2000~2010年大鹏湾溶解有机氮的时空分布

依据2000~2010年每月一次的调查资料,简要描述和讨论了大鹏湾中溶解有机氮(DON)质量浓度的时空分布,并结合现场盐度、5d生化需氧量(BOD5)、总溶解氮(TDN)和叶绿素a (Chl a)实测数据探讨DON的组成、来源和滞留时间(TDON).结果表明,大鹏湾的水动力条件对DON的分布变化影响不大.DON质量浓度为(0.15±0.08)mg/L,与大亚湾的相近,但比珠江口的低,而比南海北部沿岸的高.由二元混合质量平衡模式结合周边小河溪(向海排放淡水)中TDN的DON质量分数估算的大鹏湾中陆源DON质量分数约为19%,远小于海源的,暗示大鹏湾中的DON以自生来源为主.由平均不稳定DON(LDON):BOD5比率估算的LDON质量分数约为41%.由表层平均浮游植物DON (PDON):Chl a比率估算的PDON质量分数约为17%,而由此结合累计DON估算的大鹏湾中的TDON约为15d.11a研究期间,LDON的年际变化呈下降趋势,而DON和难降解DON (RDON)的年际变化略呈上升趋势,表明RDON在大鹏湾中逐渐缓慢积累.     

Hydrodynamic characteristics of a four-compartment periodic anaerobic ba ed reactor

Periodic anaerobic baffled reactor (PABR) is a novel reactor based on the design concept of anaerobic baffled reactor (ABR). Residence time distribution (RTD) studies on both clean and working reactors at the same hydraulic residence time (HRT) of 2 d were carried out to investigate the dead spaces and mixing patterns in PABRs at different organic loading rates (OLRs) in various switching manners and frequencies.The results showed that the fraction of dead space in PABR was similar to that in ABR,which was low in comparison with other reactor designs.Dead space may be divided into two categories,hydraulic and biological.In RTD studies without biomass,the hydraulic dead space in the PABR run in an"every second"switching manner with T=2 d was the lowest whereas that in the PABR run in a T=∞(ABR) switching manner was the highest.The same trend was obtained with the total dead space in RTD studies with biomass no matter what the OLR was.Biological dead space was the major contributor to dead space but affected decreasingly at higher OLR whichever switching manner the PABR run in.The flow patterns within the PABRs were intermediate between plug-flow and perfectly mixed under all the conditions tested.     

Lake management under severe drought: Lake Mead,Nevada/Arizona

Drought can affect both the quantity and quality of water in lakes and reservoirs, yet larger, highly managed waterbodies, such as Lake Mead, may be somewhat buffered from drought effects. From 2000 to present, Lake Mead has experienced a 71% decline in volume; however, influent water quality has remained high and consistent outflow volumes through Hoover Dam have been maintained. Furthermore, management activities, such as increased removal of phosphorus by wastewater dischargers and legacy contamination cleanup efforts, have been initiated since the drought began. These efforts have led to small improvements in values of water quality parameters, such as phosphorus, nitrogen, and perchlorate, despite loss of volume for dilution of constituents, and consequently, decreased residence time. As the drought continues, Lake Mead is projected to continue declining in volume, inflows are projected to become warmer, and the population of Las Vegas is projected to grow, potentially adding additional stress to the hydrologic system. Maintenance of outflow may mitigate some potentially negative consequences, and understanding the drivers behind continued high water quality despite prolonged drought is important to continue to maintain the health and vitality of the entire Lower Colorado River Basin.     

基于情景模拟的上海中心城区居民住宅的暴雨内涝风险评价

内涝是影响上海的主要灾害之一,上海城区居民住宅特别是旧式住宅容易因之受损乃至倒塌。基于情景模拟和指标体系方法,开展了上海中心城区住宅的风险评估。利用上海水务信息中心开发的内涝仿真模型,设置暴雨情景并对该情景下的内涝进行模拟,得到了区域水深分布状况,利用G IS技术求得每座住宅的水深,体现其在内涝中的暴露程度,并构造暴露性评价模型,综合反映区域总体暴露状况。根据旧式住宅较易受到影响的事实,构造脆弱性指数,最终衡量区域住宅面临灾害的整体风险状况,实现区域间居民住宅内涝风险的对比分析。设置了五十年一遇的暴雨内涝情景,针对中心城区各街道开展了实证研究,最终评价结果显示出的危险性、暴露性、脆弱性和风险分布规律,与实际情况基本符合。该方法可以为市政部门提供必要的信息,提高内涝灾害的管理水平。     

