The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators...The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators were assessed against their corresponding erosion intensity through a correlation analysis. Eight highly correlated indicators were then chosen for the soil erosion assessment. In addition, threshold limits to delineate the class size for these indicators and weights to rank them were determined. Next, a grading model incorporating the selected indicators class rating and their associated weights was developed and verified by an on site evaluation of the soil erosion intensity in the study area. Results of the verification showed that the overall accuracy of the indicator system for assessing soil erosion in the Loess Plateau gully regions could reach 85%.展开更多
Phytochemical constituents of the shoots and roots extract of chosen eight medicinal plants （Plantago major, Verbesina encelioides, Glinus lotoides, Helotropium supinum, Mentha microphylla, Euphorbia hirta, Juncus su...Phytochemical constituents of the shoots and roots extract of chosen eight medicinal plants （Plantago major, Verbesina encelioides, Glinus lotoides, Helotropium supinum, Mentha microphylla, Euphorbia hirta, Juncus subulatus and Convolvulus arvensis） were estimated using standard qualitative analysis. The extract contained alkaloids, glycosides, saponins, phenols, tannins, f[avonoids and terpenoids in some medicinal plants while others contain some only of these phytochemical components. Allelopathic effect of the various concentrations of the extracts on the soil algal diversity was also investigated. Wollea saccata was the only algal species disappeared from all applied investigated plant extracts. Phormidium richardsii, Monoraphidium braunii, Eunotia verneris and Nitzschia bilobata were the highly sensitive algal species to all applied shoot and root extract from all tested plants, they disappeared from most of the studied plants. On the other hand, Phormidium animale and Chlorella neustonice were highly tolerant algal species to all applied extracts. Counts of Cyanophyceae, Chlorophyceae and Bacillariophyceae were decreased by addition of some investigated medicinal plants extracts such as Juncus subulatus, Convolvulus arvensis and Euphorbia hirta. So the authors can use these plants extracts in biocontrol of the nuisance of algal bloom or any other microorganisms. Also, these plants may be useful to recover eutrophic water which needs further investigation.展开更多
Combining ecological niche modeling with phylogeography has become a popular approach to understand how historical climate changes have created and maintained population structure. However, methodological choices in g...Combining ecological niche modeling with phylogeography has become a popular approach to understand how historical climate changes have created and maintained population structure. However, methodological choices in geographic extents and environmental layer sets employed in modeling may affect results and interpretations profoundly. Here, we infer range-wide phylogeographic structure and model ecological niches of Cyanoderrna ruficeps, and compare results to previous studies that examined this species across China's Mainland and Taiwan only. Use of dense taxon sampling of closely related species as outgroups question C. ruficeps monophyly. Furthermore, previously unsampled C. ruficeps populations from central Vietnam were closely related to disjunct western populations （Nepal, Tibet, Myanmar, Yunnan）, rather than to geographically proximate populations in northern Vietnam and eastern China. Phylogeographic structure is more complex than previously appreciated; niche model projections to Last Glacial Maximum climate scenarios identified larger areas of suitable conditions than previous studies, but potential distributional limits differed markedly between climate models employed and were dependent upon interpretation of non-analogous historical climate scenarios. Previously identified population expansion across central China may result from colonization from refugial distributions during the Last Interglacial, rather than the Last Glacial Maximum, as previously understood [Current Zoology 61 （5）： 901-909, 2015].展开更多
文摘氧化运行期间,通过化学连续取样测定冷却剂中^(58)Co的活度浓度峰值和达到氧化运行结束条件的时间(活度浓度<25 GBq·t-1)时,会产生大量放射性废液。为减少取样产生的放射性废液,设计利用高纯锗就地γ测量系统在管道外进行γ谱测量,获得^(58)Co特征峰净计数率随停堆时间实时变化数据,藉此预判^(58)Co活度浓度达到峰值时间和氧化运行结束时间,然后进行取样分析。在某核电站氧化运行期间,利用系统进行γ谱连续测量,判断^(58)Co活度浓度峰值时间是停堆后33h39min(±10min),氧化运行结束时间是停堆后57h(±10 min);连续取样数据测量判断^(58)Co活度浓度峰值时间是停堆后33 h 34 min,氧化运行结束时间是停堆后57 h 9 min。两种方法判断达到峰值和氧化运行结束时间误差都在10 min以内。
基金supported by the State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, China (No. 10501-88) the National High Technology Research and Development Program of China (863 Program) (No. 2001AA245041).
