Gas Transfer Coefficient Evaluation in the Mediterranean Sea Using Bomb Produced Radiocarbon

A study on the carbon dioxide exchange at the water-air interface in the Western Mediterranean Sea was carried out. the attention was focused on the mean air-sea flux estimations by radiocarbon profiles and bomb ¹⁴C concentration atmospheric data. Sampling techniques and analytical methods are reported; mass balance evaluations on data recorded during the MED'92 cruise are presented and discussed briefly.     

水位对小叶章湿地CO2、CH4排放及土壤微生物活性的影响

湿地生态系统对全球碳平衡和气候变化起着极其重要的作用,而水位波动将影响湿地生物地球化学过程,导致温室气体通量变化,为了明确湿地生态系统温室气体通量以及土壤微生物活性对水位梯度的生态响应,通过野外盆栽培养试验,设T1:-5 cm,T2:0 cm,T3:5 cm,T4:10 cm 4种水位梯度,T1和T2模拟湿地非淹水的水分状况,T3和T4模拟淹水状况,研究了不同水位梯度下小叶章(Calamagrostis angustifolia)湿地CO2、CH4通量、土壤微生物量碳、氮及土壤酶活性的变化规律.结果表明:不同水位条件下,小叶章湿地系统CO2和CH4通量差异较大,-5 cm水位时小叶章湿地CO2通量为(643.35±61.89) mg·m-2·h -1,随着水位增加,CO2通量依次降低6.9%、12.1%、40.0%,且水位升高到10 cm时,小叶章湿地CO2排放量显著降低(P<0.05);而CH4通量则随水位增加呈显著增加趋势,通量变化为(1.52±0.12)~(5.34±0.61) mg·m-2·h-1;水位对微生物活性影响显著,非淹水条件下小叶章湿地土壤微生物量碳、氮含量以及土壤蔗糖酶、淀粉酶活性高于淹水土壤,且随着淹水位增加,微生物活性显著降低.     

Fluent软件在地表水源热泵系统温排水数值模拟中的运用

运用Fluent软件对重庆市嘉陵江化龙桥段瑞安新天地江水水源热泵系统尾水排入受纳水域的过程进行二维数值模拟,选取Fluent中非耦合、隐式求解器对模型内的定常流动进行求解,得出受纳水域受水源热泵系统温排水影响后的温升面积和温度梯度。结果表明:在温排水流量为2.0×103 m3/h、温差为4℃的条件下,计算该水域沿水流方向温升超过1℃的最大影响距离为150.4 m,温升超过1℃的水域面积约为1 525 m2,为模拟江水面积的8.59%。选取1℃温升值作为温升带的边界控制值,并在热泵系统最大负荷工况下,根据W=Q×ΔT计算研究水域热环境容量为19.402 m3.℃/s,剩余热环境容量为17.736 m3.℃/s。根据地表水环境质量标准,该工程温排水量小于受纳水域的热承载力,不会对受纳水域生态环境造成热污染。     

秦皇岛主要入海河流污染及其对近岸海域影响研究

利用饮马河、洋河、汤河和戴河的水文和水质监测资料,分析了各河流的污染状况、营养状态、污染物入海通量及其对海域水质的影响。结果表明：秦皇岛市入海河流中饮马河和洋河污染较重;通过污染分担率分析,秦皇岛入海河流的首要污染物为DIN、COD,其次为PO43--P;采用综合营养状态指数法评价,汤河处于轻度富营养状态,戴河处于中度富营养状态,而洋河和饮马河都已达到重度富营养化状态,可见秦皇岛入海河流的富营养化现象非常严重;秦皇岛主要河流污染物入海通量近年来基本呈减小趋势,饮马河和洋河年均入海污染物量占到秦皇岛市陆源入海污染物总量的94.91%;通过相关分析表明,秦皇岛近岸海域的水质主要受入海河流影响,尤其是CODMn、DIN、PO43--P在河、海间存在线性关系,具有强相关性。因此应加强对入河污染物的管理,重点应放在生活污水、农业面源污染的治理上,从而改善近岸海域的水质状况。     

