Responses of alkaline phosphatase activity to wind-driven waves in a large, shallow lake: Implications for phosphorus availability and algal blooms

Phosphorus is a vital nutrient for algal growth, thus, a better understanding of phosphorus availability is essential to mitigate harmful algal blooms in lakes. Wind waves are a ubiquitous characteristic of lake ecosystems. However, its effects on the cycling of organic phosphorus and its usage by phytoplankton remain poorly elucidated in shallow eutrophic lakes. A mesocosm experiment was carried out to investigate the responses of alkaline phosphatase activity fractions to wind waves in large, shallow, eutrophic Lake Taihu. Results showed that wind-driven waves induced the release of alkaline phosphatase and phosphorus from the sediment, and dramatically enhanced phytoplanktonic alkaline phosphatase activity. However, compared to the calm conditions, bacterial and dissolved alkaline phosphatase activity decreased in wind-wave conditions. Consistently, the gene copies of Microcystis phoX increased but bacterial phoX decreased under wind-wave conditions. The ecological effects of these waves on phosphorus and phytoplankton likely accelerated the biogeochemical cycling of phosphorus and promoted phytoplankton production in Lake Taihu. This study provides an improved current understanding of phosphorus availability and the phosphorus strategies of plankton in shallow, eutrophic lakes.     

液化天然气(LNG)瞬时泄漏扩散的模拟研究

对液化天然气泄漏扩散过程进行了分析,考虑其泄漏后发生闪蒸时的液滴夹带以及混合空气量,将闪蒸完的状态作为箱模型的初始状态,考虑空气的湿度影响建立了重气扩散过程的箱模型,并应用实例进行了验证,得出了泄漏后有火灾爆炸危险性的区域以及距离泄漏源的位置,为应急救援预案的制定提供参考,模拟结果显示了重气扩散过程中的重力沉降,空气夹带等一般特征,同时云团初始闪蒸时的液滴夹带对云团的扩散行为具有一定的影响,不能忽略.最后提出了今后的研究方向.     

氨气敏电极法和纳氏试剂分光光度法对地表水中氨氮的比对测试

采用不同质量浓度的氨氮标准样品和实际样品,用氨气敏电极法和纳氏试剂分光光度法进行同步测试。结果表明,2种分析方法在水样氨氮质量浓度在0. 159～2. 81 mg/L范围内具有良好的可比性、精密性和准确性。氨气敏电极法的检出限为0. 03 mg/L,平行6次测定样品的相对标准偏差为0. 4%～4. 2%,加标回收率为85. 0%～110%;纳氏试剂分光光度法的检出限为0. 025 mg/L,平行6次测定样品的相对标准偏差为0. 5%～6. 4%,加标回收率为93. 0%～99. 8%。同时氨气敏电极法在样品预处理、试剂配制和分析时间上要优于纳氏试剂分光光度法。氨气敏电极法能够满足地表水自动监测在线比对实际工作的需求,该方法具有良好的适用性。     

Suitable error evaluation criteria selection in the wind energy assessment via the K-means clustering algorithm

In this paper, wind energy potential of four locations in Xinjiang region is assessed. The Weibull distribution as well as the Logistic and the Lognormal distributions are applied to describe the distributions of the wind speed at different heights. In determining the parameters in the Weibull distribution, four intelligent parameter optimization approaches including the differential evolutionary, the particle swarm optimization, and two other approaches derived from these two algorithms and combined advantages of these two approaches are employed. Then the optimal distribution is chosen through the Chi-square error (CSE), the Kolmogorov–Smirnov test error (KSE), and the root mean square error (RMSE) criteria. However, it is found that the variation range of some criteria is quite large, thus these criteria are analyzed and evaluated both from the anomalous values and by the K-means clustering method. Anomaly observation results have shown that the CSE is the first one should be considered to be eliminated from the consequent optimal distribution function selection. This idea is further confirmed by the K-means clustering algorithm, by which the CSE is clustered into a different group with KSE and RMSE. Therefore, only the reserved two error evaluation criteria are utilized to evaluate the wind power potential.     

