基于植被状态指数的干旱化特征及气候驱动因素分析——以江苏省为例

干旱是危害最大的自然灾害之一,给农业生产及地区经济造成了巨大的损失。以AVHRR和MODIS遥感数据集所计算的植被状态指数(Vegetation Condition Index,VCI)为监测指标,研究江苏省干旱的时空变化特征,并结合江苏省气象站台1982~2010年的实测气象资料,分析降水量、气温、相对湿度和日照时数这四个气候因子的变化趋势及其对干旱化的影响,不仅能够定量地描述植被干旱的空间变化,还可以反映长期气候对其起到的正反作用。研究结果表明:江苏省近30年的年均VCI值呈上升趋势,区域整体旱情有所缓解;四个气候因子中,年均温度逐渐升高,年均降水量基本保持不变,年均相对湿度和日照时数则呈下降趋势,其中气温和相对湿度与VCI的相关性达极显著水平,是影响江苏省旱情的主要因素。     

强化混凝去除尖针杆藻

嘉陵江水系藻类暴发,水源水中的藻类在水厂前处理工艺中难以去除,造成该流域附近10余个水厂发生滤池堵塞现象,其中个别水厂滤池反冲洗周期由正常情况的24 h缩短至2~3 h,严重影响净水厂的正常运行,使得制水能力大幅降低。针对藻类（优势藻为硅藻中的针杆藻）暴发问题,通过对比PAFS、PAC和PFC3种混凝剂的除藻除浊效果,选取PAFS为最佳混凝剂;通过添加预氧化剂和助凝剂强化混凝除藻效果,其结果表明,使用助凝剂PDMDAAC的对PAFS的助凝效果最好,其余药剂结合PAFS的除藻效果为PPC〉ClO2〉PAM〉H2O2〉HCA-1,并将其应用到现有水厂,结果表明,0.6mg/L PDMDAAC＋25 mg/L PAFS在水厂混凝沉淀,尖针杆藻含量降至49×104~55×104cells/L,其除藻率可达70%~75%,大大减轻了滤池的运行负荷,使得水厂运行恢复到正常水平。     

AOAB工艺处理难降解混合化工污水的挂膜启动

采用AOAB(水解酸化A1+生物接触氧化O+深度水解酸化A2+曝气生物滤池BAF)工艺处理难降解混合化工污水,重点研究工艺挂膜方式和生物膜的驯化。结果表明,采用分段连续式挂膜法进行反应器挂膜,20 d即可完成快速挂膜启动;采用分阶段同步培养驯化法驯化生物膜,30 d内可完成高浓度多组分混合化工污水进水的驯化,最终进水COD 1 456 mg/L,出水COD 324 mg/L,总去除率76.85%,驯化效果显著;整个工艺对COD的降解主要集中在生物接触氧化池和曝气生物滤池,驯化期间生物接触氧化池去除率稳定在40%左右,曝气生物滤池去除率稳定在50%以上。同时,通过对比一段水解酸化和深度水解酸化的VFA(挥发性脂肪酸)产出,表明在高有机负荷进水时,一段水解酸化降解大分子有机物的能力有限,但这些有机物可通过二段水解酸化再次降解,由此体现了AOAB工艺在处理多组分混合型的难降解化工污水的优势。     

温度和污泥浓度对碱性条件下剩余污泥水解酸化的影响

挥发性脂肪酸(VFAs)是脱氮除磷过程中易于利用的碳源。剩余污泥在碱性条件下发酵能产生大量的VFAs,而温度和污泥浓度是影响剩余污泥发酵的两个重要因素,为此考察了厌氧环境,温度15℃和35℃,pH为10的条件下,剩余污泥挥发性悬浮污泥浓度(VSS为1.708～11.049 g/L)对水解酸化的影响,为实现剩余污泥的资源化提供理论依据。研究得出如下结论:污泥浓度对剩余污泥溶解性化学需氧量(SCOD)溶出率影响不大。低污泥浓度和高污泥浓度均不利于剩余污泥产酸,最佳产酸的污泥浓度为8.540 g/L。各污泥浓度条件下产生的6种挥发性有机酸中乙酸的比例总是最大,且低污泥浓度条件下乙酸的百分含量要高于高污泥浓度条件下。温度对高污泥浓度条件下污泥的最大SCOD溶出量影响较大,而对低污泥浓度条件下污泥最大的产酸量影响较大。无论15℃还是35℃,中等污泥浓度对氨氮的释放量影响不大,35℃条件下污泥浓度对正磷酸盐的释放要比15℃条件下大。     

