Climate change and the cost of conserving species in Madagascar

We examined the cost of conserving species as climate changes. We used a Maxent species distribution model to predict the ranges from 2000 to 2080 of 74 plant species endemic to the forests of Madagascar under 3 climate scenarios. We set a conservation target of achieving 10,000 ha of forest cover for each species and calculated the cost of achieving this target under each scenario. We interviewed managers of projects to restore native forests and conducted a literature review to obtain the net present cost per hectare of management actions to maintain or establish forest cover. For each species, we added hectares of land from lowest to highest cost per additional year of forest cover until the conservation target was achieved throughout the time period. Climate change was predicted to reduce the size of species' ranges, the overlap between species' ranges and existing or planned protected areas, and the overlap between species' ranges and existing forest. As a result, climate change increased the cost of achieving the conservation target by necessitating successively more costly management actions: additional management within existing protected areas (US$0-60/ha); avoidance of forest degradation (i.e., loss of biomass) in community-managed areas ($160-576/ha); avoidance of deforestation in unprotected areas ($252-1069/ha); and establishment of forest on nonforested land within protected areas ($802-2710/ha), in community-managed areas ($962-3226/ha), and in unprotected areas ($1054-3719/ha). Our results suggest that although forest restoration may be required for the conservation of some species as climate changes, it is more cost-effective to maintain existing forest wherever possible.     

Effects of climate and exurban development on nest predation and predator presence in the southern Appalachian Mountains (USA)

In the eastern United States, land-use and climate change have likely contributed to declines in the abundance of Neotropical migrant birds that occupy forest interiors, but the mechanisms are not well understood. We conducted a nest-predation experiment in southern Appalachian Mountain forests (North Carolina, U.S.A.) during the 2009 and 2010 breeding seasons to determine the effects of exurban development and temperature on predator presence and the average number of days until eggs in an artificial nest were disturbed by predators. We baited artificial nests with quail (Excalfactoria chinensi) eggs and monitored them for 18 days. We used clay eggs, track plates, and motion-triggered cameras to detect and identify nest predators. The average number of days a nest was undisturbed decreased as mean temperature increased and, to a lesser extent, as the density of buildings increased. Nests on the ground were more often depredated than those in trees, likely due to increased predation by opossum (Didelphis virginiana) and other carnivores. Raccoons (Procyon lotor), opossums, corvids (Corvus brachyrhynchos and Cyanocitta cristata), chipmunks (Tamias striatus), black bears (Ursus americanus), and domestic cats (Felis catus) were the most commonly detected predators. Presence of these predators did not vary as a function of mean temperature. Domestic cats and corvids were detected more frequently in plots with high rather than low densities of buildings. Forest-interior specialists and Neotropical migrants often nest in cool, high-elevation areas with low housing density. These bird species, especially those that nest on the ground, may be most vulnerable to increased nest predation if temperature and exurban development increase at higher elevations as anticipated.     

活性艳红X-3B的厌氧生物降解与机理

以活性艳红X-3B(RBR)为研究对象,分3个不同浓度组研究其在厌氧颗粒污泥作用下的降解性能,并采用生物降解动力学方程拟合其降解过程,同时利用GC-MS分析RBR的生物降解途径.试验结果表明,RBR在厌氧颗粒污泥中降解性能很好,去除率可达93.67%,且其降解过程符合二级反应动力学,其半衰期约为3.561 h.从GC-MS和UV-可见光谱的分析得出,RBR在厌氧颗粒污泥的作用下偶氮键断裂,且生成的芳香胺类化合物进一步降解为小分子的烃类、酚类、醇类和脂类化合物.     

响应面法优化仿酶Fe_3O_4/Fe~0非均相类Fenton降解P-NP

采用原位氧化沉淀法制备出仿酶Fe_3O_4/Fe~0,并采用扫描电子显微镜和X射线衍射对样品进行表征,结果表明,Fe_3O_4与Fe~0负载牢固且保持良好的晶型。采用响应面分析法对仿酶Fe_3O_4/Fe~0催化降解P-NP的工艺条件进行优化,方差分析得到二次模型显著,优化条件为:催化剂用量1.2 g/L,反应温度30℃,初始pH=2.9,初始H_2O_2浓度10 mmol/L,对硝基苯酚去除率的实际值与预测值几乎一致。     

An adaptive online safety assessment method for mechanical system with pre-warning function

The safety status of a dynamic mechanical system is determined by its historical, current and future states together. Therefore the safety assessment process of such system should have dynamic and diachronic characteristics, which helps to track the dynamic states of system and predict future probable danger in advance. In order to overcome the disadvantages of traditional static safety assessment approaches, the results from which are often delayed and prone to produce false alarms, an adaptive online safety assessment method is proposed in this paper, which consists of two steps. A dynamic adaptive weighting method is first introduced and an aggregation scheme based on “3-D” time perspective is further presented to integrate system’s historical, current and future safety performance in a unit framework, considering both of assessment and pre-warning functions. The proposed method is able to track and predict the safety status of system dynamically and discover the potential fault in time. Its feasibility and benefits are investigated with a field case study of gas turbine compressor system, which validates that the proposed method improves the accuracy of safety assessment in dynamic conditions, and finally helps to restrain the fault symptom by proactive maintenance successfully.     

