中国技术灾害的时序变化与区域差异

近年来,由于生产的全球化、工业水平的迅速提高、技术系统的复杂化和规模化,以及社会结构急剧变化,我国技术灾害的发生频次增多,强度加剧,经济损失趋于上升.技术灾害继自然灾害之后,已逐渐发展为威胁我国人民生命安全和生存环境的主要灾种.基于技术灾害数据库,从致灾因子多度、风险频数、相对损失强度和综合风险指数等4个方面对中国技术灾害的时序变化和区域差异进行了分析与探讨,以期加深对中国技术灾害的系统认识,并为中国技术灾害的风险管理提供依据.     

邀山阁游客流量控制研究

邀山阁是一座4层砖石结构楼阁,目前西北角墙体倾斜严重且墙体、石柱存在竖向裂缝。基于保护邀山阁的需要,应用等效体积单元(RVE)进行墙体的有限元分析,通过调整弹性模量和优化有限元模型来模拟砌体带裂缝时的工作状态;在应力值及其变化值比较大的关键部位选取了26个控制点,进行应力包络分析;在合理的安全系数和游客荷载最不利工况下,得到了邀山阁游客的合理控制数量。本研究将有益于古建筑的长期保护和合理开发利用。     

The performance of nitrate-reducing Fe(II) oxidation processes under variable initial Fe/N ratios: The fate of nitrogen and iron species

•Bacterially-mediated coupled N and Fe processes examined in incubation experiments. •NO₃⁻ reduction was considerably inhibited as initial Fe/N ratio increased. •The maximum production of N₂ occurred at an initial Fe/N molar ratio of 6. •Fe minerals produced at Fe/N ratios of 1–2 were mainly easily reducible oxides. The Fe/N ratio is an important control on nitrate-reducing Fe(II) oxidation processes that occur both in the aquatic environment and in wastewater treatment systems. The response of nitrate reduction, Fe oxidation, and mineral production to different initial Fe/N molar ratios in the presence of Paracoccus denitrificans was investigated in 132 h incubation experiments. A decrease in the nitrate reduction rate at 12 h occurred as the Fe/N ratio increased. Accumulated nitrite concentration at Fe/N ratios of 2–10 peaked at 12–84 h, and then decreased continuously to less than 0.1 mmol/L at the end of incubation. N₂O emission was promoted by high Fe/N ratios. Maximum production of N₂ occurred at a Fe/N ratio of 6, in parallel with the highest mole proportion of N₂ resulting from the reduction of nitrate (81.2%). XRD analysis and sequential extraction demonstrated that the main Fe minerals obtained from Fe(II) oxidation were easily reducible oxides such as ferrihydrite (at Fe/N ratios of 1–2), and easily reducible oxides and reducible oxides (at Fe/N ratios of 3–10). The results suggest that Fe/N ratio potentially plays a critical role in regulating N₂, N₂O emissions and Fe mineral formation in nitrate-reducing Fe(II) oxidation processes.     

Less attention paid to waterborne SARS-CoV-2 spreading in Beijing urban communities

• A survey on individual’s perception of SARS-CoV-2 transmission was conducted. • Waterborne transmission risks are far less perceived by individuals. • Precautions of preventing wastewater mediated transmission are implemented. • The precautions for wastewater transmission are less favored by the public. • Education level differs the most regarding to waterborne transmission perception. SARS-CoV-2 has been detected in various environmental media. Community and individual-engaged precautions are recommended to stop or slow environmentally-mediated transmission. To better understand the individual’s awareness of and precaution to environmental dissemination of SARS-CoV-2, an online survey was conducted in Beijing during March 14–25, 2020. It is found that the waterborne (especially wastewater mediated) spreading routes are far less perceived by urban communities. The precautions for wastewater transmission are less favored by the public than airborne and solid waste mediated spreading routes. Such risk communication asymmetry in waterborne transmission will be further enlarged in places with fragile water system. Furthermore, education level is the most significant attribution (Sig.<0.05) that causes the difference of awareness and precautions of the waterborne transmission among the respondents, according to the variance analysis results. Our survey results emphasize the urgent need for evidence-based, multifactorial precautions for current and future outbreaks of COVID-19.     