工业和建筑固体废弃物再生研究

为了减轻我国的工业/建筑固体废弃物的污染压力,通过对工业和建筑固体废物、粉煤灰、水泥以及外加剂的组合配比实验,优化制作具有轻质高性能的混凝土建筑砌块的方法,并对所研制的混凝土砌块的强度和导热性能进行了测试,最终结果显示砌块性能良好。预计此类复合建筑材料可以在未来的市政建筑中发挥应有的作用。     

Changes in CO2 flux for different recovery processes of desertification in the alpine meadows of Northwest Sichuan北大核心CSCD

Desertification has emerged as a serious threat to the alpine meadows of Northwest Sichuan in recent decades. Artificial vegetation had certain effects on desertification recovery, while how the CO2 flux changed and its reasons are still unclear. During the growing season in 2016 (i.e., from July to September), we selected the desertified alpine meadows with different recovery degrees, including the early stage of restoration, the middle stage of restoration, the late stage of restoration, and control (the unrecovered desertification meadow) as four transects. CO2 flux was measured by the instrument LI-8100, and the microenvironment factors that affected CO2 flux changes were analyzed. The results showed that the carbon sequestration function of desertified alpine meadows gradually increased with the degree of recovery. Net ecosystem exchange (NEE) were -1.61, -3.55, and -4.38 μmol m-2 s-1 in the early, mid-term, and late transects, respectively, and the most dramatic changes occurred from the early stage to mid-term stage, increasing by 120.50%. Both ecosystem respiration (ER) and soil respiration (SR) were enhanced significantly with restoration (P < 0.05). In mid or late July, NEE, ER, and SR reached their maximum values, and thereafter, the indicators varied to near zero (P < 0.05). During the whole growing season, the daily dynamic in CO2 flux for the control alpine meadow was mild and retained the trend of continuous release all day, but that in the desertified alpine meadow was a single peak pattern. Moreover, with restoration process, the peak of CO2 flux increased and reached a peak in the late stage of the recovery process. The regression analysis showed that there was a significant positive correlation between CO2 flux and vegetation coverage, aboveground biomass, and soil moisture (0-5 cm) (P < 0.01), and a weak correlation with 0-5-cm soil temperature (P < 0.01). This indicates that topsoil moisture (5 cm) is a more significant factor for CO2 flux than topsoil temperature during the growing season in the restoration of desertified alpine meadows in Northwest Sichuan. In general, the vegetation recovery significantly improved the carbon-sequestration ability of the desertified alpine meadows during the growing season in Northwest Sichuan, and at the middle stage of restoration, the carbon-sequestration ability improved significantly due to vegetation restoration and increase in topsoil (0-5 cm) moisture. © 2018 Science Press. All rights reserved.     

热力管加热桥面抗冰融冰试验研究

为了研究热力管加热桥面抗冰融冰对于公路交通安全的影响,制作了尺寸为600 mm×600 mm×380 mm的桥梁试件,在人工环境室对热力管融冰进行了模型试验。结果表明:试件上表面温升速率和融冰时间取决于热力管间距、隔热层、风速、环境温度和热力管外表面温度。在相同工况条件下,100 mm间距的热力管融冰能力要大于150 mm间距的热力管,无隔热层时,100 mm间距热力管向上传递的热量占总加热量的13.4%,融冰时间为211 min;150 mm间距热力管向上传递的热量占总加热量的18.3%,融冰时间为271 min。在热力管层下面铺设厚度为2 mm、导热系数为0.062 W/（m· K）的隔热材料后,100 mm间距热力管向上传递的热量占总加热量的46.9%,融冰时间为175 min;150 mm间距热力管向上传递的热量占总加热量的51.9%,融冰时间为161 min。热力管层铺设隔热材料可有效阻止热量向下传递,从而缩短融冰时间。     

