Phosphorus dynamics in waters of the Pacific Ocean

Tagged phosphorus was used to measure principal indices of mineral phosphorus variations in the euphotic zone of the East Pacific, i.e. total rate of uptake of phosphate phosphorus by microplankton (A_t), fraction consumed by phytoplankton (A_p/A_t), and turnover time (T). A_t reached its greatest values (150-280 ng/l/hour) in the upwelling zone of the Peru traverse, where development of phytoplankton was induced by upwelling. In other areas of this traverse values were 40-80 ng/l/hour in surface layers. In less productive waters on two other profiles (off Central America and California), values were lower, between 20 and 40 ng/l. On the vertical profile maxima of A_t were found at the upper boundary of the thermocline. Turnover time of PO4 phosphorus (T) in zones of phytoplankton abundance was very short, between 1.5 and 4 days. At most other stations it was 10-40 days, increasing to 100-200 days or longer at the lower boundary of the euphotic zone. In areas of phytoplankton abundance it accounted for 60-80% of total uptake of PO4 phosphorus. But in zones of elevated bacterial abundance, A_p/A_t fell to 20-40%. Data indicating lack of correlation between PO4 phosphorus and productivity are presented. It is emphasized that the above measures of PO4 phosphorus dynamics can be used for obtaining measures of functional condition and successional phase of marine plankton communities.

(Table 1) Geochemistry of glass shards at DSDP Leg 84 Holes

Three Leg 84 sites provided a good record of explosive volcanism onshore (in Central America). Ash layers and many ashy pods are interbedded in Recent to Oligocene strata. Evidence of the main periods of activity was noted in Recent to upper Pleistocene, Pliocene-Pleistocene, lower Pliocene to upper Miocene, lower Miocene, and upper Oligocene. Noticeable traces of older volcanism were found in upper Eocene strata. The chemical analyses of glass shards show a dacitic to rhyolitic composition with a low to moderate calc-alkalinity. A preliminary distinction of samples in three geochemical groups according to their K2O/SiO2 contents is done to test a magmatic evolution. Comparisons are made with Leg 67 and on-land data.

(Table 1) Sea surface temperature reconstruction for eastern equatorial Pacific surface sediment samples

Significant uncertainties persist in the reconstruction of past sea surface temperatures in the eastern equatorial Pacific, especially regarding the amplitude of the glacial cooling and the details of the post-glacial warming. Here we present the first regional calibration of alkenone unsaturation in surface sediments versus mean annual sea surface temperatures (maSST). Based on 81 new and 48 previously published data points, it is shown that open ocean samples conform to established global regressions of Uk'37 versus maSST and that there is no systematic bias from seasonality in the production or export of alkenones, or from surface ocean nutrient concentrations or salinity. The flattening of the regression at the highest maSSTs is found to be statistically insignificant. For the near-coastal Peru upwelling zone between 11-15°S and 76-79°W, however, we corroborate earlier observations that Uk'37 SST estimates significantly over-estimate maSSTs at many sites. We posit that this is caused either by uncertainties in the determination of maSSTs in this highly dynamic environment, or by biasing of the alkenone paleothermometer toward El Niño events as postulated by Rein et al. (2005).

Marketing in Mexico /

Supersedes OBR 74-58.

World survey of agricultural machinery and equipment.

[1] Asia.--[2] Europe.--[3] South America.--[4-5] Africa, Australia-Oceania.--[6] North and Central America.

Los mayas de las tierras altas en el siglo XVI : tradición y cambio en Guatemala /

Mode of access: Internet.

Memorandum no. 1 sobre el ferrocarril de Zacapa á la frontera del Salvador, con motivo de las cuestiones suscitadas entre la Compañía de los Ferrocarriles Internacionales de Centro América y el gobierno de la República de Guatemala.

Spanish and English; opposite pages, numbered in duplicate.

Mœurs des sauvages ameriquains, comparées aux mœurs des premiers temps /

Illustrated with 42 engraved plates.

Indian notes and monographs.

Kislak Ref. Collection: No. 47, published 1928.

The works of Hubert Howe Bancroft.

For discussion of authorship and authors see Quarterly of the Oregon historical society, v. 4 (1903) p. 287-364.

Travels;

Cover title.

The works of Hubert Howe Bancroft.

For discussion of authorship and authors see Quarterly of the Oregon Historical Society, v. 4 (1903) p. 287-364.

Historia de las conquistas de Hernando Cortés,

Appended to v. 2 is a supplement (1 p. l., 39 p.) having caption title and colophon: Suplemento a la Historia de las conquistas de Hernan Cortés escrita por Chimalpain, ó sea: Memoria sobre la guerre del Mixtón en el estado de Xalisco, cuya capital es Guadalaxara. Mexico, Impr. de Galva á cargo de M. Arévalo, 1827.