南极半岛海洋气候区的土壤 I.风化作用

南极海洋性气候区是南极风化与成土作用相对较强的地区。本文在对本区气候特点进行分析的基础上,明确了冻胀风化是本区最主要的物理风化形式,强烈的现代地貌过程对本区风化与成土过程具有显著影响。阐述了本区内化学风化的主要过程、机制与产物,同时指出生物因素在本区的岩石风化与原始土壤形成过程具有重要意义。     

Degradation and binding of atrazine in surface and subsurface soils

Understanding the dissipation rates of chemicals in unsaturated and saturated zones of subsurface soils will help determine if reductions of concentrations to acceptable levels will occur. Chemical properties and microbial biomass and activity were determined for the surface (0-15 cm), lower root (50-105 cm), and vadose (175-220 cm) zones in a Huntington silty clay loam (Fluventic Hapludoll) collected from an agricultural field near Piketon, OH. The rates of sorption, mineralization, and transformation (formation of bound residues and metabolites) of atrazine were determined. Microbial activity was estimated from the mineralization of (14)C-benzoate. We observed decreased levels of nutrients (total organic carbon, N, and P) and microbial biomass with depth, while activity as measured with benzoate metabolism was higher in the vadose zone than in either the surface or the root zones. Sorption coefficients (K(f)) declined from 8.17 in the surface to 3.31 in the vadose zone. Sorption was positively correlated with organic C content. Rates of atrazine mineralization and bound residues formation were, respectively, 12-2.3-fold lower in the vadose than in the surface soil. Estimated half-lives of atrazine ranged from 77 to 101 days in the surface soil, but increased to over 900 days in the subsurface soils. The decreased dissipation of atrazine with increasing depth in the profile is the result of decreased microbial activity toward atrazine, measured either as total biomass or as populations of atrazine-degrading microorganisms. The combination of reduced dissipation and low sorption indicates that there is potential for atrazine movement in the subsurface soils.     

Konzeptbodenkarten für den städtischen Raum

Conception soil maps for urban areas The demand for soil maps increased strongly during the last years. This concerns urban soils, too. Conception soil maps constructed from a lot of basic informations (basic maps and point data) are the alternative to traditional soil mapping, which is expensive in time and money for urban areas. Further informations are to evaluate maps from these conception soil maps. Using graphic information-systems is advantageous for construction and evaluation.     

Einfluß der Erosion auf die Standortproduktivität im Silomaisanbau

Influence of erosion on productivity of maize ( Zea mays L.) cultivation
Accelerated erosion was monitored in Eastern Schleswig-Holstein (F.R.G.) during the last decades. The objective of this study was to compare agricultural productivity of upper, middle and base slope segments to the respective soil parameters, reflecting results of long-term erosion.
Five soil catenas were surveyed. Each catena was divided into three segments representing an eroded area (upper segment), an area with an equilibrium between erosion, accumulation and soil development (middle segment) and an area with accumulation (base slope segment).
In 1986 soil qualities, growth characters and yield components of maize were analysed for each slope segment. At eroded slope segments vegetation cover and yield were significantly lower than at middle and base slope segments. Middle slope segments (equilibrium between erosion, accumulation and soil development) snowed balanced soil quality parameters and high maize yields with a desired combination of yield components.     

Endotoxin-stimulated opioid peptide secretion: two secretory pools and feedback control in vivo

Small doses of endotoxin evoked a dramatic biphasic response of opioid peptide secretion into blood in sheep. The first phase began within minutes and coincided with a brief hypertensive response to endotoxin well before the appearance of fever or hypotension. The ratio of beta-endorphin to beta-lipotropin fell abruptly at the onset of the second phase of release, suggesting early depletion of a pool rich in beta-endorphin and subsequent emergence of a pool rich in unprocessed precursor. The concentration of cerebrospinal fluid opioids increased tenfold during the second phase. Naloxone administration augmented endotoxin-induced opioid secretion in both early and late phases, suggesting a short-loop feedback regulation of stress-induced endorphin secretion.