矿区河流底质锌解吸规律的研究

通过不同转速搅拌污染底质与蒸馏水的混合液,以摹拟河流不同流速状态,分析不同转速与底质锌溶出量的关系,分析不同静置时间对悬液中锌浓度的影响,以揭示底质中锌的解吸与水质中锌沉降的规律。研究结果表明,搅拌运动加速了底质中锌的解吸,不同转速显著地影响底质锌溶出量,转速越高,锌溶出量越多。但当水样放置一段时间后,水中锌量不断减少,但放置时间从30分钟至60分钟水中锌量没有显著的区别,120分钟和240分钟之间也没有显著差异。30分钟后,水质中的锌量不断缓慢地衰减。当水样放置30分钟后,各转速间锌量没有显著的差异性。     

含水量对垃圾土中有机物降解的影响

含水量是影响垃圾土中有机物降解的因素之一,本文根据重庆市垃圾土的成分特点,自配生活垃圾试样进行试验,研究在不同的含水量情况下,由于有机物的降解而引起的垃圾土的质量变化情况。试验结果表明:试样的质量变化在试验初期较大,随着时间推移,质量变化逐渐减小,至试验后期,质量基本无变化。通过数据拟合可知,质量变化及有机物的降解率呈现指数型衰减规律,降解速率有先增大后减小的趋势。水对有机质降解有促进作用,当含水量为50%时,有机物最易发生降解。     

黄河三角洲外来入侵物种米草的分布面积与扩展速度

2005年和2007年,对黄河三角洲外来入侵种米草的引种历史、分布面积及扩展速度进行了社会调查、实地勘察和测量,结果表明:小清河口大米草(Spartina anglica)于1985年引种,现已发展到42.77 hm~2,年均扩展0.39～0.40倍;无棣套儿河口大米草于1987年引种,现已发展到0.23 hm~2,年均扩展0.35～0.36倍;东营市仙河镇五号桩互花米草(S.alterniflora)和大米草于1990年引种,现已发展到571.59 hm~2,年均扩展0.52～0.53倍.以五号桩互花米草和大米草扩展速度最快,小清河口大米草扩展速度次之,与米草分布区的生态环境有关.     

间接火焰原子吸收光谱法测定水和废水中铝

Al3+在一定酸度及1-(2-吡啶偶氮)-2-萘酚(PAN)存在的条件下,与Cu(Ⅱ)-EDTA发生定量交换反应,生成物Cu(Ⅱ)-PAN可被氯仿萃取,通过测定水相残余铜,从而间接测定铝。本文利用这一原理,进行了火焰原子吸收光谱法测定水和废水中铝的试验。结果表明,铝浓度在0.1~1.0 mg/L范围内有良好的线性关系,方法检测范围为0.05mg/L~100mg/L。本法用于不同加标水样中铝的测定,相对标准偏差为3.2%~7.2%,加标回收率为94%~106%。方法灵敏度高,精密度和准确度好,检测范围宽,检出限低,完全满足现行卫生标准对水体中铝检验的要求,且实验仪器普通易得,便于推广应用。     

通过速度调整解决城际铁路环境噪声研究

近几年来,随着我国高速铁路技术的迅猛发展,城际铁路的建设也在相继展开。由于城际高速铁路的线路分布在城区及市郊,所以,在为旅客带来快速服务的同时,沿线部分地点也会不同程度地出现噪声超标、电磁干扰等环境问题。针对其中的噪声问题,利用降速减噪的方法,综合考虑时间效益、社会效益与环境效益,在最小程度的影响列车运行时间的前提下调整列车运行速度,满足噪声指标要求。最后,通过实例分析,探讨利用速度调整措施解决噪声超标问题的适用性。     

降雨对城市道路交通行驶速度的影响分析

天气状况是影响城市道路交通行驶效率的重要因素。本研究的目的是结合浮动车GPS数据和气象站降雨量检测数据,分析降雨对城市道路交通行驶速度的影响。应用t检验比较了广州市降雨天和非降雨天的城市路段交通行驶速度的差异性,分别用Spearman相关系数和Pearson相关系数描述了降雨量和速度变化的关系。结果表明:降雨天和非降雨天的交通行驶速度的差异比较显著;持续性降雨造成交通行驶速度的较大波动,同时造成部分路段交通行驶速度的下降,快速路和主干道的速度下降比较明显;降雨量和速度变化量之间的相关性不明显。     

A renewable waste material for the synthesis of a novel non-halogenated flame retardant polymer

The recognition of toxicity and environmental persistence of halogenated flame retardant (FR) materials has prompted the reduction in their usage across the globe. There is an immediate need for new types of non-toxic and effective FR produced preferably through sustainable routes. Here we report the synthesis and characterization of a new polyphenolic FR material based on a renewable and biodegradable starting material, cardanol (a byproduct of cashew nut processing). Cardanol was polymerized in aqueous media using various types of oxidants. The thermal properties of the resulting polymers were investigated. Polycardanol synthesized using a specific type of oxidant exhibited good thermal stability and low heat release capacity. Preliminary results obtained from this study are quite promising and indicate the possibility of synthesizing new types of FR materials from bio-based phenols.     

