根际土-辣椒系统中重金属的分布及食物安全风险评价

采集整株辣椒及其根际土壤,并将植株分为根、茎和果实三部分,分别测定铬、砷、镉、汞和铅的含量。探讨了五种重金属元素在根际土-辣椒系统中的分布规律,并评估了人群食用辣椒导致五种重金属元素暴露的健康风险。结果显示,辣椒果实中Cr、As、Cd、Hg和Pb五种重金属含量(干重)分别为0.30~9.93、0.01~0.03、0.01~0.13、0.01~0.09和0.01~0.58mg/kg;在根际土与辣椒果实间,重金属的累计富集系数为CdHgCrPbAs,Cd和Hg表现出较强的富集能力。虽然辣椒果实中各重金属的含量平均值均低于《农产品安全质量:无公害蔬菜安全要求》(GB 18406.1-2001)限值要求,但贵州居民通过食用辣椒途径摄入重金属Cr和As占其临时性每周人体可耐受摄入量的比例相对较高,食用辣椒摄入Cr和As造成的食品安全风险应引起关注。     

饮用水在线监测及预警研究

饮用水是人类生存的基本需求之一,其安全是影响人民生命健康和社会经济可持续发展的重要因素.在取水、制水、输配水和贮水各个环节对饮用水水质的卫生指标进行实时动态监测及预警,可有效预防因为自然灾害、人为事故、犯罪引起的用水安全事故的发生.文章概述了水质在线监测系统在从水源到用户的全流程的应用,并对饮用水在线监测与预警各种关键技术的应用予以简单的介绍.     

可靠性强化试验在失速告警振杆器上的应用

介绍了可靠性强化试验的概念及其国内外研究现状。以某型失速告警振杆器为对象,通过设计试验剖面,制定了相应的可靠性强化试验方案,并进行实际应用。在试验实施过程中成功地将产品缺陷激发为可被检测的故障,有效地发现了产品设计的薄弱环节。通过分析其故障模式和失效机理,提出了有效的改进措施,提高了产品的健壮性和可靠性。     

丁腈橡胶5171密封件热氧老化研究

开展了腈橡胶5171热氧老化试验,结合老化前后宏观、微观性能的变化,对其热氧老化行为及规律进行了研究。结果表明,老化前期,丁腈橡胶5171的物理力学性能出现了较大幅度下降,表面氧元素相对含量及分子链交联密度明显增大,说明橡胶发生了以交联反应为主的吸氧老化;随着老化时间的延长,表面碳元素相对含量上升,氧、氮元素相对含量下降,说明防老剂D和增塑剂癸二酸二丁酯发生了向表面的扩散和迁移,进一步劣化了橡胶的性能。     

Analysis of floc morphology in a continuous-flow flocculation and sedimentation reactor

The floc morphology was investigated in a continuous-flow reactor, in order to understand the evolution of flocs in practical flocculation and sedimentation processes in water utilities. Kaolin-humic acid suspension was used as the test water, and polyaluminum chloride was chosen as the coagulant. An in-situ recognition system was applied to analyze the floc size, boundary fractal dimension, and eccentricity ratios. Particle numbers and turbidity were also determined in the sedimentation stage. At a coagulant dose of 1 mg/L as Al, the average floc size increased from 62 to 78 μm and the boundary fractal dimension was around 1.14, suggesting that flocs were compact and continuously grew during the entire flocculation process. However, with the dose increased to 5 mg/L, the average floc size decreased and stabilized at around 65 μm, with the fractal dimension of 1.20. It can be concluded that the excess coagulant doses resulted in the formation of chain-shaped, lower density, and more branched structure flocs, thereby restricting flocs' further growth in the subsequent flocculation. Floc morphology analysis suggested that charge neutralization dominated in the initial flocculation stage, then the bridge and sweep mechanisms were dominant in the subsequent flocculation. In addition, compared with the traditional inclined plate settler, a novel V-shaped plate settler introduced in this study had an advantage in small size floc(less than 5 μm) removal. The V-shaped region could promote aggregate restructuring and re-flocculation; therefore, the V-shaped plate settler provides an alternative method for sedimentation.     

La/Ce-codoped Bi2O3 composite photocatalysts with high photocatalytic performance in removal of high concentration dye

A series of La/Ce-codoped Bi_2O_3 composite photocatalysts were fabricated via hydrothermal–calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N_2 physical adsorption, X-ray powder diffraction(XRD), scanning electron microscope(SEM), transmission electron microscope(TEM), UV–Vis diffuse reflectance(UV–Vis DRS), Fourier transform infrared spectroscopy(FT-IR),photoelectrochemical measurements, and photoluminescence(PL) spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi_2O_3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi_2O_3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi_2O_3 displayed much higher photocatalytic performance than that of bare Bi_2O_3, single La or Ce doped Bi_2O_3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons(e~-) and holes(h~+).     

