Nutrient spiralling, streams

Fig. 1 Scheme illustrating the influence of water discharge (y axis) and solute concentration (metals and nutrients on the x axis) on in-stream retention efficiency measured on the basis of the nutrient spiraling concept. The most remarkable Metal (M) effects on biofihns are indicated in the... 

Table 2 Fate and effects of metals in a stream receiving a point-source of metals (upper part of the table) or diffuse input via urban runoff (lower part of the table). Summary of the expected influence of four different hydrological situations base-flow in a rainy period a flood after a rainy period low-flow after a long period of low rainfall (water scarcity) and a flood produced after this drought. Metal concentration (M) metal retention efficiency (measured on the basis of the nutrient spiraling concept) exposure (dose and duration) bioaccumulation (in fluvial biofilms) and metal sensitivity (of biofihns)...

Ensign SH, Doyle MW (2006) Nutrient spiraling in streams and river networks. J Geophys Res 111 G04009. doi 10.1029/2005JG000114... 

Newbold JD, Elwood JW, O Neill RV, van Winkle W (1981) Measuring nutrient spiralling in streams. Can J Eish Aquat Sci 38 860-863... 

Newbold, J. D., Elwood, J. W., O Neill, R. V. van Winkle, W. (1981). Measuring nutrient spiralling in streams. Canadian Journal of Fisheries and Aquatic Sciences, 38, 860-3. 

While some of the nutrient stream nitrate originates in the southern hemisphere with SAMW, a fraction has recirculated within the subtropical gyre (Fig. 13.9B). Jenkins and Doney (2003) hypothesize a nutrient spiral in which enhanced diapycnal mixing associated with the eddy-rich, western boundary current also leads to a significant vertical transfer of nutrients (and other properties including helium) into the mixed-layer of the subtropical gyre. 

Stream ecologists are the major proponents of two recent theories, the river continuum concept (Vannote et al., 1980) and the nutrient spiraling concept (Elwood et al., 1983), which they believe may be important frameworks for studying stream humic substances. These theories emphasize the diverse and dynamic aspects of different reaches within the same stream, the differences among streams, and the differences in seasonal patterns among streams in various geographical regions. The theories predict enormous vari-... 

The placenta develops from a portion of the zygote and thus has the same genetic endowment as the developing fetus (78). The embryonic/fetal component consists of trophoblastic-derived chorionic villi/ which invade the maternal endometrium and are exposed directly to maternal blood in lake-like structures called lacunae. These villi create the large surface area necessary for maternal-fetal transfer in what becomes the intervillous space of the placenta. Here the maternal blood pressure supplies pulsatile blood flow in jetlike streams from the spiral arteries of the endometriunX/ to bathe the chorionic villi and allow for transfer of gaseS/ nutrientS/ and metabolic products. Biologically/ the human placenta is classified as a hemochorial placenta because maternal blood is in direct contact with the fetal chorionic membrane. It is this membrane that determines what is transferred to the fetus. 

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