Relative importance of iron and molybdenum in restricting phytoplankton biomass in high phosphorus saline lakes
Relative importance of iron and molybdenum in restricting phytoplankton biomass in high phosphorus saline lakes
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DOI：
10.4319/lo.1997.42.3.0461
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发表时间：
1997-05-01
影响因子：
4.5
通讯作者：
Prepas, EE
中科院分区：
文献类型：
--
作者：
Evans, JC;Prepas, EE
对11个草原盐湖(电导率为1.8~58.8ms cm(-1))进行了1994年生长季的研究，以确定与盐度有关的一个或多个因素对浮游植物现存量作物的控制作用。研究湖泊具有较高的全P(0.15~24.2 mg L~(-1))、全N(3.75~12.35 mg L~(-1))、全Fe(55~2 800 m g L~(-1))、溶解有机C(40~195 mg L~(-1))、pH和碱度较高的特点，但相对较低(通常为3ms cm~(-1))，表明P充足；湖泊底栖生物缺乏N而不是蛋白质。固氮蓝藻只在所研究的一个湖泊中起重要作用。营养盐添加生物测定表明，浮游植物的生物量不仅受到无机氮有效性的限制，也不受钼和氮的组合的限制。对于除一个磷充足的湖泊以外的所有湖泊的水，在生物测定中添加铁导致CHIA浓度显著增加。添加Fe和Mo的效果与单独添加Fe的效果相同，而盐度最高的湖泊似乎受到一种或多种额外微量元素(而不是Mo)的限制。降低生物测定水的碱度以与添加铁相同的方式刺激生长，这表明已经存在的(主要是颗粒状)铁的生物有效性受到湖水碱度的严重限制。湖水碱度的某些成分(在这些湖泊中随着电导率的增加而增加)似乎是限制铁的生物有效性和限制浮游植物在高盐度湖泊中生长的关键因素。
Eleven prairie saline (conductivity 1.8-58.8 mS cm(-1)) lakes were examined over the 1994 growing season to determine what salinity-related factor or factors were responsible for controlling phytoplankton standing crops. The study lakes were characterized by high total P (0.15-24.2 mg liter(-1)), total N (3.75-12.35 mg liter(-1)), total Fe (55-2,800 mu g liter(-1)), dissolved organic C (40-195 mg liter(-1)), pH and alkalinity, but comparatively low (usually 3 mS cm(-1)), indicating P sufficiency; seston from these lakes was deficient in N but not protein. Nitrogen-fixing cyanophytes were important only in one of the lakes examined. Nutrient addition bioassays indicated that phytoplankton biomass was not limited exclusively by inorganic N availability, nor by a combination of Mo and N. For water from all but one of the P-sufficient lakes, addition of Fe to bioassays resulted in a remarkable increase in Chi a concentrations. Addition of Fe and Mo had the same effect as that of Fe alone, while the most saline lake appeared to be limited by one or more additional trace elements (but not Mo). Reducing the alkalinity of the bioassay water stimulated growth in the same manner as the Fe additions, suggesting that the bioavailability of the (largely particulate) Fe already present was severely restricted by lake-water alkalinity. Some component of lake-water alkalinity (which increased with conductivity in these lakes) appears to be the key factor limiting Fe bioavailability and restricting phytoplankton standing crops in the higher salinity lakes.