广州市近年空气质量现状及趋势分析

为掌握广州市空气质量现状及其变化趋势,对广州市2001～2009年空气质量监测数据进行系统的分析。结果表明,近年来广州市空气质量总体良好;整体空气质量有逐步好转的趋势,尤其是SO2浓度下降明显,NO2稳中有降,PM10略有下降但2009年仍有上升趋势,且PM10超标率居于首位;污染物浓度时空分布不均匀,NO2与PM10夏季浓度较低,春冬季较高,表现出明显的季节性特征;主城区NO2浓度明显较高,但总体呈下降趋势,主城区外NO2浓度较低,但呈上升趋势。全年灰霾天数也呈现下降的趋势,变化规律与PM10浓度变化规律一致。     

2015—2020年全国重污染天变化趋势及时空分布特征分析

2015—2020年,全国重污染发生天数、比例及城市数量整体呈逐年下降趋势。与2015年相比,2020年全国337个地级及以上城市重污染天数减少1 847 d,降幅达55.2%;重污染天数比例下降1.6个百分点;发生过重污染天气的城市数量减少60个。其中,全国细颗粒物重污染天数整体呈下降趋势,沙尘重污染天数随气象条件的差异波动变化,臭氧重污染天数呈波动上升趋势。"十四五"期间,消除重污染天气的主要对象仍是细颗粒物重污染。应将天山北坡城市群、"2+26"城市、汾渭平原及苏皖鲁豫交界地区作为"十四五"期间污染减排的重点关注区域。此外,需遏制"2+26"城市臭氧重污染上升势头。     

环境综合分析报告的发展趋势

对环境综合分析报告的特点和分类进行了阐述。指出目前的环境综合分析报告对环境监测成果的利用不够，对环境管理政策措施的了解不足，环境质量评价方法有待改进，环境综合分析手段有待提高。提出环境综合分析报告应由讲述型向解答型发展，由纯文本型向多媒体型发展，由专业型向通俗型发展，由定期型向实时型发展。     

Assessing conservation status with extensive but low-resolution data: Application of frequentist and Bayesian models to endangered Athabasca River rainbow trout

Use of extensive but low-resolution abundance data is common in the assessment of species at-risk status based on quantitative decline criteria under International Union for Conservation of Nature (IUCN) and national endangered species legislation. Such data can be problematic for 3 reasons. First, statistical power to reject the null hypothesis of no change is often low because of small sample size and high sampling uncertainty leading to a high frequency of type II errors. Second, range-wide assessments composed of multiple site-specific observations do not effectively weight site-specific trends into global trends. Third, uncertainty in site-specific temporal trends and relative abundance are not propagated at the appropriate spatial scale. A common result is the propensity to underestimate the magnitude of declines and therefore fail to identify the appropriate at-risk status for a species. We used 3 statistical approaches, from simple to more complex, to estimate temporal decline rates for a designatable unit (DU) of rainbow trout in the Athabasca River watershed in western Canada. This DU is considered a native species for purposes of listing because of its genetic composition characterized as >0.95 indigenous origin in the face of continuing introgressive hybridization with introduced populations in the watershed. Analysis of abundance trends from 57 time series with a fixed-effects model identified 33 sites with negative trends, but only 2 were statistically significant. By contrast, a hierarchical linear mixed model weighted by site-specific abundance provided a DU-wide decline estimate of 16.4% per year and a 3-generation decline of 93.2%. A hierarchical Bayesian mixed model yielded a similar 3-generation decline trend of 91.3% and the posterior distribution showed that the estimate had a >99% probability of exceeding thresholds for an endangered listing. We conclude that the Bayesian approach was the most useful because it provided a probabilistic statement of threshold exceedance in support of an at-risk status recommendation.     

2010—2016年上海城区臭氧长时间序列变化特征初探

基于2010—2016年上海城区近地面大气臭氧（O₃）的连续在线观测数据，研究了上海城区O₃长时间序列变化规律和污染特征.结果表明，近7年来上海城区O₃污染逐渐凸显，但总体以轻度污染为主，7—8月高温炎热季节以中度污染居多.城区O₃-8 h（臭氧日最大8 h滑动平均）年均增速为3.81 μg·m^-3·a^-1，99%和95%分位值增速较快，分别为6.65和4.94 μg·m^-3·a^-1；25%、50%和75%分位值的增速在3.06~4.45 μg·m^-3·a^-1之间.春季O₃浓度均值较高，年际变化小；夏季极值较高，且污染超标情况最为突出；秋季O₃浓度次于春、夏季，冬季最低；夏、秋和冬季O₃浓度总体呈上升态势.O₃日变化呈"单峰型"，最大值出现在13：00左右，且峰值逐年增加，污染持续时间变长，最小值出现在早晨7：00.城区O₃"周末效应"逐渐减弱.基于KZ过滤器方法的数据分析结果表明，上海城区O₃-8 h长期变化主要受O₃-BF（O₃-8 h的基准组分）影响；O₃-SF（O₃-8 h的天气影响组分）在5—9月对O₃-8 h影响较大，其范围为-98.85~139.60 μg·m^-3.     

国产旋压设备的发展和应用

概述了国内旋压设备 30余年来的发展历程 ,指出了国产设备与发达国家的产品存在的差距 ,以及近年来国内旋压机床制造业取得的成绩。并结合国内外市场的需求 ,提出了旋压设备今后发展的方向