (water and sediment) collected during year 2011–2012, and analyzed the following USEPA methods. Water and sediment samples were extracted using liquid-liquid and ultrasonication techniques, respectively. Glass column chromatography with activated silica was used for sample extracts clean-up, followed by quantification on HPLC equipped with diode array detector at 254 nm wavelength using mixture of acetonitrule and water as mobile phase. Concentrations of total 16 PAHs (∑16PAHs) in all drain water samples ranged from 0.29–35.22 μg/L (mean ± SD, 10.83 ± 10.66 μg/L), predominated by two- and three -ring PAHs. The ∑16PAHs concentrations in all collected sediments ranged between 220–19321 μg/kg (mean±SD, 5574 ± 6820 μg/kg) dry weights. High molecular weight PAHs (≥4-ring PAHs) were dominant in sediment samples. Benzo(a)pyrene equivalent (BaPeq), a relative carcinogenic potential to the corresponding PAHs to BaP was estimated and presented. A selected number of concentration ratios of specific PAHs compounds were calculated and used to diagnose the possible sources of PAHs contamination. The diagnostic ratios reflected pyrogenic input from gasoline or diesel powered vehicular emissions as the major source of PAHs. The levels of PAHs observed in water and sediments were compared with similar studies undertaken in other regions of the world.

Further Understanding of the Impacts of Rainfall and Agricultural Management Practices on Nutrient Loss from Rice Paddies in a Monsoon Area

As rice paddies are widespread sources of water pollution in the agricultural regions of the Asian monsoon area, a mechanistic understanding of nutrient loss from paddies is critical for water quality management. A 2-year experiment was conducted in a typical monsoon-affected rice field to improve our understanding of the impacts of rainfall and agricultural management practice on nitrogen (N) and phosphorus (P) loss. Samples of paddy drainage water were collected during rainfall events (n = 25) and analyzed for total N (T-N) and total P (T-P) concentrations. The impacts of rainfall (amount, duration, and intensity) and agricultural management practice (transplanting and fertilization) on the event mean concentration (EMC) and loss of nutrient were assessed using regression analyses. The results showed that T-N and T-P concentrations were affected by agricultural practice; meanwhile, loss of T-N and T-P was correlated with rainfall characteristics. Specifically, the EMC of T-N but T-P was negatively (p < 0.001) correlated with the number of days after agricultural practice in both years, which likely represents a decrease in nutrient availability in paddy water over time. Loss of T-N and T-P was positively (p < 0.01) correlated with rainfall amount, and this suggests that the rainfall-runoff process is a key driver of nutrient loss in the study area. Our results suggest that rainfall amount and days after transplanting need to be taken into account when estimating nutrient loss from rice paddies in monsoon regions.

Rapid Detection of Methomyl and Organophosphorous Pesticides with Portable Potentiometric Biosensor

Simple portable potentiometric biosensor has been assessed for rapid in-field detection of neurotoxic anticholineesterase pesticides. The proposed biosensor based on inhibition of the acetylcholinesterase enzyme (AChE) by carbamate, organophosphorous pesticides, namely; methomyl, prothiofos and chlorpyrifos. Comprehensive studies were performed for the optimum measuring parameters for each pesticide and its degradation products. Based on the relative inhibition action of pesticide on AChE activity, different sensitivities were recorded ranging between 0.25 ng to 37.5 µg mL-1 depending on the nature of pesticide tested and its detoxification affect (LD). From different degradation products of methomyl, inhibition by methomyl S-oxide and methomyl S,S-dioxide were more potent allowing determination of 0.20 and 0.088 ng mL-1, respectively. Reasonable average recoveries ranging between 96.22±1.98 and 106.02±2.10 % were obtained. The applicability of the proposed method was tested by determination of pesticides in their commercial formulation and agricultural drainage water samples without pre-treatment procedures. Acceptable sensitivity and accuracy were obtained compared with the official chromatographic method indicated by good average recoveries between 94.73±2.74 and 108.3±0.80 %. The proposed sensors are promising and can be used as simple and direct screening devices for pesticide monitoring in field conditions available to unskilled end-users with significant decrease in cost per analysis to complement or replace the classical chromatographic methods.