EFFECTIVENESS OF POLYACRYLAMIDE (PAM) IN IMPROVING RUNOFF WATER QUALITY FROM CONSTRUCTION SITES1

ABSTRACT: Erosion from construction sites significantly affects water quality in receiving streams. A rainfall simulator was used to evaluate the effectiveness of different methods for controlling erosion from construction sites. Erosion control methods investigated included dry and liquid applications of polyacrylamide (PAM), hydroseed, and straw mulch. Fertilizer was also applied to each plot to examine the effectiveness of the methods in reducing nutrient losses in runoff. Runoff samples were analyzed for total suspended solids (TSS), nitrate, total Kjeldahl nitrogen (TKN), ammonium, total phosphorus (TP), and orthophosphate. Among all treatments investigated, straw mulch was the most effective treatment for controlling TSS and nutrient losses during short term and long term simulations. The low liquid PAM (half the recommended PAM) treatment resulted in the highest reduction in runoff, TSS bound nitrogen, and total nitrogen (TN) concentrations and loadings. The study results indicate that a high application rate (twice the recommended rate) of PAM could actually increase runoff and TSS losses. At a low application rate, both liquid and dry PAM were effective in reducing TSS and nutrient losses in runoff. However, application of the liquid form of PAM to construction sites is more practical and perhaps more economical than applying the PAM in the dry form.     

Geochemical and geostatistical investigations of chromium pollution in groundwater.

Geochemical and geostatistical study of the chromium concentration in groundwater occurring at variable depths of 12 to 33.5 m (40 to 110 ft) in the Karachi urban area of Pakistan have been made. Samples were collected at variable distances, with a maximum of 1 km interval, on the bases of population, industries, types, and density. The chromium concentration has also been worked out to deduce the threshold value of the area under study and the estimation of probability impact modeling, in terms of concentration variation, by using the disjunctive kriging technique. The outcome of the present work appears to be a good tool to decipher pollution variation in the groundwater of highly urbanized areas, with respect to the population and industries. The patterns of distribution of chromium concentration in groundwater and pollution hotspots in particular localities appear to be more related to the types of industries than to the effect of population types.     

Dengue fever awareness: effect of an educational intervention on nursing students,Tanta, Egypt

Environmental Science and Pollution Research - Dengue fever (DF) is one of the world’s most important vector-borne illnesses. In 2017, Egypt experienced a dengue outbreak. This study aimed to...     

Method to Partition Between Attached and Unattached E. coli in Runoff From Agricultural Lands1

Abstract: Remediation of waters impaired by bacterial indicators is usually dictated by total maximum daily load plans, which are heavily dependent on fate and transport modeling of bacterial indicators. Nonpoint source pollution models are most frequently used to assess bacterial transport to surface waters and most models typically simulate bacterial transport as a dissolved pollutant. Previous studies have found that cells preferentially attach to sediments; however, a variety of techniques have been used to assess attachment including filtration, fractional filtration, and centrifugation. In addition, a variety of chemical and physical dispersion techniques are used to release attached and bioflocculated cells from particulates. Here we developed and validated an easy‐to‐replicate laboratory procedure for separation of unattached from attached E. coli which will also identify particle sizes to which E. coli preferentially attach. Physical and chemical dispersion techniques were evaluated and a combined hand shaker treatment for 10 min followed by dilutions in 1,000 mg/l of Tween 85 significantly increased total E. coli concentrations by 31% when compared with a control. In order to separate unattached from attached fractions, two commonly used techniques, fractional filtration, and centrifugation were combined. The filtration and centrifugation treatments did not reduce E. coli concentrations when compared with a control (p > 0.05), indicating that damage was not inflicted upon the E. coli cells during the separation procedure.     

PULSED TRICKLING EFFECTS ON SOIL MOISTURE DISTRIBUTION1

ABSTRACT Laboratory experiments were conducted to study effects of trickle emitter discharge rate on the distribution of soil moisture in a silty-clay loam soil. Both pulsed and continuous irrigation treatments were studied. A simulation model was used to evaluate the results obtained in the laboratory. The agreement between the predicted and measured soil moisture distribution patterns was quite good. For both pulsed and continuous applications, increasing trickle discharge rate resulted in a decrease in the horizontal component and an increase in the vertical component of the wetted soil profile. Compared to the continuous treatments, pulsed applications resulted in significant reduction in water loss below the root zone. Pulsed applications rates can replace continuous small discharge rates to reduce irrigation water runoff problems on heavy soils and with restricted infiltration allow the use of larger emitter orifices to decrease potential clogging of the trickle system.     

