Borno state is the second largest state in Nigeria with over 70,000 square kilometers of diverse ecosystems including parts of the fertile Lake Chad basin. However, more than 2/3 of this landmass is threatened with dr...Borno state is the second largest state in Nigeria with over 70,000 square kilometers of diverse ecosystems including parts of the fertile Lake Chad basin. However, more than 2/3 of this landmass is threatened with drought, advancing desertification and degraded soils. Most restoration efforts involve revegetation, which in the past has met with limited success. Microbial communities of soils play a pivotal role in soil fertility and plant cover. We conducted the first metagenomic amplicon sequencing study, comparing two soil depths to determine whether soil bacteria abundance and diversity in the harsh bare soils were sufficient to sustain greening efforts. The goal was to glean insights to guide microbial inoculant formulation needed in the region. Samples from top (0 - 15 cm) and sub (16 - 65 cm) soils were collected from five strategic locations in the state. Using next generation Illumina sequencing protocols, total DNA extracted directly from the soils was sequenced and analyzed by QIIME. Metadata collected from site showed scorching temperatures of over 46?C, near zero moisture level and a pH of about 6 for top soil. At 65 cm depth, the temperature averaged 32?C with a pH of 5 and significantly higher soil moisture of 0.1%. The bacterial community structure was unexpectedly very diverse at both soil depths samples, recording a ChaO1 index ranging from 909 to 4296 and a Shannon diversity range of 3.54 to 6.33. The most abundant phyla in both soil depths were the Firmicutes and Proteobacteria;however the relative abundance of composite lower taxa was strikingly different. Operational taxonomic units and diversity indices were highest for top soils and were dominated by members of resilient groups of Actinobacteria, Firmucutes, Acidobacteria and numerous other less well-known taxa whose individual relative abundance did not exceed 3% of total population. The high diversity and richness of Proteobacteria (at 65 cm depth), some of which are key to soil fertility, suggest that revegetation efforts could be improved by shifting the gradient of these microbiota upwards using shades and micro-irrigation. Soils in semi-arid regions in Nigeria contain numerous operational taxonomic bacterial groups with potential thermophilic and drought genetic resources to be mined. Microbial community structure beneath the top soil appears stable and should be the target sample for the assessments of climatic change impact on microbial community structure in environments like this.展开更多
The current study reports the concentration of lead in top of the soil samples and its penetration until the depth of approximately 120 cm. Representative soil samples are collected around the former Factory Productio...The current study reports the concentration of lead in top of the soil samples and its penetration until the depth of approximately 120 cm. Representative soil samples are collected around the former Factory Production of Batteries to Berat, Albania at a distance 80 - 900 m from factory. We have chosen 12 sampling points. We have collected a total of 55 samples where 31 were soil samples (12 top of soil and 19 were profile soil samples) and 24 were random vegetation samples. All soil samples were analyzed using Atomic Absorption Spectrometry for their lead content, at the Institute of Applied Nuclear Physics, University of Tirana, Albania. From results obtained the fraction of lead in profile soil samples was in range: 78 mg/kg - 52,982 mg/kg and average concentration of lead was 2976 mg/kg, while in random vegetation samples was in range: 0.238 - 5.573 mg/kg. In general, trend of the content of lead in profile soil samples was decreasing compared to the content of lead in the respective top soil samples. The concentrations of lead which have been found in analyzed soil samples are compared with the Maximum Contaminant Levels specified by the Directive 86/278/EEC. Also, we have calculated Hazardous Quoted for each sampling point which is found very high. HQ in representative surface soil samples is 0.4 - 80.7 times higher than normal.展开更多
In this study height growth models for hybrid aspen were developed using three growth equations. The mean age of the hybrid aspen was 21 years （range 15-51 years） with a mean stand density of 946 stems ha-~ （87-237...In this study height growth models for hybrid aspen were developed using three growth equations. The mean age of the hybrid aspen was 21 years （range 15-51 years） with a mean stand density of 946 stems ha-~ （87-2374） and a mean diameter at breast height （over bark） of 19.6 cm （8.5-40.8 cm）. Site index was also examined in relation to soil type. Multiple samples were collected for three types of soil： light clay, medium clay and till. Site index curves were constructed using the col- lected data and compared with published reports. A number of dynamic equations were assessed for modeling top-height growth from total age.展开更多