文摘The Wangdonggou Watershed on the Loess Plateau in China was selected as the study area to develop a model for soil erosion assessments. Using the data collected at 20 sampling sites all tentatively selected indicators were assessed against their corresponding erosion intensity through a correlation analysis. Eight highly correlated indicators were then chosen for the soil erosion assessment. In addition, threshold limits to delineate the class size for these indicators and weights to rank them were determined. Next, a grading model incorporating the selected indicators class rating and their associated weights was developed and verified by an on site evaluation of the soil erosion intensity in the study area. Results of the verification showed that the overall accuracy of the indicator system for assessing soil erosion in the Loess Plateau gully regions could reach 85%.
文摘Phytochemical constituents of the shoots and roots extract of chosen eight medicinal plants （Plantago major, Verbesina encelioides, Glinus lotoides, Helotropium supinum, Mentha microphylla, Euphorbia hirta, Juncus subulatus and Convolvulus arvensis） were estimated using standard qualitative analysis. The extract contained alkaloids, glycosides, saponins, phenols, tannins, f[avonoids and terpenoids in some medicinal plants while others contain some only of these phytochemical components. Allelopathic effect of the various concentrations of the extracts on the soil algal diversity was also investigated. Wollea saccata was the only algal species disappeared from all applied investigated plant extracts. Phormidium richardsii, Monoraphidium braunii, Eunotia verneris and Nitzschia bilobata were the highly sensitive algal species to all applied shoot and root extract from all tested plants, they disappeared from most of the studied plants. On the other hand, Phormidium animale and Chlorella neustonice were highly tolerant algal species to all applied extracts. Counts of Cyanophyceae, Chlorophyceae and Bacillariophyceae were decreased by addition of some investigated medicinal plants extracts such as Juncus subulatus, Convolvulus arvensis and Euphorbia hirta. So the authors can use these plants extracts in biocontrol of the nuisance of algal bloom or any other microorganisms. Also, these plants may be useful to recover eutrophic water which needs further investigation.
基金We thank Nikki Boggess, who assisted in labwork. Fieldwork in Vietnam was facilitated by Dr. Le Mahn Hung, and supported by the National Geographic Committee for Research and Exploration. Fieldwork in China was supported by the National Science Foundation （DEB-0344430 to ATP）. The laboratory portions of this work were supported by the National Science Foundation （DEB-0743576 to RGM）. We thank recordists who shared their Stachyris/Cyanoderma recordings on Xeno-canto.
文摘Combining ecological niche modeling with phylogeography has become a popular approach to understand how historical climate changes have created and maintained population structure. However, methodological choices in geographic extents and environmental layer sets employed in modeling may affect results and interpretations profoundly. Here, we infer range-wide phylogeographic structure and model ecological niches of Cyanoderrna ruficeps, and compare results to previous studies that examined this species across China's Mainland and Taiwan only. Use of dense taxon sampling of closely related species as outgroups question C. ruficeps monophyly. Furthermore, previously unsampled C. ruficeps populations from central Vietnam were closely related to disjunct western populations （Nepal, Tibet, Myanmar, Yunnan）, rather than to geographically proximate populations in northern Vietnam and eastern China. Phylogeographic structure is more complex than previously appreciated; niche model projections to Last Glacial Maximum climate scenarios identified larger areas of suitable conditions than previous studies, but potential distributional limits differed markedly between climate models employed and were dependent upon interpretation of non-analogous historical climate scenarios. Previously identified population expansion across central China may result from colonization from refugial distributions during the Last Interglacial, rather than the Last Glacial Maximum, as previously understood [Current Zoology 61 （5）： 901-909, 2015].