Variation in root density along stream banks

While it is recognized that vegetation plays a significant role in stream bank stabilization, the effects are not fully quantified. The study goal was to determine the type and density of vegetation that provides the greatest protection against stream bank erosion by determining the density of roots in stream banks. To quantify the density of roots along alluvial stream banks, 25 field sites in the Appalachian Mountains were sampled. The riparian buffers varied from short turfgrass to mature riparian forests, representing a range of vegetation types. Root length density (RLD) with depth and aboveground vegetation density were measured. The sites were divided into forested and herbaceous groups and differences in root density were evaluated. At the herbaceous sites, very fine roots (diameter < 0.5 mm) were most common and more than 75% of all roots were concentrated in the upper 30 cm of the stream bank. Under forested vegetation, fine roots (0.5 mm < diameter < 2.0 mm) were more common throughout the bank profile, with 55% of all roots in the top 30 cm. In the top 30 cm of the bank, herbaceous sites had significantly greater overall RLD than forested sites (alpha = 0.01). While there were no significant differences in total RLD below 30 cm, forested sites had significantly greater concentrations of fine roots, as compared with herbaceous sites (alpha = 0.01). As research has shown that erosion resistance has a direct relationship with fine root density, forested vegetation may provide better protection against stream bank erosion.     

50 Hz alternating extremely low frequency magnetic fields affect excitability,firing and action potential shape through interaction with ionic channels in snail neurones

In spite of growing concern about the influence of magnetic fields on biological systems, the interaction between extremely low frequency magnetic field (ELF magnetic fields) and biological structures at the cellular level remains obscure. The aim of this study was to investigate if 50 Hz magnetic fields could have an effect on the neuronal excitability and firing responses. Under Current-Clamp condition, exposure to 50 Hz ELF magnetic fields at 2 mT or 0.8 mT intensities resulted in an increase in the peak amplitude of action potential and after hyperpolaization potential in a time dependent manner. Both magnetic field intensities decreased also the firing frequency and the duration of action potential. Taken together, these data suggest that 50 Hz ELF magnetic fields at 2 mT or 0.8 mT intensities may change the electrophysiological behavior of neuronal cells and underlying ion channel currents.     

Development of bacteria and benthic total maximum daily loads: a case study, Linville Creek, Virginia

Two total maximum daily load (TMDL) studies were performed for Linville Creek in Rockingham County, Virginia, to address bacterial and benthic impairments. The TMDL program is an integrated watershed management approach required by the Clean Water Act. This paper describes the procedures used by the Center for TMDL and Watershed Studies at Virginia Tech to develop the Linville Creek TMDLs and discusses the key lessons learned from and the ramifications of the procedures used in these and other similar TMDL studies. The bacterial impairment TMDL was developed using the Hydrological Simulation Program-Fortran (HSPF). Fecal coliform loads were estimated through an intensive source characterization process. The benthic impairment TMDL was developed using the Generalized Watershed Loading Function (GWLF) model and the reference watershed approach. The bacterial TMDL allocation scenario requires a 100% reduction in cattle manure direct-deposits to the stream, a 96% reduction in nonpoint-source loadings to the land surface, and a 95% reduction in wildlife direct-deposits to the stream. Sediment was identified as the primary benthic stressor. The TMDL allocation scenario for the benthic impairment requires an overall reduction of 12.3% of the existing sediment loads. Despite the many drawbacks associated with using watershed-scale models like HSPF and GWLF to develop TMDLs, the detailed watershed and pollutant-source characterization required to use these and similar models creates information that stakeholders need to select appropriate corrective measures to address the cause of the water quality impairment when implementing the TMDL.     

Maximum ground level concentration for Gaussian plume formula using standard and Briggs methods

This work aims to determine the maximum concentration and downwind distance at the earth's surface in two methods Briggs and standard for two conditions are slightly unstable and neutral by using the Gaussian equation at different effective heights and wind seeped at (8.9, 8.5 and 8 m/s) under lateral and vertical dispersion coefficient measurement.     

Efficient oxidation and epoxidation using a chromium(VI)-based magnetic nanocomposite

The oxidation of alcohols and alkenes to aldehydes, ketones and epoxides is a major reaction in organic synthesis, but is usually hard to perform due to the lack of efficient methods. The use of ultrasounds may improve yield because ultrasonic-assisted reactions are often more efficient than traditional methods. Here, we prepared a hybrid chromium(VI)-based magnetic nanocomposite catalyst by co-precipitation. This catalyst was characterized by Fourier transform infrared, solid-state ultraviolet–visible, elemental analysis, X-ray fluorescence, scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer analyses. The catalytic activity was tested by the oxidation of benzyl alcohol to benzaldehyde, cyclohexanol to cyclohexanone, and epoxidation of cyclohexene, using hydrogen peroxide at room temperature under ultrasonic irradiation. Results show conversions ranging from 27 to 100 % according to gas chromatography–mass spectrometry. This is the first report of using magnetic nanocomposites with ultrasonic irradiation for oxidation reactions.