Phosphorous control in a eutrophied reservoir.

Water in lakes and reservoirs accumulate phosphorous (P) from both internal and external loads. The external P load (EPL) coming from the watershed is considered to be the main cause of eutrophication of water bodies, and control strategies therefore focus on its reduction. However, algae blooms and anoxic conditions often continue even after EPL have been controlled, being the internal P load (IPL) originating from the sediment the main sources of P. To assess the efficiency of the adsorbent Phoslock (a modified bentonite) in controlling P concentrations in water and immobilize releasable P in sediments, mesocosm trials were carried out in a eutrophied reservoir and a model was described and applied that determines the amount of adsorbent and the application frequency necessary to control P concentrations in a eutrophied reservoir. The mesocosm trials confirm that Phoslock reduced P concentrations to or below the limits that define water in mesotrophic state, in approximately 2 weeks. The modeling results suggest that periodic reapplications of the adsorbent are required, unless EPL is reduced by 36 %, which allows the P concentrations in the water column to be constant. Such reduction in EPL would allow future applications of the adsorbent to be required only for control of IPL. The developed model allows planning remediation actions by determining quantities and frequencies for application of adsorbents for P control in eutrophied lakes and reservoirs.

Effects of lifestyle factors on concentrations of salivary cortisol in healthy individuals.

OBJECTIVE: Salivary cortisol is widely used in occupational health research. However, many ordinary daily activities can influence the concentrations of cortisol and the interpretation of field studies. The aim of the present study was to evaluate the effect of lifestyle factors on salivary cortisol in everyday settings. MATERIAL AND METHODS: Healthy employees participated in one or more sub-studies on the effect of eating a vegetable salad versus protein-rich mid-day meal (n = 40), drinking coffee and smoking (n = 12), drinking alcohol (n = 32), awakening at different times (n = 29) and exercising (n = 21). Cortisol in saliva was measured by radioimmunoassay (RIA). RESULTS: When eating a mid-day meal, salivary cortisol was increased by 10 % (CI -1 % to 24 %) 1 h after eating compared to before eating in the case of both types of meal. Salivary cortisol increased by 80 % (CI 9 % to 199 %) after exercising compared to before exercise. The relative awakening response was approximately 100 % when using an alarm clock on both work-days and days off. However, the awakening response was 39 % (CI 10 % to 75 %) on a day off with spontaneous awakening. No effects of alcohol, coffee or smoking were observed. DISCUSSION: In field studies, the biological variation in salivary cortisol may be reduced by restricting physical exercise and in collecting pre-meal samples. However, the protein content of food and moderate consumption of alcohol had no effect on concentrations of cortisol. Differences in relative awakening responses on work-days and days off are related to time and mode of awakening.