Acid Mine Drainage is a water pollution type characterized by several topics such as high acidity, sulfate and heavy metal concentrations. One of the chemical characteristics is the absence of correlation between pH and conductivity, as could be expected. This last parameter is well correlated with other variables such as sulfate concentration and can be used as a field assessment. The absence of pH/conductivity correlation is largely discussed by several authors. In this work, the use of fuzzy logic algorithms in a large temporal database (over 20,000 records) has allowed us to study the "hidden" relation between them. This work finds this correlation, with some conditions such as the range of pH where it happens. Maybe the study of the usual range of pH values in previous studies has disturbed the correlation because of other chemical processes.

No abstract

In this work, the determination of moving averages is proposed as a method for quantifying metal, arsenic, and sulfate discharges into a water course undergoing acid mine drainage processes which flows into a public water supply dam in the Iberian Pyrite Belt. The analysis of the results obtained by applying moving averages shows that the highest metal and sulfate concentrations occur in October, coinciding with the first rainfall and the sponging of mine dumps, with November and December being the months when the highest contributions to the Andevalo Dam take place. The discharge of acid mine waters with its corresponding metal load into the Andevalo Dam means, for a single hydrological year, more than 6,000 t of sulfates, almost 600 t of iron, and 1 t of As, of special relevance for the hydrochemical quality of the stored waters. When they arrive at the dam, these metals precipitate, since the water pH is near 7, and remain latent in the bottom sediment as long as the chemical makeup of the dam water does not change.

Acid mine drainage is the main problem encountered by sulphide mining operations, not only because of its ecological aspects, but also because, once it appears, it is very difficult to remediate both technologically and economically. This paper characterises the response of an acid mine drainage-affected channel in the Iberian Pyrite Belt (Southwest of the Iberian Peninsula, Huelva, Spain) to the stimulus of rainfall in its drainage basin by studying the cause-effect relationships between sulphate, iron, copper, zinc, manganese, arsenic and cadmium concentrations in water samples taken at three points and rainfall in the zone.

The lack of statistical interdependence relationships between pH and conductivity in channels exposed to Acid Mine Drainage processes is a phenomenon reported by various authors. Based on the study of a large mass of data with over 23,000 records of pH and conductivity taken in a typical mining channel in the Iberian Pyrite Belt in SW Spain, the present work confirms the existence of a quite different fact, which is the appearance of high negative correlation coefficients between both variables.