Chemical composition of plants

Let us consider the influence of various factors on the chemical composition of plant species in the arctic islands. It seems that the most influential factor is the distance from the ocean shore. For example, in arctic willow growing a few meters from the tide line, the content of Zn, Cu, Pb, and Ni was higher than that of the same plant species growing about 1 km from the coast line and sheltered from the sea by a morain hill. The coastal plants contain also more sea salt cations like Na, Ca, K, and Mg. 

For comparison, the mobile forms of trace metals were extracted from local geological rocks, as water-soluble and TON HCl-soluble forms. The results are shown in Table 3. 

We can see that the content of trace metals in water extraction is very low. This means that the direct involvement of these metals in biogeochemical cycles is very restricted. The significant increase of metal contents in acid-soluble form was shown only for Fe, Mn and, partly, forZn. These data testify to the importance of atmospheric deposition for the Arctic ecosystems as a source of nutrients. 

The supply of sea salts and trace metals via precipitation appears to contribute to the elevated content of water soluble forms of alkaline and earth-alkaline elements and trace metals in the uppermost soil layer. 

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The biodiversity of Mangrove ecosystems is the most profound in the islands and coastline of the Indo-West-Pacific region, where the occurrence of 44 varieties has been reported. On the Atlantic Ocean coast Mangrove ecosystems are especially widespread in the Caribbean region. The chemical composition of plant species and soils of Mangrove ecosystems have been recently discussed (Dobrovolsky, 1994). 

Structure, function, and distribution of plants Chemical composition of plants, active constituents... 

Biochemical Effects It is usual to find some changes in the chemical composition of plant tissue after exposure to ozone. One cannot be certain whether the changes are associated with early reactions to ozone or are merely delayed consequences of cell injury. 

Wilman, D. and Altimimi, M.A.K. (1982) The digestibility and chemical composition of plant parts in Italian and perennial ryegrass during primary growth. Journal of the Science of Food and Agriculture, 33, 595-602. 

At the same time insects are able to discriminate between host and non-host plant species as they select plants on which feeding ultimately results in growth and reproduction, and on the other hand avoid poisoning or malnutrition on non-host plants. By means of chemosensory sensilla, insects are able to perform the difficult task, being well equipped analytical chemists, of identifying the chemical composition of plants that insects meet in their environment (6). 

Regulate the chemical composition of plants and the color of fruit. 

Vegetation has been classified into a number of reaction types (Ernst, 1993). Within the group of plants that react to their environment (reactors), those with visible (or overt) reactions can be distinguished from those with non-visible (or covert) reactions. In the case of geobotany as defined by Ernst (1993), visibility means to the unaided human eye, that is colour, morphology, presence, abundance or absence of species. Cole has pointed out (Cole and Smith, 1984) that is was not until about 1945, when rapid routine methods of analysis for large numbers of samples became available, that biogeochemistry, that is the study of the chemical composition of plants from various habitats, was used for mineral exploration in many parts of the world. 

Poorter H. and ViUar R. (1997) Chemical composition of plants causes and consequences of variation in aUocation of C to different plant compounds. In Resource Allocation in Plants (eds. E. Bazzaz and J. E. Grace). Academic Press, San Diego, CA, pp. 39—72. 

Black commented on good and bad marl as early as the 1760s Black, Lectures 176718, 58. Agricultural topics were also covered by leading chemists like Herman Boerhaave and Pierre Macquer, both of whom were required reading for chemistry course run by Cullen and Black. Boerhaave s interest in the chemical composition of plants is addressed in Ursula Klein, Experimental history and Herman Boerhaave s chemistry of plants, Studies in the History and Philosophy of the Biomedical Sciences 34, 2003, 533-67. 

In general, the chemical composition of plants closely reflects the chemical properties of whole environments, soils, waters, and air. Using plant chemical status for geochemical prospecting is very old practice (Kabata-Pendias and Pendias 2001), but recently it has been used broadly for the bioindication of contaminated sites and for the environmental biomonitoring (see Part I, Chapter 12). 

Before examining biomass conversion approaches in detail, we first briefly review the chemical composition of plant biomass. The main biomass compraients [16, 17] are cellulose [18-20], hemicellulose [21], starch, sugars, lignin [22], oils, fats, and waxes [23, 24], proteins [25, 26], and various extractives. Those most relevant to the biorefinery are shown in Fig. 3. 

Plant material collected in the wild (Fig. 3.49), with few exceptions, cannot be accepted in pharmacy. One of the reasons is that non-professional collectors do not necessarily collect the desired plants exclusively they may also collect other similar-looking or even toxic plants. Some plants have several subspecies, which are very difficult to distinguish, but may differ significantly in composition. The chemical composition of plants is also influenced by environmental factors (soil, moisture, light conditions, time of harvest etc.) and even by the site and time of the... 

The surfaces of all higher plants are covered by a layer of cuticular waxes. These are composed mainly of long-chain aliphatic components but also of cyclic compounds. The primary role of the waxes is to prevent uncontrolled water loss. The chemical composition of plant cuticular waxes can affect the resistance of plants to herbivores and herbivore behaviour. Cuticular waxes and their separate components enhance or deter insect oviposition, movement or feeding. 

Finally, some data on heavy metal concentration in plants grown within the sanitary protections zones will be presented, as they illustrate the problem of current environmental pollution in the surroundings of copper smelters. However, it should be emphasized that not only the metal uptake from soil, but first of all direct dust deposition contribute to final metal concentration in the plant tissues. Table 6.9 presents data on Cu, Pb, Zn and Cd concentrations in the straw and grains of different cereals collected in years 1989-93 from the "fixed sampling points" described above. Although chemical compositions of plants grown in the pot experiments and under field conditions should not be simply compared, it can be easily seen that Cu and Pb concentrations in the straw were much higher in the field that in the pot experiment, where soil was the only source of heavy metals for plants. 

Geochemical Analysis of soils or plants is useful in prospecting for metals. Underlying deposits prospecting of minerals have some influence on the chemical composition of plants and of the soil in which they grow. 

Table 3. Chemical Composition of Plant Opal separated from Soil. Cisne Silt Loam Occurs in Illinois, and the Glassy-Ash Soil (Onji type) Occurs in Japan (Kanno and Arimura)...

Although the chemical composition of plant wax has not been well characterized, Cheng and co-workers [40] found that the wax material on the Lotus is intrinsically, moderately hydrophilic with a water contact angle of 74°. As will be discussed in the next two sections, re-entrant structure and multi-scale roughness at... 

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