Decreased carbon and nutrient input to boreal lakes from particulate organic matter following riparian clear-cutting

The plankton communities of oligotrophic Canadian Shield lakes are strongly regulated by the allochthonous supply of total phosphorus (TP) and dissolved organic carbon (DOC), a proportion of both of which originate from particulate organic matter. Although decreased inputs of allochthonous leaf litter have been documented for small streams whose riparian forests have been removed, no such data exist for boreal lakes. Through estimates of airborne litter input from forested and clear-cut shorelines and laboratory measurements of concentrations released from leaf leachate, we determined that riparian deforestation resulted in reductions of DOC from 17.8 to 0.4 g/m shoreline/yr and of TP from 2.9 to 0.3 g/m shoreline/yr. Previous predictive models indicate that such reductions may be substantial enough to decrease basic metabolic processes of lake plankton communities by as much as 9% in primary production and 17% in respiration.     

碳底物含量对厌氧条件下水稻土N2、N2O、NO、CO2和CH4排放的影响

理解底物碳氮对厌氧条件下水稻土排放氮素气体——氮气(N2)、氧化亚氮(N2O)和一氧化氮(NO)以及二氧化碳(CO2)和甲烷(CH4)的影响,有助于制定合理的温室气体减排措施,定量了解反硝化产物组成对碳底物水平的依赖性,也有助于氮转化过程模型研发中制定正确的关键过程参数选取方法或参数化方案.本研究采用粉砂壤质水稻土为研究对象,设置对照(CK)和加碳(C+)两个处理,前者的初始硝态氮和可溶性有机碳(DOC)含量分别为~50 mg·kg-1和~28 mg·kg-1,后者的分别为~50 mg·kg-1和~300 mg·kg-1.采用氦环境培养-气体及碳氮底物直接同步测定系统,研究了完全厌氧条件下碳底物水平对上述气体排放的影响.结果表明,CK处理无CH4排放,而C+处理可观测到CH4排放;C+处理的综合增温潜势显著高于CK处理(P<0.01);NO、N2O和N2排放量占这3种氮素气体排放总量的比重,在CK处理分别约为9%、35%和56%,在C+处理分别约为31%、50%和19%,处理间差异显著(P<0.01).由此表明,碳底物水平可显著改变所排放氮素气体的组成;对于旱地阶段硝态氮比较丰富的水稻土,避免在淹水前或淹水期间施用有机肥,有利于削减温室气体排放.     

Degradation of dibromophenols by UV irradiation

We examined the degradation of dibromophenols （DBPs）, i.e. 2,4-DBP, 2,6-DBP and 3,5-DBP by ultraviolet （UV） irradiation and estimated the relationship between degradability and molecular orbital properties of each dibromopbenol. The removal of DBPs under a UV lamp system was successfully performed in an aqueous solution. After 5 min of irradiation, the initial DBPs concentration of 20 mg/L was decreased to below 1 mg/L, and about 60% of bromide ion was released. A decrease in the concentration of dissolved organic carbon （DOC） suggested the mineralization of DBPs, The mineralization may occur after release of bromide ions because the decrease of DOC was slower than the release of bromide ions. The degradability of 3,5-DBP was slightly lower than 2,6-DBP and 2,4-DBE Molecular orbital calculation suggested that the electrophilic frontier density and the highest occupied molecular orbital （HOMO） energy may be related to the degradability of DBPs.     

DMDF电控单体泵柴油机结合简单后处理装置实现国V排放的研究

在一台原机为满足国Ⅲ排放法规的增压中冷电控单体泵四缸发动机上采用柴油/甲醇双燃料（DMDF）燃烧方式,结合废气再循环（EGR）技术及不同后处理装置进行台架试验.结果表明：加装DMDF系统并经过精细标定,在不添加任何后处理器的情况下,仅结合EGR,氮氧化物（NO_x）和颗粒物（PM）的排放即可满足国V规定法规,但总碳氢化合物（THC）和一氧化碳（CO）排放高于法规限值;增加采用氧化催化转化器（DOC）或DOC+颗粒氧化催化转化器（POC）简单的后处理装置可以使电控单体泵DMDF发动机排放全面满足国V排放标准要求.其中,仅采用DOC的方式,THC和CO十三点加权比排放与后处理之前相比的降幅可分别达98.0%和99.8%,且分别仅为国V限值的35.2%和2.4%,采用DOC+POC的方式,HC和CO十三点比排放较原机的降幅分别达99.2%和99.9%,且分别仅为国V限值的13.5%和1.2%.     

雨水中碳丰度季节性特征及对酸雨形成的贡献

针对广州市连续1 a内降雨展开碳丰度的研究,通过对雨水中总有机碳(TOC)、可溶性有机碳(DOC)、颗粒物有机碳(POC)和颗粒物元素碳(PEC)的测定,进一步探讨雨水中碳丰度的季节性特征及其对酸雨形成的贡献作用.结果表明,TOC年均含量7.10 mg/L,DOC年均含量3.58 mg/L,POC年均含量3.60 mg/L,PEC年均含量O.72 mg/L,证明广州市污染物排放对降雨影响较严重.雨水中碳丰度具有一定季节性特征,TOC和DOC含量春季最高,夏季较低,表明广州市春季的总污染物排放量相对大于其它季节;POC对TOC的贡献率夏季要明显高于其它季节,说明固体颗粒物的排放量在夏季达到最高;干季POC相对含量要明显高于湿季,表明由机动车尾气排放导致的有机污染物排放量在秋冬季节要明显高于其它季节.TOC、DOC含量与pH值具有一定负相关性.这些特征从碳丰度角度证明机动车尾气等有机污染物排放对酸雨形成有一定的贡献作用.     