高位巷瓦斯抽采下采空区自燃危险性数值分析及应用

针对大流量高位巷瓦斯抽采可能诱发采空区自燃问题,以南山矿18层5分段综放面为研究背景,构建采空区气体渗流分析模型。利用变渗透系数和Forchheimer方程,求解非线性流与层流并存下采空区三维氧气分布。结果表明:高位巷瓦斯抽采使工作面氧气更易沿漏风方向采空区纵深发展,氧化带总体宽度会随抽放流量的提高而增加。在进风侧氧气分布后移程度较小,而回风侧受抽放负压显著影响,出现明显氧气富集区。上下隅角封堵配合注氮,会降低抽放对氧气渗入的诱导影响。依据研究结论,利用综合防火措施消除了高位巷附近潜在的自燃危险。     

多因素影响下巷道变形特性数值模拟研究

基于FLAC3D有限差分软件对开挖深度、侧压力系数、断面形状等多因素影响下的巷道变形参数进行正交试验，根据正交试验分析结果，分别选取同一深度条件下的圆形、马蹄形、直墙拱形、矩形巷道进行模拟试验并以圆形巷道作为典型断面，对不同深度下的巷道变形特征进行模拟试验。研究结果表明:开挖深度对巷道开挖后的应力差变化影响明显，断面形状对巷道围岩内的塑性区深度和具有显著影响；巷道开挖后的塑性区深度和随形状指数增加而呈线性增长趋势，圆形巷道的塑性区深度和最小，矩形最大；应力差随着巷道开挖深度的增加呈线性增加，深部开采应重视巷道内的应力分布情况。     

陶瓷管表面NaHCO3粉体干法脱硫研究

探讨Na HCO3的加热分解特性并将其负载于陶瓷管表面进行了脱硫实验研究,发现Na HCO3在合理的灼烧温度下将在热分解为Na2CO3的过程中形成多孔结构,可在没有液相水存在的情况下成功实现SO2去除,灼烧温度过高则发生颗粒烧结从而降低脱硫效果;进口气流SO2浓度150 ppm的情况下,陶瓷管表面厚度仅仅50μm的Na HCO3粉体可以在20~40 min内将出口气流中的SO2限制在17.5 ppm(50 mg/m^3)的超净排放限值以下。Na HCO3作为干法脱硫剂可在不明显提高烟气湿度和降低其温度的条件下成功实现脱硫,结合陶瓷过滤管的除尘作用,有望实现烟气的深度除尘和脱硫操作的一体化。     

北京市地铁列车运行引起的建筑室内结构噪声污染特征与评价

以200 Hz以下低频部分等效A声级(L_Aeq200)、12.5~20 kHz频率的等效A声级(L_{Aeq20 k})与倍频带声压级作为评价量,结合HJ 793—2106《城市轨道交通(地下段)结构噪声监测方法》、GB 22337—2008《社会生活环境噪声排放标准》和JGJ/T 170—2009《城市轨道交通引起建筑物振动与二次幅射噪声限值及其测量方法标准》监测和评价地铁列车运行引起临近建筑室内结构噪声,并应用于北京市实测研究。结果表明:北京市地铁列车运行引起建筑室内结构噪声的频率范围为12.5~200 Hz;L_{Aeq20 k}不适用于地铁低频结构噪声的评价;北京市2条地铁线路列车运行的结构噪声特征频率分别为31.5、40、50、63和100 Hz,以40 Hz为主。实测表明,地铁结构噪声污染的特征是列车通过时特征频率上的声压增量明显,由于地铁结构噪声在200 Hz以下低频部分的能量分布差异,以及A计权对低频段声压级的消减差异,L_Aeq200评价结果不能客观反映地铁结构噪声的实际影响;低矮楼房对地铁结构噪声有放大作用,而高层楼房则有一定衰减作用;建筑物体量大小和隧道埋深较水平距离对地铁结构噪声衰减的影响更为明显。因此,地铁建设宜综合考虑地铁埋深,并避免穿越低矮楼房和平房区以控制结构噪声污染。     

Spatial and temporal distribution of cyanobacteria in Batticaloa Lagoon

The necessity to understand the relationship between cyanobacterial species abundance and water quality variations in coastal lagoons is crucial to develop strategies to prevent further cyanobacterial proliferation. This paper evaluates the relationship between water quality variations on the distribution of cyanobacteria during a 12-month period in Batticaloa Lagoon (Sri Lanka) using Redundancy analysis and Pearson correlations. Drastic variations in pH, temperature, salinity, dissolved oxygen (DO) and total phosphorus (TP) levels were reported, but not turbidity and NO₃⁻. This brackish waterbody is hypereutrophic (TP levels > 0.1 mg/L). The cyanobacterial community contained 13 genera and 22 species. NO₃⁻, TP and turbidity levels positively influenced cyanobacterial abundance during all seasons indicating that nutrient (largely phosphorus) and sediment entry control is highly crucial along with periodic monitoring of cyanobacterial growth.