Masayuki Kunugi

PHOSPHATE ACCUMULATION AND METABOLISM BY HETEROSIGMA AKASHIWO (RAPHIDOPHYCEAE) DURING DIEL VERTICAL MIGRATION IN A STRATIFIED MICROCOSM1

Diel vertical migration by Heterosigma akashiwo (Hada) Hada (Raphidophyceae) was monitored in a 1.5 in tall microcosm. Vertical stratification, with low salinity and low orthophosphate (Pi) concentration in the upper layer and high salinity and high Pi concentration in the lower layer, was simulated in the tank, analogous to summer stratification in the Seto Inland Sea. The phosphate metabolism of H. akashiwo during this vertical migration was studied using 31P‐NMR spectroscopy. At night this species migrated to the lower phosphate‐rich layer and took up inorganic phosphate (Pi) which then was accumulated as polyphosphate (PPi) by an increase in the chain length of PPi During the daytime this species migrated to the phosphate‐depleted surface water and utilized the accumulated PPi for photophosphorylation by decreasing the chain length of PPi During the first night after the phosphorus was introduced to the previously impoverished waters, the cells took up inorganic phosphate, accumulating the new phosphorus nutrient internally as Pi But the cells did not convert Pi to PPi presumably due to their lack of ATP. After the second day of the experiment, conversion of Pi to PPi at night was much more rapid than on the first day, presumably due to increased ATP availability. Then the cycle continued, with uptake of Pi and conversion to PPi at night at the bottom and its utilization during the day at the surface. These data suggest that the role of PPi in the metabolism of this species appears to be as a phosphate pool which regulates the level of Pi and ATP in the cell. Diel vertical migration allows this red tide species to shuttle between the phosphate‐rich lower layer and the photic upper layer in stratified waters. 31P‐NMR is shown to be a valuable tool in studying the phosphorus metabolism in migrating organisms.

LUXURY PHOSPHATE UPTAKE AND VARIATION OF INTRACELLULAR METAL CONCENTRATIONS IN HETEROSIGMA AKASHIWO (RAPHIDOPHYCEAE)1

The effectr of phosphate starvation and subsequent uptake on distribution and concentration of phosphate metabolic intermediates and metals were studied in Heterosigma akashiwo (Hada) Hada by 31P‐NMR spectroscopy, neutron activation analysis and ESR spectroscopy. Excess orthophosphate (4.5 μM Pi, as NaH2PO4) added to a medium with P‐depleted H. akashiwo cells was rapidly taken up resulting in an increase in P cell quota (qp)from 68.2 to 99.6 fmol. cell‐1in 2 h and to 156.3 fmol. cell‐1in 6 h. After three days, qp approached about 190 fmol. cell−1. Polyphosphate (PPi) rapidly increased from 0 to 11.4 fmol· cell−1in 2 h and to 24.7 fmol·cell−1in 6 h. Diel variation of cell quota indicated that cellular Pi increase was synchronized with cellular PPi decrease and vice versa. The average chain length of PPi increased from ca. 0 to ca. 10.2 phosphate residues in 2 h after addition of Pi and one day later, from ca. 9.8 to ca. 12.5.

Vertical distributions of suspended particles and their components as measured on a meteorological observation tower

Abstract Suspended particles have been continuously sampled at different heights in various seasons on the Meteorological Observation Tower (213 m) of the Meteorological Research Institute, Tsukuba, Japan. The concentration of suspended particles near the ground was found to be influenced by the atmospheric stability, which imposed a major effect on the seasonal variation of particle concentrations. The chemical components of the particles were divided into three groups according to their vertical distributions. The sources of chloride and nitrate in the suspended particles at Tsukuba were also discussed.

Construction of individual contribution type database for environmental problems

We have constructed an individual contribution type database on a private forum in one of the major telecommunications networks. Members of the private forum have sent and contributed various kinds of environmental information to a computer conference and a data library inside the private forum. Telecommunication is useful for retrieving and exchanging information with mutual understanding among members of the forum

XRF determination of trace metals in airborne particulates.

大気浮遊粒子状物質中の金属成分の分析を行うため,3種類のローボリウムエアサンプラーで捕集を行った.この試料を非破壊分析法であるXRF法に適用するため試料の均一性について調べた.多段型とサイクロン型のローボリウムエアサンプラーは,試料が不均一でありXRF用の試料としてそのままでは適さない.ダイコトマスサンプラーは均一な試料が得られるので適当と思われる.XRF用標準試料としてジエチルジチオカルバミン酸錯体フイルターケーキを作製し定量を試みた.ダイコトマスサンプラーで捕集した筑波の大気浮遊粒子状物質中の金属成分について約1年半観察し,春の黄砂の影響によるFe,Ca,Tiの増加と,冬の接地逆転時のPb,Zn,Cu,V,Brなど,人為発生源元素の増加が観測された.