Since the 1950s,numerous soil and water conservation measures have been implemented to control severe soil erosion in the Liuhe River Basin(LRB),China.While these measures have protected the upstream soil and water ec...Since the 1950s,numerous soil and water conservation measures have been implemented to control severe soil erosion in the Liuhe River Basin(LRB),China.While these measures have protected the upstream soil and water ecological environment,they have led to a sharp reduction in the downstream flow and the deterioration of the river ecological environment.Therefore,it is important to evaluate the impact of soil and water conservation measures on hydrological processes to assess long-term runoff changes.Using the Soil and Water Assessment Tool(SWAT)models and sensitivity analyses based on the Budyko hypothesis,this study quantitatively evaluated the effects of climate change,direct water withdrawal,and soil and water conservation measures on runoff in the LRB during different periods,including different responses to runoff discharge,hydrological regime,and flood processes.The runoff series were divided into a baseline period(1956-1969)and two altered periods,i.e.,period 1(1970-1999)and period 2(2000-2020).Human activities were the main cause of the decrease in runoff during the altered periods,contributing 86.03%(-29.61 mm),while the contribution of climate change was only 13.70%(-4.70 mm).The impact of climate change manifests as a decrease in flood volume caused by a reduction in precipitation during the flood season.Analysis of two flood cases indicated a 66.00%-84.00%reduction in basin runoff capacity due to soil and water conservation measures in the upstream area.Soil and water conservation measures reduced the peak flow and total flood volume in the upstream runoff area by 77.98%and 55.16%,respectively,even with nearly double the precipitation.The runoff coefficient in the reservoir area without soil and water conservation measures was 4.0 times that in the conservation area.These results contribute to the re-evaluation of soil and water conservation hydrological effects and provide important guidance for water resource planning and water conservation policy formulation in the LRB.展开更多
目的了解极早产儿生后1个月肠道菌群的动态变化及分布特征,为益生菌早期干预提供理论依据。方法采取前瞻性研究方法,选取2022年9月至2023年3月本院收治的极早产儿为研究对象,收集生后第7、14、21、28天的粪便标本行16 S rRNA高通量测序...目的了解极早产儿生后1个月肠道菌群的动态变化及分布特征,为益生菌早期干预提供理论依据。方法采取前瞻性研究方法,选取2022年9月至2023年3月本院收治的极早产儿为研究对象,收集生后第7、14、21、28天的粪便标本行16 S rRNA高通量测序及生物信息分析。结果共纳入极早产儿35例,男22例,女13例,出生胎龄210±11天,出生体重1419±339 g,收集粪便样本140份。在门水平上检测到的优势菌群包括厚壁菌门、变形菌门,占80%以上;属水平上检测到的优势菌群主要以条件致病菌为主,包括埃希菌属、梭菌属、葡萄球菌属、不动杆菌属和克雷伯杆菌属,而双歧杆菌属相对丰度均<5%。关键菌群差异分析发现,门及属水平的差异菌群主要为拟杆菌门(P=0.029)、蓝藻菌门(P=0.011)及葡萄球菌属(P=0.010)、罗氏菌属(P=0.040)。肠道菌群的多样性分析发现,四个时间点Alpla多样性指数Ace值及Shannon值比较差异无统计学差异(P>0.05),而Chao值呈逐渐下降趋势(P=0.001);四个时间点的Beta多样性分析Weighted-unifrac值分别为0.412(0.281~0.493)、0.498(0.214~0.526)、0.428(0.289~0.490)、0.143(0.077~0.423),差异有统计学意义(P<0.001)。结论极早产儿生后7~28天肠道优势菌群从厚壁菌门逐渐转变为变形菌门,并以条件致病菌为主,而双歧杆菌属定植数量少,肠道菌群多样性呈下降趋势。展开更多
基金Fundamental Research Funds for the Central Universities(ZY20230206)Langfang City Science and Technology Research and Development Plan Self-raised Funds Project(2023013216).
文摘Since the 1950s,numerous soil and water conservation measures have been implemented to control severe soil erosion in the Liuhe River Basin(LRB),China.While these measures have protected the upstream soil and water ecological environment,they have led to a sharp reduction in the downstream flow and the deterioration of the river ecological environment.Therefore,it is important to evaluate the impact of soil and water conservation measures on hydrological processes to assess long-term runoff changes.Using the Soil and Water Assessment Tool(SWAT)models and sensitivity analyses based on the Budyko hypothesis,this study quantitatively evaluated the effects of climate change,direct water withdrawal,and soil and water conservation measures on runoff in the LRB during different periods,including different responses to runoff discharge,hydrological regime,and flood processes.The runoff series were divided into a baseline period(1956-1969)and two altered periods,i.e.,period 1(1970-1999)and period 2(2000-2020).Human activities were the main cause of the decrease in runoff during the altered periods,contributing 86.03%(-29.61 mm),while the contribution of climate change was only 13.70%(-4.70 mm).The impact of climate change manifests as a decrease in flood volume caused by a reduction in precipitation during the flood season.Analysis of two flood cases indicated a 66.00%-84.00%reduction in basin runoff capacity due to soil and water conservation measures in the upstream area.Soil and water conservation measures reduced the peak flow and total flood volume in the upstream runoff area by 77.98%and 55.16%,respectively,even with nearly double the precipitation.The runoff coefficient in the reservoir area without soil and water conservation measures was 4.0 times that in the conservation area.These results contribute to the re-evaluation of soil and water conservation hydrological effects and provide important guidance for water resource planning and water conservation policy formulation in the LRB.
文摘目的了解极早产儿生后1个月肠道菌群的动态变化及分布特征,为益生菌早期干预提供理论依据。方法采取前瞻性研究方法,选取2022年9月至2023年3月本院收治的极早产儿为研究对象,收集生后第7、14、21、28天的粪便标本行16 S rRNA高通量测序及生物信息分析。结果共纳入极早产儿35例,男22例,女13例,出生胎龄210±11天,出生体重1419±339 g,收集粪便样本140份。在门水平上检测到的优势菌群包括厚壁菌门、变形菌门,占80%以上;属水平上检测到的优势菌群主要以条件致病菌为主,包括埃希菌属、梭菌属、葡萄球菌属、不动杆菌属和克雷伯杆菌属,而双歧杆菌属相对丰度均<5%。关键菌群差异分析发现,门及属水平的差异菌群主要为拟杆菌门(P=0.029)、蓝藻菌门(P=0.011)及葡萄球菌属(P=0.010)、罗氏菌属(P=0.040)。肠道菌群的多样性分析发现,四个时间点Alpla多样性指数Ace值及Shannon值比较差异无统计学差异(P>0.05),而Chao值呈逐渐下降趋势(P=0.001);四个时间点的Beta多样性分析Weighted-unifrac值分别为0.412(0.281~0.493)、0.498(0.214~0.526)、0.428(0.289~0.490)、0.143(0.077~0.423),差异有统计学意义(P<0.001)。结论极早产儿生后7~28天肠道优势菌群从厚壁菌门逐渐转变为变形菌门,并以条件致病菌为主,而双歧杆菌属定植数量少,肠道菌群多样性呈下降趋势。
