Optical Resilience of the Paraíba do Sul River (Brazil) during a Toxic Spill of a Wood-Pulping Factory: The Cataguazes Accident

Environ Monit Assess (2007) 129:137150 DOI 10.1007/s10661-006-9348-9

Optical Resilience of the Paraba do Sul River (Brazil) during a Toxic Spill of a Wood-Pulping Factory:The Cataguazes Accident

Paulo Pedrosa

Received: 26 January 2006 /Accepted: 14 June 2006 / Published online: 21 October 2006 # Springer Science + Business Media B.V. 2006

Abstract This study investigates the inherent optical properties (IOP) of a Brazilian river during a non-natural, anthropogenically mediated, toxic spill of a wood-pulping factory (the Cataguazes accident). The results indicated an outstanding transformation in the river water chromophoric dissolved organic matter (CDOM) pools. For instance, increases in CDOM absorption coefficients, aCDOM(1), which

were averaged at specific spectral intervals, CDOM(1), ranged from 58-fold at the UV-B and

UV-A ranges to 95-fold at the PAR range. As a result, the water color expressed as CDOM absorption at 440 nm, aCDOM(440), varied from 4.16 to 365.03 m-1.

For S-coefficient, the variations ranged from 1.1 to5.6-fold, respectively, at the 300650 nm and UV-B range. The variability of S as a proxy of dissolved chromophores was thus clearly influenced by the spectral range used. Optical proportions were also investigated through the use of CDOM(1) and S ratios

at the UV-B, UV-A, and PAR ranges and, in the case of CDOM(1), also at the NIR range. This approach

also showed clear variations between the water samples, likely reflecting changes in the composition

of optically active substances in the river system. As a whole, the findings obtained here indicated that both the quantity and quality of the chromophoric material dissolved in the river water were greatly altered by the toxic spill. The changes in the optical properties of the river water, although extreme and likely with no parallel in the literature, were quite rapid as indicated by the optical resilience of the system. Overall, this study indicates that IOP might be thought, and possibly used, as a metric tool for monitoring the state of waters and aquatic ecosystems.

Keywords IOP. aCDOM(1) and S coefficients .

pulp-mill environmental accident . water monitoring

1 Introduction

In aquatic systems such as rivers, lakes, estuaries, and oceans, the water itself and a variety of solutes comprise the dissolved fraction of the water medium. The solutes are more or less optically active and may function as both...