Biogenic contributions

Most of the emissions data available in the literature was obtained within alterniflora marshes, and hence reflect the complexity of this ecosystem. Our data set extends the available emissions data to less complex systems, and at the same time lowers our estimation of the biogenic contribution to atmospheric sulfur loading. Even our highest estimate of biogenic emissions, that of... 

Hitchock, D.R., 1975. Biogenic contributions to atmospheric sulfate levels. Paper presented at 2nd Annual Conference on Water Reuse. Chicago, 111., May 1975. 

A particularly important consequence of the release of gaseous pollutants into the atmosphere is the local acidification of the environment. Rainwater reaching Earth s surface has a pH of about 5.6 (it is lower than 7 because of the dissolved carbon dioxide). In some parts of North America, Europe, and even Asia, however, acidic rainwater of pH < 5.6 is quite widespread. This is believed to be due to the presence of acidic gases, particularly oxides of sulfur (SOjc) and oxides of nitrogen (NO ) in the atmosphere. The contribution of HCl, if any, is relatively minor. A biogenic contribution to acidification caused by emissions from volcanos or forest fires also exists, but is relatively small. 

On a local or regional basis, terpenes may contribute significantly to oxidant problems (16,60,85,86,87, ), making control of anthropogenic hydrocarbons problematical. The question of relative controls on hydrocarbon and NOjj emissions from automobiles and industry has been a matter of longstanding controversy and debate in the US, particularly because of the potential role of biogenic hydrocarbons in oxidant production (16,89,90). This controversy is yet unresolved. 

Recognition among bone-chemistry researchers that strontium enters bone in proportion to dietary levels has resulted in widely accepted yet erroneous inferences about the relationships among various elements in bone and past diet. One such inference is that more of any element in the diet translates directly to more of that element in bone. If an element is not biogenically incorporated within bone, or if biological levels are metabolically controlled, then that element will not reflect diet. A second erroneous inference is that strontium can be used to measure the dietary plant/meat ratio. Sr/Ca ratios in meat are generally lower than those of plants, but meat is also low in calcium and hence has little effect on the composition of bone. Plants, on the other hand, contribute substantially to bone composition. Variations in the strontium levels of bone thus more likely reflect differential consumption of plants rather than trophic position. Although efforts to determine plant/meat ratios from strontium and to draw dietary inferences from elements other than strontium and barium have not been successful, this failure has been due to inappropriate expectations, not to a failure of bone strontium to reflect diet. 

The most important factors contributing to the production of biogenic amines during postharvest handling are the duration of storage and the storage temperature. Both the post-mortem formation of amino acids and their rapid decarboxylation are temperature dependent. 

There are many different types of fermented meats, each with its own particular process. The microbial and biochemical reactions during fermentation cause the characteristic acidification, proteolysis and drying that make the product safe. The distinctive flavor of sausage is also produced in these processes. The conditions under which fermented meats are produced are very favorable for the production of biogenic amines (Bover-Cid et al., 2000). Many factors contribute to the quality and acceptability of the final product. 

A global map of quartz abundance is given in Figure 14.12. In this case, the contribution of quartz is presented as the contribution to the bulk sediment from which biogenic carbonate and silica have been removed. This map is very similar to the global distribution of dust presented in Figure 11.4, reflecting the importance of aeolian transport for this detrital silicate. 

In terms of organic carbon generation, the coccolithophorids are a minor player, representing only 6 to 8% of global marine primary production. But their detrital remains contribute disproportionately to the burial of carbon in marine sediments. This is due to near complete loss of POC via remineralization as the detrital hard and soft parts settle to the seafloor. As estimated from Broecker s Box model in Chapter 9, only about 1% of the POM that sinks out of the surfece water is buried in marine sediments. In comparison, about 20% of the biogenic PIC survives to become buried in the sediments. 

The geographic distribution of opal in the surfece sediments is controlled by (1) the local rain rate of biogenic silica, (2) the degree of its preservation in the sediments, and (3) the relative rate of accumulation of other types of particles. Preservation is promoted by rapid burial as this isolates BSi from seawater. But if the BSi is buried by other particle types, the relative contribution of BSi to the sediment is diluted. This dilution effect causes the BSi content of most continental margin sediments to be low despite high rain rates. Preservation efficiency is also dependent on (1) the intensity of bioturbation and suspension feeding and (2) the various factors that control... 

Sabkhat also form inland, where river input and saline groundwater seeps contribute salt and water, forming an evaporitic pan. As illustrated in Figure 17.6, these continental sabkhat are fer more isolated from the ocean than a marine sabkha. They also contain far less biogenic detritus. 

The chemical weathering of crustal rock was discussed in Chapter 14 from the perspective of clay mineral formation. It was shown that acid attack of igneous silicates produces dissolved ions and a weathered solid residue, called a clay mineral. Examples of these weathering reactions were shown in Table 14.1 using CO2 + H2O as the acid (carbonic acid). Other minerals that undergo terrestrial weathering include the evaporites, biogenic carbonates, and sulfides. Their contributions to the major ion content of river water are shown in Table 21.1. 

This biogenic amine transmitter contributes to the regulation of a variety of psychological functions which include mood, arousal, attention, impulsivity. 

The abundance of diverse oximes as naturally occurring products is attributed, in general, to complicated metabolic processes that include enzyme-induced oxidation of either amino acids or biogenic amines, as well as to the relatively low reactivity of oximes compared to HA. The co-occurrence of HA and a variety of carbonyl-containing molecules in plants and animals may also contribute to the formation of the oxime bond in nature. 

Biogenic magnetite may persist once the organism that produced it has died and may, therefore, contribute to the natural magnetic remanence of sediments (Stolz et al., 1986). The discovery in a calcareous Martian ( ) meteorite found in Antarctica, of magnetite crystals with properties very similar to these biogenic magnetites, sup-... 

---