TY - JOUR
T1 - When large lakes respond fast
T2 - A parsimonious model for phosphorus dynamics
AU - Katsev, Sergei
PY - 2017/2/1
Y1 - 2017/2/1
N2 - This article illustrates how the time scale of lake responses to external inputs of limiting nutrients, such as phosphorus, can be evaluated with minimum calculation from a simple mass balance model that takes into account nutrient recycling in sediments. The characteristic transient time can be estimated from τtrans≡τ−1+η1−k−1where τ (yr) is the hydrological residence time, η (yr− 1) characterizes the rate of nutrient removal by settling from the water column, and k (between 0 and 1) is the efficiency of nutrient recycling in sediment. At steady state, τtrans is equivalent to the nutrient residence time with respect to inputs Ist, so that, for given inputs, the steady state nutrient level (Wst) can be calculated as Wst=τtransIst Application of the model to the Laurentian Great Lakes reproduces the historical data for total phosphorus levels and suggests changes in recent decades in the rate of P sequestration from the water column into sediments. The model demonstrates that lakes with sediment phosphorus recycling efficiencies of < 50%, such as many oligotrophic and well-oxygenated large lakes of the world, can respond to external P inputs quickly even when the hydrological residence time of water is long. Higher recycling efficiencies lead to a dominance by internal loading and increased response times. When net sedimentation is positive (k< 1), however, lakes should respond to changes in external P inputs faster than their hydrological residence time even when their P budgets are dominated by internal loading.
AB - This article illustrates how the time scale of lake responses to external inputs of limiting nutrients, such as phosphorus, can be evaluated with minimum calculation from a simple mass balance model that takes into account nutrient recycling in sediments. The characteristic transient time can be estimated from τtrans≡τ−1+η1−k−1where τ (yr) is the hydrological residence time, η (yr− 1) characterizes the rate of nutrient removal by settling from the water column, and k (between 0 and 1) is the efficiency of nutrient recycling in sediment. At steady state, τtrans is equivalent to the nutrient residence time with respect to inputs Ist, so that, for given inputs, the steady state nutrient level (Wst) can be calculated as Wst=τtransIst Application of the model to the Laurentian Great Lakes reproduces the historical data for total phosphorus levels and suggests changes in recent decades in the rate of P sequestration from the water column into sediments. The model demonstrates that lakes with sediment phosphorus recycling efficiencies of < 50%, such as many oligotrophic and well-oxygenated large lakes of the world, can respond to external P inputs quickly even when the hydrological residence time of water is long. Higher recycling efficiencies lead to a dominance by internal loading and increased response times. When net sedimentation is positive (k< 1), however, lakes should respond to changes in external P inputs faster than their hydrological residence time even when their P budgets are dominated by internal loading.
KW - Great Lakes
KW - Internal and external loading
KW - Lake Baikal
KW - Phosphorus
KW - Sediment
KW - Time scales
UR - http://www.scopus.com/inward/record.url?scp=85008214297&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85008214297&partnerID=8YFLogxK
U2 - 10.1016/j.jglr.2016.10.012
DO - 10.1016/j.jglr.2016.10.012
M3 - Article
AN - SCOPUS:85008214297
SN - 0380-1330
VL - 43
SP - 199
EP - 204
JO - Journal of Great Lakes Research
JF - Journal of Great Lakes Research
IS - 1
ER -