959 resultados para Lignin Units
Resumo:
A study of composition of biomarkers (lignin and phenols) in aerosols and bottom sediments from the Tropical North Atlantic was carried out. It was shown that organic matter of aerosols was mostly composed of products of terrestrial plants (arboreal fibers, pollen, and spores). Biomarker composition in the aerosols and in the bottom sediments was practically similar, which proved delivery of terrigenous organic matter to the ocean via the atmosphere.
Resumo:
Muskoxen populations were surveyed in the course of 3 expeditions to North East Greenland to provide data on present status and habitat requirements in the region between 72 and 74 deg latitude North. The distribution is primarily affected by the snow cover pattern and shows densities from less than 0.1 ind/km**2 to 1.5 ind/km**2. Ranges unutilized by muskoxen prior to 1940 now support high densities. The snow cover influences also the population dynamics, as shown by the streng correlation between the calf crop and the amount of snow. The total population is estimated to be about 1000 to 1500 individuals far the whole region.
Resumo:
This study relates the organic sedimentation characteristics to the lithostratigraphic successionsthat were observed at Site 767 (Celebes Sea) and Site 768 (Sulu Sea) during ODP Leg 124. It is based on the total organic carbon content (TOC) of the sediments, on the petrographictype and maturity of the organic matter, and on the TOC accumulation rates calculated for the lithostratigraphic units. In the Celebes and Sulu Seas sediments, the organic matter is mainly of terrestrial origin with the highest concentrations and TOC accumulation rates occurring in the middle Miocene turbiditic sequences that correspond to a major compressive event between the Philippine Mobile Belt and the Palawan, Cagayan, and Sulu Ridges. Petrographic analysis of the Eocene and lower Miocene organic matter in the Celebes Sea shows that it consists only of highly degraded terrestrial particles. This observation and the very low TOC accumulation rates indicate poor conditions for organic carbon preservation during this open-ocean phase of the Celebes Basin formation. The organic matter, either of marine or terrestrial origin, is much better preserved in the younger sediments, suggesting physico-chemical changes in the depositional environment. Because of the dilution phenomena by turbidites, it is difficult to observe the progressive improvement of the organic matter preservation throughout the turbiditic series. The same change in preservation is broadly observed in the Sulu Sea from the early Miocene (rapid opening phase of the basin with massive pyroclastic deposits) to the present.
Resumo:
Three bottom sediment cores were collected from the top, slope, and foot of a small topographic high located near the West European continental rise within the Porcupine abyssal plain at the battleship Bismark wreck site. Using high-efficient gas chromatography technique we determined content and examined molecular composition of n-alkane fraction of hydrocarbons and phenol compounds of lignin. n-Alkane and phenol concentrations in bottom sediments of all three cores were low both in values per unit mass of sediments and in organic matter composition that is typical for pelagic deposits of the World Ocean. They vary from 0.07 to 2.01 µg/g of dry sediment and from 0.0001 to 0.01% of TOC; phenol ranges are from 1.43 to 11.1 µg/g and from 0.03 to 0.6%. Non-uniform supply of terrigenous matter to the bottom under conditions of changes in sedimentation environment in different geological epochs is the principal reason for significant variations in n-alkane and lignin concentrations with depth in the cores. Lignin and its derivatives make the main contribution to formation of organic matter composition of the region in study. With respect to n-alkane and lignin concentrations organic matter of deposits of the West European Basin is composed of remains of higher plants and of autochtonous organic matter of marine flora; they have mixed terrigenous-autochtonous (terrigenous-planktonogenic) origin.
Resumo:
The concept of homogenous response units (HRU) was designed as a general concept for the delineation of basic spatial units. Only those characteristics of landscape, which are relatively stable over time (even under climate change) and largely unsusceptible to anthropogenic influence, were selected. The HRU can be seen as a basic spatial framework for the implementation of climate change and land management alternative scenarios into global modeling and therefore is a basic input for delineation of landscape units. HRUs are defined based on classifications of altitude (five classes: 1 (0 - 300m), 2 (300 - 600m), 3 (600 - 1100m), 4 (1100 - 2500m), 5 (> 2500m)), slope (seven classes(degrees): 1 (0 - 3), 2 (3 - 6), 3 (6 - 10), 4 (10 - 15), 5 (15 - 30), 6 (30 - 50), 7 (> 50)) and soil composition (five classes: 1 (sandy), 2 (loamy), 3 (clay), 4 (stony), 5 (peat)). e.g. HRU111 refers to Altitude class 1: 0-300m; Slope class 1: 0-3 degrees; and Soil class 1: sandy. Areas of non-soil are assigned 88. HRUs have a spatial resolution of approximately 10 km**2.