Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2)O) are greenhouse gases (GHGs) which cause global warming. Natural sources of GHGs include wetlands and termites. Previous studies have quantified GHG emission...Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2)O) are greenhouse gases (GHGs) which cause global warming. Natural sources of GHGs include wetlands and termites. Previous studies have quantified GHG emissions from upland termites and no study has reported GHG emissions from seasonal wetlands (dambo) located termite mounds. The objective of this study was to evaluate the effect of dambo catena position on termite mound distribution and GHG emissions. It was hypothesized that mound density and GHG emissions from Odontotermes transvaalensis mounds, vary with catena position. The evaluated catena positions were margin, mid-slope, lower slope and bottom. Mound density was significantly lower in the bottom when compared to the other catena positions. The mean GHG fluxes were 88 μg m2 hr-1, 0.78 mg m2 hr-1 and 1361 mg m2 hr-1 for N2) O, CH4 and CO2 respectively. Fluxes varied with catena position and were 0.48, 0.72, 1.35 and 0.79 mg m-2 hr-1 for CH4 , and 1173.7, 1440.7, 1798.7 and 922.8 mg m-2 hr-1 for CO2 in the margin, mid-slope, lower slope and the bottom catena position respectively. For N2) O, there were no significant differences between catena positions. It was concluded that dambo located Odontotermes transvaalensis termite mounds are an important source of GHGs, and emissions varied with catena position for CO2 and CH4.展开更多
Understanding the effects of elevation and related factors(climate,vegetation) on the physical and chemical soil properties can help to predict changes in response to future climate or afforestation forcings.This work...Understanding the effects of elevation and related factors(climate,vegetation) on the physical and chemical soil properties can help to predict changes in response to future climate or afforestation forcings.This work aims to contribute to the knowledge of soil evolution and the classification of forest soils in relation to elevation in the montane stage,with special attention to podzolization and humus forms.The northern flank of the Moncayo Massif(Iberian Range,SW Europe) provides a unique opportunity to study a forest soils catena within a consistent quartzitic parent material over a relatively steep elevation gradient.With increasing elevation,pH,base saturation,exchangeable potassium,and fine silt-sized particles decrease significantly,while organic matter,the C/N ratio,soil aggregate stability,water repellency and coarse sand-sized particles increase significantly.The soil profiles shared a set of properties in all horizons:loamy-skeletal particle-size,extreme acidity(pH-H_2O<5.6) and low base saturation(<50%).The most prevalent soil forming processes in the catena include topsoil organic matter accumulation and even podzolization,which increases with elevation.From the upper to lower landscape positions of wooded montane stage of the Moncayo Massif,mull-moder-mor humus and an UmbrisolCambisol-Podzol soil unit sequences were found.展开更多
Soil erosion is one of the main environmental problems in the Mediterranean area.This problem is becoming even more important especially in Italy,in the Apennines,where severe erosive processes occur due to the action...Soil erosion is one of the main environmental problems in the Mediterranean area.This problem is becoming even more important especially in Italy,in the Apennines,where severe erosive processes occur due to the action of concentrated running water.The erodibility(K-Factor)of a soil,estimated using the Revised Universal Soil Loss Equation(RUSLE),is a measure of its susceptibility to erosion and depends on several soil properties such as organic matter,texture and permeability and structure.To assess the spatial variability of soil properties and soil erodibility in hilly agricultural areas and to investigate the relationships between soil features and landscape morphodynamics,a detailed study in Molise region(southern Italy),in a small drainange basin located along its hilly Adriatic flank,was carried out.In this catchment,63 topsoil samples(A horizons)were collected and 10 soil profiles,forming a catena crossing 3 land units,were sampled.The calculated K-Factors ranges between 0.012 and 0.048 t ha h ha-1 MJ-1 mm-1 indicating a complex spatial distribution,due to the several local pedological and geomorphological factors affecting soil erodibility.The results give clear evidence about the relationships among soil characteristics,soil erodibility and landscape morpho-dynamics(land units).Comparing the soil loss rates estimated for the study area with those reported in literature,a good correspondence can be observed only for the more stable land unit,not characterized by intense erosive processes.The proposed methodology is suitable to highlight areas characterized by similar morphodynamics features,and comparable soil erodibility,for a more effective spatialization of K factor.展开更多
A novel one-dimensional coordination polymer, Catena-poly [bis(4-cyano-pyridyl) copper (Ⅱ) -di-thiocyanate], [Cu~Ⅱ-(cypy)_2(μN,s-SCN)_2] (cypy =4-cyano-pyridyl), was synthesized in a solution reaction of CuCNO_3)_2...A novel one-dimensional coordination polymer, Catena-poly [bis(4-cyano-pyridyl) copper (Ⅱ) -di-thiocyanate], [Cu~Ⅱ-(cypy)_2(μN,s-SCN)_2] (cypy =4-cyano-pyridyl), was synthesized in a solution reaction of CuCNO_3)_2·3H_2O, 4-cyano-pyridine andKSCN in mole ratio of 1:2:2 at room temperature. Its crystal structure was determined bysingle-crystal X-ray diffraction. The crystal belongs to monoclinic crystal system, space groupP2_1/c with cell parameters a = 1.0719(2), b = 1.8441(4), c = 0.9144(2) nm, β = 110.49(3)° and Z =4. A full-matrix least-squares refinement gave R_1 = 0.0393 and wR_2 = 0.0916 for 1554 reflectionshaving I > 2σ (Ⅰ). The crystal is thermally stable up to approximately 170℃.展开更多
