Nutrients dissolved organic

The exchange of solutes such as nutrients, dissolved organic substances, and metals and their associated processes at soil-floodwater interfaces are measured using laboratory-incubated cores or in situ pore water equilibrators as has been described. But these methods often underestimate fluxes because they do not account for processes such as bioturbation and bioirrigation at the soil-floodwater interface. To overcome these limitations, autonomous benthic chambers installed on top... 

Jackson, G. A. and Williams, P. M. (1985). Importance of dissolved organic nitrogen and phosphorus in biological nutrient cycling. Deep Sea Res. 32, 223-235. 

Fig. 2 Longitudinal changes in nutrient concentrations below the effluent input of a WWTP without tertiary treatment in La Tordera Stream. Values are the average ( SEM) of monthly measurements done over a year (see more details in [47]). In the left panel, note the net decline of ammonium concentration with concomitant net increases in nitrate concentration, suggesting a potential hot spot for nitriflcation. However, in the latest meters downstream, dissolved inorganic nitrogen (DIN) tends to decrease, which indicates net lost of DIN possibly due to denitrification. The right panel shows net changes in phosphate and dissolved organic carbon (DOC) concentrations. While phosphate does not exhibit any clear trend on an annual basis, DOC seems to decline similarly to DIN, which supports the relative dominance of denitrification...

Soil solution is the aqueous phase of soil. It is in the pore space of soils and includes soil water and soluble constituents, such as dissolved inorganic ions and dissolved organic solutes. Soil solution accommodates and nourishes many surface and solution reactions and soil processes, such as soil formation and decomposition of organic matter. Soil solution provides the source and a channel for movement and transport of nutrients and trace elements and regulates their bioavailability in soils to plants. Trace element uptake by organisms and transport in natural systems typically occurs through the solution phase (Traina and Laperche, 1999). 

Seawater reference materials are recommended for nutrients and for trace metals (especially iron). There is an urgent need for a certified reference material for nutrients. Completed global surveys already suffer from the lack of previously available standards, and the success of future surveys as well as the development of instruments capable of remote time-series measurements will rest on the availability and use of good nutrient reference materials. The reference materials for trace metals— though initially characterized only for the important micronutrient, iron— should ultimately be useful for the analysis of the other metals and some dissolved organic materials. The committee also recommends the devel-... 

This equation describes the ratios with which inorganic nutrients dissolved in seawater are converted by photosynthesis into the biomass of "average marine plankton" and oxygen gas 02. The opposite of this reaction is respiration, or the remineralization process by which organic matter is enzymatically oxidized back to inorganic nutrients and water. The atomic ratios (stoichiometry) of this reaction were established by... 

Fig.1 Generalized pelagic food web [ 13]. The old view of a simple food chain vertical line in this figure) with phytoplankton (mainly diatoms) at the base, herbivorous mesozoo-plankton (mainly copepods) at the second trophic level, and planktivorous fish has been extended to a pelagic food web including nanoplankton (<20 pm), picoplankton (<2 pm), and their protozoan feeders lower left). Herbivorous tunicates and jellyfish as primary carnivores also play a role, as do mixotrophic flagellates. The main pathway of energy flow depends on the nutrient scenarios [13]. DOC=dissolved organic carbon, HNF=heterotrophic nanoflageUates. From [13] with permission of Kluwer Academic Press...

Table 2 shows the mean values of the main chemical parameters measured between 2000 and 2004. Dependent on the lake and the parameter the sample number varies between 7 and 10 (data not shown). The chemical water composition is typical for carbonate-poor mountain regions low conductivity, alkalinity and pH and small nutrient and DOC (dissolved organic carbon) concentrations. Data of DOC are not shown, they vary between 0.14 and 0.70 mg C Ortho-phosphate is always smaller than the quantification limit of 4.3 P pg and ammonia and nitrite are negligibly small compared to nitrate (data not shown). 

Nguyen, V. D., A. G. A. Merks, and P. Valenta. 1990. Atmospheric deposition of acid, heavy metals and dissolved organic carbon and nutrients in the Dutch delta area in 1980—1986. Science of the Total Environment 99 77—91. 

Qualls R. G., and B. L. Haines. 1991. Geochemistry of dissolved organic nutrients in water percolating through a forest ecosystem. Soil Science Society of America Journal 55 1112-1123. 

Qualls, R. G., B. L. Haines, and W. T. Swank. 1991. Fluxes of dissolved organic nutrients and humic substances in a deciduous forest. Ecology 72 254-266. 

In many freshwater aquatic systems, dissolved organic material (DOM) represents a major pool of organic material. Processes that produce, consume, and transform DOM are important in the overall cycling of carbon, energy, and nutrients in these aquatic ecosystems. Current research has... 

Mulholland, P. J., and W. R. Hill. 1997. Seasonal patterns in streamwater nutrient and dissolved organic carbon concentrations Separating catchment flow path and in-stream effects. Water Resources Research 33 1297—1306. 

The concentration and flux of dissolved organic carbon (DOC) are important characteristics of aquatic ecosystems, with important effects on light and ultraviolet (UV)-B attenuation, ecosystem respiration, nutrient... 

Reche, I., M. L. Pace, and J. J. Cole. 1998. Interactions of photobleaching and inorganic nutrients in determining bacterial growth on colored dissolved organic carbon. Microbial Ecology 36 270-280. 

The formula for BCD in Eq. (2) was derived under the assumption that the bacterial growth rate was mineral nutrient limited. If the supply rate of labile organic carbon from allochthonous and autochthonous sources is insufficient to meet this demand, the pool of labile dissolved organic carbon (DOC) will eventually be depleted and the bacteria will become carbon... 

Zweifel, U. L., B. Norrman, and A. Hagstrom. 1993. Consumption of dissolved organic carbon by marine bacteria and demand for inorganic nutrients. Marine Ecology Progress Series 101 23-32. 

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