Age and engine displacement are associated with unsafe motorcycle rider actions

Background: Our goal was to examine the relationship between age and engine displacement in cubic centimeters (CCs) and crash responsibility. Methods: Male motorcyclists, aged 16–94, involved in a fatal crash in the United States (1987–2015) who tested negative for both drugs and alcohol were included. Employing a case control design, cases had committed one or more Unsafe Motorcyclist Actions (UMAs), the proxy measure of responsibility; controls had no UMAs recorded. Odds ratios were computed via multinomial regression examining the effect of motorcyclists’ age and motorcycle displacement (up to 1500 CCs, in 250 CC increments) on crash responsibility by any UMA and top three individual UMAs committed. Results: A total of 19,166 motorcyclists met our inclusion criteria. Increased displacement was observed in older motorcyclists and in more recent crashes. Fifty-six percent of motorcyclists committed one or more UMAs (n = 10,743). The top three individual UMAs were: Speeding (35%, n = 6,728), Weaving (24%, n = 3,269), and Erratic Operation (6%, n = 1,162). Odds ratios for committing any UMA were the greatest for riders on 750 CC motorcycles, followed closely by 500 and 1000 CC motorcycles. By 1250 CCs the effect of displacement on rider crash responsibility (any UMA) was no longer statistically significant. Typically, younger ages (e.g., 20–30) on motorcycles with 500–1000 CCs were associated with the highest odds of either speeding, weaving, or erratic riding compared to similar aged riders on 250 CC motorcycles. Exceptions were observed, for example riders at 70 years of age on 1500 CCs having higher odds of speeding than younger riders on equivalent CC motorcycles. Conclusion: Education and legislative measures should be considered. Educationally, the development of training interventions focusing on control, stability, and breaking differences with more powerful motorcycles (750 to 1250 CCs) is needed. Legislatively, licensing tiers could be employed based on displacement and educational requirements. Education and legislative measures could help to curb the trend seen between high-powered motorcycles and crash responsibility.     

The importance of physico-chemical parameters on the speciation of natural radionuclides in riverine ecosystems

External gamma radiation levels were measured in the catchment areas of the Sharavathi River and the dose rates in air were found to be in the range 26.0-61.0 nGy h⁻¹. Soil and sediment samples of the riverine environment were analysed for natural radionuclides such as ²²⁶Ra, ²³²Th and ⁴⁰K using a NaI(Tl) gamma spectrometer. The activity concentration of ²¹⁰Pb and ²¹⁰Po in soil and sediment samples was determined by radiochemical separation techniques. Evaluation of the activity concentration of radionuclides with grain size revealed an increase in the activity of ²²⁶Ra, ²³²Th and ⁴⁰K towards fine grain size. The activity concentrations for all isotopes in all samples were not significantly correlated with pH. However, the activity of ²¹⁰Po and ²¹⁰Pb in sediment showed a moderate positive correlation with organic matter content and a good correlation with clay content of sediment.     

Cell size dependent toxicity thresholds of polycyclic aromatic hydrocarbons to natural and cultured phytoplankton populations

The toxicity of pyrene and phenanthrene to phytoplankton was studied by analyzing the effect on the growth, abundance and cell viability of cultured species and natural communities of the Atlantic Ocean and the Mediterranean Sea. A decrease in cell abundance, and growth rate was observed as concentration of PAHs increased, with catastrophic cell mortality induced at the highest PAH concentration tested. A strong positive linear relationship was observed between the LC50 (the PAH concentration at which cell population will decline by a half), and the species cell volume, for both phenanthrene and pyrene. Natural communities were however significantly more sensitive to PAHs than cultured phytoplankton, as indicated by the lower slope (e.g. 0.23 and 0.65, respectively, for pyrene) of the relationship LC50 vs. cell volume. The results highlight the importance of cell size in determining the phytoplankton sensitivity to PAHs identifying the communities from the oligotrophic ocean to be more vulnerable.     

重庆四面山杉木林优势种群径级结构与空间分布格局

种群空间格局分析有利于更好地理解格局形成的潜在生态过程。本研究以重庆四面山杉木林为研究对象,采用单变量和双变量函数分析了样地中杉木林主要种群的空间分布格局以及种群间的空间关联性。结果表明:(1)四面山杉木林共调查到乔木65种、灌木31种、草本20种。杉木种群径级结构呈衰退型,表现为以大树为主,中树次之,无小树;腺萼马银花、元江栲、细枝柃等种群径级结构呈增长型,表现为以小树、中树为主,大树次之。(2)在0~25 m尺度内,杉木种群呈随机分布,栲和元江栲呈聚集分布,而腺萼马银花、细枝柃、光叶山矾和长蕊杜鹃等4个种群则在小尺度下呈聚集分布,随着尺度的增大,呈现出随机分布的趋势。(3)生物学特性以及生境因子的差异导致杉木林主要种群间空间关联差异较大,杉木与元江栲和腺萼马银花种群之间呈负相关,而与光叶山矾、栲和长蕊杜鹃种群呈无相关,因此,在该区杉木纯林的近自然改造上,应优先考虑竞争力强的乡土树种,如长蕊杜鹃、栲、光叶山矾等进行混交。     

化学活化法制备羊骨基活性炭工艺的优化及其孔结构的表征

以氯化锌为活化剂,用羊骨为原料,利用化学活化法制备羊骨基活性炭。通过正交实验和单因素实验相结合得出最优工艺条件为:氯化锌溶液浓度0.05 g/100 mL、活化温度350℃、活化时间10 min、浸渍时间为36 h。在此最佳工艺条件下羊骨基活性炭的碘吸附量为407.35 mg/g,得率为62%;用此工艺制备的羊骨基活性炭等温曲线类型属于多层吸附;BET比表面积为59 m2/g,总孔容为0.1945 cm3/g,孔径分布落在1.31～20 nm之间,为中孔结构;羊骨基活性炭SEM图可看出,颗粒呈不规则状,结构疏松。     

