A simplified approach to modelling underground migration of radionuclides from contaminated river sediments

Accidental releases of waste water from the first Czechoslovak nuclear power plant, A1, caused contamination of sediments of the Dudváh river, flowing into the Vah river, in Slovakia. Rather high concentrations of ¹³⁷Cs and ⁹⁰Sr (2150Bq dm⁻³ and 215Bq dm⁻³, respectively) were found in bottom sediments of a former channel of the re-engineered river body at a distance of about 250 m from a village, Siladice, with water-supply wells. In order to assess the possibility of contamination of the wells, underground migration of both radionuclides from the contaminated area was simulated using an original layered convection-diffusion model. K_d values determined in laboratory experiments were used. The analysis of the hydrological situation in the area reveals that the critical condition is a dominant horizontal groundwater flow near the water table in the direction from the Váh bank to Siladice, in the periods when the contaminated body lies under the water table. The simulation calculated under conservative conditions showed that the contamination of water-supply wells would not exceed permissible concentration limits.     

锶—89在珍珠岩中吸附的研究

研究了不同粒径的珍珠岩对＾８９Ｓｒ的吸附。结果表明，珍珠岩对＾８９Ｓｒ具有较强的吸附能力，饱和吸附率大于９５％；通过振荡能加速珍珠岩对＾８９Ｓｒ的吸附；珍珠岩对＾８９Ｓｒ的吸附率与时间关系由多项指数描述；不同粒径的珍珠岩对＾８９Ｓｒ的吸附率没有明显差异。     

长江口及邻近海域水体主元素和锶同位素地球化学

根据2005年6月对长江口及其邻近海域水体的现场调查,分析探讨了长江口水体主元素、Sr及Sr同位素的组成变化。长江河水的Sr含量和87Sr/86Sr同位素比值分别为1.75μmol/L和0.7105,反映出长江流域以碳酸盐岩风化为主的化学风化特征;河口区主元素与盐度的显著正相关关系显示出它们在河水与海水混合过程中的保守特性;87Sr/86Sr与1/Sr的非线性关系则暗示了长江口水体的Sr不是河水与海水的简单混合,可能伴有其他端元水体的混入。     

90锶在核排污水域中的分布与监测

本文报告了川江上游核排污水环境中９０ Ｓｒ 的监测结果。表明：９０ Ｓｒ 在河水和底泥中的含量与排污距离密切相关,在不同水生物种之间的蓄积分布有显著性差异,其中底泥和含钙高的生物对９０ Ｓｒ 有较强的浓集作用。所以,选用指示性物种能提高９０ Ｓｒ 监测灵敏度,是核污染监测的较好方法。     

厦门某旱地土壤垂直剖面中重金属迁移规律及来源解析

采用ICP-MS和TIMS分析测定厦门市农业区某旱地土壤垂直剖面中8种重金属元素(V、Cr、Co、Ni、Cu、Zn、Sr和Pb)含量及铅锶同位素组成,重点分析土壤剖面金属的纵向分层和淋失迁移特征.结果表明,除Sr外,其余重金属在大部分剖面深度中均未超过背景值,表明受外来源的影响较小. Sr在整个剖面的迁移系数均大于0,表明存在不同程度的富集; Zn和Co在近地表处富集; Cr、Ni和Cu在整个剖面中以亏损为主; V和Pb受外来活动的干扰小.淋洗迁移特征分析表明,Sr和Pb淋洗下移较活跃,其下移深度较大,但Pb下移深度低于Sr下移深度.因子分析表明,重金属主要为自然因子的输入,其次为农业活动和交通运输等复杂人为活动的输入.富集因子分析表明,Sr受外源不同程度影响.铅锶同位素组成分析表明,垂直剖面土壤中Pb主要来源于母质层,而Sr除来源于母质层外,还受到复杂人为源的影响,并已有向底层(30～70 cm)迁移的趋势.     

2492名新生SCL-90项测试结果数据分析与报告

为了解高职新生的心理健康状况,取得心理辅导及咨询的有效数据材料,运用SCL—90项量表,对湖南环境生物职业技术学院2010级新生进行心理健康普查.结果表明：心理健康问题的检出率为6.7%,大大低于全国平均水平,且9个因子项目均与全国常模存在显著差异,同时对男女性别、农村、城镇生源地群体进行比较,发现分别在强迫症状、抑郁、焦虑、恐怖及人际关系敏感、焦虑、恐怖及精神病性等多个因子上存在差异,并根据相关数据进行分析讨论.     

