The Negro River (Ancash-Peru): A unique case of water pollution, three environmental scenarios and an unresolved issue.

This paper is focused on the hydrogeochemical characterization of the Negro River along its course, as well as in the proposal of a functioning model for the contamination processes in order to establish potential cause-effect relationships between water quality, geology (ARD), mining activities (AMD) and the tectonic framework as transmission vector of acidity, metals and sulphates. The scenario shows a heavily-contaminated river compared to the unaffected regional background. By graphical and statistical treatments of physico-chemical data of Negro River and the unaffected values of regional background and other AMD/ARD representative rivers' it is possible to conclude that Antamina Mine, is not the cause of the Negro River contamination, without the need of isotopic tracers, but just through the inexistent concentrations of Cu, Bi and Mo found in the waters. In the proposed contamination model, climatic factors (glacial retreat) activate geological (ARD) processes. The tectonic scenario (faults) intervenes as a transport medium of the contamination flux from the sulphide oxidation surface in upper altitudes until the spring in lower altitudes. At the end, it is concluded that this contamination comes from the recent glacial retreat in areas near the Cordillera Blanca that has left massive amounts of sulphide materials exposed to weathering conditions, oxidizing naturally (ARD processes) and finally contributing to the contamination of the Negro River through faults. In this case, we would face an ARD process in the strict sense, which is the direct oxidation of sulphides outcropping in the upper part of the mountain with the generation of sulphates, the release of hydrogen ions and the consequent generation of acid and the dissolution of the metals. This ARD process would come from the glacial retreat, which, through the faults, transports contaminated water until the spring.

Application of fuzzy logic tools for the biogeochemical characterisation of (un)contaminated waters from Aljustrel mining area (South Portugal).

Aljustrel mining area (South Portugal) belongs to the Iberian Pyrite Belt (IPB). It is classified of high environmental risk due to its large tailings and to the Acid Mine Drainage (AMD) affected waters, generated by sulphides' oxidation. Integrating biological parameters (for the first time) in the input data matrix of the software PreFuRGe, allowed a better discrimination of the diatoms' responses to the stimuli caused by the hydrochemical changes imposed by the processes affecting water quality. Each hydrochemical scenario, was modeled by imposing maximum and minimum limits for each antecedent, according to the conditions imposed by the consequent, which in this case were the number of diatom species and pH. Thus, PreFuRGe evidenced some qualitative aspects that could not be achieved by classic statistics. pH appeared as the main discriminator of diversity and diatom species composition, nevertheless and due to the complex environment under study other chemical interactions must be considered: (a) AMD waters, with extremely low pH values, but also with extremely high hydrogeochemical complexity, represented by a mixture of metals, do not allow to associate, unequivocally, the reduction in diatom diversity to pH, but also to high metal (loid)s concentrations; (b) in the most alkaline waters, with higher abundance of diatom species, average to high concentrations of Na and Cl (due to Cenozoic sediments) do not seem to affect diatom diversity. This methodology proved to be an efficient tool to establish, for the first time, cause-effect relationships, improving the comprehension between biological (diatoms) and hydrochemical parameters.

Studies of practolol on mitochondrial metabolism.

The possible effect of practolol (ICI 50,172) on mitochondrial metabolism was studied. The drug inhibited the oxidation of glutamate, alpha-ketoglutarate and succinate by heart mitochondria. The polarographic determinations showed that practolol is an inhibitor of the oxidative phosphorylation. The activity of NADH-oxidase, NADH-ferricyanide reductase, NADH-cytochrome c redutase was inhibit by the drug; no effect was observed on the succinate dehydrogenase. The electron microscopy of isolated mitochondria treated with practolol showed that the drug promote conformational changes of the mitochondrial membrane, probably concerning with the detergent characteristics of the drug.