The effects of an industrial waste (cryolite recovery sludge) upon the atlantic Salmon, Salmo Salar (l.) detection thresholds and the effects of exposure to the waste upon detection of an amino acid

Thresholds for detection of cryolite recovery sludge (CRS, an aluminium smelter waste dumped at sea) were determined for salmon. Salmo salar (L.). in sea water using a cardiac conditioning technique. Some effects of exposure of salmon to CRS filtrate (mean concentration 5.5°_D) for up to 1 h were monitored. Oxygen consumption and ventilation rate increased and heart rate decreased after presentation of the filtrate. The effects were transient and the physiological parameters monitored returned to pre-exposure levels within 2 h of ceasing filtrate presentation. Detection levels for an amino acid (glycine) were determined for salmon in sea-water before and after exposure to CRS filtrate (mean concentration 5.5%). Within 24 h of exposure to the CRS filtrate the mean threshold level was significantly different from the pre-exposure detection level. However, 24–48 h after exposure the threshold for detection of glycine was no longer significantly different.     

An evaluation of the relative importance of food and water as sources of p,p′-DDT to the goldfish, carassius auratus (l.)

Goldfish (Carassius auratus) were simultaneously exposed to p,p′-DDT from two sources—food ([³⁶Cl]p,p′-DDT) and water ([¹⁴C]p,p′-DDT). The concentration of p,p′-DDT in food was maintained at about 1 μg g⁻¹ while the water concentration of p,p′-DDT was varied for each experiment (2, 20 and 177 ng dm⁻³). In these experiments the contribution of p,p′-DDT from food to the total body residue varied over the duration of the exposure from 0 to 81% (water concentration about 2 ng dm⁻³) and from 3.8 to 4.8% (water concentration about 171 ng dm⁻³). The results from these experiments were compared with those of experiments in which some goldfish were exposed to DDT-contaminated food and others to DDT-contaminated water. Comparison suggested that goldfish exposed to DDT-contaminated food and water simultaneously, had accumulated p,p′-DDT from the two sources additively.The data supports the concept that p,p′-DDT residues in fish can be derived from both food and water. We suggest that the importance of each source is determined by its relative concentration over the period of exposure. p,p′-DDT taken up by goldfish was converted, slowly at first, then more rapidly to p,p′-DDE reaching a maximum of > 80% from both water and food sources after about 40 days. Dietary p,p′-DDT was converted to p,p′-DDD to a greater extent (max. 15.9%) than water-borne p,p′-DDT is converted to p,p′-DDD (max. 2.8%).