Seasonal variation in composition

In addition to the variations in the LHC composition that occur from species to species, each species has its extractives, which include resins and waxes. These constituents are capable of interfering with cellulose hydrolysis because of their hydrophobic nature. Tannins and other highly reactive materials are constituents of some woody species. When LHC is obtained from nonwoody (herbaceous) species, the range of interfering constituents increases greatly. Sugars, starches, dextran, carotenoids, and many isoprenoids are to be found. Operators of a cellulose hydrolysis process that uses municipal solid waste as its biomass resource may experience seasonal variations in composition and chance inclusion of crankcase oil and other products that inhibit enzymes or kill yeast. 

Day, D. E., W. C. Malm, and S. M. Kreidenweis, Seasonal Variations in Aerosol Composition and Acidity at Shenandoah and Great Smoky Mountains National Parks, J. Air Waste Manage. Assoc., 47, 411-418 (1997). 

With the recent commercial availability of ultrafiltration, it has become possible to increase the concentration of casein, thus levelling out seasonal variations in milk composition and consequently in gel characteristics and... 

Seasonal Variation and the Influence of Temperature. In temperate latitudes, rather characteristic seasonal variations in milk composition are commonly observed. Both fat and solids-not-fat contents are lower in summer than in winter. In the survey by Overman (1945) of individual cows at the University of Illinois, monthly extremes for fat were 4.24 and 3.81% in January and August and for protein were 3.61 and 3.37% in January and July, respectively. Nickerson (1960) found significant seasonal differences in 18 components of bulk milks from six areas in California. Seasonal differences in fat and protein contents were similar to those observed in Illinois. Seasonal variations in milk composition could conceivably be caused by differences in temper-... 

Hansen, R. P. and Shorland, F. B. 1962, Seasonal variations in fatty acid composition of New Zealand butter fat. Biochem. J. 52, 207-216. 

Application of Isotopic Methods to Non-Steady-State Groundwater-Lake Systems. Isotopic compositions of lakes whose hydraulic-residence times are relatively short (about 2 years or less) vary seasonally (32). Seasonal response occurs whenever a significant mass of water of a different isotopic composition is either added to or removed from the lake. Seasonal variations in P, E, G, 8P, 8a, and 8 are the principal driving forces behind observed variations in 8j for isotopically non-steady-state systems. In northern Wisconsin, many lakes are isotopically non-steady-state. 

Rivers and streams not only integrate the precipitation amount weighted hypsometric mean elevation of the drainage basin above the sampling site, but also the seasonal variation in the isotopic composition of the precipitation falling on that watershed. This will be most... 

Fricke HC, Clyde WC, O Neil JR (1998) Intra-tooth variations in 8180(P04) of mammalian tooth enamel as a record of seasonal variations in continental climate variables. Geochim Cosmochim Acta 62 1839-1850 Fricke HC, O Neil JR (1996) Inter-and intra-tooth variation in the oxygen isotope composition of mammalian... 

Table 10 shows seasonal variation in the age composition of Black Sea anchovy and sprat. The weight of an average fish in a population is evaluated from the age structure of the population and the share of the total biomass contributed by each age group. In horse-mackerel, pickerel and whiting, the proportion of the different age groups keeps stable all the year round, while in... 

Eliassen, J.-E. and Vahl, O. (1982). Seasonal variations in biochemical composition and energy content of liver, gonad and muscle of mature and immature cod, Gadus morhua L, from Balsfjorden, northern Norway. Journal of Fish Biology 20, 707-716. 

Toor RK, Savage GP and Lister CE, Seasonal variations in the antioxidant composition of greenhouse grown tomatoes. J Food Comp Anal 19 1-10 (2006). 

The size distribution of air particles not only influences the distribution and partitioning dynamics of POPs, but also determines dry and wet deposition flux of POPs. An interesting phenomenon was observed for relationship among atmospheric PAHs, particle size distribution, and the levels of PAHs in soil (Kim, 2004). For urban sites, the composition pattern and absolute concentrations of PAHs in soil were well correlated with those in air where the atmospheric particles size was distributed evenly among seasons with predominant amount of fine particles < 3 pm. Dry deposition flux of PAHs followed seasonal variation in atmospheric concentration in urban site. However, at a suburban site with large seasonal variation in particle size distribution, dry deposition flux and soil residue did not reflect the seasonal variation of atmospheric PAHs. From this result, site-specificity in atmospheric particle distribution may also influence the distribution and residues in the underlying soil. 

Chanton, J.P., and Martens, C.S. (1988) Seasonal variations in ebulhtive flux and carbon isotopic composition of methane in a tidal freshwater estuary. Global Biogeochem. Cycles 2, 289-298. 

P. A. W. van Hees, U. S. Lundstrom, and R. Giesler, Low molecular weight organic acids and their Al-complexes in soil solution—composition, distribution and seasonal variation in three podzolized soils, Geoderma 94, 173-200 (2000). 

O Brien, B., Mehra, R., Connolly, J.F., Harrington, D. 1999. Seasonal variation in the composition of Irish manufacturing and retail milks. 1. Chemical composition and renneting properties. Irish J. Agric. Food Res. 38, 53-64. 

The amount of monthly rain varies during the year, causing a seasonal variation in the isotopic composition. This point is demonstrated in a case study from northeastern Brazil (Fig. 9.13). 

In the North Atlantic and the North Sea seasonal variations in marine phytoplankton composition are well known, but annual variations in abundance... 

Nabil, S., and Cosson, J. 1996. Seasonal variation in sterol composition of Delesseria sanguinea (Ceramiales, Rhodophyta). Hydrobiologia, 326/327, 511-514. 

R. D. Villanueva, N. E. Montano, I. B. Romero, A. K. A. Aliganga, and E. P. Enriquez, Seasonal variations in the yield, gelling properties, and chemical composition of agars from Gracilaria eucheumoides and Gelidiella acerosa (Rhodophyta) from the Philippines, Bot. Mar., 42 (1999) 175-182. 

---