Carbon budget for a groundwater-fed lake: Calcification supports summer photosynthesis

Abstract

A chemical budget analysis for Williams Lake, Minnesota, tracks the seasonal progression of carbon inputs and outputs. CO, exchanges with the atmosphere reverse seasonally, with uptake by the lake in summer preceded and followed by larger losses to the atmosphere. Calcium bicarbonate-rich groundwaters seep steadily into the lake, augmented by remobilization of lacustrine marls. Most of the carbon used in summer photosynthesis nevertheless derives from depletion of lake carbon stores, facilitated significantly by plant calcification.Calcification in summer reduces alkalinity and calcium inventories by 15 and 25%, respectively, while generating equal molar quantities of CO,. Marl precipitates mainly on submersed macrophytes, several of which calcify in 1 : 1 ratio to photosynthesis when incubated in Ca-supplemented lake water. Despite calcite supersaturation within the epilimnion, there is little authigenic calcification.

Carbon source/sink function of a subtropical, eutrophic lake determined from an overall mass balance and a gas exchange and carbon burial balance

“…Although there are some studies on the carbon source/sink function of lake ecosystems from carbon burial and gas exchange balances (Hanson et al, 2004) or from overall mass balances (Charlton, 1977;Eadie and Robertson, 1976;Maier and Swain, 1978;Mcconnaughey et al, 1994;Quay et al, 1986), we have found no published lake carbon budgets made using both methods simultaneously. As such, there are currently no direct comparisons of the two methods.…”

“…Consequently, the number of carbon budgets from lake ecosystems using an overall mass balance is currently limited. Up until now, mass balance carbon budget studies have been heavily biased towards north temperate lakes (Charlton, 1977;Eadie and Robertson, 1976;Maier and Swain, 1978;Mcconnaughey et al, 1994;Quay et al, 1986) where gaseous carbon (CO 2 and CH 4 ) fluxes, in particular CH 4 , were usually not taken into account. However, CO 2 and CH 4 fluxes across the watereair interface are relatively high (Cole et al, 1994;Xing et al, 2005) and are important parts of whole-lake carbon budgets (Quay et al, 1986;Cole and Caraco, 1998).…”

The mitigating effect of calcification-dependent of utilization of inorganic carbon of Chara vulgaris Linn on NH4-N toxicity

“…In previous studies, calcification to photosynthesis ratio varied from 1 to 2 as a function of solution pH between 9 and 10 ( McConnaughey et al, 1994;McConnaughey and Whelan, 1997;McConnaughey, 1998). This suggested the ratio of calcification to the utilization of DIC would varied between 0.5 and 0.67.…”

Hydrological and chemical estimates of the water balance of a closed‐basin lake in north central Minnesota

“…Chemical composition of the lake fluctuates seasonally in response to biological activity which causes the removal of CO2 by photosynthesis and precipitation of calcite [McConnaughey et al, 1994]. Approximately 10% of the seasonal change in mass of magnesium in the lake was due to magnesium uptake by plants and incorporation into marls.…”

“…Production of organic matter in the lake [McConnaughey et al, 1994] could provide the source of carbon needed to maintain dissolved organic carbon concentrations at levels measured in the lake despite the imbalance between input and output ( Figure 13). Furthermore, loss of organic carbon due to biodegradation and sorption as water seeps out of the lake could mean that export has been overestimated.…”