黄海、东海溶解有机碳的分布特征

研究了2007年秋季黄海、东海海域溶解有机碳(DOG)的空间分布情况.结果表明,该海域DOC的浓度范围为0.44～12.03 mg/L,平均浓度为(0.99±0.80)mg/L,其平面分布呈现近岸高、远岸低的特征,垂直方向上除了底层外随着深度增加DOC的浓度降低.位于南黄海中部的03断面,DOC的分布整体上比较均匀,断...     

树皮支持的厌氧生物法去除地下水中的高氯酸盐

通过批实验,考察了树皮作为固体碳源和反应介质去除地下水中高氯酸盐(ClO4-)的可行性,研究了树皮用量、温度、ClO4-污染负荷等因素对高氯酸盐去除效果的影响.结果表明,相比玉米芯、红薯及马铃薯,树皮可与PRMs结合高效去除地下水中的ClO4-,可被微生物利用的DOC是影响ClO4-去除效果的制约因素.以树皮为固体碳源,降解10 mg ClO4-需要耗用35～40 mg DOC;当树皮用量增至3∶500时,高氯酸盐的去除速率约比1∶500时提高3倍;若将树皮用量提高至大于5∶500,不能明显提高ClO4-的去除速率.当温度为(38±1)℃时,ClO4-的表观速率常数最大[1.365 mg.(L.d)-1],表观活化能Ea为31.08 kJ·mol-1.树皮支持的厌氧生物法对水质具有良好的抗冲击性,ClO4-的污染负荷较高时,未造成底物抑制作用.     

Impact of Lime and Ash Applications on Soil Solution Chemistry of an Acidified Podzolic Soil

Soil solution samples were taken from two sites (Horröd and Hasslöv) in the south part of Sweden to evaluate how soil solution chemistry responded to different treatmentswith dolomite and wood ash. At Horröd, samples were taken four years after application of wood ash, 4.28 ton ha^-1 and dolomite, 3.25 ton ha^-1. At Hasslöv dolomite, 3.45 ton ha^-1 and 8.75 ton ha^-1 was applied and samples were taken 15 yr later. It was found that treatment with dolomite at one site (Hasslöv) resulted in higher pH values (<2 pH units) and higher nitrification. It was also found at this site that the total Al and the inorganic Al concentrations decreased with dolomite treatment. The Ca, Mg, DOC, Fe, SO₄ ^2- and Cl^- concentrations, mainly in the topsoil, were found to be higher at both sites, following dolomite treatment; Ca and Mg concentrations were 2–8 times higher (<820 M) than in controls (<70 M). Wood ash was found to have less impact. The PO₄ concentration in the O2 horizon at Hasslöv decreased due to dolomite-treatment. ANOVA (Analyse of Variance) and PLS (Partial Least Square) were used to evaluate the data from the two sites.     

贵金属和助剂负载量对柴油公交车CDPF颗粒净化性能的影响

为研究CDPF(催化型颗粒捕集器)贵金属和助剂负载量对柴油公交车颗粒排放特性的影响,对一台满足国Ⅲ排放法规的柴油公交车进行改造,加装4种不同后处理装置,并进行道路实车排放试验.结果表明,CDPF贵金属负载量越高,排气颗粒数量浓度越低,在中高车速下尤为明显(60 km·h-1车速下贵金属负载量增加5 g·ft-3,颗粒排放总数降低70.8%).贵金属负载量对排放颗粒物中核态颗粒的影响大于聚集态颗粒.在保证对排气颗粒的净化效果的前提下,在CDPF中添加适量镧系助剂,可使贵金属和助剂负载量大幅降低.不同后处理方案对加速工况不敏感,净化效果差异较小,但减速工况,各方案对颗粒的净化效果差异较大.     

青海湖老碳效应的时空变化初步研究

本文通过对青海湖周边的湖水和河流DOC、DIC浓度、~(14)C浓度,以及1F孔不同深度13个碳酸盐的~(14)C年代分析,厘清青海湖老碳效应空间分布情况。研究表明:在空间上,青海湖DIC和DOC的~(14)C的老碳各条河流分布极不均匀,南边的老碳效应明显比北边小,河流的老碳明显比湖水偏老,引起青海湖沉积物老碳效应的原因极有可能是由于北边主要河流将流域内的老碳输入湖区引起,并非由于湖水和大气的交换不畅引起的碳库效应。在时间尺度上,碳酸盐~(14)C的老碳平均值比有机碳的~(14)C老碳平均值偏老。由于入湖物质的变化,在全新世前,有机碳和碳酸盐的老碳比全新世后偏老。