[Identification of the long-term patterns of catchment development and diatom community changes in Xihu Lake, Dali, Yunnan, China]. / å¤§ç†è¥¿æ¹–æµåŸŸå¼€å‘åŽ†å²ä¸Žç¡ è—»ç¾¤è½å˜åŒ–çš„æ¨¡å¼è¯†åˆ«.

Limnological studies have long focused on the nine largest plateau lakes and ecological assessment of lake eutrophication in Yunnan. However, comprehensive surveys of small and me-dium-sized lakes and their response to multiple stressors are largely absent. Here, we combined multi-proxy sediment analyses and documentary data, aiming to identify the long-term pattern of diatom community changes under the influence of climate change and anthropogenic disturbances, and to quantify their driving strengths. The results showed that Xihu Lake was in a pre-impact state with little ecological variability before the 1950s. Thereafter, expansion of land use increased the nutrient input and altered the lake hydrology, resulting in a significant shift of dominant diatoms from Cocconeis placentula to Fragilaria spp. From 1997, accelerating nutrient enrichment and hydrological changes led to the replacement of benthic diatoms by planktonic ones, resulting in a consistent loss of macrophytes and a decrease of ecological stability. Therefore, the types and strength of catchment development should be fully evaluated for effective protection of small and medium-sized alpine lakes in the context of global warming.

Effectiveness of Secundum Atrial Septal Defect Occlusion with the Septal Occluder through Right-chest Small Incision: Clinical Analysis of 140 Cases.

Objective To evaluate the feasibility and effectiveness of secundum atrial septal defect(ASD)occlusion with the septal occluder through right-chest small incision. Methods The clinical data of 140 secundum ASD patients (47 males and 93 females) aged 3-63 years who were treated in our center from August 2004 to July 2014 were retrospectively analyzed. The diameter of ASD was 6 to 36 mm. Under general anesthesia, all patients underwent intraoperative transtsophageal echocardiography (TEE), during which no associated cardiac deformity was found. All patients received ASD occlusion via a small incision (3-4 cm) at the right anterior chest. The occluders were released with the help of TEE. Results The atrial septal defect closure was successfully completed in 134 cases. Six cases received surgical closure of ASD after the failure of occlusion. The reasons of conversion included postoperative dislodgement of occlusion device (n=2, both were central type with large size) and technically unsuitable for occlusion (n=4, in whom residual shunt was found in 2 case, sieve pore type in 1 case, and intraoperative dislodgement in 1 case). All of these 6 patients were treated surgically under cardiopulmonary bypass. No dislocation of the device or atrial shunt was found within 3 to 48 months after the operation. Conclusion Occlusion via small chest incision of ASD under TEE guidance without cardiopulmonary bypass is a safe, minimally invasive, effective, and convenient treatment and worth clinical application.

[Long-term pattern of diatom community structure changes in response to multiple environmental stressors at Datun Lake, Southeast Yunnan, China].

Subtropical plateau lakes in Southeast Yunnan are known to have experienced multiple environmental stressors (lake pollution, eutrophication, land reclamation and droughts) during the past decades. Here, we applied multi-proxy analyses (i.e., diatom, grain size, C and N isotopic and chronology) of lake sediments, aiming to track the history of lake environment change and the characteristics of diatom community responses in Datun Lake for the past century. The results proved that the sedimentary diatom community records showed significant changes with the replacement of Fragilaria construens by Achnanthes minutissima. Combining with multiple-proxy records (i.e., isotopic data) and modern monitoring records, the ordination analyses and variation partitioning further suggested that industrial pollution and eutrophication were the major driving factors that led to the long-term shift of diatom community. In addition, the grain size results and meteorological data revealed that the reductions in hydrodynamic and water exchange intensity associated with damming and the occurrence of extreme droughts, thus led to the corresponding diatom community change.