兰州市沙尘天气与痤疮门诊量的时间序列

研究沙尘天气、非沙尘天气下颗粒物（PM_2.5、PM_C、PM₁₀）对痤疮门诊量的影响,并进行性别、年龄分层研究,筛选敏感人群.收集了2013~2017年兰州市沙尘期与非沙尘期3家三甲医院痤疮门诊量资料、大气颗粒物及气象数据,采用基于泊松分布的分布滞后非线性模型（DLNM）,控制气象因素、季节性和长期趋势、星期几效应等混杂因素,分析沙尘期与非沙尘期颗粒物对痤疮门诊量的影响及滞后效应.结果表明：沙尘期时,兰州市3家三甲医院痤疮日均门诊量为26人次,范围3~54人次.非沙尘期时痤疮日均门诊量为37人次,范围1~89人次;单污染物模型显示,PM_2.5、PM_C、PM₁₀均在滞后第6d （lag6）时效应量达到最大值,其浓度每增加10μg/m³,痤疮门诊量的超额危险度（ER）及95%可信区间（95% CI）分别为1.065（95% CI：0.260~1.877）、0.355（95% CI：0.018~0.693）、0.310（95% CI：0.054~0.567）,PM_2.5对痤疮门诊量的影响最为显著;性别及年龄分层发现,性别分层中PM_2.5对女性的影响有统计学意义,其浓度每增加10μg/m³,痤疮门诊量增加1.077（95% CI：0.124~2.039）;年龄分层中,0~18岁组受PM_C、PM₁₀影响显著,19~24岁组受PM_2.5、PM₁₀影响显著,各颗粒物对25~34岁组及≥35岁组效应无统计学意义.在非沙尘期时,PM_2.5、PM_C、PM₁₀不引起痤疮门诊量增加.双/多污染物模型显示,分别调整其他污染物后,PM_2.5、PM_C、PM₁₀对痤疮门诊量的影响与单污染物模型类似,仍具有统计学意义.兰州市沙尘天气下大气颗粒物（PM_2.5、PM_C、PM₁₀）可使痤疮门诊量增加,对女性及青少年影响显著.     

建筑垃圾产量预测与时空特征研究:以南京江北新区为例

建筑垃圾的产量预测与时空特征分析是制定城市建筑垃圾资源化管理方案的重要参考依据。界定了建筑垃圾的定义与分类,提出基于情景分析的单位建筑面积建筑垃圾产量预测方法,并以南京市江北新区直管区为例,采集控制性详细规划、倾斜摄影地图、地形图、百度全景地图、年度在建施工项目与征收项目清单等基础资料,对江北新区直管区近期（2018年）与远期（2019—2030年）的拆建垃圾产量进行估算与分析;同时借助ArcGIS技术,采用核密度分析实现拆建垃圾空间分布的可视化与特征分析,为后续建筑垃圾资源化处置方案设计提供基础数据与决策依据。     

Relationships of ozone formation sensitivity with precursors emissions, meteorology and land use types, in Guangdong-Hong Kong-Macao Greater Bay Area, China

Due to the influences of precursors emissions, meteorology, geography and other factors, ozone formation sensitivity (OFS) is generally spatially and temporally heterogeneous. This study characterized detailed spatial and temporal variations of OFS in Guangdong-Hong Kong-Macao Greater Bay Area (GBA) from 2012 to 2016 based on OMI satellite data, and analyzed the relationships of OFS with precursors emissions, meteorology and land use types (LUTs). From 2012 to 2016, the OFS tended to be NO_x-limited in GBA, with the value of FNR (HCHO/NO₂) increasing from 2.04 to 2.22. According to the total annual emission statistics of precursors, NO_x emissions decreased by 33.1% and VOCs emissions increased by 35.2% from 2012 to 2016, directly resulting in OFS tending to be NO_x-limited. The Grey Relation Analysis results show that total column water (TCW), surface net solar radiation (SSR), air temperature at 2 m (T2) and surface pressure (SP) are the top four meteorological factors with the greatest influences on OFS. There are significant positive correlations between FNR and T2, SSR, TCW, and significant negative correlations between FNR and SP. In GBA, the OFS tends to be NO_x-limited regime in wet season (higher T2, SSR, TCW and lower SP) and VOCs-limited regime in dry season (lower T2, SSR, TCW and higher SP). The FNR displays obvious gradient variations on different LUTs, with the highest in “Rural areas”, second in “Suburban areas” and lowest in “Urban areas”.     

