Fracionamento de substâncias húmicas do solo por cromatografia de exclusão em coluna.

Representacao esquematica do principio da exclusao; moleculas grandes (MG) somente se movem externamente ao granulo ou matriz cromatografica (volume morto = Vo), ao passo que moleculas pequenas (Mp) podem se mover tambem por dentro dos granulos (volume interno = Vi); Vp indica volume ocupado pelos granulos; Cromatografia em granulos porosos de vidro (Controlled-Pore Glass); Cromatografia em granulos porosos de vidro de substancias humicas de um Latossolo Roxo de Londrina, PR; Cromatogramas dos extratos de substancias humicas de um Latossolo Vermelho distroferrico de Londrina, PR; Teores totais de substancias humicas extraidas (d.o. = densidade otica do extrato total a 400 nm) de um Latossolo Vermelho eutroferrico de Londrina, PR; A se refere ao solo sob floresta secundaria; B se refere ao solo sob plantio direto e C se refere ao solo sob plantio convencional (uma aracao seguida de duas gradagens leves niveladoras); Medida da distribuicao do peso molecular (E1/E2%) das substancias humicas de um Latossolo Vermelho eutroferrico de Londrina, PR; Cromatogramas de substancias humicas e teor de aluminio associado de Latossolo Vermelho eutroferrico (A) sob floresta de eucalipto (Al troc = 12 mmolc.kg-1; C org = 50,0 g.kg-1; teor de argila = 700 g.kg-1) e de Latossolo Vermelho distrofico (B) sob floresta de Pinus sp. (Al troc = 19 mmolc.kg-1; C org = 7 g.kg-1; teor de argila = 130 g.kg-1).bitstream/item/62213/1/Fracionamento-de-substancias.pd

How are soil use and management reflected by soil organic matter characteristics: a spectroscopic approach

We studied the quantitative and qualitative changes of soil organic matter (SOM) due to different land uses (arable versus grassland) and treatments (organic manure and mineral fertilizer) within an agricultural crop rotation in a long-term field experiment, conducted since 1956 at Ultuna, Sweden, on a Eutric Cambisol. The organic carbon (OC) content of the grassland plot was 1.8 times greater than that of the similarly fertilized Ca(NO3) 2 treated cropped plots. The comparison of two dispersion techniques (a lowenergy sonication and a chemical dispersion which yield inherent soil aggregates) showed that increasing OC contents of the silt-sized fractions were not matched by a linear increase of silt-sized aggregates. This indicated saturation of the aggregates with OC and a limited capacity of particles to protect OC physically. Thermogravimetric analyses suggested an increase of free organic matter with increasing OC contents. Transmission FT-IR spectroscopy showed relative enrichment of carboxylic, aromatic, CH and NH groups in plots with increasing OC contents. The silt-sized fractions contained the largest SOM pool and, as revealed by 13C NMR spectroscopy, were qualitatively more influenced by the plant residue versus manure input than the clay fractions. Alkyl and O-alkyl C in the silt-sized fractions amounted to 57.4% of organic carbon in the animal manure treated plots and 50–53% in the other treatments.We thank the Austrian Science Fund (Fonds zur FÖrderung der wissenschaftlichen Forschung) for funding this bilateral project.Peer reviewe

Modelling of interactions of polar and nonpolar pollutants with soil minerals and soil organic matter