The first area is rock instability in conglomerates walls, and the second area is soil instability in a slope composed of sand gravel and shale in the south of the study area. In the first area, rock slopes were studi...The first area is rock instability in conglomerates walls, and the second area is soil instability in a slope composed of sand gravel and shale in the south of the study area. In the first area, rock slopes were studied by fractures condition, slope morphology, measured engineering features of rocks, and then interpreted by Dips software to define the fracture types for analysis of block toppling. The rock slope of the area was modeled by Rock plan by adding water penetration and earthquake. The results showed that in dry condition these slopes were stable, but by penetrating water and saturation of the open spaces of the fractures, the block toppling will occur. Also, seismic activities in the area caused the instability of the slopes, and landslide will happen. In the second area, landslides were spoon-shaped type. To investigate the soil slope stability, the condition of slope was modeled by using soil engineering properties and measuring the morphological condition of the slope such as slope dip, layers thickness, layers dip and slope elevation. It was shown instability of the soil slopes. To stabilize the sliding areas, the dip changing method and formation of stepped-style slope were done. However, the new condition changed the formation of sliding areas in the upper most part of the stairs. The retaining walls formed from the local materials were applied to the slope to provide the desire stability.展开更多
以东北地区为研究对象,分析多年冻土退化程度及空间分布。通过收集关键气象要素,使用多元线性回归模型修正部分地面温度,基于多年冻土顶部温度(temperature at the top of permafrost,TTOP)模型,利用ANUSPILN软件进行插值,分析东北多年...以东北地区为研究对象,分析多年冻土退化程度及空间分布。通过收集关键气象要素,使用多元线性回归模型修正部分地面温度,基于多年冻土顶部温度(temperature at the top of permafrost,TTOP)模型,利用ANUSPILN软件进行插值,分析东北多年冻土时空分布变化。结果表明,1970 s、1980 s、1990 s、2000 s、2010 s的多年冻土面积分别约为3.99×10^(5)、3.41×10^(5)、2.31×10^(5)、1.80×10^(5)、1.59×10^(5) km^(2)。1970 s—2010 s,东北地区的多年冻土面积显著减少约2.40×10^(5) km^(2),降幅高达60.08%。多年冻土面积占东北地区总面积的比例从27.66%下降至11.04%,而季节性冻土面积比例则从72.34%增加至88.96%。模型结果与实际钻孔数据差值仅为0.05℃,且使用修正地面温度数据的模型结果高于现有研究结果。展开更多
文摘Borno state is the second largest state in Nigeria with over 70,000 square kilometers of diverse ecosystems including parts of the fertile Lake Chad basin. However, more than 2/3 of this landmass is threatened with drought, advancing desertification and degraded soils. Most restoration efforts involve revegetation, which in the past has met with limited success. Microbial communities of soils play a pivotal role in soil fertility and plant cover. We conducted the first metagenomic amplicon sequencing study, comparing two soil depths to determine whether soil bacteria abundance and diversity in the harsh bare soils were sufficient to sustain greening efforts. The goal was to glean insights to guide microbial inoculant formulation needed in the region. Samples from top (0 - 15 cm) and sub (16 - 65 cm) soils were collected from five strategic locations in the state. Using next generation Illumina sequencing protocols, total DNA extracted directly from the soils was sequenced and analyzed by QIIME. Metadata collected from site showed scorching temperatures of over 46?C, near zero moisture level and a pH of about 6 for top soil. At 65 cm depth, the temperature averaged 32?C with a pH of 5 and significantly higher soil moisture of 0.1%. The bacterial community structure was unexpectedly very diverse at both soil depths samples, recording a ChaO1 index ranging from 909 to 4296 and a Shannon diversity range of 3.54 to 6.33. The most abundant phyla in both soil depths were the Firmicutes and Proteobacteria;however the relative abundance of composite lower taxa was strikingly different. Operational taxonomic units and diversity indices were highest for top soils and were dominated by members of resilient groups of Actinobacteria, Firmucutes, Acidobacteria and numerous other less well-known taxa whose individual relative abundance did not exceed 3% of total population. The high diversity and richness of Proteobacteria (at 65 cm depth), some of which are key to soil fertility, suggest that revegetation efforts could be improved by shifting the gradient of these microbiota upwards using shades and micro-irrigation. Soils in semi-arid regions in Nigeria contain numerous operational taxonomic bacterial groups with potential thermophilic and drought genetic resources to be mined. Microbial community structure beneath the top soil appears stable and should be the target sample for the assessments of climatic change impact on microbial community structure in environments like this.