白洋淀夏季入淀区沉积物间隙水-上覆水水质特征及交换通量分析

为揭示白洋淀夏季入淀区上覆水-间隙水氮磷营养盐相互作用,本研究于2019年7月对白洋淀主要6条入淀河流取样,通过分析上覆水、间隙水水质特征以及营养盐在沉积物-水界面的扩散通量,评估了营养盐扩散对沉积物与上覆水的影响.结果表明白洋淀水质呈弱碱性;溶解氧（DO）含量较低,为沉积物内源污染物的释放提供了厌氧环境;氨氮（NH₄⁺-N）浓度在0.35~1.76mg·L^-1,作为主要给水来源的潴龙河淀区最高;硝氮（NO₃^--N）浓度在0.75~1.97mg·L^-1;溶解性总氮（TDN）浓度在0.99~2.70mg·L^-1,位于自然区的S2瀑河含量最高;溶解性总磷（TDP）浓度在0.03~0.15mg·L^-1,靠近居民区的白沟引河含量最高.间隙水氨氮浓度在5.24~10.64mg·L^-1,是上覆水体的10倍,内源污染严重;硝氮浓度在0.36~0.79mg·L^-1;溶解性总氮浓度在5.36~12.02mg·L^-1,是上覆水体的5倍;溶解性总磷浓度在0.03~0.3mg·L^-1.应用综合污染指数法对水质进行评价发现间隙水污染程度远高于上覆水,各采样点呈现出严重污染状态.对NH₄⁺-N、TDN和TDP进行交换通量分析显示,NH₄⁺-N的扩散通量在1.71~7.43mg·（m²·d）^-1,作为保定市纳污河流的府河采样点内源氨氮向上覆水扩散速率最快;TDN的扩散通量除白沟引河较低,其余5个采样点均值达到9.11mg·（m²·d）^-1,夏季水体中溶解氧含量较低且沉积物-水界面TDN浓度差较大,导致沉积物中含氮营养盐在厌氧条件下大量释放到上覆水中,对水质造成严重污染;萍河采样点TDP的扩散通量是负值表示上覆水体的磷污染物向沉积物聚集的状态,剩余5个采样点的扩散通量范围在0.03~0.16mg·（m²·d）^-1,表现出磷营养盐向上覆水释放的状态.扩散通量显示内源污染物是上覆水污染物的重要来源,为有效治理入淀区水质,沉积物氮磷营养盐的清淤处理迫在眉睫.     

大豆蛋白粉喷雾干燥塔尾气余热的回收与利用

针对大豆蛋白粉生产过程中喷雾干燥塔尾气温度较高,有回收利用价值的现实,也针对目前的节能需求,对现有的喷雾干燥塔的尾气排放部分进行改造,设计一个片状空气预热器,以利用高温的尾气与系统的进气做热交换,实现热量再利用,降耗和提高蛋白粉产率的目的,并对投资收益进行了分析。     

北京城区大气多环芳烃的沉降特征

从2006年6月至2007年6月期间采集了北京市区的降尘和大气TSP,分析了其中的PAHs和降尘的粒度。降尘颗粒大部分在100μm以下,体积平均径和中位径D50的范围分别为18.89-53.117μm和11.59-28.98μm。全年降尘平均沉降通量为0.451 9 t/（km2.d）,冬季高,夏秋季低;∑16PAHs的沉降通量平均为4.76 g/（km2.d）,冬季高,夏季低,与同期的大气SO2的API指数显著相关。TSP中的∑16PAHs与降尘中的∑16PAHs具有显著的相关关系,成分谱一致。PAHs的沉降速率变化范围为0.004-5.46 cm/s,夏季高、冬季低。交通沿线∑16PAHs的沉降通量远远高于非交通线的沉降通量。