Search results for "ORGANIC MATTER"
showing 10 items of 577 documents
Influence of inheritance and pedogenesis on heavy metal distribution in soils of Sicily, Italy
2000
Abstract The recognition of the potential health hazards associated with heavy metals has focused attention on the levels and behaviours of these elements both in natural and contaminated environments. Various soil types developed from different parent materials in Sicily, Italy, have been analysed in order to compare heavy metal distribution under different geopedological conditions. Total metal concentrations, metal partitioning and distribution profiles are discussed in relation to the inheritance factor and pedogenic processes. Parent material composition largely influences the contents of heavy metals in most of the analysed soils, mainly differentiating pedons for their metal concentr…
Selenium Partitioning and Stable Isotope Ratios in Urban Topsoils
2011
oxides. Th e δ82/76 Se values of total Se in the topsoils were close to the bulk Earth composition with an average δ82/76 Se value of −0.03 ± SD 0.38‰ suggesting that there was no or little Se isotope fractionation in soil. We attribute the small isotope fractionation to the low bioavailability of Se as a consequence of the presence of Fe oxides (adsorbing the dominating Se(IV) forms strongly), organic matter, and SO 4 2− (prevents biouptake of the Se(IV) forms) in the study soils. Small Se isotope fractionations of −0.59 to −0.35‰ in mainly forest soils and of 0.26 to 0.45‰ in mainly alluvial soils were presumably caused by soil/plant-recycling and Se contamination by river water, respecti…
Pedogenesis in disturbed alpine soils (NW Italy)
2002
In alpine environments, natural or man-induced disturbances are fairly common and acknowledged as determining factors in pedogenesis and soil distribution. We have selected a representative alpine valley in the Italian Northwestern Alps to evaluate the effects of perturbations of different intensity and frequency on soil development and weathering during the last few centuries. In order of decreasing disturbances, we selected: (i) an active avalanche shoot; (ii) a man-built terrace; (iii) a park-like forest; and (iv) a coniferous forest. In the two most disturbed sites, independently of the intensity and frequency of the disturbances, the active pedogenic processes are restricted to the top…
Effect of climate and vegetation on soil organic carbon, humus fractions, allophanes, imogolite, kaolinite, and oxyhydroxides in volcanic soils of Et…
2007
A soil sequence along an elevational gradient ranging from subtropical to subalpine climate zones in the Etna region (Sicily, southern Italy) was investigated with respect to organic C, kaolinite, and crystalline to noncrystalline Al and Fe phases. Special emphasis was given to the stabilization of soil organic carbon (SOC) and its interaction with the inorganic phases. The soils were variations of Vitric Andosols that developed on a trachy-basaltic lava flow with an age of 15,000 years. Two main vegetation systems dominated the sites: at the lower sites, it was mainly maquis vegetation and, at the higher elevated sites, predominantly coniferous forest. The concentration of SOC in the topso…
Factors influencing carbon decomposition of topsoils from the Brazilian Amazon Basin
1999
The influence of texture and local climate, especially precipitation, on C decomposition was evaluated in topsoils under forest and pastures at different sites located in the western, central, and eastern Brazilian Amazon Basin. Independent of the geographical location and vegetation cover, C decomposition was lower in topsoils of fine texture with a sand/clay ratio of less than 1, compared to topsoils of coarse a texture with a sand/clay ratio ranging from 2 to 8. In the former, the low sand/clay ratio appears to reduce C decomposition. In the latter, besides the effect of the high sand/clay ratio, the local climate, especially the annual precipitation, seems to play an important role in c…
Characterisation of humic acids in fen peat
2020
Fens store significant amounts of organic matter and thus are of high importance from the perspective of the organic carbon biogeochemical cycle. Fen peat comprises moderately to highly decomposed higher plant remains with relatively high mineral matter content. Humic acids form the major part of fen peat organic matter; they are also the most refractory and recalcitrant natural substances to degradation, and thus they contain essential information regarding mire and peat development over large periods of time as well as the organic carbon biogeochemical cycle. Moreover, humic substances in fen peat are a prospective resource for applications in agriculture and other sectors. The aim of thi…
Natural organic matter coagulation in Valencia water supply. Pilot plant studies
1998
: To reduce disinfection by-product (DBP) formation in drinking water treatment, the presence of natural organic matter in surface waters must be minimised. This paper describes pilot plant studies carried out on two surface waters to assess the effectiveness of coagulation in organic matter removal, the Turia and Jucar rivers, which supply the city of Valencia (1m inhabitants). The experiments were conducted with different coagulants (iron sulphate, polyaluminium chloride (PACl)) and treatment schemes. Process effectiveness was evaluated in terms of effluent turbidity, presence of residual metal in final water, and organic matter removal. Four parameters were used to quantify organic matte…
Natural organic matter export from boreal catchments (the Salaca River basin, Latvia) and its influencing factors
2012
A noteworthy increase in the organic matter concentration and export, as well as water colour, in the catchments of the Salaca River has been observed during the last decades. This study investigates factors behind this increase: the impact of climate, land use and human loading changes on the concentrations and export of the organic matter in the Salaca River/Lake Burtnieks catchments. Proportion of wetlands in the river basin, type of land use, and runoff regime can be considered as the main factors influencing the organic carbon loadings. Despite a steady overall tendency of increase, considerable oscillations of organic matter loadings influenced by the changes in the river discharge re…
Meiofauna and benthic microbial biomass in a semi-enclosed mediterranean marine system (Stagnone di Marsala, Italy)
2004
Microbial and meiofaunal dynamics and their relationships with the biochemical composition of the sedimentary organic matter were investigated in a semi-enclosed marine system (Marsala lagoon, Western Sicily, Mediterranean Sea). Sediment samples were collected on a monthly basis from March 1996 to February 1997 in four stations located along a N–S transect characterized by different hydrodynamic regimes. Total sedimentary organic matter concentration ranged from 5.681.11 to 156.2812.63 mg g1, while the biopolymeric fraction of organic carbon (BPC, measured as sum of the lipids, carbohydrates and proteins) accounted for only a small fraction (24%) of total organic matter. Total meiofaunal de…
Holothuria tubulosa Gmelin 1791 (Holothuroidea, Echinodermata) enhances organic matter recycling in Posidonia oceanica meadows
2014
Abstract The role of Holothuria tubulosa in organic matter recycling of Posidonia oceanica detritus was estimated in a laboratory feeding experiment. The individual mean ingestion rate of seagrass detritus by holothurians was evaluated and carbon and nitrogen stable isotopes, carbon and nitrogen content and C:N ratio analyzed in H. tubulosa , P. oceanica detritus and surface sediment. Results showed that H. tubulosa is capable of ingesting from 30% to 100% of the detritus produced by P. oceanica meadows, depending on the holothurian density. Stable isotope analysis provided evidence for the assimilation of seagrass detritus by H. tubulosa as their signatures were compatible with 1 trophic l…