Net community production, Thorium-234 activity and particle flux during the Southern Ocean iron fertilization experiment LOHAFEX

A closed eddy core in the Subantarctic Atlantic Ocean was fertilized twice with two tons of iron (as FeSO4), and the 300 km**2 fertilized patch was studied for 39 days to test whether fertilization enhances downward particle flux into the deep ocean. Chlorophyll a and primary productivity doubled after fertilization, and photosynthetic quantum yield (FV/FM) increased from 0.33 to >0.40. Silicic acid (<2 µmol/L) limited diatoms, which contributed <10% of phytoplankton biomass. Copepods exerted high grazing pressure. This is the first study of particle flux out of an artificially fertilized bloom with very low diatom biomass. Net community production (NCP) inside the patch, estimated from O2:Ar ratios, averaged 21 mmol POC/m**2/d, probably ±20%. 234Th profiles implied constant export of ~6.3 mmol POC/m**2/d in the patch, similar to unfertilized waters. The difference between NCP and 234Th-derived export partly accumulated in the mixed layer and was partly remineralized between the mixed layer and 100 m. Neutrally buoyant sediment traps at 200 and 450 m inside and outside the patch caught mostly <1.1 mmol POC/m**2/d, predominantly of fecal origin; flux did not increase upon fertilization. Our data thus indicate intense flux attenuation between 100 and 200 m, and probably between the mixed layer and 100 m. We attribute the lack of fertilization-induced export to silicon limitation of diatoms and reprocessing of sinking particles by detritus feeders. Our data are consistent with the view that nitrate-rich but silicate-deficient waters are not poised for enhanced particle export upon iron addition.

Laboratory investigation of residual liquid organics from spills, leaks, and the disposal of hazardous wastes in groundwater /

Mode of access: Internet.

Comparison of methods for the determination of total available residual chlorine in various sample matrices /

Bibliography: p. 28-29.

A study of the residual ionization in a gas with reference to temperature effects ...

"Reprinted from the Physical review, n. s., vol. XVI, no. 4, October, 1920."

Yield and composition of corn forage as influenced by soil fertilization /

Cover title.

On the queen bee, : with especial reference to the fertilization of her eggs. /

Journal of the Quekett Microscopical Club, v. 5 (1878), p. 1-6.

Facts for farmers : also for the family circle : a compost of rich materials for all landowners, about domestic animals and domestic economy, farm buildings, gardens, orchards, and vineyards : and all farm crops, tools, fences, fertilization, draining, and irrigation : with an appendix on the diseases and cures of domestic animals /

Paged continuously.

[Miscellaneous bulletins on improvement, reclamation, fertilization, irrigation, etc., of lands.]

Mode of access: Internet.

Long-term responses of understory vegetation on a highly erosive Louisiana soil to fertilization /

Life sciences collection

Farm soils, their management and fertilization.

Mode of access: Internet.

The determination of dominance and the modification of behavior in alternative (Mendelian) inheritance, by conditions surrounding or incident upon the germ cells at fertilization.

"Correction and addendum."

Methods to reduce built-in residual stresses in steel bridge diaphragms (Phase I) /

"July 2000."

Pasture productivity of crested wheatgrass as influenced by nitrogen fertilization and alfalfa

Prepared in cooperation with Dept. of Animal Science, North Dakota Agricultural Experiment Station.

Effects of weed control and fertilization on botanical composition and forage yields of Kentucky bluegrass pasture

Bibliography: p. 27-28.