Correlation of precipitable water vapour values over the United States with physical and chemical parameters Part I: Seasonal trends with precipitation and its nitrate content. Geographic changes of nitrate

Summary The analysis ofReitan's data on precipitable water vapour in the atmosphere, and data ofJunge on the nitrate content of precipitation, is extended onto a seasonal basis. Computations indicate consistency between precipitable water vapour, precipitation and its nitrate content, within a semiemprical law proposed, and especially for the warmer trimestres of the period July 1956–June 1957. A simple expression correlating the atmospheric content of precipitable water vapour over stations situated between sea level and 580 ft of altitude, with temperature, is suggested and tested. Increasing trends of atmospheric nitrate with latitude are established for all seasons of the period examined.Contribution of the Centro Nucleazione Aerosoli of the National Research Council of Italy, Via Vettore 4 (Monte Sacro),Rome.     

On the biophilic nature of iodine in seawater

Vertical profiles of concentrations of iodate- and total-iodine have been measured at thirty stations in the Pacific, Atlantic and Antarctic Oceans. The salinity-normalised iodine profiles are indicative of both iodine removal and iodate reduction in the euphotic zone. Thus, surface waters appear to be depleted in iodate-iodine (by 0.03?0.22 μM) but less so in total-iodine (by<0.01?0.06 μM) when compared with the near-constant iodine concentrations (～0.46 μM) at depth. Graphs of specific total-iodine versus specific phosphate fit a linear model well and lie within a narrow envelope for all stations, suggesting a direct coupling of iodine and nutrients during assimilation/regeneration. The I/C atom ratio calculated from these hydrographic data (1.0 × 10^?4) agrees well with contemporary plankton compositions (I/C= 1.4 (±0.8) × 10^?4). Similar graphs involving specific iodate also fit a linear model well. However, their gradients vary from station to station leading to a variability in I/C interconversion ratio, analogous to the variability of Redfield nutrient ratios for coastal waters. This variation is attributed to changes in both productivity and nitrate availability. Pacific deep waters contain anomalously high total-iodine concentrations which may reflect regional differences of I/P ratio in surface waters or else diffusion of iodine from bottom sediments.     

On ground-level visibilities in the Po-Valley during winter,and on their intercorrelations

Summary Results of intercorrelations between daily average visibilities, at 18 Observatories situated in the Po-Valley, indicate the existence there of several areas within which conditions of fog are similarly affected. The position of those areas reflects the influence of geographic and topographic factors on fogs which regularly recur, during the cold seasons, in that extensive part of Northern Italy.     

The New Certification Procedure of the Canadian Certified Reference Materials Project

The Canadian Certified Reference Materials Project has amended its procedure in interla-boratory certification programs. The reasons for reducing to one from two the number of bottles of a candidate reference materials submitted to each participating laboratory are discussed. The effect of the smaller number of results of the one-bottle approach to be expected on the certified value and 95% confidence interval is shown to be minor.     

Eigenvector analysis of reconstructed Holocene July temperature departures over northern Canada

July temperatures for the past 6000 yr at 11 sites in northern Canada have been predicted by transfer-function equations. Normalized departures from the mean of each time series at 250-yr intervals are analyzed by principal component (eigenvector) analysis. An initial analysis included 9 sites and the first three principal components accounted for 85.7% of the variance. Maps of the loadings on the principal components show broad spatial coherence on all three components. Temporal coefficients (principal component scores) illustrate major regional and local midsummer temperature variations. An additional 2 sites were then included but the spatial pattern of the loadings remained essentially unchanged. A further test of this approach, with a view toward predicting paleoclimates of northern regions, was to use the spatial coefficients (loadings) to estimate the July temperature departures at an “unknown” site (Long Lake, Keewatin). This reconstruction compares favorably with an independent transfer-function reconstruction (Kay, 1979). Power spectrum analysis of the significant principal component scores (temperature departures) over the 6000 yr showed that the temporal fluctuations associated with the first three principal components follow a “red noise” spectrum, indicative of strong persistence in the reconstructed climatic records. The scores on the fourth principal component approximate a “white noise” spectrum. A peak in power between 2000 and 3000 yr occurs in the variance spectrum of the second principal component (significance 10%). We conclude that eigenvector analysis of Holocene paleoclimatic data has considerable power and may be useful for identifying regional and local climatic variations.     

Continental Oxygen Isotopic Record of the Last 170,000 Years in Jerusalem

A long radiometrically dated oxygen isotopic record of continental climatic variations since the penultimate glaciation was obtained from a stalagmite deposited in a sealed cave in Jerusalem. This record shows that speleothems have the potential of assigning dates to long- and short-term climatic events, with possible refining of Milankovitch tuning of ice and marine records which themselves are not datable. Short-term (1000-yr) events are very significant in the region, reaching 50% of glacial/interglacial fluctuations. The Mediterranean Sea was the most probable source of local precipitation throughout the last glacial cycle.     

Palaeoclimatic implications of isotopic data from modern and early Holocene shells of the freshwater snail Melanoides tuberculata, from lakes in the Ethiopian Rift Valley

Carbon and oxygen isotope ratios in the shells of the freshwater snail Melanoides tuberculata yield information on the isotopic composition of the water in which the shell was formed, which in turn relates to climatic conditions prevailing during the snails' life span. Melanoides is particularly important because it is widespread in Quaternary deposits throughout Africa and Asia and is ubiquitous in both fresh and highly evaporated lakes. Whole-shell and incremental growth data were collected from modern and fossil shells from two lakes in the Ethiopian Rift Valley. 18O values in the modern shells from Lake Awassa are in equilibrium with modern waters, while 18O values in subfossil shells from the margins of Lake Tilo indicate high rainfall during the early Holocene. Sequential analysis along the growth spiral of the shell provides information on seasonal or shorter-term variability of lake water during the lifetime of the organism.     

Formation of nitrite during the decomposition of aqueous ammonium niumate,under natural ultraviolet radiation

Summary The photodecomposition of ammonium nitrate at various concentrations, in ventilated, aqueous solutions, is investigated as a function of radiation intensity, both under sunlight illumination and under artificial ultraviolet light. The process of decomposition, to nitrogen and water, of ammonium nitrite formed, competes with the formation of NO ₂ ^– which is, otherwise, proportional to the radiation absorbed.