基于MODIS地面温度数据的成都市热岛时空变化

研究利用2000、2005和2010年逐月的MODIS/Terra和MODIS/Aqua卫星的地表温度数据产品,通过等间距法进行分析,得出成都市建成区2000~2010年间昼夜热岛的时空变化以及相互间差异。研究结果表明:成都市昼夜热岛存在显著差异,日间热岛主要呈散点分布,夜间热岛集中在城市中心区域。日夜间热岛变化趋势有显著不同,日间热岛继续分散而夜间热岛范围则有所扩大。日间热岛分布与植被覆盖存在一定的负相关性,但道路也在一定程度上促使了地面温度的增加,夜间城市热岛范围及变化则与其下垫面组成存在关系。     

Vegetation dynamics and climate change on the Loess Plateau,China: 1982–2011

Monitoring the dynamics of vegetation growth and its response to climate change is important to understand the mechanisms underlying ecosystem behaviors. This study investigated the relationship between vegetation growth and climate change during the growing seasons on the Loess Plateau in China by analyzing the normalized difference vegetation index (NDVI) derived from the Land Long Term Data Record dataset from 1982 to 2011. Results showed that growing-season NDVI had increased at an annual rate of 0.0028, particularly in the semi-arid and semi-humid regions. By contrast, the NDVI first increased from 1982 to 1994 (0.0013 year^?1, P < 0.05) and then decreased from 1994 to 2011 (0.0016 year^?1, P < 0.05) in the arid region. Temperature had a positive effect on NDVI in most periods within and across seasons in the semi-humid region but had no significant effect in the arid region. Precipitation had a positive effect on NDVI in the arid region in summer and in the semi-arid region in autumn. Summer precipitation was important for autumn vegetation growth in the arid region, whereas summer temperature increased autumn vegetation growth in the semi-arid and semi-humid regions. Further analyses supported the lag-time effects of climate change on vegetation growth on the Loess Plateau. Precipitation shifts had 15- to 18-month time lag effects on vegetation growth in the three climate regions. Vegetation NDVI had a 17-month lag response to temperature in the semi-arid region. Human activities should not be neglected in analyzing the relationship between vegetation growth and climate change on the Loess Plateau.     

优势菌对焦化废水中几种有机物降解特性的实验研究

从焦化厂曝气池活性污泥和废水处理工艺出水中筛选出6株革兰氏阳性优势菌,根据菌株、菌落形态和大量生化实验将菌株鉴定到属.确定了降解所需的最佳实验条件.分别为温度30 ℃,转速100　r/min,菌株投加量20%(V(菌液)/V(废水)).实验发现,筛选出的6株优势菌对喹啉、吡啶和萘有良好的降解效果,但以喹啉为碳源和氮源筛选出来的H24,H26和H31对喹啉的去除率优于其他3株菌株,而以萘为唯一碳源的H14对萘的去除率优于其他菌种.6株优势菌的驯化活性污泥能进一步提高对喹啉、吡啶和萘的去除能力,去除率在90%以上.      

生物法处理含油钻井废水的影响因素研究

以含油钻井废水原浆为处理对象,研究了生物法处理过程中的相关影响因素.实验结果表明,氮、磷源是影响钻井废水中石油烃降解的重要因素,最佳氮、磷源及其加入量分别为(NH4)2SO4100 mg/L和KH2PO460 mg/L.在30～36℃,接种量15%,pH=6～8条件下处理72 h后可使钻井废水中的石油烃含量由805.6 mg/L下降到17.6 mg/L.     

Investigation of PM2.5 pollution during COVID-19 pandemic in Guangzhou, China

The COVID-19 pandemic has raised awareness about various environmental issues,including PM_2.5 pollution.Here,PM_2.5 pollution during the COVID-19 lockdown was traced and analyzed to clarify the sources and factors influencing PM_2.5 in Guangzhou,with an emphasis on heavy pollution.The lockdown led to large reductions in industrial and traffic emissions,which significantly reduced PM_2.5 concentrations in Guangzhou.Interestingly,the trend of PM_2.5     

全白土催化剂生产废水的处理

用4种无机絮凝剂和3种有机絮凝剂进行了脱除全白土催化剂生产废水（简称废水）中固体悬浮物（SS）的实验研究。实验结果表明：在废水pH6．8条件下,无机絮凝剂和有机絮凝剂脱除废水中SS的效果均较差,用无机絮凝剂时的SS去除率低于26％,用有机絮凝剂时的SS去除率低于18％;废水pH对SS去除率的影响较大,当调节废水pH为8．0时,无机絮凝剂中硫酸铝脱除废水中的SS效果最好,在硫酸铝加入量为0．02mg／L、沉降时间为2h的最佳操作条件下,SS的去除率可达93％。