Uptake of 203Hg++ and 115 mCd++ by Chlamydomonas reinhardi under various conditions

The uptake of radioactively labeled mercury and cadmium ions by living and dead cells of Chlamydomonas reinhardi WT⁺ was measured at 25 °C under minimal and optimal conditions (dark/nitrogen or light/air, respectively). In each case, incorporation was completely independent of external energy. Living and dead cells incorporated almost the same amount of the added heavy metal ions; after about 4 to 8 hours, saturation was obtained. Furthermore, the distribution of mercury in the system of algea/culture medium/gas phase and the amount of mercury and cadmium adsorbed by cells were studied.     

Reviewing the relevance of dioxin and PCB sources for food from animal origin and the need for their inventory,control and management

Background

In the past, cases of PCDD/F and PCB contamination exceeding limits in food from animal origin (eggs, meat or milk) were mainly caused by industrially produced feed. But in the last decade, exceedances of EU limit values were discovered more frequently for PCDD/Fs or dioxin-like(dl)-PCBs from free range chicken, sheep, and beef, often in the absence of any known contamination source.

Results

The German Environment Agency initiated a project to elucidate the entry of PCBs and PCDD/Fs in food related to environmental contamination. This paper summarizes the most important findings. Food products from farm animals sensitive to dioxin/PCB exposure—suckling calves and laying hens housed outdoor—can exceed EU maximum levels at soil concentrations that have previously been considered as safe. Maximum permitted levels can already be exceeded in beef/veal when soil is contaminated around 5 ng PCB-TEQ/kg dry matter (dm). For eggs/broiler, this can occur at a concentration of PCDD/Fs in soil below 5 ng PCDD/F–PCB-TEQ/kg dm. Egg consumers—especially young children—can easily exceed health-based guidance values (TDI). The soil–chicken egg exposure pathway is probably the most sensitive route for human exposure to both dl-PCBs and PCDD/Fs from soil and needs to be considered for soil guidelines. The study also found that calves from suckler cow herds are most prone to the impacts of dl-PCB contamination due to the excretion/accumulation via milk. PCB (and PCDD/F) intake for free-range cattle stems from feed and soil. Daily dl-PCB intake for suckler cow herds must in average be less than 2 ng PCB-TEQ/day. This translates to a maximum concentration in grass of 0.2 ng PCB-TEQ/kg dm which is less than 1/6 of the current EU maximum permitted level. This review compiles sources for PCDD/Fs and PCBs relevant to environmental contamination in respect to food safety. It also includes considerations on assessment of emerging POPs.

Conclusions

The major sources of PCDD/F and dl-PCB contamination of food of animal origin in Germany are (1) soils contaminated from past PCB and PCDD/F releases; (2) PCBs emitted from buildings and constructions; (3) PCBs present at farms. Impacted areas need to be assessed with respect to potential contamination of food-producing animals. Livestock management techniques can reduce exposure to PCDD/Fs and PCBs. Further research and regulatory action are needed to overcome gaps. Control and reduction measures are recommended for emission sources and new listed and emerging POPs to ensure food safety.

     

Humic acids from oxidized coals I. Elemental composition, titration curves, heavy metals in HA samples, nuclear magnetic resonance spectra of HAs and infrared spectroscopy

The formation of humic acids (HAs) from bituminous coal was verified by laboratory oxidation. In a relatively short time the oxidation by air at temperature above 150 degrees C led to the formation of HAs. These HAs were compared with those isolated from oxidized bituminous coal from the vicinity of red bed bodies, from weathered bituminous coal, oxihumolite and lignite. For this the organic and inorganic elemental composition of HAs, apparent dissociation constants, metal-binding capacities, nuclear magnetic resonance and infrared spectra were determined and evaluated. With increasing temperature of laboratory oxidation of bituminous coal the percentage of aromaticity of HAs increases. HAs prepared from coal oxidized at 150 degrees C are characterized by an aromaticity index 78% while for HAs prepared at 250 and 300 degrees C by 95% aromaticity. The same index for HAs isolated from naturally oxidized bituminous coals is of about 87% whereas it is of about 50% for oxihumolite and lignite. The apparent dissociation constants (Kapp) are much higher in HAs isolated from oxihumolite and lignite (pKapp from 3.35 to 3.80) than those from oxidized bituminous coal samples (pKapp from 4.47 to 4.85). There is a good negative correlation between Pb-binding capacity and pKapp of all samples suggesting that metallic ions are bonded to acidic groups of HAs. Also contents of inorganic elements like Fe, Al, Si are much higher in HAs isolated from lignite and oxihumolite than those in HAs from oxidized bituminous coal. Thus, it seems that the temperatures below 150 degrees C and the long oxidation time are necessary conditions for the formation of HAs in oxidative altered bituminous coal deposited deeply under the earth surface.