Sources and health risks of PM2.5-bound polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in a North China rural area

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are typical persistent organic pollutants (POPs), which have high toxicity, bioaccumulation and long-distance transfer capability. Daily variation, sources of PCBs and OCPs in PM_2.5 are rarely explored in polluted rural area. Here, the sources and health risks of the PCBs and OCPs were evaluated for 48 PM_2.5 samples collected in winter 2017 in Wangdu, a heavy polluted rural area in the North China Plain. The average diurnal and nocturnal concentrations of Σ₁₈PCBs and Σ₁₅OCPs were 1.74-24.37 and 1.77-100.49, 11.67-408.81 and 16.89-865.60 pg/m³, respectively. Hexa-CBs and penta-CBs accounted for higher proportions (29.0% and 33.6%) of clean and polluted samples, respectively. Hexachlorobenzene (HCB) was the dominant contributor to OCPs with an average concentration of 116.17 pg/m³. Hexachlorocyclohexane (ΣHCHs) and dichlorodiphenyltrichloroethane (ΣDDTs) were the other two main classes in OCPs with the average concentrations of 4.33 and 15.89 pg/m³, respectively. β-HCH and p,p’-DDE were the main degradation products of HCHs and DDTs, respectively. The principal component analysis and characteristic ratio method indicated both waste incineration and industrial activities were the main sources of PCBs, contributing 76.8% and 12.7%, respectively. The loadings of OCPs were attributed to their application characteristics and the characteristic ratio method reflected a current or past use of OCPs. Health risk assessment showed that the respiratory exposure quantity of doxin-like PCBs (DL-PCBs) and the lifetime cancer risk from airborne OCPs exposure was negligible, while the other exposure modes may pose a risk to human bodies.     

甲型流感的流行与防控分析及其对新冠肺炎疫情的启示

目前新型冠状病毒肺炎（COVID-19）疫情在全球流行,对人类生命健康造成威胁.对甲型流感这一常见传染病进行流行特征、影响因素和防控措施分析,回顾总结全球为防控甲型流感做出的努力及相关科学研究成果,为新型冠状病毒肺炎疫情提供防控经验和研究思路.结果表明:①甲型流感呈季节性流行,受气候、社会、政治和文化等多因素影响,在低温低湿、人口密集的环境中表现出强流行性.②甲型流感防控研究工作主要包括季节性流感病毒监测、流感病毒的生态学研究、广谱中和抗体及通用疫苗的研究、应对流感大流行的病原学风险评估四方面,其中季节性流感病毒监测是制定公共卫生政策及后续研究的核心防控措施.③与甲型流感类似,新型冠状病毒肺炎疫情流行受温度等气候因素影响,同时社会、政治、文化等因素也影响其传播,亟需借鉴较成熟的甲型流感的防控经验、技术和平台.建议在加强病毒监测的同时,深入开展病毒生态学研究、病原学风险评估和药物开发,对完善疫情防控工作和预警预测未来可能出现的二次暴发及传播至关重要.研究结果将为新型冠状病毒肺炎疫情和未来传染病疫情的防控及预测预警提供参考和研究思路.      

贵州南明河水环境综合整治与水质模拟

以贵州南明河为例,对城市河道水环境综合治理全流程进行了系统的定量综合分析.污染识别结果表明,外源污染是造成南明河污染的关键原因,其对南明河COD、氨氮和TP等污染物的贡献分别达68%、95%和77%;COD和氨氮是南明河的主要入河污染物(80%和60%的入河外源来水中COD和氨氮水平劣于地表V类水).采取截污纳管、污水处理及河底清淤等针对性的治理措施,可共削减南明河COD、氨氮和TP污染负荷41414.6、874.2和218.0 t·a~(-1);通过生态建设恢复河道自净能力并运行半年后,南明河整治段劣V类河道长度占比从整治前的51.0%下降至17.4%,达到地表水V类的水质段由原来的10.1%提高至24.3%.建立MIKE模型预测综合整治措施3期工程全部完工时南明河水质运营情况发现,南明河下游水质断面能稳定达到IV类水体,但在枯水期仍可能存在部分河段TP和氨氮超标的情况.通过从上游水库(红枫湖,II类水)进行生态补水以保障南明河干流城区段稳定达标IV类水体,在考虑模拟误差且保证率高于90%的情况下,枯水期最高补水量应达到3.47m~3·s~(-1).     