Exogenously applied oxalic acid assists in the phytoremediation of Mn by Polygonum pubescens Blume cultivated in three Mn-contaminated soils

• The OA supply significantly increased the water-extractable Mn in all soils. • All OA supply levels promoted plant growth in unexplored soil. • Low OA supply level promoted plant growth in explored and tailing soils. • OA amendment increased the Mn concentrations and total Mn in P. pubescens. • P. pubescens experienced less Mn stress in unexplored soil than in the other two soils. The current study evaluated the effects of oxalic acid (OA) application on the growth and Mn phytoremediation efficiency of Polygonum pubescens Blume cultivated in three different manganese (Mn)-contaminated soils sampled from an unexplored area (US), an explored area (ES) and a tailing area (TS) of the Ertang Mn mine, South China. The supplied levels of OA were 0 (control), 1 (low level), 3 (medium level), and 9 (high level) mmol/kg, referred to as CK, OA1, OA3 and OA9, respectively. The results revealed that the average water-extractable Mn concentrations US, ES and TS amended with OA increased by 214.13, 363.77 and 266.85%, respectively. All OA supply levels increased plant growth and Mn concentrations in US. The low OA supply level increased plant growth in ES and TS; however, contrasting results were found for the medium and high OA supply levels. Plant Mn concentrations and total Mn increased in ES and TS in response to all OA supply levels. Total Mn in the aerial parts increased by 81.18, 44.17 and 83.17% in US, ES and TS, respectively; the corresponding percentages for the whole plants were 81.53, 108.98 and 77.91%, respectively. The rate of ·O₂⁻ production and malondialdehyde (MDA) concentrations increased in response to OA amendment, especially the medium and high OA supply levels in ES and TS. In general, antioxidant enzymes might play a vital role in alleviating Mn stress in plants cultivated in US, while non-enzymatic antioxidants might be the main factor for plants cultivated in ES and TS.     

晋中城市群县域可达性及经济联系格局研究

以晋中城市群为研究对象,运用加权平均旅行时间和引力模型分析了2000—2018年晋中城市群县域单元可达性水平及经济联系的时空演变格局。结果表明:(1)晋中城市群县域单元的可达性水平显著提升但地域分布不均衡,受地形和距离因素的影响存在"断崖式"梯度变化和"中心高、边缘低"的圈层式空间分布特征。(2)晋中城市群县域单元的经济联系强度持续增强,其空间分布格局具有显著的廊道指向特征和行政区指向特征。(3)晋中城市群核心区域的辐射带动作用显著,不同县域单元对外经济联系能力差异较大,但城市群内部的发展差距在逐渐缩小。     

会仙岩溶湿地地下水主要离子特征及成因分析

以我国最大的低海拔岩溶湿地会仙岩溶湿地为研究区,对该区丰水期、平水期和枯水期共采集的27组地下水样品中常规离子进行检测和分析,在分析会仙岩溶湿地地下水主要离子化学特征和不同时期变化基础上,运用单指标污染标准指数法对不同时期地下水进行污染评价,利用多元统计、Gibbs模型和离子比例关系识别地下水主要离子成因.结果表明,研究区内岩溶地下水主要为弱碱性淡水,Ca²⁺和HCO₃^-为优势离子.不同时期地下水主要离子总浓度顺序为：平水期 > 丰水期 > 枯水期,枯水期水质优于丰水期和平水期.地下水中K⁺和NO₃^-主要受含水层空间分布差异影响,Mg²⁺、SO₄^2-、NO₂^-、NH₄⁺和TDS受时空尺度综合作用,Na⁺、Ca²⁺、HCO₃^-和Cl^-为水体中较稳定离子.受碳酸盐岩控制,丰水期、平水期和枯水期地下水化学类型具有高度一致性,HCO₃-Ca水占比分别为77.78%、77.78%和88.89%.地下水主要受SO₄^2-、NO₃^-和NO₂^-污染,NO₃^-出现极严重程度污染样点,SO₄^2-在丰水期和平水期出现较重污染样点.地下水化学组分主要受水岩作用控制,Ca²⁺和HCO₃^-主要来源于方解石风化溶解,少量水点受白云岩、白云质灰岩及硫铁矿控制导致Mg²⁺和SO₄^2-浓度偏高,K⁺、Na⁺、SO₄^2-、NO₃^-和Cl^-部分来源于大气降水,Na⁺和Cl^-部分来源于当地居民生活,K⁺与种植施用的钾肥相关,NO₃^-主要来源是化学肥料.     

