Artificial sweat enhances dermal transfer of chlorpyrifos from treated nylon carpet fibers

The dermal transfer and absorption of 14C-ring-chlorpyrifos from nylon carpet fibers was measured in skin penetration-evaporation cells with excised pig skin. Prior to application, synthetic sweat was applied to skin in half of the cells. Radioactivity was measured in receptor fluid, dermis, epidermis, tape stripping samples, and vapor trap samples during a 24-h period. The sum of radiolabel recovered from the dermis and receptor fluid represented the absorbed dose. There was no significant difference (p > 0.05) in percutaneous absorption between cells that received the synthetic sweat application and "dry" cells (1.3 +/- 0.3% of applied dose). There was significantly more (p < 0.05) radiolabel recovered from tape stripping (5.4 +/- 2.1 vs. 2.8 +/- 0.6%) and in the epidermis (4.5 +/- 0.8 vs. 3.1 +/- 0.3%) from cells that received the synthetic sweat application, which indicated synthetic sweat facilitated transfer of chlorpyrifos from a treated substrate to the skin surface. The measured value for percutaneous absorption of chlorpyrifos agreed with the value predicted from an empirical model previously developed for nitro compound-containing soil.     

Evaluation of relative photonic efficiency in heterogeneous photocatalytic reactors

The evaluation of photonic efficiency in heterogeneous photocatalysis remains elusive because the number of absorbed photons is difficult to assess experimentally. The photonic efficiency of heterogeneous photocatalytic reactors depends on the reactor geometry, irradiation source, and photocatalyst properties. In this work, the relative photonic efficiency of heterogeneous photocatalytic reactors to degrade an azo dye was evaluated using phenol as the standard system. The experimental tests were carried out in a batch reactor under different conditions of pH, catalyst dosage, initial concentration, and ultraviolet (UV) lamps. The kinetics of disappearance of both phenol and azo dye were studied using the initial rate method and were described according to the Langmuir-Hinshelwood (L-H) kinetic model. It was observed that the relative photonic efficiency depends on the adsorption/desorption properties of the photocatalyst.     

A simple model for estimating emissions of volatile organic compounds from grass and cut grass in urban airsheds and its application to two Australian cities

Grass, and particularly cut grass, recently has been shown to emit significant amounts of volatile organic compounds (VOCs) into the atmosphere. Some components of these emissions are highly reactive and may contribute to photochemical smog in urban areas. A simple model for estimating the VOC emissions from grass and for grass cutting that allows these processes to be included in urban/regional emissions inventories is presented here. Using previous work and recent literature values, estimates are made of these biogenic volatile organic compound (BVOC) emissions for two typical urban airsheds, those including the cities of Sydney and Melbourne in Australia. Grass and cut grass could contribute approximately 2% for Sydney and 3% for Melbourne of the total VOCs emitted into these urban atmospheres annually. These contributions could rise to 4 and 5%, respectively, during the weekends of the summer growing season and, thus, could contribute to weekday/weekend ozone differences. It is recommended that the emissions of BVOCs from grass and cut grass be included in urban and global emissions inventories so that more accurate predictions of smog chemistry can be determined.     

Removal of nitrogen and phosphate from wastewater by addition of bittern

Removal of nitrogen and phosphate through crystallization of struvite (MgNH(4)PO(4).6H(2)O) has gained increasing interest. Since wastewaters tend to be low in magnesium relative to ammonia and phosphates, addition of this mineral is usually required to effect the struvite crystallization process. The present study evaluated the feasibility of using bittern, a byproduct of salt manufacture, as a low-cost source of magnesium ions. High reaction rates were observed; the extent of nitrogen and phosphorus removals did not change beyond 10 min. Phosphorus removals from pure solutions with bittern added were equivalent to those obtained with MgCl(2) or seawater. Nitrogen removals with bittern were somewhat lower than with the alternate Mg(2+) sources, however. Application of bittern to biologically treated wastewater from a swine farm achieved high phosphate removal, but ammonia removals were limited by imbalance in the nitrogen:phosphorus ratio.     

Heavy and toxic metals in staple foodstuffs and agriproduct from contaminated soils

This article presents basic data on the content of Cr, Fe, Ni, Cu, Zn, As, Cd, Sb, Hg, and Pb in staple foodstuffs and agriproduct grown in Russia (Astrakhan region and the town of Belovo) and Egypt (Helwan region). The dependence of the concentration of metals in agriproducts on the content and chemical form of existence in irrigation water and soils is indicated.     

Sorption of As(V) ions by akaganéite-type nanocrystals

A priority pollution problem, the removal of arsenate oxyanions from dilute aqueous solutions by sorption onto synthetic akaganéite (beta-FeO(OH)) was the aim of the present study. This is an innovative inorganic adsorbent material prepared in the laboratory, following a new method of preparation. The effect of akaganéite and arsenate concentration, the contact time, temperature, solution pH value, and ionic strength variation on the treatment process was mainly investigated during this study. Typical adsorption isotherms were determined, which were found to fit sufficiently the typical Langmuir equation. The mechanism of sorption was examined by electrokinetic, X-ray diffraction, Fourier transmission infrared and scanning electron microscopy measurements. Promising results were obtained, due to the favourite characteristics of the adsorbent applied.