Contribution of zooplankton to the total cadmium pool in Canadian shield lakes varying in acidity

Crustacean zooplankton >250 m in size contributed 0.002 to 11% (median of 1.3%) of the total Cd in the epilimnia of 39 Canadian Shield lakes that ranged in pH from 4.7 to 8.3. The contribution of zooplankton to the total Cd pool was consistently low (1%) only in clear water lakes with pH < 5.0.=" in=" three=" intensively=" studied=" lakes,=" the=" contribution=" of=" zooplankton=" to=" total=" aqueous=" cd=" varied=" with=" time=" and=" depth,=" the=" maximum=" contribution=" (4=" to=" 6%)=" occurring=" in=" the=" metalimnion=" in=" mid-summer.=" changes=" with=" depth=" and=" time=" were=" principally=" a=" product=" of=" seasonal=" changes=" in=" zooplankton=" biomass=" and=" seasonal=" succession=" of=" species=" with=" inherently=" different=" tendencies=" to=" accumulate=" cd.=" implications=" for=" the=" study=" of=" cd=" cycling=" in=" lakes=" are=">