安溪铁观音茶园垂直剖面土壤中稀土元素的地球化学特征

采集了安溪某茶园一条垂直剖面土壤样(深度160 cm,共16个样),用电感耦合等离子体质谱法(ICP-MS)分析测定了其中的稀土元素含量,研究了剖面土壤中稀土元素的地球化学特征。结果表明:土壤样品中稀土元素总量范围为165.38~229.91 mg/kg,其平均含量高于中国土壤和世界土壤的平均值;土壤中轻重稀土分馏明显,其稀土元素组成特点表现为轻稀土(LREE)富集,重稀土(HREE)亏损,Eu呈负异常,Ce呈正异常;稀土元素的富集因子平均值的分布范围为0.28~1.34,稀土元素均处于无污染或轻微污染。本研究为了解安溪茶园中稀土含量特征提供了基础数据,为现有茶园的治理和后备茶园基地的合理选址提供了科学依据。     

模糊数学法在晋江水质评价中的应用研究

利用模糊数学综合评价法,选取溶解氧(DO)、高锰酸钾指数(CODMn)、氨氮(NH3-N)、总磷(TP)、六价铬[Cr(Ⅵ)]做为指标对2010年-2014年泉州湾河口湿地晋江流域石砻断面进行水质综合评价与分析,并将评价结果与综合污染指数法的评价结果进行对比.结果显示:在模糊数学评价法中2010、2012、2014年均为Ⅱ类水质,2011和2013年为Ⅰ类水质;评价结果与综合污染指数法的基本一致.表明2010年-2014年晋江流域石砻断面水质良好,模糊数学综合法在水质评价中可行.     

调控絮体形态强化电絮凝减缓膜污染

本研究通过调节电絮凝工艺参数来实现对絮体形态的调控,进而达到减缓膜污染的目的.主要考察了电流密度、初始pH、初始电导率对絮体性质以及膜通量的影响,并解析了超滤膜对不同形貌结构絮体的膜污染响应机制.结果表明,电絮凝减缓膜污染的关键是在膜表面形成疏松多孔的滤饼层,电絮凝-超滤(electrocoagulation-ultrafiltration,EC-UF)工艺不但能够有效地减缓膜污染,而且还极大提升了出水水质.增加电流密度,以及在pH中性水质条件下,EC-UF工艺中膜通量保持更高.j=20 A·m~(-2)、初始pH=7、初始电导率=1 000μS·cm~(-1),EC-UF工艺对水中的腐殖酸(humic acid,HA)去除率为97%,平衡阶段归一化通量J/J0达到81%.     

广西北海涠洲岛春季大气颗粒物浓度特征及影响因素

为了解我国北部湾区域大气环境特征和可能的跨界输送,于2015年3~4月在涠洲岛开展了对大气颗粒物浓度水平和粒径分布特征的外场观测研究,并结合气象因子和后向轨迹探讨了颗粒物浓度变化原因和来源.结果表明涠洲岛大气PM_1、PM_(2.5)、PM_(10)质量浓度分别为(21±12)、(35±19)、(43±20)μg·m~(-3).PM1、PM_(1~2.5)和PM_(2.5~10)质量浓度分别占PM10的50%、32%、18%.0.5~1、1~2.5和2.5~20μm粒径段颗粒物数浓度分别占总数浓度的93.5%、6.1%和0.4%.颗粒物数浓度与能见度和气压呈弱负相关.后向轨迹模拟分析发现,来自涠洲岛西南方向东南亚一带的气团影响频率最高(45.9%),0.5~1μm、1~2.5μm数浓度和PM_(2.5)浓度最低但NO浓度最高;其次为来自正东方向气团(34.1%),SO2浓度最低但O3浓度最高;来自正南方向的气团(12.5%)NO2、NOx、O3和CO浓度最低;来自东北方向的大陆气团影响频率最低(7.4%),但颗粒物数浓度、质量浓度和气体污染物浓度(除O3和NO)最高.涠洲岛大气细颗粒物和气态污染物主要受大陆和东南亚地区输送影响,来自大陆方向的输送以工业污染为主,来自东南亚方向的输送以港口船舶及航运污染为主.