基本单分散气溶胶透过率测试中真实值的计算

通过对高效、超高效滤料透过率测试台工作原理的分析得到:利用基本单分散粒子作为气溶胶测得的透过率关系与滤料真正的透过率-粒径曲线有区别,实际上是所使用实验气溶胶的综合透过率。详细研究了真正透过率与实验透过率的关系、误差和偏离产生原因,最终提出了一种独特的计算方法,实现了根据实验得到的表观透过率-粒径关系,就可以计算出真实透过率-粒径曲线,并得到了采用较为理想的实验气溶胶测试出的真实透过率的实际验证,这将大大提高高效、超高效滤料性能测试台的精度,拓展了其应用范围,为高效滤料的过滤理论和应用研究提供了比较理想的测试手段。     

不同粒径垃圾焚烧飞灰金属形态分布比较研究

研究了华南地区某垃圾焚烧厂的除尘器飞灰的化学组成和粒径分布,并采用分级提取法对不同粒径飞灰中的重金属化学形态进行了研究。同时比较了华南、华东、西南地区以及台湾地区垃圾焚烧飞灰的筛下累积分布和不同粒径飞灰中各重金属组成。结果表明,飞灰的组要成分为：CaO、SiO2和SO3等;各地区75%的飞灰粒径都主要集中在38.5～75μm。华南地区各粒径飞灰中挥发性金属（Zn和Pb）含量明显高于其他金属。除Ni和Cr外,Cu、Zn、Pb和Cd含量随粒径减小呈先减少后增大的趋势。华南地区Cu、Zn、Ni、Cr、Pb和Cd的含量均高于其他地区（台湾地区除外）。Cu、Zn和Cd的弱酸提取态和可还原态含量较高。高于40%的水溶态Pb表明其对环境有较大潜在危害;40%Ni和Cr主要以残渣态存在,对环境的潜在影响较小。     

昆明市街道灰尘粒度特征及其环境意义

对昆明市2008年1、3、4、5、7和9月份6次采集的街道灰尘样品进行了粒度分析。结果表明：昆明市街道灰尘粒度主要呈三峰特征,第一众数为65～125 μm,第二众数为3～15 μm,第三众数为0.15～0.3 μm,平均粒径范围在39.91～255.85 μm,平均值为87.1 μm,旱季（90.6 μm）大于雨季（83.7 μm）;粒度分布以正偏度为主,峰态为中等到偏窄且不对称,分选很差;与现代粉尘源区尘暴降尘的粒度分布模式高度相似,街道灰尘沉积是大气环流对远近不同距离粗细颗粒物的混合搬运的结果,应是风积作用的继续;灰尘细粒含量较高,≤100 μm的颗粒平均为635%,在适当的大气动力条件下,昆明市街道灰尘颗粒有60%～90%可以进入大气;灰尘主要来源于土壤风沙尘、建筑尘、工业烟尘和汽车尾气排放,灰尘中可吸入颗粒平均占25.2%,潜在危害性大。     

改性活性炭脱除硫化氢工艺参数研究

针对改性活性炭脱除硫化氢过程,研究了空速、温度、原料气浓度、颗粒分布孔径4个主要工艺参数对脱硫效率的影响。结果表明:空速在1 500～4 200h-1时穿透硫容随着空速的降低而增加,当空速继续降低为1 200h-1时穿透硫容基本不变;当0～40℃时,随着温度的升高,穿透时间增加,脱硫效率提高,当温度超过40℃时,随着温度继续升高脱硫效率降低;相同空速下原料气硫化氢浓度变化只改变穿透时间;改性活性炭脱硫剂发挥脱硫作用的微孔结构范围是1～5nm。     

Enhancement effect of water associated with natural organic matter (NOM) on organic compound-NOM interactions: a case study with carbamazepine

Natural organic matter (NOM) in soils and sediments is recognized to strongly affect environmental distributions of organic compounds. Water associated with NOM may have a significant impact on NOM-organic compound interactions. The objectives of this research were (1) to determine the effect of hydration of a model NOM sorbent on interactions with a probe organic compound, carbamazepine (CBZ), and (2) based on the comparison with the literature data, to evaluate the effect of organic compound structure on the cooperative participation of water molecules in organic sorbate-NOM interactions. CBZ is one of the most widely reported water pollutants from the pharmaceutical and personal care products family. Therefore, CBZ sorption on Pahokee peat was compared from water and from n-hexadecane, using solubility-normalized solute concentrations. CBZ-NOM interactions were enhanced by one to two orders of magnitudes when NOM became fully hydrated. This enhancement is associated with the distinct ability of CBZ to undergo strong, specific interactions with NOM which was revealed by comparing the transfer of CBZ and another model sorbate, phenanthrene, from solution in n-hexadecane to the hydrated NOM sorbent. The enhancing effect of NOM hydration on CBZ-NOM interactions was also observed when CBZ sorption was examined on partially hydrated NOM. In comparison with a smaller-size organic sorbate such as phenol, CBZ needs more NOM-associated water in order to demonstrate the strengthening of interactions with NOM. Therefore, for penetration of the larger sorbate molecules into the NOM interior, a greater number of water molecules are needed to compensate for the local NOM disintegration thus suggesting the greater extent of the cooperativity in an involvement of water molecules in the CBZ-NOM interactions.