Steady-state solutions for subsurface chlorophyll maximum in stratified water columns with a bell-shaped vertical profile of chlorophyll

[摘要] A bell-shaped vertical profile of chlorophyll a (Chl a) concentration,conventionally referred to as a subsurface chlorophyll maximum (SCM)phenomenon, has frequently been observed in stratified oceans and lakes. Thisprofile is assumed to be a general Gaussian distribution in this study. Bysubstituting the general Gaussian function into ecosystem dynamicalequations, the steady-state solutions for SCM characteristics (i.e., SCMlayer depth, thickness, and intensity) in various scenarios are derived.These solutions indicate that (1) the maximum concentration of Chl aoccurs at or below the depth of maximum growth rates of phytoplankton locatedat the transition from nutrient limitation to light limitation, and the depthof SCM layer deepens logarithmically with an increase in surface lightintensity; (2) thickness and intensity of the SCM layer are mainly affectedby nutrient supply, but independent of surface light intensity; and (3) intensityof the SCM layer is proportional to the diffusive flux of nutrients frombelow, which becomes stronger as a result of this layer being shrunk by a higherlight attenuation coefficient or a larger sinking velocity of phytoplankton.In addition, the limitation and potential application of the analyticalsolutions are also presented.

[学科分类] 地球化学与岩石