不同水平磷对磷饥饿墨兰某些生化特性的影响

本文研究不同水平磷对磷饥饿墨兰［Ｃｙｍｂｉｄｉｕｍｓｉｎｅｎｓｅ（Ａｎｄｒ．）Ｗｉｌｌｄ］植株某些生化特性的影响．随着ＮａＨ２ＰＯ４浓度的增高,植株中的无机磷酸、磷脂酸、肌醇六磷酸、磷酸已糖、高能磷酸化合物和核酸等的含量都有不同程度的提高,其中以肌醇六磷酸提高最显著．酸性磷酸酯酶活性与磷浓度呈负相关．０．２０ｍｍｏｌ／ＬＮａＨ２ＰＯ４可能基本满足墨兰植株生长的要求．缺磷时叶片的蛋白质、无机磷酸和可溶性糖的含量较低,而游离氨基酸和淀粉的含量较高．因此,缺磷条件下生长的植株矮小的原因,可能主要是缺乏蛋白质。     

不同固磷方式对巢湖沉积物磷吸附行为的影响

内源磷负荷将严重阻碍富营养化湖泊的恢复,其控制技术的关键在于有效增强沉积物吸附磷的能力,而相关研究相对较少。研究以典型富营养化湖泊(巢湖)严重污染区域的沉积物为实验对象,系统比较了常规固磷方式(施用CaCl2、FeCl3、AlCl3与曝气)对沉积物磷吸附行为和间隙水溶解态可反应磷(SRP)浓度的影响。结果表明:施用不同剂量的CaCl2之后,沉积物磷最大吸附量和吸附能均无显著变化,间隙水SRP浓度和沉积物磷平衡浓度(EPC0)仅有较小幅度的下降;FeCl3和AlCl3的施用可明显增加沉积物磷的最大吸附量和吸附能,同时有效降低间隙水SRP浓度和EPC0值,即沉积物显示更强的从水中吸附磷的能力。当同处低剂量水平时,铁能更有效地降低沉积物EPC0值;反之,曝气对沉积物最大吸附量和吸附能均无显著影响,却明显提高了间隙水SRP浓度和沉积物EPC0值,进而导致更强的磷释放风险。故建议将适量铁的施用作为富营养化湖泊沉积物修复的有效技术,且慎用曝气处理。     

COMPETITION FOR PHOSPHORUS BETWEEN DESMIDS1

During competition for phosphate in continuous cultures, Cosmarium subcostatum Nord. routinely displaced Staurastrum paradoxum Meyer. The rate of displacement was independent of cell density between 100 and 6000 cells mL^?1. This suggests that competition for nutrients is important over a wide range of naturally occurring cell densities. C. subcostatum had higher saturated rates of phosphate uptake but also higher half saturation values for uptake. As a result, the two desmids were similarly able to take up phosphate at low concentrations. The competitive advantage of C. subcostatum lay in its greater yield per unit of phosphorus. Growth of the two algae in shared medium in a dual-chamber chemostat had no effect on uptake or yield characteristics.     

三种鱼的磷排泄及其在微型生态系统磷再循环中的作用

在考查罗非鱼或鲢、鳙下行影响的微型生态系统实验后期 ,对三种鱼的特定正磷酸盐 (PO4 P)排泄率进行了测定 ,并且估算了系统中实验鱼的PO4 P排泄率。结果表明 ,在个体大小相同的情况下 ,罗非鱼的特定PO4 P排泄率明显地高于链、鳙 ,似乎同它们的食物含磷量无关而由其体组织含磷量所决定 ;放养罗非鱼的系统中鱼的PO4 P排泄率比放养链、鳙的系统平均高 2倍多 ,其磷排泄对浮游植物的PO4 P供给率分别为 10 0 %— 15 8%和 6 1%—7 5 %。根据有鱼系统中PO4 P的供求关系和实验结束时磷分布的观测结果推断 ,沉积物的磷释放是系统中磷再生的主要途径 ,而实验鱼调节系统磷再循环的主要机制是排粪。     

PHOSPHORUS DYNAMICS IN THE MONIMOLIMNION OF SWARTVLEI

SUMMARY

The exchange of phosphorus between the bottom sediment and monimolimnion of Swartvlei, a meromictic, humic lake, was investigated during the last three months of 1980. The concentrations of oxygen, dissolved salts, phosphorus and Fe⁺⁺ in the water column were monitored, and electrode potentials in the bottom mud were measured, at approximately weekly intervals. At the same time laboratory experiments were performed, using Jenkin core samples, to observe the effect of changing oxygen concentration and salinity on phosphate exchange between sediment and water, and on electrode potentials at the sediment-water interface. Phosphorus was released under unaerobic conditions at a rate of 2,5 mg P m^?2 d^?1 and was taken up again under aerobic conditions at 1,6 mg P m^?2 d^?1 These values were in agreement with existing observed data on changes in phosphate concentration.     

