Determination and characterization of chloroguaiacol conjugates in fish bile by HPLC

In this study a small-scale technique for direct analysis of metabolic conjugates of 4,5,6-trichloro- (CG-3) and tetrachloroguaiacols (CG-4) in fish bile by RP-HPLC is presented. Only one metabolite, glucuronic acid conjugate, was demonstrated in two Lake Baikal fishes (Leuciscus leuciscus baikalensis and Cottus kessleri) exposed to CG-3 or CG-4 at 6 degrees C for 1-2 days. In Leuciscus the ratio between free CG-4 in the ambient water and conjugated CG-4 in the bile averaged 264,000. Intraperitoneal injections of tetrachloroveratrol (CV-4) into Thymallus arcticus baikalensis did not reveal any traces of free CV-4 or CG-4 glucuronide in the bile in 2 days at 5 degrees C. We therefore suggest that CV-4 was not demethylated and subsequently conjugated with glucuronic acid in the liver of this fish species.     

Leaching study of polycyclic aromatic hydrocarbon bioavailability from a coal-derived solid product

The leaching behavior of selected four- to six-ring polycyclic aromatic hydrocarbons (PAH) from a tumorigenic coal-derived solid product was determined using three media to evaluate their potential bioavailabilities. Equilibrium PAH concentrations generally exceeded the aqueous solubilities after less than five days of leaching. PAH selectively accumulated in phospholipid vesicles at individual concentrations greater than 1 μg/g, which is ca. 100-fold over that in the bulk aqueous leachate. The results suggest that the PAH are quite bioavailable from the solid product, and that cell membranes can be exposed to considerable quantities of these PAH over an extended bioassay.     

Cadmium in the diet and body tissues of dunlins Calidris alpina, from the Bristol channel, UK

Cadmium levels were determined in sediments, sediment-dwelling invertebrates and in one of their predators, the dunlin, at five sites in the Bristol Channel. The highest sediment cadmium levels were found in the Taff Estuary and at Avonmouth. The highest invertebrate levels were found at Avonmouth and Swansea. In dunlins, the highest cadmium levels were found in the kidneys, followed by the liver, sternum and pectoral muscle. Adult males had higher levels than adult females. Although first year birds of both sexes had low levels, these increased throughout the course of the winter. There was no simple correlation between the amount of cadmium in the sediments, and that in invertebrates or birds, although the levels in both sediments and invertebrates reached a peak in mid-winter. The most contaminated birds were, however, found closest to a known point source of cadmium.     

Atmospheric deposition of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in the Kanto Region, Japan

The atmospheric bulk (dry and wet) deposition of dioxins was investigated at four locations (Tokyo, Yokohama, Tsukuba, and Tanzawa) in the Kanto region (in Japan) over one year using a stainless-steel pot. Annual average polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/PCDF) deposition fluxes were estimated to be from 450 to 1300 ng/m2/yr, and the annual average TEQ fluxes from 5.7 to 17 ng-TEQ/m2/yr at the four locations. The PCDD/PCDF deposition flux was higher in winter than in summer. The deposition flux could be related to ambient temperature, particularly for less chlorinated PCDDs/PCDFs, while the deposition flux is not necessarily related to the amount of precipitation. The PCDD/PCDF deposition flux increased as the particle deposition flux increased, for the winter samples. Based on the ratio of the PCDD/PCDF deposition fluxes to the particle deposition fluxes, the contribution of the reentrainment of soil particles to the TEQ of PCDD/PCDF deposition was considered to be negligible in this region. Based on the air concentrations monitored near our deposition sampling points by the municipalities, the ratio of the annual deposition flux to the annual average air concentration was roughly estimated to be 0.082 cm/s. The range of deposition flux in the Kanto region was estimated to be from 1.5 to 31 (median: 9.8) ng-TEQ/m2/yr based on the range of air concentration data measured by the municipalities. The total annual deposition flux in the entire Kanto region was estimated to range from 50 to 900 g-TEQ/yr (median 320 g-TEQ/yr). This estimated flux was of the same order as the sum of estimated emissions from municipal solid waste incinerators and industrial waste incinerators in the Kanto region. The contributions of dioxin-like PCBs in Yokohama, Tsukuba, and Tanzawa depositions were less than 10% of the total TEQ; however, in Tokyo it was almost equal to or more than 50%.     

Non-aqueous-phase-liquid breakthrough during evaporative drying of clay barriers

In this study, an attempt has been made to model a real field scenario, whereby an initially almost saturated clay liner in a waste site is gradually drying, due to evaporation at its lower boundary. A detailed conceptual model that deals with the penetration and breakthrough of non-aqueous-phase-liquid (NAPL) in clay liners is introduced. Water content of clay samples was monitored during ambient evaporation through apertures at the base of sample holders. Clay drying rate served as the primary parameter for the NAPL breakthrough study. The interconnection between drying rates, structural damage formation (cracks and suction) and NAPL penetration is especially addressed. The processes taking place in the clay samples during drying appear to be associated with the capillary effects between the different fluid phases in the vicinity of either the NAPL-clay or the clay-air boundaries. A conceptual model of NAPL penetration and breakthrough of the clay layer has been considered, based on both indirect and direct observations of structural damages produced on either clay boundaries. A mutual interaction between these two boundaries is suggested and discussed. NAPL breakthrough is suggested to take place through cracks initiated on the upper soil surface.     

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.