Tokyo Bay, a eutrophic bay in Japan, receives nutrients from wastewater plants and other urban diffuse sources via river input. A transect was conducted along a line from the Arakawa River into Tokyo Bay to investigate the ecological relationship between the river outflow and the distribution, abundance and population structure of ammonia-oxidizing bacteria (AOB). Five surficial marine sediments were collected and analysed with polyphasic approaches. Heterogeneity and genetic diversity of beta-AOB populations were examined using restriction fragment length polymorphism (RFLP) analysis of 16S rRNA and amoA genes. A shift of the microbial community was detected in samples along the transect. Both 16S rRNA and amoA genes generated polymorphisms in the restriction profiles that were distinguishable at each sampling site. Two 16S rRNA gene libraries were constructed using the reverse transcription polymerase chain reaction (RT-PCR) method to determine the major ammonia oxidizers maintaining high cellular rRNA content. Two major groups were observed in the Nitrosomonas lineage; no Nitrosospira were detected. The effort to isolate novel AOB was successful; the isolate dominated in the gene libraries. For quantitative analysis, a real-time PCR assay targeting the 16S rRNA gene was developed. The population sizes of beta-AOB ranged from 1.6 x 10(7) to 3.0 x 10(8) cells g(-1) in dry sediments, which corresponded to 0.1-1.1% of the total bacterial population. An immunofluorescence staining using anti-hydroxylamine oxidoreductase (HAO) antibody was also tested to obtain complementary data. The population sizes of ammonia oxidizers ranged between 2.4 x 10(8) and 1.2 x 10(9) cells g(-1) of dry sediments, which corresponded to 1.2-4.3% of the total bacterial fraction. Ammonia-oxidizing bacteria cell numbers deduced by the two methods were correlated (R = 0.79, P < 0.01). In both methods, the number of AOB increased with the distance from the river mouth; ammonia-oxidizing bacteria were most numerous at B30, where the ammonium concentration in the porewater was markedly lower and the nitrite concentration was slightly higher than nearby sites. These results reveal spatial distribution and shifts in the population structure of AOB corresponding to nutrients and organic inputs from the river run-off and phytoplankton bloom.

Adhesion of ice, or ice-bonding phenomenon, at temperatures below 0° C was studied from the viewpoint of sintering. The growth rate of necks between ice spheres having radii R < 100 μ was measured in both saturated air and kerosene environments. The results showed that icebonding, or adhesion, takes place as a result of solid diffusion. Many photomicrographs of icebonds were taken by making use of thin-section technique.

AeSTRACT. The forma tion o f superimposed ice in the accumul a tion a rea o f sub-pola r glac ie rs pl ays a n importa nt role in the hea t and m ass bala nce of the glac iers. In order to study the process of superimposed ice form a tion in d etail , field observa ti ons were conduc ted o n M cCall G lacier, a sub-pola r gla cie r in Arcti c Alaska. It was found th a t the a pproximate thickn ess of superimposed ice fo rmed in a whol e summ er was 20 cm in the upper region a nd 30-40 cm in the lower r egion of the accumulatio n a rea of the gl acier. This difference in thi ckness may be a ttributed to the differe nce in the tempera ture of the underlying ice a nd the r a te of supply of melt water. T h e ratio of the a mount of superimposed ice fo rmed in the accumul a tion area from M ay to July in 1972 to the to ta l amount of melt was d etermined. Approxima tely 50 % o f the tota l melt wa ter w as discharged from the gl acier as run-off wate r, a nd the rem a ind er contributed to th e formation of superimposed ice.An experimental study on the a rtifi cia l forma tion of superimposed ice w as conducted in th e cold laboratory to obtain the ratio of superimposed ice, tha t of run-o ff wa ter, a nd that of free wa ter suspe nded between snow gra ins, to the total amount o f melt water produced in the snow. Th e ra ti os obtained in the la bora tory experiment a gree fairl y well with those d eri ved from the observationa l d a ta o n M cCall Glac ie r.Num eri cal calculations wer e conduc ted to exa mine the relationship b e tween the growth rate of superimposed ice, the ra te of snow m elting, the rate of discha rge of excess melt-wa te r , a nd the temper a ture of the u nderl ying ice. C alcula tions wer e m a d e in refere nce to both the labora to r y exp eriment and the field observations on M cC a ll Gla cier. It was found tha t the predomina nt fac tors co ntro lling the growth ra te or the tota l a mount o f superimposed ice in a sub-polar glacie r are the ra te of supply o f melt water to the snow-ice interface a nd the initial tempera ture distribution in the underlying ice. By u sing the prese nt ca lculation, it may be possibl e to estima te the growth rate, the total amount of superimposed ice, a nd the ra tio of superimposed ice to the to tal a mount o f m elting in the accumula tion area of a n y sub-polar glacier, if o bservational d a ta on the initia l tempera ture distribution in ice a nd th e ra te of snow m elting at the snow surface a re ava il a bl e. R ESUME. Observations de terra ills, i tlldes experimentales et thioriques de la glace de sllrimpositioll dll M cCall Glacier, Alaska . La form a tion de glace d e surimposition da ns la zone d 'accumul a ti o n d es glaciers sub-pola ires j oue un role importa nt dans les bilans d e m asse et de cha lcur d es glaciers. P our e tudier en deta il le processus de form a tion d e la gl ace de surimpositio n , d es observa tions d e terra in ont e te co nduites sur le M cC a ll G lacier, un gl acier sub-pol a ire d a ns I' Ar c tique A laska i...