Elevated atmospheric CO2 and drought effects on leaf gas exchange properties of barley

Atmospheric CO₂ concentration (C_a) is rising, predicted to cause global warming, and alter precipitation patterns. During 1994, spring barley (Hordeum vulgare L. cv. Alexis) was grown in a strip-split-plot experimental design to determine the effects that the main plot C_a treatments [A: Ambient at 370 μmol (CO₂) mol⁻¹; E: Enriched with free-air CO₂ enrichment (FACE) at ∼550 μmol (CO₂) mol⁻¹] had on several gas exchange properties of fully expanded sunlit primary leaves. The interacting strip-split-plot irrigation treatments were Dry or Wet [50% (D) or 100% (W) replacement of potential evapotranspiration] at ample nitrogen (261 kg N ha⁻¹) and phosphorous (29 kg P ha⁻¹) fertility. Elevated C_a facilitated drought avoidance by reducing stomatal conductance (g_s) by 34% that conserved water and enabled stomata to remain open for a longer period into a drought. This resulted in a 28% reduction in drought-induced midafternoon depression in net assimilation rate (A). Elevated C_a increased A by 37% under Dry and 23% under Wet. Any reduction in A under Wet conditions occurred because of nonstomatal limitations, whereas under Dry it occurred because of stomatal limitations. Elevated C_a increased the diurnal integral of A (A′) that resulted in an increase in the seasonal-long integral of A′ (A″) for barley leaves by 12% (P = 0.14) under both Dry and Wet - 650, 730, 905 and 1020 ± 65 g (C) m⁻² y⁻¹ for AD, ED, AW and EW treatments, respectively. Elevated C_a increased season-long average dry weight (DW_S; crown, shoots) by 14% (P = 0.02), whereas deficit irrigation reduced DW_S by 7% (P = 0.06), although these values may have been affected by a short but severe pea aphid [Acyrthosiphon pisum (Harris)] infestation. Hence, an elevated-C_a-based improvement in gas exchange properties enhanced growth of a barley crop.     

黔中地区不同林龄马尾松小气候特征研究

以黔中地区不同林龄马尾松人工林为研究对象,采用时空替代法,选取农田（对照）、林窗、中林龄、近熟林、成熟林和过熟林6个样地,每月选择代表日分时段测量光照强度、光通量密度、气温、相对湿度、蒸气压亏损和风速等小气候指标,同时对样地内不同垂直高度（0.5,1.0和1.5m）观测指标进行比较.结果表明：（1）除风速随测量高度变化（1.5m > 1.0m > 0.5m）差异极显著外（P<0.01）,其余观测指标随测量高度均无显著差异（P>0.05）.（2）观测时段内,不同林龄马尾松林小气候均存在显著性差异（P<0.05）,其中光照强度、光通量密度、气温、蒸气压亏损和风速变化为农田 > 林窗 > 马尾松林;相对湿度变化为马尾松林 > 林窗 > 农田.（3）与农田相比,马尾松林分别降低了光照强度、光通量密度、气温、蒸气压亏损和风速的917.36%、837.35%、5.33%、30.77%、193.58%,增加了6.39%的相对湿度,具有显著的遮阳降温、增湿保湿、维持林冠下小气候稳定的作用.在演替前期,抵挡阳光和风速的效果明显,而在后期,降温增湿以及保湿效果显著.舒适度评价显示,除冬季外,黔中地区马尾松林可发挥良好的森林康养和游憩生态功能.     

Flame propagation mechanisms in dust explosions

To reveal the effects of particle characteristics, including particle thermal characteristics and size distributions, on flame propagation mechanisms during dust explosions clearly, the flame structures of dust clouds formed by different materials and particle size distributions were recorded using an approach combining high-speed photography and a band-pass filter. Two obviously different flame propagation mechanisms were observed in the experiments: kinetics-controlled regime and devolatilization-controlled regime. Kinetics-controlled regime was characterized by a regular shape and spatially continuous combustion zone structure, which was similar to the premixed gas explosions. On the contrary, devolatilization-controlled regime was characterized by a complicated structure that exhibited heterogeneous combustion characteristics, discrete blue luminous spots appeared surrounding the yellow luminous zone. It was also demonstrated experimentally that the flame propagation mechanisms transited from kinetics-controlled to devolatilization-controlled while decreasing the volatility of the materials or increasing the size of the particles. Damköhler number was defined as the ratio of the heating and devolatilization characteristic time to the combustion reaction characteristic time, to reflect the transition of flame propagation mechanisms in dust explosions. It was found that the kinetics-controlled regime and devolatilization-controlled regime can be categorized by whether Damköhler number was less than 1 or larger than 1.