居室天然气泄漏扩散过程仿真研究

随着我国城市环境保护的提高,城市燃料结构也在逐步改变。天然气作为一种清洁、高效的能源已经成为居民应用最广泛的燃料。随着天然气用户的不断增加,其事故次数也在不断上升。为了系统的研究居室内天然气泄漏扩散的过程和发展,预防居民家庭天然气火灾和爆炸事故以及发生事故后的应急提供依据。本文以普通的居民居室为研究对象,建立居室天然气泄漏扩散几何模型。并对室内天然气泄漏后的扩散状态进行仿真模拟,得到天然气泄漏后的室内扩散过程,以及在不同时间内存在爆炸极限的区域和达到爆炸极限的范围,并对爆炸后果进行了评估。结果显示：在设定条件下,泄漏发生后640 s,冰箱电源处达到爆炸下限,790 s时达到爆炸上限;其爆炸能量已达到使大型钢架结构破坏,大部分人员死亡的程度。泄漏1800 s后,可燃区域就扩散到厨房之外,存在于客厅之中了。     

低碳经济理念下江苏省农民集中居住分析研究

根据低碳经济理念内涵,构建"资源损耗与环境污染成本——最终产出"分析框架,对江苏省农民集中居住过程中建筑用能消耗与建筑垃圾污染、庭院经济消失与生活垃圾污染、集中居住后土地集约节约化程度和农民福利变化进一步分析探讨,研究发现农民集中居住后原有农村社区的低碳功能减弱,土地集约化程度、农民经济福利和生态福利水平变化具有明显的区域差异性;需将低碳经济理念和原则纳入农村居民点整理评价体系以及政府绩效评价体系;农村集中居住政策不宜全面展开,应优先在发达地区开展.     

芜湖市美食旅游产品开发初探

近几年来,随着旅游业的发展和人们收入的提高,芜湖市美食旅游市场呈现繁荣景象.通过七大指标综合评价安徽省内若干城市发展美食旅游的条件,发现芜湖市具有发展美食旅游的优势,但仍存在问题.针对芜湖市美食旅游的发展现状和存在问题,提出了应从提高产品文化内涵、与其它类型产品进行联动开发等方面开发美食旅游产品的策略.     

Formaldehyde degradation by UV/TiO2/O3process using continuous flow mode

The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount on degradation of formaldehyde gas were investigated. The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action, e.g,, it could considerably increase decomposing of formaldehyde. The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84--24 mg/m^3 by O3/TiO2flJV process. The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m^3. Furthermore, the kinetics of formaldehyde degradation reaction could be described by Langmuir-Hinshelwood model. The rate constant k of 46.72 mg/（m^3.min） and Langmuir adsorption coefficient K of 0.0268 m^3/mg were obtained.     

清淤疏浚工程对七里海潟湖湿地水体交换的影响

七里海潟湖湿地受到人类活动的影响,湖盆淤积、湖面萎缩、水质恶化,其生态修复工程（一期）通过对湖盆进行清淤疏浚来改善潟湖生态环境.基于三重嵌套非结构网格建立七里海潟湖湿地水动力和物质输运数学模型,采用实测资料对模型的潮位、流速和流向进行验证,运用欧拉法计算潟湖整体滞留时间及其空间分布,分析工程对七里海潟湖水动力和水体交换的影响,结果表明：（1）工程对潮位的影响较小,工程后潮汐通道口门处涨落潮流量增大,涨落潮流速也随之增加;（2）工程后,潟湖纳潮量较工程前提升87%,滞留时间较工程前降低38%,水体交换能力自潮汐通道向潟湖内部逐渐减弱,工程对潟湖水体交换能力的改善主要集中在河道及潟湖中心水域;（3）工程前水体滞留时间的分布主要受到潟湖地貌影响,工程后水深增大,流场受地貌的影响变小,水体交换能力的分布主要受到潟湖流场影响.清淤疏浚工程有助于潟湖改善水体的交换能力和生态环境.     

Place attachment and place identity in natives and non-natives

Place attachment is an affective bond that people establish with specific areas where they prefer to remain and where they feel comfortable and safe. Place identity, however, has been defined as a component of personal identity, a process by which, through interaction with places, people describe themselves in terms of belonging to a specific place. Most research has observed positive correlations between these variables in populations that have maintained ongoing interactions over long periods of time. This work presents two studies in which we compare place attachment to place identity in samples differentiated according to birthplace and length of residence, and the magnitude of these bonds to different places. The results of the first study revealed differences between intensity of attachment and identity depending on place of origin and place assessed. The second study found that identity and attachment tend to coincide in natives, while individuals from other places give higher scores for attachment than for identity. Results from the two studies have enabled us to consider that place attachment develops before place identity, at least in the case of the non-natives. Both studies reveal that bonds are stronger with the city than with the neighbourhood, but that attachment and identity with the island are stronger than either of them.