CHARACTERISTICS OF PHOSPHORUS DEFICIENCY IN ANABAENA1

Several aspects of the metabolism and composition of a strain of Anabaena have been studied during phosphorus deficiency. The effects of medium composition, substrate concentration, temperature, pH, and illumination on alkaline phosphatase activity and phosphate uptake have been examined. Of particular interest among these results was the dependence of maximum alkaline phosphatase activity on Ca and of phosphate uptake on Mg. Depletion of dissolved phosphate from the culture medium runs accompanied by a marked increase in alkaline phosphatase activity, initial rate of phosphate uptake, and total amount of phosphate taken up to satisfaction of the phosphorus debt. Readdition of phosphate to a phosphorus-deficient culture resulted in a rapid decline in the ability to take up phosphate but no loss of alkaline phosphatase beyond dilution of activity already present. Entry into phophorus deficiency was accompanied by a loss of heterocysts, a decline in chlorophyll a, protein, RNA, and cellular phosphorus, and an increase in carbohydrate per unit dry weight. The possible use of these changes as physiological indicators of phosphorus limitation in natural situations is discussed.     

SOME ASPECTS OF THE DISTRIBUTION OF REACTIVE PHOSPHORUS IN LAKE McILWAINE,RHODESIA: PHOSPHORUS LOADING AND ABIOTIC RESPONSES

SUMMARY

This study was designed to investigate the apparent loss from the water column in Lake McIlwaine This study of significant quantities of reactive phosphorus. The Total Reactive Phosphorus mass-balance for the lake for 1977/78 was calculated, and both in situ and laboratory experiments were carried out to determine the effect of the lake sediments on the phosphorus loading of the lake. The experimental results showed that both uptake and release of phosphorus occurs in the lake, but that uptake of phosphorus by the sediments was by far the dominant process, thus accounting for the observed loss of phosphorus from the water column. The availability of the bound phosphorus for algal growth was also studied and it is suggested that algal uptake of bound phosphorus is possible. Various factors affecting phosphorus uptake by the sediments are discussed.     

不同水平磷对磷饥饿墨兰生长发育及某些生理特性的影响

将磷饥饿的墨兰无土栽培在5个NaH_2PO_4水平的营养液中,结果表明:0.20mmol/L NaH_2PO_4有利于叶芽生长;当叶片张开后,1mmol/NaH_2PO_4促进光合作用和呼吸作用,叶片生长较快,褐斑病病斑较少,每株花数增多.     

不同水平磷对磷饥饿墨兰生长发育及某些生理特性的影响

将磷饥饿的墨兰无土栽培在5个NaH_2PO_4水平的营养液中,结果表明:0.20mmol/L NaH_2PO_4有利于叶芽生长;当叶片张开后,1mmol/NaH_2PO_4促进光合作用和呼吸作用,叶片生长较快,褐斑病病斑较少,每株花数增多.     

DISSOLVED ORGANIC PHOSPHORUS EXCRETION BY MARINE PHYTOPLANKTON1,2

The amounts of extracellular dissolved organic phosphorus (DOP) produced by 8 species of marine planktonic algae under various conditions of light, salinity, and nutrition were compared. Large amounts, more than 20% of the total P in the system, were excreted by Cyclotella cryptica, Thalassiosira fluviatilis, Dunaliella tertiolecta, and Synechococcus under 1 or more of the experimental conditions. Excretion of DOP was proportional to light intensity in Dunaliella, Rhodomonas, Chlorella sp., and Coccolithus huxleyi. Phosphorus limitation reduced DOP production by Cyclotella and Thalassiosira, nitrogen limitation reduced DOP production by Phaeodactylum, Dunaliella, and Rhodomonas, and lack of iron reduced DOP levels in Cyclotella cultures. Salinity affected growth, but no clear relationship to DOP excretion was evident. The DOP eliminated during growth was reassimilated by the species that produced it and by other species, but lack of alkaline phosphatase reduced the amount of DOP that was available to certain algae.