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Showing papers on "Phosphorus published in 1970"







Journal ArticleDOI
14 Aug 1970-Science
TL;DR: After diversion of sewage effluent from Lake Washington, winter concentrations of phosphate and nitrate decreased at different rates, but nitrate remained at more than 80 percent of the 1963 value and free carbon dioxide and alkalinity remained relatively high.
Abstract: After diversion of sewage effluent from Lake Washington, winter concentrations of phosphate and nitrate decreased at different rates. From 1963 to 1969, phosphate decreased to 28 percent of the 1963 concentration, but nitrate remained at more than 80 percent of the 1963 value. Free carbon dioxide and alkalinity remained relatively high. The amount of phytoplanktonic chlorophyll in the summer was very closely related to the mean winter concentration of phosphate, but not to that of nitrate or carbon dioxide.

275 citations



Journal ArticleDOI
TL;DR: The phosphorus of glucose-6-phosphate residue in potato starch (P(G6P)) was estimated specifically by means of glucose 6-phophosphate dehydrogenase (E.C.1.49) after acid hydrolysis.
Abstract: The phosphorus of glucose-6-phosphate residue in starch (P(G6P)) was estimated specifically by means of glucose-6-phosphate dehydrogenase (E.C.1.1.1.49) after acid hydrolysis. Sixty to 70 % of total phosphorus in potato starch was found to be P(G6P)). It was shown that the rest of phosphorus (Px) was incorporated as glucose-2-phosphate and/or glucose-3-phosphate, since it was determined as glucose by periodate oxidation, borohydride reduction, acid hydrolysis and treatment with alkaline phosphatase. The Px was more labile to acid and heat than P(G6P) and decomposed yielding inorganic phosphate. The phospholigosacharide (D. P. 3.6), which was prepared by the limit hydrolysis of potato starch with glucoamylase of Rh. delemar (α-1,4-Glucan glucohydrolase E.C.3.2.1.3) was fractionated by gel-filtration through Sephadex G-25 into fractions with D.P. 2 to 7. Each fraction contained a mole of phosphorus per mole of the saccharide. The P(G6P) and the Px were enriched in the low and the high D.P. fractions, respectively.

197 citations


Journal ArticleDOI
TL;DR: In this paper, the rates of photosynthesis (carbon dioxide fixation in the light expressed on a per unit chlorophyll or per unit fresh-weight basis) and respiration (Carbon dioxide evolution in the dark expressed on either per unit nitrogen, phosphorus, sulphur, manganese, zinc and molybdenum deficiencies resulted in reduced respiration rates.
Abstract: Spinach plants were grown in nutrient-culture solutions containing reduced levels of all the macro- and micro-nutrient elements except cobalt and chlorine. The rates of photosynthesis (carbon dioxide fixation in the light expressed on a per unit chlorophyll or per unit fresh-weight basis) and respiration (carbon dioxide evolution in the dark expressed on a per unit nitrogen or per unit fresh-weight basis) for whole plants were measured using infra-red gas analysis techniques. Measurements were made when the plants displayed clear symptoms of deficiency relative to control plants. All nutrient deficiencies except iron and molybdenum depressed photosynthesis when chlorophyll was the basis of calculation; manganese-, copper-, phosphorus- and potassium-deficient plants showed the greatest depression. Alternatively when photosynthesis was calculated on a fresh weight basis calcium was the only deficiency which had no affect. Similarly when respiration was calculated on a nitrogen basis all deficiencies except iron, molybdenum and nitrogen result in depressed rates but when respiration was expressed on a fresh-weight basis potassium deficiency resulted in enhanced respiration rates and nitrogen, phosphorus, sulphur, manganese, zinc and molybdenum deficiencies resulted in reduced respiration rates.

141 citations



Journal ArticleDOI
TL;DR: Higher plant levels of phosphorus and sulphur were measured in the ammonium treatment and higher Ca and Mg in the nitrate treatment indicating a predominately cation-anion balance effect.
Abstract: No yield differences in tops or roots were measured between ammonium and nitrate nitrogen sources in flow ‘United 108’ grown for 14 or 28 days in constant flow culture solution. There was a greater uptake of N from the nitrate source but approximately 25% of the total uptake remained as nitrate within the plant. Higher plant levels of phosphorus and sulphur were measured in the ammonium treatment and higher Ca and Mg in the nitrate treatment indicating a predominately cation-anion balance effect.





