秋分养生

每年的阳历9月7至9日为白露。白露是个典型的秋天节气，从这一天起，露水一天比一天凝重成露而名。农历言：“斗指癸为白露，阴气渐重，凌而为露，故名白露。”白露节气已是真正的凉爽季节的开始，很多人在调养身体时一味地强调海鲜肉类等营养品的进补，而忽略了季节性的易发病，给自己和家人造成了机体的损伤，影响了学习和工作。     

广州灰霾现象特征分析

依据灰霾的发布和判定依据,对中山大学大气环境自动监测站的能见度、风速、相对湿度和ρ(PM_2.5)等观测数据进行分析,分析其随时间变化的规律和相关性,得出近年来广州灰霾变化规律和多类特征. 结果表明:近年来广州整体灰霾现象有所改善,且主要呈现非夏季和夏季2种典型季节性特征. 非夏季灰霾具有持续时间长、状态稳定和风力突破性强等特点;夏季灰霾具有持续期短、状态变化快,ρ(PM_2.5)与能见度的曲线图镜像对称明显等规律;灰霾现象与城市空气质量有密切的关系,且API大于100的时间与较严重灰霾日的分布相似.      

洱海浮游桡足类群落结构对季节性休渔的响应

为了解洱海浮游桡足类群落结构的季节动态特征,于2009年2~11月对洱海浮游桡足类进行逐月采样.结果显示:洱海浮游桡足类生物量的季节性分布呈"双峰型",峰值分别出现在休渔期中期和捕鱼期中期.在休渔期中期,桡足类以杂食性的剑水蚤Mesocyclops dissimilis为优势种;在捕鱼期中期,则以滤食性的哲水蚤舌状叶镖水蚤为优势种.季节性休渔不仅导致鱼类对桡足类的捕食压力出现季节性变化,而且通过影响枝角类的群落结构,改变枝角类对桡足类的竞争压力.在相对较低的捕食压力和较大的食物竞争压力影响下,桡足类以杂食性的剑水蚤为优势类群;在相对较大的捕食压力和较低的食物竞争压力下,以滤食性的哲水蚤为优势类群.     

不同粒径大气颗粒物中多环芳烃的含量及分布特征

采集了北京城乡结合部与郊区2003年4个季节的不同粒径大气颗粒物样品 ,运用GC/MS分析了其多环芳烃组成 .结果表明 ,17种PAHs总量为 0.84～15.223ng/m³,城乡结合部含量是郊区的1.07～6.60倍 .PAHs总量的季节性变化表现为冬季>秋季>春季>夏季,且随颗粒物粒径减小,含量逐渐增大,大约有68.4%～84.7%的PAHs吸附在≤2.0μm颗粒上.2～3环PAHs呈双峰型分布,4～6环PAHs呈单峰型分布 ,PAHs分子量越大 ,MMD值越小 ,燃煤取暖与低温是导致冬季PAHs污染增高的主要因素.     

青海高原季节性降雪中的黑碳气溶胶

对青海高原2012年季节性降雪进行采集.6个采样点集中在青海高原东南部地区,共包括36袋雪样.从分析结果可知,青海高原东南部地区季节性降雪中含有较多的沙尘,滤膜颜色多为土黄色.6个采样点雪中的黑碳浓度为(184±123)ng/g,表层雪的黑碳浓度范围是59~238ng/g,平均值为152ng/g.通过后向轨迹聚类分析知道气流主要来自南亚和青藏高原地区,有少部分是来自塔克拉玛干沙漠和戈壁地区.     

灰色季节性指数自记忆模型及其在海河区降水模拟与预测中的应用

准确的降水模拟与预测,对防汛、抗旱及区域水资源管理有着重要的指导作用。由于降水序列波动较大,传统的灰色模型所得到的降水模拟值和预测值往往趋于平均值,论文从输入数据和模型结构改进两个方面对传统的灰色模型进行改进——采用季节性指数法对降水数据进行平滑处理,引入自记忆函数,构建灰色季节性指数自记忆模型（SS-GM）,并将其应用于海河区降水过程的模拟和预测。结果表明：①该模型较传统灰色模型而言,模拟效果有很大程度的提高,能够准确模拟年和月尺度的降水过程,各水资源二级区的月尺度Nash-Sutcliffe 系数（NSE）和决定系数（R²）均达到了0.60 以上,大部分区域年降水模拟的NSE和R²均在0.70 以上,且在较大的时空尺度上,模拟效果更佳;②模型具有一定的月降水量的预测能力,在1~2 月预见期内,各分区降水预测值NSE达到0.50 以上,大部分地区NSE值超过0.60;③模型结构简单、计算方便,能很好地反映降水数据序列的变化趋势,且具有较高的模拟及预测精度。     