Adhesion of ice, or ice‐bonding phenomenon, at temperatures below 0° C was studied from the viewpoint of sintering. The growth rate of necks between ice spheres having radii R < 100 μ was measured in both saturated air and kerosene environments. The results showed that ice‐bonding, or adhesion, takes place as a result of solid diffusion. Many photomicrographs of ice‐bonds were taken by making use of thin‐section technique.

ABSTRACT. This p a per presents many experimental data of fri ction between a slider a nd snow or ice in rela tion to ski-ing a nd ska ting. M easure m e nts of the kinetic coeffi cient of friction /-'k for a metallic or plasticresin ring in con tact w ith a snow surface were made using an oscillograph. The mechanism of this fri ction was a nal ysed through oscillograms showing fri ctional resistance be tween a slid er a nd a snow surface together with observations of the real contact a rea between the surface of the slider a nd sno w grains. It was sh own th a t fri ction at low sliding speeds caused plas tic deformation within snow, but, when sliding velocity was in creased, a stick-slip fri ction occurred accompanying fra c tures and a brasions o f snow grains. Since the la boratory experiment of friction on snow is limited to a range of low sliding speed s, the measurem ents of /-'k for high sliding velocities were mad e b y the use of practical skis. The value of /-'k for practical skis in creased from 0.03 to o. J as the speed increased from for veloci ties 5 to 22 m /soThe measureme nts of Ilk for skates w er e made using a sp ecially d esigned dev ice o n ska ting rinks pre pared both on na tural lake ice a nd artificial ice. The temperature d e pendence of /-'k was studied for the bl a d es of ska tes; Ilk showed a minimum value fo r both rinks a round -J to -2°C, na m ely, 0.003 for the natura l la ke ice and 0.007 8 for the artificial rink ice.R ESUME. La frictioll cill/!tique de la Il eige et de la glace. C e t article presente d e nombreux resultats ex perim e nta ux sur la friction entre un modele glissant et la neige ou la glace en relation avec le ski et le pa tin. D es mesures du coeffi cient cinetique d e fri ction Ilk pour un anneau metallique ou plastique en contact avec la surface de la neige ont ete realisees a I'a ide d' un oscillographe. Le mecanisme de cette friction a ete a nalyse a travers des oscillogrammes montrant la resistance due au frottement e ntre un glisseur et une surfa ce Versuchen zur R eibung zwischen ein em Gleitgerat und Schn ee oder Eis im Hinbli ck a uf Ski-und E isla uf. D e r K oeffi zient d er kin etischen R eibung /-'k fur einen M etall-oder Pl aslikring a uf e iner Schn eefl ach e wurde mit Hilfe eines O sz illographen gem esse n . D er R eibungsm echanismus wurde mit Oszillogrammen der R eibungswidersta nd es zwischen einem G leitgera t und Schnee sowie a us Beobachtungen einer wirklichen K o ntaktzone zwischen d en Oberflach e n d es G leitgera tes und d en Schneekornern a na lysiert. Es zeigte sich, d ass R eibung bei kl einen Gleitgeschwindigkeiten zu plastisch e n Verformungen im Schnee fuhrt , dass aber bei grosserer G leitgesch windigkeit eine H a ft-und Gleitreibung eintritt, mit d er Risse und Abbruche der Schneekorner verbunden sind. Da R eibungsversuche im Labor a ufkl eine Gleitgeschwindigkeiten beschra nkt sind, wurden die M essungen von Ilk bei hohen Gleitgeschwindigkeiten an wirk li ch e n Skiern vorgenommen. Dabei wuchs Ilk von 0,03 auf 0, J bei ei...