文摘Methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2)O) are greenhouse gases (GHGs) which cause global warming. Natural sources of GHGs include wetlands and termites. Previous studies have quantified GHG emissions from upland termites and no study has reported GHG emissions from seasonal wetlands (dambo) located termite mounds. The objective of this study was to evaluate the effect of dambo catena position on termite mound distribution and GHG emissions. It was hypothesized that mound density and GHG emissions from Odontotermes transvaalensis mounds, vary with catena position. The evaluated catena positions were margin, mid-slope, lower slope and bottom. Mound density was significantly lower in the bottom when compared to the other catena positions. The mean GHG fluxes were 88 μg m2 hr-1, 0.78 mg m2 hr-1 and 1361 mg m2 hr-1 for N2) O, CH4 and CO2 respectively. Fluxes varied with catena position and were 0.48, 0.72, 1.35 and 0.79 mg m-2 hr-1 for CH4 , and 1173.7, 1440.7, 1798.7 and 922.8 mg m-2 hr-1 for CO2 in the margin, mid-slope, lower slope and the bottom catena position respectively. For N2) O, there were no significant differences between catena positions. It was concluded that dambo located Odontotermes transvaalensis termite mounds are an important source of GHGs, and emissions varied with catena position for CO2 and CH4.
基金supported by project CGL2013-43440-R,funded by the Ministerio de Economiay Competitividad of Spain
文摘Understanding the effects of elevation and related factors(climate,vegetation) on the physical and chemical soil properties can help to predict changes in response to future climate or afforestation forcings.This work aims to contribute to the knowledge of soil evolution and the classification of forest soils in relation to elevation in the montane stage,with special attention to podzolization and humus forms.The northern flank of the Moncayo Massif(Iberian Range,SW Europe) provides a unique opportunity to study a forest soils catena within a consistent quartzitic parent material over a relatively steep elevation gradient.With increasing elevation,pH,base saturation,exchangeable potassium,and fine silt-sized particles decrease significantly,while organic matter,the C/N ratio,soil aggregate stability,water repellency and coarse sand-sized particles increase significantly.The soil profiles shared a set of properties in all horizons:loamy-skeletal particle-size,extreme acidity(pH-H_2O<5.6) and low base saturation(<50%).The most prevalent soil forming processes in the catena include topsoil organic matter accumulation and even podzolization,which increases with elevation.From the upper to lower landscape positions of wooded montane stage of the Moncayo Massif,mull-moder-mor humus and an UmbrisolCambisol-Podzol soil unit sequences were found.
文摘Soil erosion is one of the main environmental problems in the Mediterranean area.This problem is becoming even more important especially in Italy,in the Apennines,where severe erosive processes occur due to the action of concentrated running water.The erodibility(K-Factor)of a soil,estimated using the Revised Universal Soil Loss Equation(RUSLE),is a measure of its susceptibility to erosion and depends on several soil properties such as organic matter,texture and permeability and structure.To assess the spatial variability of soil properties and soil erodibility in hilly agricultural areas and to investigate the relationships between soil features and landscape morphodynamics,a detailed study in Molise region(southern Italy),in a small drainange basin located along its hilly Adriatic flank,was carried out.In this catchment,63 topsoil samples(A horizons)were collected and 10 soil profiles,forming a catena crossing 3 land units,were sampled.The calculated K-Factors ranges between 0.012 and 0.048 t ha h ha-1 MJ-1 mm-1 indicating a complex spatial distribution,due to the several local pedological and geomorphological factors affecting soil erodibility.The results give clear evidence about the relationships among soil characteristics,soil erodibility and landscape morpho-dynamics(land units).Comparing the soil loss rates estimated for the study area with those reported in literature,a good correspondence can be observed only for the more stable land unit,not characterized by intense erosive processes.The proposed methodology is suitable to highlight areas characterized by similar morphodynamics features,and comparable soil erodibility,for a more effective spatialization of K factor.
文摘A novel one-dimensional coordination polymer, Catena-poly [bis(4-cyano-pyridyl) copper (Ⅱ) -di-thiocyanate], [Cu~Ⅱ-(cypy)_2(μN,s-SCN)_2] (cypy =4-cyano-pyridyl), was synthesized in a solution reaction of CuCNO_3)_2·3H_2O, 4-cyano-pyridine andKSCN in mole ratio of 1:2:2 at room temperature. Its crystal structure was determined bysingle-crystal X-ray diffraction. The crystal belongs to monoclinic crystal system, space groupP2_1/c with cell parameters a = 1.0719(2), b = 1.8441(4), c = 0.9144(2) nm, β = 110.49(3)° and Z =4. A full-matrix least-squares refinement gave R_1 = 0.0393 and wR_2 = 0.0916 for 1554 reflectionshaving I > 2σ (Ⅰ). The crystal is thermally stable up to approximately 170℃.
