Influence of metallic species for efficient photocatalytic water disinfection: bactericidal mechanism of in vitro results using docking simulation

Environmental Science and Pollution Research - TiO2-based heterogeneous photocatalysis systems have been reported with remarkable efficiency to decontaminate and mineralize a range of pollutants...     

Concentrations and bioaccessibility of polycyclic aromatic hydrocarbons in wastewater-irrigated soil using in vitro gastrointestinal test

BACKGROUND, AIM, AND SCOPE: Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and contribute to the pollution of soil environment. Soil ingestion is of increasing concern for assessing health risk from PAH-contaminated soils because soil ingestion is one of the potentially important pathways of exposure to environmental pollutants, particularly relevant for children playing at contaminated sites due to their hand-to-mouth activities. In vitro gastro-intestinal tests imitate the human digestive tract, based on the physiology of humans, generally more simple, less time-consuming, and especially more reproducible than animal tests. This study was conducted to investigate the level of PAH contamination and oral bioaccessibility in surface soils, using physiologically based in vitro gastro-intestinal tests regarding both gastric and small intestinal conditions. MATERIALS AND METHODS: Wastewater-irrigated soils were sampled from the metropolitan areas of Beijing and Tianjin, China, which were highly contaminated with PAHs. Reference soil samples were also collected for comparisons. At each site, four soils were sampled in the upper horizon at the depth of 0-20 cm randomly and were bulked together to form one composite sample. PAH concentrations and origin were investigated and a physiologically based in vitro test was conducted using all analytical grade reagents. Linear regression model was used to assess the relationship between total PAH concentrations in soils and soil organic carbon (SOC). RESULTS: A wide range of total PAH concentrations ranging from 1,304 to 3,369 mug kg(-1) in soils collected from different wastewater-irrigated sites in Tianjin, while ranging from 2,687 to 4,916 mug kg(-1) in soils collected from different wastewater-irrigated sites in Beijing, was detected. In general, total PAH concentrations in soils from Beijing sites were significantly higher than those from Tianjin sites, indicating a dominant contribution from both pyrogenic and petrogenic sources. Results indicated that the oral bioaccessibility of PAHs in small intestinal was significantly higher (from P < 0.05 to P < 0.001) than gastric condition. Similarly, the oral bioaccessibility of PAHs in contaminated sites was significantly higher (from P < or = 0.05 to P < 0.001) than in reference sites. Individual PAH ratios (three to six rings), a more accurate and reliable estimation about the emission sources, were used to distinguish the natural and anthropogenic PAH inputs in the soils. Results indicated that PAHs were both pyrogenic and petrogenic in nature. DISCUSSION: The identification of PAH sources and importance of in vitro test for PAH bioaccessibility were emphasized in this study. The oral bioaccessibility of individual PAHs in soils generally decreased with increasing ring numbers of PAHs in both the gastric and small intestinal conditions. However, the ratio of bioaccessibility of individual PAHs in gastric conditions to that in the small intestinal condition generally increased with increasing ring numbers, indicating the relatively pronounced effect of bile extract on improving the bioaccessibility of PAHs with relatively high ring numbers characterized by their high K ( ow ) values. Similarly, total PAH concentrations in soils were strongly correlated with SOC, indicating that SOC was the key factor determining the retention of PAHs in soils. CONCLUSIONS: Soils were contaminated with PAHs due to long-term wastewater irrigation. PAHs with two to six rings showed high concentrations with a significant increase over reference soils. Based on the molecular indices, it was suggested that PAHs in soils had both pyrogenic and petrogenic sources. It was also concluded that the oral bioaccessibility of total PAHs in the small intestinal condition was significantly higher than that in the gastric condition. Furthermore, the bioaccessibility of individual PAHs in soils generally decreased with the increasing ring numbers in both the gastric and small intestinal conditions. RECOMMENDATIONS AND PERSPECTIVES: It is suggested that more care should be given while establishing reliable soil criteria for PAHs, especially concerning the health of children who may ingest a considerable amount of PAH-contaminated soil via outdoor hand-to-mouth activities.     

Challenges of textile waste composite products and its prospects of recycling

Journal of Material Cycles and Waste Management - Every year, a massive volume of textile waste is disposed of in a landfill or incinerated, contributing to resource loss and environmental...     

Recent advances in SO2, NOx, and O3 personal monitoring

Since the air pollution as measured by stationary monitoring stations is a poor indicator of the population exposure, personal monitors are indispensible to health effects studies. This article reviews the current research on the development of personal monitors. Although most of the analytical methods reviewed in this study appear to be sensitive to the levels of the target pollutants NO₂, SO₂, and O₃ generally encountered in indoor and outdoor air, they lack the desired performance characteristics for a personal monitoring device, such as user safety and ease of operation, weight, and maintenance. Electrochemical transducers/sensors, which have not yet been exploited, are attractive candidates for the application to personal monitoring. This technique has an added feature of generating real-time measurements. A few research models and commercially attractive devices that can be used in field studies are included.     