文摘The current study reports the concentration of lead in top of the soil samples and its penetration until the depth of approximately 120 cm. Representative soil samples are collected around the former Factory Production of Batteries to Berat, Albania at a distance 80 - 900 m from factory. We have chosen 12 sampling points. We have collected a total of 55 samples where 31 were soil samples (12 top of soil and 19 were profile soil samples) and 24 were random vegetation samples. All soil samples were analyzed using Atomic Absorption Spectrometry for their lead content, at the Institute of Applied Nuclear Physics, University of Tirana, Albania. From results obtained the fraction of lead in profile soil samples was in range: 78 mg/kg - 52,982 mg/kg and average concentration of lead was 2976 mg/kg, while in random vegetation samples was in range: 0.238 - 5.573 mg/kg. In general, trend of the content of lead in profile soil samples was decreasing compared to the content of lead in the respective top soil samples. The concentrations of lead which have been found in analyzed soil samples are compared with the Maximum Contaminant Levels specified by the Directive 86/278/EEC. Also, we have calculated Hazardous Quoted for each sampling point which is found very high. HQ in representative surface soil samples is 0.4 - 80.7 times higher than normal.
文摘In this study height growth models for hybrid aspen were developed using three growth equations. The mean age of the hybrid aspen was 21 years （range 15-51 years） with a mean stand density of 946 stems ha-~ （87-2374） and a mean diameter at breast height （over bark） of 19.6 cm （8.5-40.8 cm）. Site index was also examined in relation to soil type. Multiple samples were collected for three types of soil： light clay, medium clay and till. Site index curves were constructed using the col- lected data and compared with published reports. A number of dynamic equations were assessed for modeling top-height growth from total age.
文摘The first area is rock instability in conglomerates walls, and the second area is soil instability in a slope composed of sand gravel and shale in the south of the study area. In the first area, rock slopes were studied by fractures condition, slope morphology, measured engineering features of rocks, and then interpreted by Dips software to define the fracture types for analysis of block toppling. The rock slope of the area was modeled by Rock plan by adding water penetration and earthquake. The results showed that in dry condition these slopes were stable, but by penetrating water and saturation of the open spaces of the fractures, the block toppling will occur. Also, seismic activities in the area caused the instability of the slopes, and landslide will happen. In the second area, landslides were spoon-shaped type. To investigate the soil slope stability, the condition of slope was modeled by using soil engineering properties and measuring the morphological condition of the slope such as slope dip, layers thickness, layers dip and slope elevation. It was shown instability of the soil slopes. To stabilize the sliding areas, the dip changing method and formation of stepped-style slope were done. However, the new condition changed the formation of sliding areas in the upper most part of the stairs. The retaining walls formed from the local materials were applied to the slope to provide the desire stability.
文摘以东北地区为研究对象,分析多年冻土退化程度及空间分布。通过收集关键气象要素,使用多元线性回归模型修正部分地面温度,基于多年冻土顶部温度(temperature at the top of permafrost,TTOP)模型,利用ANUSPILN软件进行插值,分析东北多年冻土时空分布变化。结果表明,1970 s、1980 s、1990 s、2000 s、2010 s的多年冻土面积分别约为3.99×10^(5)、3.41×10^(5)、2.31×10^(5)、1.80×10^(5)、1.59×10^(5) km^(2)。1970 s—2010 s,东北地区的多年冻土面积显著减少约2.40×10^(5) km^(2),降幅高达60.08%。多年冻土面积占东北地区总面积的比例从27.66%下降至11.04%,而季节性冻土面积比例则从72.34%增加至88.96%。模型结果与实际钻孔数据差值仅为0.05℃,且使用修正地面温度数据的模型结果高于现有研究结果。