水分管理和外源硒对水稻吸收累积铅的影响

通过盆栽试验,研究了不同水分管理和外源亚硒酸盐的添加对水稻根际铅的动态变化和水稻吸收累积铅的影响.结果表明,淹水显著增加了根表铁膜对铅的吸附和根系对铅的吸收,淹水下苗期和成熟期水稻根系铅含量分别是非淹水处理时的4.2~8.5和1.4~1.5倍;淹水降低了地上部的铅分配,在苗期和成熟期分别降低85.9%~86.7%和51.8%~74.0%.加硒降低了土壤溶液、苗期水稻根系和地上部的铅含量以及成熟期水稻根表铁膜、根系和茎中的铅含量.与对照相比,淹水和非淹水下加硒处理使苗期水稻根系铅含量分别降低了5.4%~24.3%和2.7%~61.7%,使成熟期水稻根系铅含量分别降低了56.1%~64.1%和53.8%~63.2%.水稻籽粒中的铅含量在不同处理间无显著差异.因此,水分管理和外源硒的添加显著影响了水稻根系对铅的吸收,而对水稻籽粒对铅的累积无显著影响.     

苯为前驱物形成二噁英的反应机理

苯作为垃圾中普遍存在的成分是形成多氯二苯并对二噁英/呋喃（PCDD/Fs）的重要前驱物之一.应用密度泛函理论（DFT）在B3LYP/6-311+G （d,p）水平上研究了苯生成PCDD/Fs的两阶段气相反应机理,获得相关基元反应的势垒与反应热.采用隧道效应校正的变分过渡态理论（VTST）对300~1300K的各基元反应进行速率常数计算.结果表明：苯的氯化过程在合成PCDD/Fs各基元反应中势垒最高,是整个过程的控速步骤;氯酚更有可能被HO·进攻氯苯发生亲核反应后经分子内脱氢形成;邻位Cl能提高芳香烃H的抽取势垒,降低分子反应活性;苯氧自由基经碳碳或碳氧耦合二聚化过程形成不同PCDD/Fs存在竞争机制.相关计算结果可以用于在总二噁英产量基础上评估由苯产生的PCDD/Fs贡献率.     

Water regime-nitrogen fertilizer incorporation interaction: Field study on methane and nitrous oxide emissions from a rice agroecosystem in Harbin, China

Water regime and nitrogen (N) fertilizer are two important factors impacting greenhouse gases (GHG) emission from paddy field, whereas their effects have not been well studied in cold region. In this study, we conducted a two-year field experiment to study the impacts of water regime and N fertilizer on rice yields and GHG emissions in Harbin, China, a cold region located in high latitudes. Our results showed that intermittent irrigation significantly decreased methane (CH₄) emission compared with continuous flooding, however, the decrement was far lower than the global average level. The N₂O emissions were very small when flooded but peaked at the beginning of the disappearance of floodwater. The N fertilizer treatments increased CH₄ emissions at low level (75kgN/ha). But both CH₄ and N₂O emissions were uninfluenced at the levels of 150kgN/ha and 225kgN/ha. Rice yields increased under intermittent irrigation and were highest at the level of 150kgN/ha. From our results, we recommended that the intermittent irrigation and 150kgN/ha as the ideal water regime-nitrogen fertilizer incorporation for this area to achieve low GHG emissions without impacting rice yields.     

Formation of water disinfection byproduct 2,6-dichloro-1,4-benzoquinone from chlorination of green algae

We report that green algae in lakes and rivers can serve as precursors of halobenzoquinone(HBQ) disinfection byproducts(DBPs) produced during chlorination. Chlorination of a common green alga, Chlorella vulgaris, produced 2,6-dichloro-1,4-benzoquinone(2,6-DCBQ), the most prevalent HBQ DBP in disinfected water. Under varying p H conditions(p H 6.0–9.0), 2,6-DCBQ formation ranged from 0.3 to 2.1 μg/mg C with maximum formation at p H 8.0. To evaluate the contribution of organic components of C. vulgaris to 2,6-DCBQ formation, we separated the organics into two fractions, the protein-rich fraction of intracellular organic matter(IOM) and the polysaccharide-laden fraction of extracellular organic matter(EOM). Chlorination of IOM and EOM produced 1.4 μg/mg C and 0.7 μg/mg C of 2,6-DCBQ, respectively. The IOM generated a two-fold higher 2,6-DCBQ formation potential than the EOM fraction, suggesting that proteins are potent 2,6-DCBQ precursors. This was confirmed by the chlorination of proteins extracted from C. vulgaris: the amount of 2,6-DCBQ produced is linearly correlated with the concentration of total algal protein(R2= 0.98). These results support that proteins are the primary precursors of 2,6-DCBQ in algae, and control of green algal bloom outbreaks in source waters is important for management of HBQ DBPs.