In vitro metabolism of deltamethrin by stem and leaf homogenates of tobacco plants

Stem and leaf homogenates from tobacco plants metabolised deltamethrin by oxidative and hydrolytic actions on the insecticide. Although a major portion of deltamethrin remained unchanged, metabolites such as 3-phenoxybenzaldehyde, 3-phenoxybenzoic acid and 3-(2,2-dibromonyl)-2,2-dimethylcyclopropanecarboxylic acid were formed. The data suggest a major portion of the insecticide would remain unchanged when absorbed by tobacco plants.     

Estimation and comparison of night-time OH levels in the UK urban atmosphere using two different analysis methods

Night-time OH levels have been determined for UK urban surface environments using two methods,the decay and steady state approximation methods.Measurement data from the UK National Environmental Technology Centre archive for four urban sites(Bristol,Harwell,London Eltham and Edinburgh) over the time period of 1996 to 2000 have been used in this study.Three reactive alkenes,namely isoprene,1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method.Hourly measurements o...     

Feasibility of relating interferon production by wild voles to types of chemical contamination of their environment

In the fall of 1980, a limited field sampling and laboratory analysis profect was undertaken to explore the feasibility of relating immunological responses of field mice (voles) living wild in an area of environmental concern to the level of chemical contamination of that area. The voles were collected in the vicinity of Love Canal by biological sampling teams already there to collect voles for other purposes.The project helped identify those areas of practical uncertainty that must be clarified before the rate of interferon production in voles can be considered as a possible indicator of chemical contamination. Two lines of research are proposed: developing optimumin vitro interferon bioassays systems for vole leukocytes; and characterizing the interferon production responses of voles following controlled exposures to selected carcinogens and other chemicals.     

Domestic Water Contamination in Rapidly Growing Megacities of Asia: Case of Karachi, Pakistan

The development of essential services including water and sanitation in many megacities of the economically developing countries of Asia cannot keep pace with their rapidly growing population and accompanying urban and industrial development. The inadequate water supply and poor sanitation services lead to contamination of their water supply. It also leads to the input of sewage water into the groundwater. The problem is seriously acute in Karachi, the largest city in Pakistan with a population of over 12 million and growing at 6 percent. This paper examines the problem of water contamination in Karachi. The paper presents the data on water quality from various sources, mainly municipal water supply, vendors and well water; the three major sources of water for domestic use in Karachi. Except municipal water from some areas and during certain periods, water from most other sources contain coliform bacteria, and in many cases faecal coliform, in amounts several magnitudes higher than any standards permit. Many samples have also been found to contain heavy metals including Chromium, Lead, Nickel and Arsenic in amounts excessive of permitted standards. The probable sources of contaminants for the various types of water (piped, vendors, wells) indicate that groundwater may be the main contributor. The very source of this groundwater is predominantly from sewage. The health hazards from consuming such contaminated water are obvious. The paper also evaluates the solutions that are being practiced, proposed or may be feasible, as well as those that are evolving.     

The effect of fly ash on plant growth and yield of tomato

A gradual increase in fly ash concentrations in the normal field soil (0, 10, 20...100% volume/volume) increased the porosity, water holding capacity, pH, conductivity, C.E.C., sulphate, carbonate, bicarbonate, chloride, P, K, Ca, Mg, Mn, Cu, Zn and B. Fly ash additions to soil caused significant reductions in nitrogen content, it being almost nil in 90 and 100%. Tomato plants grown in the ash-soil mixture showed luxuriant growth with bigger and greener leaves. Plant growth, yield, (flowering, fruiting, fruit weight/plant, mean fruit weight), carotenoids and chlorophylls were mostly enhanced in the treatments with 40-80% fly ash, being optimal at 50 or 60%. From 60 or 70% onwards, the measured parameters tended to reduce. At 100% fly ash, yield (weight of fruits/plant) was considerably reduced. The boron content of tomato leaves displayed a gradual increase with fly ash addition from 20% onwards, while response of foliar nitrogen was just the opposite. The most economic level of fly ash incorporation was 40%, which improved the yield and market value of tomato fruits (mean weight) by 81 and 30%, respectively.     

Prevalent fecal contamination in drinking water resources and potential health risks in Swat, Pakistan

Fecal bacteria contaminate water resources and result in associated waterborne diseases.This study assessed drinking water quality and evaluated their potential health risks in Swat, Pakistan. Ground and surface drinking water were randomly collected from upstream to downstream in the River Swat watershed and analyzed for fecal contamination using fecal indicator bacteria(Escherichia coli) and physiochemical parameters(potential of hydrogen, turbidity, temperature, electrical conductivity, total dissolved solid, color, odor and taste). The physiochemical parameters were within their safe limits except in a few locations, whereas, the fecal contaminations in drinking water resources exceeded the drinking water quality standards of Pakistan Environmental Protection Agency(Pak-EPA),2008 and World Health Organization(WHO), 2011. Multivariate and univariate analyses revealed that downstream urbanization trend, minimum distance between water sources and pit latrines/sewerage systems, raw sewage deep well injection and amplified urban,pastures and agricultural runoffs having human and animal excreta were the possible sources of contamination. The questionnaire survey revealed that majority of the local people using 10–20 years old drinking water supply schemes at the rate of 73% well supply,13% hand pump supply, 11% spring supply and 3% river/streams supply, which spreads high prevalence of water borne diseases including hepatitis, intestinal infections and diarrhea, dysentery, cholera, typhoid fever, jaundice and skin diseases in children followed by older and younger adults.