鸟粪石法回收制肥工业废水中氨氮的中试研究

制肥工业废水中氨氮浓度高,难以直接进行生化反应,采用鸟粪石沉淀法可有效去除并回收氨氮。利用中试反应器回收某制肥工业废水中的氨氮,采用氯化镁与氧化镁作为联用镁源,通过考察不同进料方式、搅拌速度、停留时间等因素的影响,确定了鸟粪石法回收氨氮的最佳工况:采用间歇进水、固体投加镁源的投料方式,搅拌速度300 r/min,停留时间2 h。最佳条件下,氨氮去除率达到93.5%,磷残余率小于0.3%,生成的鸟粪石纯度可达85.6%,砷和铅的质量分数分别为0.0036和0.0008,符合肥料中重金属限值(GB/T 23349-2009),其他重金属均未检出。因此,回收产品有很好的利用价值。经济分析表明磷源是此方法处理成本较高的主要原因。     

Characterizing Coral Condition Using Estimates of Three-dimensional Colony Surface Area

Coral reefs provide shoreline protection, biological diversity, fishery harvests, and tourism, all values that stem from the physically-complex coral infrastructure. Stony corals (scleractinians) construct and maintain the reef through deposition of calcium carbonate. Therefore, assessment of coral reefs requires at least some measurement endpoints that reflect the biological and physical condition of stony corals. Most monitoring programs portray coral quantity as live coral cover, which is the two-dimensional proportion of coral surface to sea floor viewed from above (planar view). The absence of the third dimension, however, limits our ability to characterize coral reef value, physiology, health and sustainability. A three-dimensional (3D) approach more realistically characterizes coral structure available as community habitat and, when combined with estimates of live coral tissue, quantifies the amount of living coral available for photosynthesis, growth and reproduction. A rapid coral survey procedure that coupled 3D coral quantification with more traditional survey measurements was developed and tested in the field. The survey procedure relied on only three underwater observations – species identification, colony size, and proportion of live tissue – made on each colony in the transect. These observations generated a variety of metrics, including several based on 3D colony surface area, that are relevant to reef management.     

Crown condition dynamics of oak in southern Sweden 1988’999

Crown defoliation of oak (Quercus robur and Q. petraea) was analysed in 808 trees during three forest condition surveys (1988, 1993, and 1999) in the southern Sweden. From 1988 to 1999 crown defoliation increased by more than 20%. Changes in crown defoliation were related to the pH in the upper 20–30 cm of the mineral soils, which was closely connected to other measures of soil fertility (cation exchange capacity, CEC and C/N ratio). Trees growing on soils with a high pH (≥4.00, in BaCl₂ filtrate), high CEC and low C/N ratio had significantly lower crown defoliation than trees growing on more acid soils (pH <4.00), indicating that less favourable soil conditions may further enhance oak decline. Age did not differentiate trees with respect to crown defoliation, indicating that decline in crown condition was not due to an age-related increase in crown transparency. Considering only trees younger than 100 years, a significant interaction was observed between changes in crown defoliation and soil pH. Trees younger than 100 years old growing on more acidic soils had a greater increase in crown transparency than trees on more basic soils between 1988 and 1999. Trees ≥100 years old had significantly higher defoliation on more acidic than on more basic soils, however defoliation dynamics of these trees over 1988–99 was not related to soil acidity. Two biotic agents (insect and fungal leaf infections) evaluated in this study did not prove to be important drivers of defoliation dynamics.     

ESP粉尘二维输运方程中紊流掺混系数及边界条件的确定

求解电除尘器ESP(Electrostatic Precipitator)电场粉尘输运方程中粉尘浓度分布时,确定紊流掺混系数及边界条件至关重要.根据紊流传质原理,推导出紊流掺混系数; 通过雷诺数将电风影响引入紊流掺混系数,推导出紊流掺混系数随电晕线到极板距离的增大而增大.极板附近存在具有一定厚度的层流边层.分析层流边层中荷电粒子迁移输运行为,得到极板处粉尘浓度变化规律,这可作为求解输运方程时极板处的边界条件.用Matlab程序求解输运方程.经验证,理论计算的数值结果与试验结果一致,这表明本文所推导的紊流掺混系数和边界条件是正确的.本文使ESP收尘过程的理论研究更加深入,对提高ESP的收尘效率也具有重要意义.     

Experience in establishing a natural standard for analyzing the dynamics of taiga ecosystems

Experience in organizing a natural reference area (standard) for studies on the functional dynamics of ecosystems in connection with paludification and forest-bog relationships is described. The essence of studies on ecosystem dynamics with the aid of natural standards and key plots is described using an example of the Yenisei region of Western Siberia. Arguments are presented for the necessity of using a differential approach to studies on the dynamics of nature and taking into account local ecological conditions while extrapolating the results of these studies to other geographic regions.     

嗜碱细菌降解木质素的复合碳源共代谢研究Ⅱ—营养条件调控机制的研究

文章研究了在蔗糖（第一碳源）＋麦草木质素（第二碳源）的复合碳源组合方式培养条件下,嗜碱木质素降解菌降解木质素的降解率及营养条件调控机制对其的影响。结果表明,蔗糖初始浓度为1g/L,添加0．3％的T－80和0.5mmol/L的ABTS并静置培养对菌株的产酶及降解能力有较大的促进作用。