In Situ Monitoring of the Diurnal Cycling of Dynamic Metal Species in a Stream under Contrasting Photobenthic Biofilm Activity and Hydrological Conditions

Abstract

The diurnal evolution of the dynamic fraction, i.e., the potentially bioavailable fraction, of Cd, Cu, and Pb in a small river impacted by mining and smelting waste was studied in situ, under contrasting biofilm activity and hydrological conditions, using an automated voltammetric analyzer. The in situ, near real-time measurements revealed persistent dynamic metal species diurnal cycles. These cycles were affected mainly by the biochemical conditions rather than hydrological conditions. The data obtained from the in situ measurements, coupled with complementary laboratory analyses, revealed that various processes control the diurnal dynamic metal species cycles in the studied site; the trends of the diurnal cycles of the dynamic metal species can be different from those observed for the dissolved metal species measured in filtered samples. Moreover, the dynamic fraction of a given cationic metal can show diurnal cycles with opposite trends depending on the environmental conditions. All these findings highlight the interest and importance of automated, continuous measurements of specific relevant environmental metal fractions, compared to punctual weekly or monthly traditional sampling strategies of total dissolved metal analysis, to allow more appropriate water quality control and reliable assessment of metal ecotoxicological impact.

Water quality change of rivers during rainy events in a watershed with different land uses in Southern Brazil

“…Instruments such as multiparameter probes measure the water quality and can make samples in short intervals, either in an order of hours or minutes (AUBERT et al, 2014;HALLIDAY et al, 2015;TERCIER-WAEBER et al, 2009;WADE et al, 2012). The multiparameter probes have aided in complex evaluation of the dynamics of nutrients (HALLIDAY et al, 2014) and in the behavioral description of biogeochemical cycles of chemical species in water bodies (HALLIDAY et al, 2015;MORAETIS et al, 2010;WADE et al, 2012).…”

Combined Effects of Trace Metals and Light on Photosynthetic Microorganisms in Aquatic Environment

“…However, the capabilities of these techniques are rarely used to follow the effects of the light and photo-transformed DOM on the metal speciation. One of the few examples revealed diurnal changes in Cu, Cd and Pb speciation in the contaminated Riou Mort river (France), which coincided with changes in water quality parameters (pH, O 2 , temperature, DOM) associated with the photosynthetic activity of benthic phytoplankton and their EPS and exudates production [11,62].…”

“…The research focused on different metals including Zn [72][73][74]103], Cd [7,64,72,98,100,102], Hg [100], Cu [62,75,76,97], Ni [64], Pb [64] and on different light radiation components: visible [72][73][74][75]99,102] and UV radiation [7,75,76,97,98,100,101]. Most of the work explored these combined effects on model organisms, mainly cyanobacterial species [72][73][74]99], but the results are rather contrasting.…”

Evolution of physicochemical species concentration in streams based on heavy rainfall event data obtained for high-frequency monitoring

“…These technological developments provide rainfall measurements, stream flow, and physicochemical parameters in short time intervals (KIRCHNER et al, 2004), such as seven-hour intervals NEAL et al, 2013;NEAL et al, 2012), two-hour intervals (DONN; BARRON; BARR, 2012), hourly intervals (BOWES et al, 2015;HALLIDAY et al, 2014;JORDAN et al, 2007;RÜCKER;SCHRAUTZER, 2010;WADE et al, 2012), or in minutes (CASSIDY; JORDAN, 2011;DOWNING et al, 2009;MORAETIS et al, 2010;TERCIER-WAEBER et al, 2009). High frequency monitoring helps our understanding of the biogeochemical processes that occur in natural waters in short time intervals (MORAETIS et al, 2010;SANDFORD;EXENBERGER;WORSFOLD, 2007;WADE et al, 2012).…”

“…Studies with high frequency sampling of streams managed to correlate changes in the electrical conductivity to the water runoff (ROBSON et al, 1992), demonstrate the diurnal and seasonal dynamics of nutrients (BOWES; SMITH; NEAL, 2009;CASSIDY;JORDAN, 2011;DONN;BARRON;BARR, 2012;HALLIDAY et al, 2014HALLIDAY et al, , 2012MORAETIS et al, 2010;NEAL et al, 2012;SANDFORD;EXENBERGER;WORSFOLD, 2007;SCHOLEFIELD et al, 2005;WADE et al, 2012) and metal species (TERCIER-WAEBER et al, 2009), enable mass balances in watersheds (JORDAN et al, 2007;RÜCKER;SCHRAUTZER, 2010), and analyze the spatial and temporal variations of dissolved oxygen (MALCOLM; SOULSBY; YOUNGSON, 2006).…”