A 14-year measurement of toxic elements in atmospheric particulates in Hong Kong from 1995 to 2008

Toxic elements in the atmosphere can enter and accumulate in the human body, seriously impacting human health. In this study, we analyzed a 14-year （1995-2008） measurement of three toxic elements （As, Cd and Cr） in PMlo in Hong Kong, China. The pollution of these toxic elements in Hong Kong was not serious. The trend analysis showed that As and Cr in PM10 increased at a statistically significant level （p〈0.05） during the 14-year period, while the Cd in PM10 did not change significantly. Typical seasonal variations were observed for all three toxic elements, largely in relation to the Asian monsoon. Hourly 10-day backward trajectories were computed and cate- gorised into four groups. The continental air masses showed much higher concentrations of the three toxic elements than the marine air masses. The abundances of As and Cd in the PM10 were much higher in the continental air masses than those in the marine air masses, while the abundances of Cr showed an opposite pattern. The trends of the three toxic elements in East China＇s air mass were consistent with those in the overall data set ofHong Kong. Examination of the toxic element data recorded at urban sites and a roadside site also indicated a large contribution of external air masses to particulate As and Cd in Hong Kong. These results suggest that the long-range transport from the mainland of China is the dominant contributor to particulate As and Cd, while both local and long-distance sources determine the particulate Cr in Hong Kong.     

Effects of seasonal climatic variability on several toxic contaminants in urban lakes: Implications for the impacts of climate change

Climate change is supposed to have influences on water quality and ecosystem. However, only few studies have assessed the effect of climate change on environmental toxic contaminants in urban lakes. In this research, response of several toxic contaminants in twelve urban lakes in Beijing, China, to the seasonal variations in climatic factors was studied. Fluorides, volatile phenols, arsenic, selenium, and other water quality parameters were analyzed monthly from2009 to 2012. Multivariate statistical methods including principle component analysis, cluster analysis, and multiple regression analysis were performed to study the relationship between contaminants and climatic factors including temperature, precipitation, wind speed, and sunshine duration. Fluoride and arsenic concentrations in most urban lakes exhibited a significant positive correlation with temperature/precipitation, which is mainly caused by rainfall induced diffuse pollution. A negative correlation was observed between volatile phenols and temperature/precipitation, and this could be explained by their enhanced volatilization and biodegradation rates caused by higher temperature. Selenium did not show a significant response to climatic factor variations, which was attributed to low selenium contents in the lakes and soils. Moreover, the response degrees of contaminants to climatic variations differ among lakes with different contamination levels. On average, temperature/precipitation contributed to 8%, 15%, and 12% of the variations in volatile phenols, arsenic, and fluorides,respectively. Beijing is undergoing increased temperature and heavy rainfall frequency during the past five decades. This study suggests that water quality related to fluoride and arsenic concentrations of most urban lakes in Beijing is becoming worse under this climate change trend.     

我国北方温带水库——周村水库季节性热分层现象及其水质响应特性

为揭示我国北方温带水库——周村水库水体季节性分层现象及其水质响应特性,于2014年7月~2015年6月对周村水库进行了37次采样,并对水体理化指标和浮游植物进行了原位监测.结果表明,周村水库在4~11月间处于水体分层,全年呈典型的温带单循环混合模式.水温分层对水库水环境的变化起着重要的作用,热分层引起的底层水体季节性缺氧,导致了沉积物中营养盐以及还原性物质的大量释放,其中热分层期底层水体总氮、总磷、锰和硫化物的平均值分别为1.18、0.11、0.47和0.48 mg·L~(-1);浮游植物垂向分布受水温分层的显著影响,热分层期上层水体浮游植物丰度较高,其均值为16.35×106cells·L~(-1),下层水体浮游植物丰度维持在较低水平.