Abschätzung der Quecksilberexposition

A site contaminated by mercury serves as an example for evaluating the environmental medicine aspects of mercury emissions on individuals living in the surroundings. Based on defined, conventional scenarios, estimations of internal exposure were made for seven different age groups and with regard to such contact media as soil, air and food. Using human monitoring methods, an attempt was made to compare the epidemiological results. The site-specific and pathway-specific estimation of exposure is based on a multitude of various samples as well as on measurements of concentrations in the compartments relevant for intake. As based upon rigid guideline values, both these calculations and the epidemiological investigations reveal a slight increase in the mercury exposure.     

佳木斯台形变观测对东北地区几次浅震“场兆”异常的探讨

大地震在主破裂前往往行成地壳变形,高应力作用下进入峰值后的变形阶段,反映到地倾斜观测日均值曲线上,表现为固体潮形变趋势异常,这些异常能否指示远距离的地震,近年来不少研究者发现,远场前兆往往出现在对应力、应变变化反应灵敏的特殊构造部位。佳木斯台可能处于这种特殊的构造部位,对东北地区浅源地震短期前兆异常“场兆”的趋势性变化具有一定的意义。     

Absch?tzung der Quecksilberexposition

Zusammenfassung  Ein quecksilberkontaminierter Altstandort dient als Beispiel für eine umweltmedizinische Beurteilung der Belastung der im Umfeld wohnenden Personen durch Quecksilberimmissionen. Dabei wird die innere Exposition für sieben verschiedene Altersgruppen bezüglich der KontaktmedienBoden, Luft undNahrungsmittel anhand von konventionell festgelegten Szenarien abgesch?tzt und ein Vergleich mit den epidemiologischen Ergebnissen eines Humanmonitorings angestrebt. Die standortspezifisch und pfadspezifisch durchgeführte Expositionsabsch?tzung stützt sich auf cine Vielzahl von unterschiedlichen Probenehmern sowie auf über mehrere Jahre durchgeführte Konzentrationsmessungen in den aufnahmerelevanten Kompartimenten. Sowohl die Berechnungen als auch die epidemiologischen Untersuchungen zeigen eine leichte Erh?hung der Quecksilberexposition, gemessen an strengen Richtwerten.      

Improvement of the photostability of selected substances in aqueous medium

The photodegradation of some pesticides in water has been investigated. The kinetics of the photochemical processes is discussed and the photolytic half‐life is calculated. The objective of this paper is to present some of the recent results on the kinetics and on the products of sunlight‐induced reactions of Parathion, Gardona, Diazinon, Atrazine and Phenmediphame at low concentrations in distilled water and fresh water. The quantum yield, measured at 263 nm for Phenmediphame in aerated water at 5 × 10^‐4 M and 30°C, was 1.4 × 10^‐2, and for Parathion, measured at 300 nm in aqueous solution at 3.42 M at pH 6.4 and 25 °C, was 1.5 × 10^‐3. The measured absorption spectra and the variable light intensity were used to estimate the environental phototransformation process and the persistence of these compounds in water.     

Half-lives of tetra-, penta-, hexa-, hepta-, and octachlorodibenzo-p-dioxin in rats,monkeys, and humans--a critical review

The elimination half-lives (t1/2) in Sprague-Dawley rats for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 1,2, 3,7,8-pentachlorodibenzo-p-dioxin (PeCDD), 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin (HxCDD), 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) and 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (OCDD) were estimated in long-term studies by Schlatter, Poiger and others. Furthermore, there are some published half-lives of TCDD in adult humans. The average half-life of TCDD in adult humans is approximately 2840 days, while in Sprague-Dawley rats the average t1/2 of TCDD is 19 days. The t1/2 of TCDD in humans is about 150 times that of rats. This factor was used to calculate the t1/2 values of the other polychlorinated dibenzo-p-dioxins (PCDDs) in humans from the rat data. Furthermore, the terminal t1/2 values of PCDDs in adult humans were calculated from the regression equation: logt1/2H = 1.34 logt1/2R + 1.25 which was recently established for 50 xenobiotics (t1/2H = terminal half-lives in days for humans, t1/2R = terminal half-lives in days for rats). The following terminal half-lives in adult humans were obtained: 12.6 years for 1,2,3,7,8-PeCDD, 26-45 years for 1,2,3,4,7,8-HxCDD, 80-102 years for 1,2,3,4,6,7,8-HpCDD and ca. 112-132 years for OCDD. These half-lives of PCDDs are critically compared with measured t1/2 values of PCDDs and other persistent organic pollutants in rats, monkeys and humans.     

Exposure analysis of the inhabitants living in the neighbourhood of a mercury-contaminated industrial site

The inhabitants living in the neighbourhood of a deserted mercury-contaminated industrial site are subjected to an age-group differentiated mercury exposure assessment based on a scenario-linked calculation. Analytical input data for the calculation procedure are provided for from soil, air and plants in a large number. The most sensitive group are small children being mainly exposed by soil ingestion which makes up nearly 80% of the ADI, followed by inhalation of mercury contaminated indoor air. On the other hand, inhalation of indoor air has a predominant impact on youth and adults.     

Alternatives for the determination of the soil adsorption coefficient, KOC, of non-ionicorganic compounds - a review

The determination of the soil adsorption behaviour of an environmental chemical is very important to the evaluation of potential dangers for man and nature. One of the major problems for European regulators working in the field of environmental protection and risk assessment is the lack of complete and comparable soil sorption data, e.g. K_oc values. The large number of existing chemicals makes it necessary to develop and apply fast methods as an alternative to classical batch or column studies. Based on this context numerous approaches to estimate K_oc have been published during the past two decades.

In this paper more than 200 existing relationships for K_oc estimations have been reviewed and divided into four categories. Regression equations for the most important classes of non-ionic organic environmental chemicals able to estimate soil adsorption coefficients are summarised, and the advantages and drawbacks of the different approaches are discussed briefly.

Due to the fact that a broad application of the proposed approaches is limited by the quality and comparability of the underlying experimental K_oc values reference soils are postulated to create a common basis for the comparison of soil adsorption coefficients.     

Determination photostability of selected agrochemicals in water and soil.

The photolysis of selected pesticides in aqueous solutions has been investigated. The photolysis produced different intermediate substances, which were also found to be soil and microbial degradation products. The phototransformation in the presence of TiO2 and humic substances leads to a disappearance of these compounds. The reaction rate is dependent on the semiconductor oxide and concentration. Photoproducts were isolated and characterized by different spectroscopic methods. Results from this study indicate that degradation products of isoproturon are more toxic on Daphnia magna than on the parent compound.