实验室条件下温度升高对水体叶绿素a的影响研究

以23℃为基础,按2℃温差设置温度梯度,最高温度组为29℃。每隔10d取样一次,进行叶绿素α浓度的测定。结果显示温度低于25℃时,增温有助于藻类生物量的提高,而温度超过25℃时,增温限制了藻类生物量的提高。水体温度量对浮游植物生物的影响程度与增温幅度和培养时间有关。Pearson相关性分析结果显示:温度与叶绿素a浓度相关性显著(P0.05),叶绿素a浓度与培养时间呈极显著正相关(P0.01)。     

Influence of temporally variable groundwater flow conditions on point measurements and contaminant mass flux estimations

Monitoring of contaminant concentrations, e.g., for the estimation of mass discharge or contaminant degradation rates, often is based on point measurements at observation wells. In addition to the problem, that point measurements may not be spatially representative, a further complication may arise due to the temporal dynamics of groundwater flow, which may cause a concentration measurement to be not temporally representative. This paper presents results from a numerical modeling study focusing on temporal variations of the groundwater flow direction. “Measurements” are obtained from point information representing observation wells installed along control planes using different well frequencies and configurations. Results of the scenario simulations show that temporally variable flow conditions can lead to significant temporal fluctuations of the concentration and thus are a substantial source of uncertainty for point measurements. Temporal variation of point concentration measurements may be as high as the average concentration determined, especially near the plume fringe, even when assuming a homogeneous distribution of the hydraulic conductivity. If a heterogeneous hydraulic conductivity field is present, the concentration variability due to a fluctuating groundwater flow direction varies significantly within the control plane and between the different realizations. Determination of contaminant mass fluxes is also influenced by the temporal variability of the concentration measurement, especially for large spacings of the observation wells. Passive dosimeter sampling is found to be appropriate for evaluating the stationarity of contaminant plumes as well as for estimating average concentrations over time when the plume has fully developed. Representative sampling has to be performed over several periods of groundwater flow fluctuation. For the determination of mass fluxes at heterogeneous sites, however, local fluxes, which may vary considerably along a control plane, have to be accounted for. Here, dosimeter sampling in combination with time integrated local water flux measurements can improve mass flux estimates under dynamic flow conditions.     

一种室外声屏障过渡区域绕射衰减测量方法

提出了一种声屏障声影区与声亮区过渡区域的绕射衰减室外测量方法。方法采用5ms的正弦波作为测试信号,利用声波到达时间的差异有效地排除地面反射和有限长声屏障两侧绕射的影响,并通过背景噪声频谱分析选取测试声以及对接受信号FIR滤波以最大限度降低背景噪声的影响,同时考虑了气象条件变化导致的大气衰减修正。为进一步验证方法有效性,选取直立声屏障作为试验案例。结果表明,与室内全消声室试验结果、几何绕射理论结果接近,试验精度高。     

Distribution of Se and its species in Myriophyllum spicatum and Ceratophyllum demersum growing in water containing Se (VI)

The uptake of Se (VI) by two aquatic plants, Myriophyllum spicatum L. and Ceratophyllum demersum L., and its effects on their physiological characteristics have been studied. Plants were cultivated outdoors under semi-controlled conditions and in two concentrations of Na selenate solution (20 μg Se L⁻¹ and 10 mg Se L⁻¹). The higher dose of Se reduced the photochemical efficiency of PSII in both species, while the lower dose had no effect on PSII. Addition of Se had no effect on the amounts of chlorophyll a and b. The concentration of Se in plants grown in 10 mg Se L⁻¹, averaged 212 ± 12 μg Se g⁻¹ DM in M. spicatum (grown from 8-13 d), and 492 ± 85 μg Se g⁻¹ DM in C. demersum (grown for 31 d). Both species could take up a large amount of Se. The amount of soluble Se compounds in enzyme extracts ranged from 16% to 26% in control, and in high Se solution from 48% to 36% in M. spicatum and C. demersum, respectively. Se-species were determined using HPLC-ICP-MS. The main soluble species in both plants was selenate (∼37%), while SeMet and SeMeSeCys were detected at trace levels.     

