MODIFICATION OF THE N-P RATIO IN LAKES BY INSITU PROCESSES

被引:67
作者
LEVINE, SN
SCHINDLER, DW
机构
[1] UNIV ALBERTA, DEPT ZOOL, EDMONTON T6G 2E9, ALBERTA, CANADA
[2] UNIV ALBERTA, DEPT BOT, EDMONTON T6G 2E9, ALBERTA, CANADA
关键词
D O I
10.4319/lo.1992.37.5.0917
中图分类号
Q [生物科学];
学科分类号
07 ; 0710 ; 09 ;
摘要
In situ mesocosms in two Canadian Shield lakes were used to evaluate the contributions of in-lake vs. external sources of nitrogen and phosphorus to nutrient budgets and N:P ratios. These mesocosms were designed to have variable exchange with sediments. Half were fertilized with N and P at a ratio great enough to ensure P limitation for most phytoplankton (atomic ratio, 33:1); the other half were fertilized at a ratio low enough to cause N limitation (4.4:1) in the absence of compensation mechanisms. For littoral mesocosms, sediments were a major source of N, but not of P. A comparison of mesocosms having sediments with one having a plastic floor indicated that sediment N return was derived largely from decomposing material at the sediment surface, rather than from deep sediments. Disproportionate returns of N from sediments, along with lower denitrification, reduced N limitation in the low N:P mesocosms. In pelagic mesocosms, which lacked sediment contact, N2 fixation and thermocline entrainment late in the experiment were the principal internal N sources at low N:P. Biogeochemical mechanisms for reducing N:P in the water column at high N:P supply ratios were less effective than those that ameliorated N shortages at low N:P. The most important mechanism for reducing N:P was denitrification, while both N2 fixation and sediment return raised N:P. We conclude that biogeochemical mechanisms allow N shortages to be more readily overcome than P shortages in Canadian Shield lakes. Due to the importance of sediments as an N source, it is important to scale mesocosms so that they have sediment: water ratios similar to those of the lakes they are designed to simulate.
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页码:917 / 935
页数:19
相关论文
共 46 条
[1]  
[Anonymous], 1971, STAT PRINCIPLES EXPT
[2]   PRELIMINARY CHEMICAL CHARACTERIZATION OF WATERS IN EXPERIMENTAL LAKES AREA, NORTHWESTERN ONTARIO [J].
ARMSTRONG, FA ;
SCHINDLER, DW .
JOURNAL OF THE FISHERIES RESEARCH BOARD OF CANADA, 1971, 28 (02) :171-+
[3]  
BOSTROM B, 1982, HYDROBIOLOGIA, V91-2, P415, DOI 10.1007/PL00020032
[4]   CHEMISTRY OF SURFACE SEDIMENTS OF 16 LAKES IN EXPERIMENTAL LAKES AREA, NORTHWESTERN ONTARIO [J].
BRUNSKILL, GJ ;
POVOLEDO, D ;
GRAHAM, BW ;
STAINTON, MP .
JOURNAL OF THE FISHERIES RESEARCH BOARD OF CANADA, 1971, 28 (02) :277-+
[5]   BENTHIC PHOSPHORUS REGENERATION IN THE POTOMAC RIVER ESTUARY [J].
CALLENDER, E .
HYDROBIOLOGIA, 1982, 91-2 (01) :431-446
[6]   NITROGEN-FIXATION IN CANADIAN PRECAMBRIAN SHIELD LAKES [J].
FLETT, RJ ;
SCHINDLER, DW ;
HAMILTON, RD ;
CAMPBELL, NER .
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES, 1980, 37 (03) :494-505
[7]   ACETYLENE-REDUCTION ASSAYS FOR NITROGEN-FIXATION IN FRESHWATERS - NOTE OF CAUTION [J].
FLETT, RJ ;
RUDD, JWM ;
HAMILTON, RD .
APPLIED MICROBIOLOGY, 1975, 29 (05) :580-583
[8]  
Freeze A, 1979, GROUNDWATER
[9]   REGULATION OF GROSS GROWTH EFFICIENCY AND AMMONIUM REGENERATION IN BACTERIA BY SUBSTRATE C-N RATIO [J].
GOLDMAN, JC ;
CARON, DA ;
DENNETT, MR .
LIMNOLOGY AND OCEANOGRAPHY, 1987, 32 (06) :1239-1252
[10]   COUPLING CARBON FLOW THROUGH SOME PELAGIC AND BENTHIC COMMUNITIES [J].
HARGRAVE, BT .
JOURNAL OF THE FISHERIES RESEARCH BOARD OF CANADA, 1973, 30 (09) :1317-1326