This study was conducted to explore the effects of topography and land use changes on particulate organic carbon(POC),particulate total nitrogen(PTN),organic carbon(OC) and total nitrogen(TN) associated with different...This study was conducted to explore the effects of topography and land use changes on particulate organic carbon(POC),particulate total nitrogen(PTN),organic carbon(OC) and total nitrogen(TN) associated with different size primary particle fractions in hilly regions of western Iran.Three popular land uses in the selected site including natural forest(NF),disturbed forest(DF) and cultivated land(CL) and three slope gradients(0-10 %,S1,10-30 %,S2,and 30-50%,S3) were employed as the basis of soil sampling.A total of 99 soil samples were taken from the 0-10 cm surface layer in the whole studied hilly region studied.The results showed that the POC in the forest land use in all slope gradients was considerably more than the deforested and cultivated lands and the highest value was observed at NF-S1 treatment with 9.13%.The values of PTN were significantly higher in the forest land use and in the down slopes(0.5%) than in the deforested and cultivated counterparts and steep slopes(0.09%) except for the CL land use.The C:N ratios in POC fraction were around 17-18 in the forest land and around 23 in the cultivated land.In forest land,the silt-associated OC was highest among the primary particles.The enrichment factor of SOC,EC,was the highest for POC.For the primary particles,EC of both primary fractions of silt and clay showed following trend for selected land uses and slope gradients:CL> DF> NF and S3 > S2> S1.Slope gradient of landscape significantly affected the OC and TN contents associated with the silt and clay particles,whereas higher OC and TN contents were observed in lower positions and the lowest value was measured in the steep slopes.Overall,the results showed that native forest land improves soil organic carbon storage and can reduce the carbon emission and soil erosion especially in the mountainous regions with high rainfall in west of Iran.展开更多
Anambra State of Nigeria is ravaged by ecological hazards of gully erosion and landslides. Over 450 active gully and landslide sites with depths ranging from 5 m to over 120 m are concentrated on both sides of the Awk...Anambra State of Nigeria is ravaged by ecological hazards of gully erosion and landslides. Over 450 active gully and landslide sites with depths ranging from 5 m to over 120 m are concentrated on both sides of the Awka-Nanka-Umuchu-Orlu cuesta. The Idemili River and Odo River form the major drainage basins of the area. The geomorphic characteristic of the cuesta/escarpment is a major controlling factor in groundwater recharge and discharge within the drainage basins. Rise in aquifer levels result in hydrogeotechnical implications of gully development and landslides. The calculated values of hydraulic properties of conductivity and transmissivity range from 1.20×10^-1 to 5.93×10^-1 cm/s and 1.15×10^5-13.05×10.3 m^2/s respectively. The values of groundwater velocity and groundwater discharge were 82 m.yearl and 2.96×10^6 m^3.yearl The plasticity index of the soil in the gully prone areas is relatively low ranging from 12.50-36.57%. The unique features of the geologic formations together with obtained aquifer characteristics favour gully/landslide hazards in the area.展开更多
文摘This study was conducted to explore the effects of topography and land use changes on particulate organic carbon(POC),particulate total nitrogen(PTN),organic carbon(OC) and total nitrogen(TN) associated with different size primary particle fractions in hilly regions of western Iran.Three popular land uses in the selected site including natural forest(NF),disturbed forest(DF) and cultivated land(CL) and three slope gradients(0-10 %,S1,10-30 %,S2,and 30-50%,S3) were employed as the basis of soil sampling.A total of 99 soil samples were taken from the 0-10 cm surface layer in the whole studied hilly region studied.The results showed that the POC in the forest land use in all slope gradients was considerably more than the deforested and cultivated lands and the highest value was observed at NF-S1 treatment with 9.13%.The values of PTN were significantly higher in the forest land use and in the down slopes(0.5%) than in the deforested and cultivated counterparts and steep slopes(0.09%) except for the CL land use.The C:N ratios in POC fraction were around 17-18 in the forest land and around 23 in the cultivated land.In forest land,the silt-associated OC was highest among the primary particles.The enrichment factor of SOC,EC,was the highest for POC.For the primary particles,EC of both primary fractions of silt and clay showed following trend for selected land uses and slope gradients:CL> DF> NF and S3 > S2> S1.Slope gradient of landscape significantly affected the OC and TN contents associated with the silt and clay particles,whereas higher OC and TN contents were observed in lower positions and the lowest value was measured in the steep slopes.Overall,the results showed that native forest land improves soil organic carbon storage and can reduce the carbon emission and soil erosion especially in the mountainous regions with high rainfall in west of Iran.
文摘Anambra State of Nigeria is ravaged by ecological hazards of gully erosion and landslides. Over 450 active gully and landslide sites with depths ranging from 5 m to over 120 m are concentrated on both sides of the Awka-Nanka-Umuchu-Orlu cuesta. The Idemili River and Odo River form the major drainage basins of the area. The geomorphic characteristic of the cuesta/escarpment is a major controlling factor in groundwater recharge and discharge within the drainage basins. Rise in aquifer levels result in hydrogeotechnical implications of gully development and landslides. The calculated values of hydraulic properties of conductivity and transmissivity range from 1.20×10^-1 to 5.93×10^-1 cm/s and 1.15×10^5-13.05×10.3 m^2/s respectively. The values of groundwater velocity and groundwater discharge were 82 m.yearl and 2.96×10^6 m^3.yearl The plasticity index of the soil in the gully prone areas is relatively low ranging from 12.50-36.57%. The unique features of the geologic formations together with obtained aquifer characteristics favour gully/landslide hazards in the area.