石盘丘小流域不同土地利用方式下土壤氮磷流失形态及通量

为了解三峡库区小流域不同土地利用方式下土壤氮、磷流失特征,为农业非点源污染防控提供科学依据;采用田间试验的方法,研究了三峡库区石盘丘小流域水田、旱坡地、林地、柑橘园和菜地这5种土地利用方式下地表径流不同形态氮、磷流失浓度与通量的特征.结果表明：全氮流失通量的顺序为水田[17.73 kg·（hm²·a）^-1] > 柑橘园[4.86 kg·（hm²·a）^-1] > 旱坡地[4.33 kg·（hm²·a）^-1] > 菜地[4.00 kg·（hm²·a）^-1] > 林地[2.41 kg·（hm²·a）^-1];全磷流失通量的顺序为菜地[4.97 kg·（hm²·a）^-1] > 柑橘园[1.87 kg·（hm²·a）^-1] > 水田[0.93 kg·（hm²·a）^-1] > 林地[0.27 kg·（hm²·a）^-1] > 旱坡地[0.19 kg·（hm²·a）^-1];5种土地利用方式下氮、磷流失主要集中在降雨频繁的4~5月,占全年氮、磷流失总负荷的53.80%~96.52%和56.03%~87.78%;氮流失主要以硝态氮（16.16%~52.70%）的形态流失,全氮流失通量与径流量呈现出显著正相关关系（R²=0.9826）;在菜地中颗粒磷是磷流失的主要形态（83.30%）,但在其他土地利用方式中表现不显著.不同土地利用方式下不同形态氮、磷流失存在显著差异,其中菜地应针对强降雨情况下颗粒磷流失的问题采取措施,水田应避免在降雨集中时期施肥;科学施肥和合理地土地利用方式配置是治理小流域农业非点源污染的重要途径.     

纸喷雾离子源质谱对易燃液体的快速分析方法研究

为提高对易燃液体的快速检测分析能力,在经典纸喷雾质谱的基础上,发展建立了三种新型的基于纸喷雾离子化的质谱方法,分别为基于针尖辅助纸喷雾质谱、基于导电纸辅助纸喷雾质谱、基于金属网辅助纸喷雾质谱。结果显示,在优化的实验条件下,可以迅速检测到样品中的目标化合物质子化峰。对于汽油样品,目标化合物主要是烷基吡啶类同系物;对于柴油样品,目标化合物主要是几种系列的含氮杂环芳香族化合物的同系物。对汽油和柴油样品的检测浓度均能达到5×103 ppm。这三种敞开式离子源质谱方法在对易燃液体的分析中,具有选择性好、无需样品前处理、分析迅速的特点。     

两种复合早强剂对煤矿封孔水泥早强效果影响的研究

基于矿井复杂环境对封孔水泥提出的要求,引入２-丙烯酰胺基-２-甲基丙磺酸（AMPS）并复合聚羧酸减水剂,三乙醇胺（TEA）作为有机组分,氯化钠（氯化钙）为无机组分,模拟井下高湿环境,通过正交试验,考察了两种有机无机复合早强剂的制备。并通过SEM,TG和XRD等手段着重研究了两种复合早强剂水化3d对封孔水泥抗压强度的影响。结果表明,当氯化钠复合早强剂组分为氯化钠3%,三乙醇胺0.05%,聚羧酸0.3%,AMPS1%时;氯化钙复合早强剂组分为氯化钙1.5%,三乙醇胺0.04%,聚羧酸0.2%,AMPS1%时早强效果最好,抗压强度比基准组分别提高了328%和217%。