Estimation of weathering rates and CO2 drawdown based on solute load: Significance of granulites and gneisses dominated weathering in the Kaveri River basin, Southern India

Controls of DSi in streams and reservoirs along the Kaveri River, South India

“…The waters were characterized by high concentrations of Si, alkalinity, Cl − , Na + , Ca 2+ and Mg 2+ and low concentrations of F − , NO 3 − , SO 4 2− and K + (Table 1) in a good agreement with previous studies (Pattanaik et al, 2013). P was always below the detection limit.…”

“…The Kaveri TSM values we measured in 2006-2007 are in the same range as those found in previous two decades: 120 mg L −1 in Ramesh and Subramanian (1993); 1-50 mg L −1 in Subramanian et al (1985); and 1-99 mg L − 1 in Ramanathan et al (1994). Higher concentrations of most of the solutes during HS than during M are in a good agreement with a dilution effect by rain water input as suggested by Ramanathan et al (1994) and Pattanaik et al (2013). Considering the averages of the dissolved solids compared to values found before the 80s by Subramanian (1979) our data show little differences such as a slight decrease in SO 4 2 − (Table 4).…”

“…It is under the influence of a tropical monsoon climate. DSi along the Kaveri and its tributaries ranges from 233 to 450 μmol Si L − 1 (Subramanian, 1979;Ramanathan et al, 1994;Pattanaik et al, 2013), and is within the range of global values for rivers (100-383 μmol Si L − 1 ; Dürr et al, 2011). Elevated DSi concentration is attributed to intense chemical weathering of the crystalline rocks that constitutes the major geological cover of the drainage basin.…”

“…Considering the averages of the dissolved solids compared to values found before the 80s by Subramanian (1979) our data show little differences such as a slight decrease in SO 4 2 − (Table 4). However, if we compare the chemical composition of the Kaveri River basin taken from Subramanian (1979) and more recently from Ramanathan et al (1994) and Pattanaik et al (2013) with the TDS average taking into account all the values from the three seasons, our data overlap the existing data range. Only DSi and Ca 2+ were found to be higher during the 2007 monsoon sampling of Pattanaik et al (2013) for unclear reasons.…”

“…The NO 3 − concentrations, ranging from under the detection limit to 81 μmol L −1 , were very low for a watershed that is intensely cultivated. Pattanaik et al (2013) showed that some ions (Ca 2+ , Cl − , Na + ) increased towards the river mouth. Our data showed a significant decrease with elevation during PM and HS for most of the variables (conductivity, alkalinity, F − , Cl − , SO 4 2− , Na + , K + , Ca 2+ , Mg 2+ ) and during M for pH, Alk, and Ca 2+ (Table 2 and Fig.…”