高寒草地土壤保持功能的风洞模拟及其定量评估

青藏高原高寒草地的土壤保持功能对于保护生态环境具有重要的作用。为了研究人类活动不同干扰方式对高寒草地土壤保持功能的影响,利用大型风洞,对不同干扰方式下高寒草甸、草原化草甸和高寒草原3个类型的土壤保持功能定量评估,以侵蚀率作为土壤保持功能的测度指标。实验结果表明,随着风速的增大,3个样品的土壤侵蚀率均呈现增大趋势,但不同处理下侵蚀率的增幅不同。当植被根系破坏后,土壤侵蚀率大小为高寒草甸<草原化草甸<高寒草原,说明,高寒草甸土壤的可蚀性低,高寒草原土壤的可蚀性高,极易遭到破坏。从总体来看,土壤保持功能的强弱依次为高寒草甸>草原化草甸>高寒草原。风蚀前后土壤中有机质和养分含量的变化分析表明,土壤有机质和养分含量显著下降,其中速效K2O的养分含量下降幅度最大。对3个草地类型单位面积土壤保持经济价值进行计算,计算主要包括保持有机碳、保持养分和减少土壤流失对河流湖泊淤积3个方面的价值。结果表明,高寒草原化草甸单位面积的土壤保持价值最高,其次为高寒草甸,高寒草原单位面积土壤保持价值最低。     

城市扩展与热岛空间分布变化关系研究——以上海为例

随着城市建设区域和格局的迅速改变,城市热岛分布也发生了巨大变化.为了了解城市热岛分布与城市建设的关系,为城市建设同时缓解改善热岛效应奠定基础,文章采用遥感动态监测和GIS多要素空间分析技术,对上海城市90年代以来的城市扩展以及热岛分布变化状况和演变规律进行监测分析,得出城市建设区域的扩大将会导致城市热岛范围和面积的增大,城市扩展与热岛扩展趋势具有空间一致性.同时,通过对上海城市不同温度情况下地面不同介质的比例、面积进行因子权重分析,得出温度越高,其建筑、交通、工业区的比例越大;反之温度越低,农田、耕地等介质的比例越高;表明不同地物对温度分布、强度的影响明显.研究还表明:城市扩展虽会导致热岛范围加大,但如注重环境和绿化建设,则在一定程度上可缓解热岛效应和缩小热岛范围.     

三峡库区太阳能资源基本特征及其演变

利用1961-2007年的日照时数建模计算了三峡库区的太阳辐射,在此基础上对库区的太阳能资源作了全面分析和评价。结果表明：库区年总辐射量介于3200～4400MJ/m²,与德国等太阳能利用大国相当;“下游多,上游少”是资源空间分布的基本特征,且在秋、冬季差异更为明显;资源的年变化具有“夏大冬小”的特点,同时呈典型“双峰结构”,最大和次大峰值分别出现在8月和5月;库区上游太阳能季节差异大,而中、下游四季差异相对较小;库区太阳辐射以散射辐射为主（平均为64%）,上游尤其明显;1961-2007年,资源量与直射比均呈明显下降趋势,且在夏、冬季下降尤为显著,分析表明这与轻雾日数和霾日数的增加有关;自20世纪90年代初起,资源量开始回升,有利于库区太阳能的开发利用。     

微塑料与有机污染物的相互作用研究进展

微塑料(粒径小于5 mm的塑料)作为海洋中一种新型的污染物正受到越来越多的关注。微塑料在全球多个海域均有检出,根据其来源分为原生微塑料和次生微塑料。原生微塑料由人工直接制造所得,常见于日常生活用品中;次生微塑料由大块塑料制品长期风化、磨损和光解形成。塑料自身含有多种有机添加剂,不断向环境中释放,污染海洋环境;微塑料表面还可吸附有机污染物,此吸附作用受两者的物理化学性质和环境条件影响,吸附污染物后的微塑料生物毒性增强。另外,聚合物复合光催化材料可加快有机污染物如染料的光降解反应速率,因而微塑料可能会促进有机污染物的光解。针对目前微塑料对有机物光降解的贡献、机理鲜见研究的问题,未来应加强以下3方面的研究:(1)微塑料对不同有机污染物光降解是否存在影响?(2)微塑料类型、尺寸以及反应条件对有机污染物光降解如何影响?(3)微塑料对有机污染物光降解影响的内在机制是什么?     