Journal ArticleDOI
TL;DR: A hypothesis for the mechanism of inositol phosphorylation is presented, based on experiments on ripening grains of rice and wheat, which shows a more active participation of phytic acid as a phosphagen, rather than as a source of phosphorus at germination.
Abstract: The ripening process of plants is characterized by the accumulation of substances in the seeds. The important mineral nutrient phosphorus is no exception to this accumulation process. The active transport of phosphorus to seeds from leaves and roots is an important part of the ripening. In the rice plant, at the end of the ripening, about 60% of the phosphorus in the whole plant is found in the grains.l Most of the phosphorus thus transported to the seeds exists in the form of phytic acid, inositol hexaphosphate. In cereal grains, 60-80% of the total phosphorus is found in phytic acid. It has been generally supposed that phytic acid functions as a storage form of phosphorus and is utilized as a source of phosphorus at germination. Recently, the occurrence of transphosphorylation between phytic acid and adenosine diphosphate has been suggested.2 Further, the occurrence of an enzyme catalyzing the transphosphorylation between phytic acid and guanosine diphosphate was established in mung bean.3 These findings show a more active participation of phytic acid as a phosphagen, rather than as a source of phosphorus at germination. We do not have much information regarding the formation of phytic acid, but the enzyme catalyzing the formation of inositol monophosphate has been fo~nd .4 -~ However, the phosphorylation mechanism in the biosynthesis of more highly phosphorylated inositol is unknown. Phytic acid is unique in having six phosphate ester linkages in one molecule of small molecular weight; hitherto, a highly phosphorylated compound such as phytic acid has not been known. From this point of view, it is supposed that phosphorylation of inositol is carried out through a mechanism different from the usual kinase reaction. A hypothesis for the mechanism of inositol phosphorylation, based on experiments on ripening grains of rice and wheat, is presented in this paper. According to this hypothesis, the phosphorylation of inositol in the formation of phytic acid does not occur in a sequential fashion through phosphorylated inositol, but occurs through a hypothetical phosphorylated inositol derivative. The occurrence of a new kind of polyphosphorylated inositol derivative in the ripening grains is postulated as a possible candidate.





Journal ArticleDOI
01 Jan 1970-Analyst
TL;DR: The photo-oxidation method described by Armstrong, Williams and Strickland for determining total phosphorus and nitrogen in sea water has been adapted for analysis of fresh-water samples and extended to include the determination of total iron.
Abstract: The photo-oxidation method described by Armstrong, Williams and Strickland for determining total phosphorus and nitrogen in sea water has been adapted for analysis of fresh-water samples and extended to include the determination of total iron. The samples are subjected to ultraviolet irradiation in a photochemical reactor consisting of a high pressure mercuryarc lamp, a reactor body with twenty-four fused silica sample tubes and a cooling fan. Organically combined phosphorus and iron are converted into orthophosphate and iron(III) ions in the presence of acid and excess of oxygen after an irradiation time of 1 hour. Organonitrogen compounds and ammonia in solutions with pH range 6·5 to 9 are oxidised to nitrate and nitrite after 4 hours' irradiation in the presence of excess of oxygen, which excess is ensured by addition of a few drops of 30 per cent. hydrogen peroxide solution.

Journal ArticleDOI
TL;DR: In this paper, the rate of sorption of phosphorus by lake muds, under aerobic conditions, from two lakes and from three depths in one lake, indicated that as little as 0.4 g (dry wt) of mud could sorb about 0.05 mg Pod-P in less than 30 min.
Abstract: Phosphorus-limited Selenastrum and CZado$zoru sp. will respond by growth or changes in extractable POa-P to as little as 0.02 mg POC-P in solution; these same spccics did not respond when exposed for a period of 1 or 2 weeks to as much as 2 mg of phosphorus as lake muds under aerobic conditions. Studies of the rate of sorption of phosphorus by lake muds, under aerobic conditions, from two lakes and from three depths in one lake, indicated that as little as 0.4 g (dry wt) of mud could sorb about 0.05 mg Pod-P in less than 30 min. These findings suggest that the sorption of phosphorus by lake muds under aerobic conditions can be used to remove phosphorus from lake water.




Journal ArticleDOI
TL;DR: Phosphorus-starved cells of Anabaena flos-aquae rapidly increase their capacity to reduce acetylene to ethylene when they receive phosphorus, which may be used as a bioassay for detecting available phosphorus in aquatic ecosystems.
Abstract: Phosphorus-starved cells of Anabaena flos-aquae rapidly increase their capacity to reduce acetylene to ethylene when they receive phosphorus. This response may be used as a bioassay for detecting available phosphorus in aquatic ecosystems. The sensitivity of the method compares favorably with conventional methods for measuring dissolved orthophosphate, and has the additional advantage that it measures available phosphorus. Studies on Wisconsin lakes show that available phosphorus generally is present, that the concentrations are higher at the lower depths than at the surface, and that there may be diurnal variations in the available phosphorus content of surface waters. Important sources of available phosphorus in Lake Mendota are the waters below the thermocline and the input from storm sewers.