Land use change impacts on floods at the catchment scale: Challenges and opportunities for future research.

Research gaps in understanding flood changes at the catchment scale caused by changes in forest management, agricultural practices, artificial drainage, and terracing are identified. Potential strategies in addressing these gaps are proposed, such as complex systems approaches to link processes across time scales, long-term experiments on physical-chemical-biological process interactions, and a focus on connectivity and patterns across spatial scales. It is suggested that these strategies will stimulate new research that coherently addresses the issues across hydrology, soil and agricultural sciences, forest engineering, forest ecology, and geomorphology.

Levels of selected elements (Fe, As, Cd, Pb, Zn, Mn) in biological samples from ferrochromium workers.

A long-term exposure to metals poses the question of whether the impaired health condition is caused exclusively by the quantitatively dominant exposure metal. In 67 workers exposed to ferrochromium alloys on average 12.5 +/- 1.09 years (mean +/- SE), the subgroups of ferrochromium workers and operators of dust removing equipment, average Cr values in urine were 0.233 +/- 0.032 mumol.l-1 (mean +/- SE). In the control group (K) the average Cr values were 0.034 +/- 0.004 mumol.l-1 of urine (mean +/- SE). The levels of plasmatic Fe were assessed photometrically; the levels of Fe, As, Cd, Pb, Mn and Zn in hair, urine and blood were assessed by atom-absorption spectrophotometry (Varian). The results were compared with the control group not significantly different in age (t-test). All the values were correlated with age, years of exposure and the number of cigarettes smoked during life. The values of the single selected metals in furnace workers and operators of dust removing devices were not higher than the limits set for the groups of workers exposed to metals. But compared to the original biological background, there was observed a significant Cd increase (hair, blood, urine) year by year. Average values of As, Pb, Fe, and Mn in hair of the exposed workers were also higher compared to the group K. As and Mn values in hair were increasing up with the years of exposure (r = 0.465, p < 0.05; r = 0.580, p < 0.001). No expected higher values of plasmatic Fe were found. Zn values in hair were falling down with the years of exposure as well as with age, in all groups including the group K. The authors discuss the possible causes of the quantitative changes in the selected metals in connection with professional exposure and non-professional effects (especially smoking). Higher cancer incidence of the organs affected has not been observed so far in the study plant. (Tab. 2, Fig. 8, Ref. 41.)