The fragmentation patterns of maternal plasma cell-free DNA and its applications in non-invasive prenatal testing

The discovery of cell-free DNA (cfDNA) in maternal plasma has opened up new promises for the development of non-invasive prenatal testing (NIPT). Application of cfDNA in NIPT of fetus diseases and abnormalities is restricted by the low amount of fetal DNA molecules in maternal plasma. Fetus-derived cfDNA in maternal plasma are shorter than maternal DNA, thus leveraging the maternal and fetus-derived cfDNA molecules size difference has become a novel and more accurate method for NIPT. However, multiple biological properties such as size distribution of plasma DNA, proportion of fetal-derived DNA and methylation levels in maternal plasma across different gestational ages still remain largely unknown. Further insights into the size distribution and fragmentation pattern of circulating plasma cfDNA will shed light on the origin and fragmentation mechanisms of cfDNA during physiological and pathological processes in prenatal diseases and enhance our ability to take the advantage of plasma cfDNA as a molecular diagnostic tool. In the review, we start by summarizing the research techniques for the determination of the fragmentation profiles of cfDNA in maternal plasma. We then summarize the main progress and findings in size profiles of maternal plasma cfDNA and cffDNA. Finally, we discuss the potential diagnostic applications of plasma cfDNA size profiling.     

固定化解脂耶氏酵母处理油脂废水研究

利用海藻酸钙包埋固定的解脂耶氏酵母(Yarrowia lipolytica)分别降解以色拉油为惟一碳源和以葡萄糖为惟一碳源的污水，结果表明，在最佳处理条件下，固定化细胞在50 h内，能较好地降解废水中浓度为2 000 mg/L的色拉油和浓度为2 000 mg/L 的COD，降解率都在80%以上；固定化细胞对色拉油、COD降解效率随着时间的延长而增加、随着底物浓度的增加而下降；与未固定菌株相比，固定化细胞有着更好的储存稳定性和可重复使用性，结果进一步提示固定化解脂耶氏酵母适于含油废水以及高COD含量的生活污水处理。     

Estimating Forest Ecosystem Evapotranspiration at Multiple Temporal Scales With a Dimension Analysis Approach1

Abstract:  It is critical that evapotranspiration (ET) be quantified accurately so that scientists can evaluate the effects of land management and global change on water availability, streamflow, nutrient and sediment loading, and ecosystem productivity in watersheds. The objective of this study was to derive a new semi‐empirical ET modeled using a dimension analysis method that could be used to estimate forest ET effectively at multiple temporal scales. The model developed describes ET as a function of water availability for evaporation and transpiration, potential ET demand, air humidity, and land surface characteristics. The model was tested with long‐term hydrometeorological data from five research sites with distinct forest hydrology in the United States and China. Averaged simulation error for daily ET was within 0.5 mm/day. The annual ET at each of the five study sites were within 7% of measured values. Results suggest that the model can accurately capture the temporal dynamics of ET in forest ecosystems at daily, monthly, and annual scales. The model is climate‐driven and is sensitive to topography and vegetation characteristics and thus has potential to be used to examine the compounding hydrologic responses to land cover and climate changes at multiple temporal scales.     

浅谈建筑施工噪声的网络化管理

通过《南宁市环境信息综合管理系统》中建筑施工噪声管理子系统的重点研究和建设，对建设施工项目审批、中午夜间施工许可登记及施工噪声投诉实时监控，加强监督，改善了管理环节，提高了管理效能，取得了良好的效果。     

Watershed Evapotranspiration Increased due to Changes in Vegetation Composition and Structure Under a Subtropical Climate1

Abstract: Natural forests in southern China have been severely logged due to high human demand for timber, food, and fuels during the past century, but are recovering in the past decade. The objective of this study was to investigate how vegetation cover changes in composition and structure affected the water budgets of a 9.6‐km² Dakeng watershed located in a humid subtropical mountainous region in southern China. We analyzed 27 years (i.e., 1967‐1993) of streamflow and climate data and associated vegetation cover change in the watershed. Land use/land cover census and Normalized Difference of Vegetation Index (NDVI) data derived from remote sensing were used to construct historic land cover change patterns. We found that over the period of record, annual streamflow (Q) and runoff/precipitation ratio did not change significantly, nor did the climatic variables, including air temperature, Hamon’s potential evapotranspiration (ET), pan evaporation, sunshine hours, and radiation. However, annual ET estimated as the differences between P and Q showed a statistically significant increasing trend. Overall, the NDVI of the watershed had a significant increasing trend in the peak spring growing season. This study concluded that watershed ecosystem ET increased as the vegetation cover shifted from low stock forests to shrub and grasslands that had higher ET rates. A conceptual model was developed for the study watershed to describe the vegetation cover‐streamflow relationships during a 50‐year time frame. This paper highlighted the importance of eco‐physiologically based studies in understanding transitory, nonstationary effects of deforestation or forestation on watershed water balances.