中国中东部地区地表水环境锶元素地球化学特征研究

水环境中锶的含量及其变化、地理分布及其控制因素等特征的研究有助于认识区域水文地球化学特征及流域盆地岩石风化速率等地球化学行为,因此河流环境中锶的地球化学行为是地球化学研究的重要课题之一。对我国中东部地区部分河流水体中溶解态锶含量进行了分析研究发现,与世界上主要河流溶解态锶含量平均值0.078 mg/L相比,中国中东部地区河水中的锶含量(0.139 mg/L)明显偏高。分析研究表明,中国中东部地区河水中的锶主要源于蒸发盐岩和碳酸盐岩的风化作用,流域锶含量从南向北逐渐增加的现象主要受流域岩石或沉积物类型的控制,化学风化作用越强烈,河流锶含量越高。除了受区域岩性的影响外,气候条件对流域河水中的锶含量水平及地理分布起到一定的控制作用。     

新型MIL-100(Fe)基MOFs材料的制备及其对Sr2+的吸附

采用水热法和溶剂热法制备了金属有机骨架材料——MIL-100(Fe)和MIL-100(Fe)-DMA.利用FTIR、XRD、SEM、XPS和N₂吸附/脱附对材料结构进行了表征.通过静态吸附实验,探究了初始Sr²⁺浓度、吸附时间、溶液pH值和不同共存阳离子对材料吸附性能的影响,研究了两种材料对Sr²⁺吸附过程的吸附动力学和吸附等温线模型.表征结果表明:两种材料基本骨架一致,吸附Sr²⁺对材料骨架影响均可忽略;虽然MIL-100(Fe)-DMA比表面积小于MIL-100(Fe),但由于晶粒尺寸小,堆积形成的介孔结构更有利于Sr²⁺的扩散.吸附实验结果表明:随着反应时间和初始Sr²⁺浓度的增加,两种材料对Sr²⁺的吸附量先迅速增大再逐渐达到平衡;随着pH值的增大,两种材料对Sr²⁺的吸附量增大,且碱性条件下吸附效果好;两种材料吸附过程均符合准二级动力学模型、颗粒内扩散模型和Langmuir吸附等温模型;采用三价铁盐作为铁源以及DMA作为有机溶剂可提高MIL-100(Fe)材料对Sr²⁺的吸附效果.     

管道结构对氢/空预混气体爆炸特性影响研究

为研究管道结构对氢-空预混气体爆炸特性影响,采用实验与数值模拟相结合的方法,分析不同管道结构内氢-空预混气体燃爆时火焰传播进程、爆炸压力、湍流动能变化及流场分布.结果表明:90°弯管对氢-空预混气体爆炸强度增强作用明显高于T型分岔管和直管.火焰阵面在结构突变处褶皱变形较明显,并出现大尺度强湍流和涡团,气团脉动速度与湍流...     

Efficacy of extracting indices from large‐scale acoustic recordings to monitor biodiversity

Passive acoustic monitoring could be a powerful way to assess biodiversity across large spatial and temporal scales. However, extracting meaningful information from recordings can be prohibitively time consuming. Acoustic indices (i.e., a mathematical summary of acoustic energy) offer a relatively rapid method for processing acoustic data and are increasingly used to characterize biological communities. We examined the relationship between acoustic indices and the diversity and abundance of biological sounds in recordings. We reviewed the acoustic‐index literature and found that over 60 indices have been applied to a range of objectives with varying success. We used 36 of the most indicative indices to develop a predictive model of the diversity of animal sounds in recordings. Acoustic data were collected at 43 sites in temperate terrestrial and tropical marine habitats across the continental United States. For terrestrial recordings, random‐forest models with a suite of acoustic indices as covariates predicted Shannon diversity, richness, and total number of biological sounds with high accuracy (R² ≥ 0.94, mean squared error [MSE] ≤170.2). Among the indices assessed, roughness, acoustic activity, and acoustic richness contributed most to the predictive ability of models. Performance of index models was negatively affected by insect, weather, and anthropogenic sounds. For marine recordings, random‐forest models poorly predicted Shannon diversity, richness, and total number of biological sounds (R² ≤ 0.40, MSE ≥ 195). Our results suggest that using a combination of relevant acoustic indices in a flexible model can accurately predict the diversity of biological sounds in temperate terrestrial acoustic recordings. Thus, acoustic approaches could be an important contribution to biodiversity monitoring in some habitats.