液相吸收-高效液相色谱法测量气相OH方法的建立

利用水杨酸溶液相OH自由基，生成的荧光产物2，5－二羟苯甲酸用高效液相色谱法分离测定，推算得到气相OH浓度，根据此原理在实验室条件下，建立了气相OH自由基的测定方法，并利用气相OH标准发生源确定了最优实验条件，得到了气相OH浓度与荣光响应关系。由相吸收－高效液相色谱法测定的浓度与标准OH气流中的理论浓度比较一致。     

废弃矿山生态复绿常用17种植物叶绿素含量及SOD和POD活力测定

选用废弃矿山绿化常用的禾本科、豆科、葡萄科和紫葳科共17种为实验材料,测定了其叶绿素各组分含量及超氧岐化酶(SOD)和过氧化物酶(POD)活力,结果表明:叶绿素a、b类胡萝卜素和叶片色素总质量比最高的植物分别是胡枝子、狗牙根、牧草型狗牙根和狗牙根,其质量比分别为2.46 mg/g.FW、1.10 mg/g.FW、0.32 mg/g.FW和3.63 mg/g.FW;4者质量比最低的是紫穗槐、三出叶爬山虎、芒和紫穗槐,为1.10 mg/g.FW、0.48 mg/g.FW、0.08 mg/g.FW和1.70 mg/g.FW。ωa(叶绿素a)/ωb(叶绿素b)最高的是牧草型狗牙根,为3.03 mg/g.FW,最低的是芒,仅为1.65 mg/g.FW。POD和SOD活力最高的是网络崖豆藤和芒,达477.00 U和217.20 U,最低的是牧草型狗牙根和紫穗槐,仅为24 U和39.43 U。     

The influence of radiopharmaceutical isotope production on the global radioxenon background

Radioxenon isotopes play a major role in confirming whether or not an underground explosion was nuclear in nature. It is then of key importance to understand the sources of environmental radioxenon to be able to distinguish them from those of a nuclear explosion.     

我国农村劳动力流动性就业计量问题研究

改革开放30年来,上亿农村劳动力实现了向城镇非农产业大规模转移,而我国沿袭至今的劳动就业统计制度突出的缺陷是将三部分人--在农村从事纯农的农民,在城镇从事非农工作但户口在农村的农民工,游移于乡城间"亦工亦农"的农村劳动力--排除于劳动统计计量之外.不解决这部分劳动力就业的统计计量的问题,则很难准确回答"中国的失业率究竟有多高?".为此,确定严格的、便于与国际接轨的劳动就业标准,从而构建我国统一的、规范的劳动就业市场至关重要.本文着重探讨了游移于农村与城市之间、就业岗位、就业时间不固定的农村劳动力就业、失业不充分的计量问题.作者在对国内外就业和失业定义和计量标准进行比较和评价基础上,结合我国实情提出了以法定劳动力年工时为核心的劳动力流动性就业的调查和计量方法,并通过调查案例证实了它的有效性与可行性.     

Species-specific effects of elevated ozone on wetland plants and decomposition processes

Seven species from two contrasting wetlands, an upland bog and a lowland rich fen in North Wales, UK, were exposed to elevated ozone (150 ppb for 5 days and 20 ppb for 2 days per week) or low ozone (20 ppb) for four weeks in solardomes. The rich fen species were: Molinia caerulea, Juncus subnodulosus, Potentilla erecta and Hydrocotyle vulgaris and the bog species were: Carex echinata, Potentilla erecta and Festuca rubra. Senescence significantly increased under elevated ozone in all seven species but only Molinia caerulea showed a reduction in biomass under elevated ozone. Decomposition rates of plants exposed to elevated ozone, as measured by carbon dioxide efflux from dried plant material inoculated with peat slurry, increased for Potentilla erecta with higher hydrolytic enzyme activities. In contrast, a decrease in enzyme activities and a non-significant decrease in carbon dioxide efflux occurred in the grasses, sedge and rush species.     

摆管淋水试验装置的校准方法探讨

文中简述了摆管淋水试验装置的基本结构及其常见的校准方式，对其中的“摆角校准”这一技术难点提出了可行的解决方案并作了较详尽的说明分析。