Environmental pollution of soils by organic contaminants such as pesticides is one of the serious problems of our civilization. Contaminants can undergo various physical, chemical and biological transformation processes in soils governing behaviour, distribution, and fate of organic species in environment and subsequent environmental risks. Mechanistic understanding of molecular interactions of organic pollutants with main soil components represents a key factor for estimating the behaviour of contaminants in soils. Molecular modelling offers an opportunity to investigate and characterize various details of these interactions at molecular level providing specifications, which are difficult to obtain at the experimental level. This work represents a comprehensive overview of our investigations of the molecular interactions of organic contaminants with selected soil components. Particularly, we focused on the characterization of the structure and the surface complexation of the phenoxyacetic acid derivatives (herbicides MCPA and 2,4-D) and typical soil minerals such as clay minerals (kaolinite and montmorillonite) and iron oxyhydroxides (goethite and lepidocrocite). Further, interactions of several representative nonpolar polycyclic aromatic hydrocarbons (e.g. naphthalene, anthracene, pyrene, and phenanthrene) with iron oxyhydroxides were modelled, as well. It was found that in case of polar species, hydrogen bonds and electrostatic interactions play an important role in the formation of the surface complexes. In case of nonpolar PAHs, dispersion forces dominate in the planar stacking of the PAHs molecules on mineral surfaces. Another study focused at a complex 3D model representing humic substances firstly, featuring polar hydrophilic and nonpolar hydrophobic domains and also a nanopore SOM structure. This model was taken to simulate trapping and interactions of MCPA (polar) and naphthalene (nonpolar) species inside of the nanopore. It was found that MCPA is preferentially stabilized close to polar functional groups (carboxyl) whereas naphthalene interacts mostly with nonpolar aliphatic chains through dispersion interactions

Gedachtnisexkursion Andalusien

Diese Gegend im Süden Spaniens ist eine autonome Region und besteht aus aeht Provinzen. Sie umfasst ein Gebiet von der GroBe Portugals, in dem die Sierra Nevada und das weite Tal des Guadalquivir liegen, und besitzt mehr als 700 km Küste. Der sumptige Coto Doñana-Park in der Nähe von Cádiz ist ein groBes Naturschlltzgebiet. Die bekanntesten Städte Andalucías (Andalusiens) sind Granada, Córdoba und die Hauptstadt Sevilla. Diese historischen Städte ziehen viele Besueher an und bilden mit den Ferienorten der Costa del Sol und dem gebirgigen Hinterland die wichtigste Urlaubsregion Spaniens. Eine Vielzahl kleinerer Orte wie Úbeda, Carmona und die berühmten "WeiBen Dorfer" ziehen ebenfalls viele Besucher nach Andalusien. Andalusien (Andalucía), mit 87.268 km2 7,234.873 Einwohnern und einer Bevölkerungsdichte von 83 Einwohnern pro km2 ist nicht nur die gröBte, sondern auch die am längsten durch die Herrschaft der Mauren geprägte Region. Neben diesen Elementen verleihen aber auch die geologisch-morphologischen Bedingungen dieser Region einen unverwechselbaren Habitus. Die automone Region Andalucía umfaBt acht Provinzen (Almería, Cádiz, Córdoba, Granada, Huelva, Jaén, Málaga und Sevilla) (vgl. Abb. 1). Andalusien kann in zwei Bereiche, in Hochandalusien und in Niederandalusien gegliedert werden (vgl. Abb. 3).Peer reviewe

Rates of biogeochemical phosphorus and copper redistribution in young floodplain soils

Nutrients and trace metals in river-floodplain systems may originate from anthropogenic activities and/or geogenic sources. Here, we analyze a soil chronosequence (2 to approximately 600 years) on a floodplain at the Danube River (Austria) to quantify the rates of P and Cu redistribution among biogeochemical pools during early soil formation under temperate continental climate. While bulk and clay mineralogy remained unchanged over the studied age gradient, we found considerable (mostly non-linear) redistribution of P and Cu among biogeochemical pools. The calcium-associated P and Cu fractions decreased rapidly during the initial decades of soil formation. The dissolution of calcium-associated P was mirrored by marked accumulation of organic P. Copper incorporated within resistant minerals showed a relative enrichment with soil age. The mean dissolution rates of calcium-associated (primary mineral) P decreased exponentially with increasing soil age from ~1.6 g m<sup>−2</sup> yr<sup>−1</sup> over ~15 years to ~0.04 g m<sup>−2</sup> yr<sup>−1</sup> over ~550 years, and were almost an order of magnitude higher than rates reported for tropical environments. Our study demonstrates that on riverine floodplains, rapid biogeochemical transformations can occur within the first centuries of soil formation under temperate climatic conditions