提高空气中氮氧化物监测质量的方法

大气监测质量保证是一项室内外密切配合的系统工程，每一个步骤对测值都有影响。为提高大气中氮氧化物测定值的准确性，我站采用双管平行对比采样，在长期实践中总结出从室外采样到室内样品分析质量保证方法和经验，以保证大气中氮氧化物测值准确可靠。     

Estuarine management strategies and the predictability of ecosystem changes

The Dutch Delta Region (S-W Netherlands) originally consisted of interconnected estuaries, interfacing the rivers Rhine, Meuse and Schelde with the North Sea. The ecosystems were immature, with physical rather than biological control of population dynamics. Main functions were shipping and shellfisheries. An emergent function of the interconnected estuaries was the buffering and upgrading of river-borne substances before they entered the sea. Execution of the Delta Project in the period 1960–1986 resulted in isolation of several water systems disconnected from rivers and sea, and loss of gradients within these systems. Population dynamics were now controlled by chemical and biological rather than physical factors. Vulnerability to external perturbation increased. These changes also affected the buffering capacity, i.e. reduced the utility of the area as stabiliser of the geosystem. Recreational use and appreciation of natural values increased, potentially conflicting with shipping and shellfisheries. Retrospective analysis of the environmental policy and management revealed three consecutive strategies in the Delta Project. 1. Reactive one-issue management, focusing on safety against flooding only. This strategy aimed at complete closure of the estuaries thus transforming them into fresh water lakes. It has destroyed feed-backs and buffering between coastal and inland waters. This strategy has not promoted sustainable development and has increased the vulnerability of the area to future catastrophes. 2. Protective bio-ecological management focused on the preservation of existing values of landscape and environment, and resulted in the maintenance of saline conditions and preservation of marshes by shore protection measures. The drawback of this passive orientation to existing values ?where they are now? is the necessity of continuous intensive care because the natural adaptive ability is not being restored. 3. Constructive geo-ecological management is based on understanding functional properties within and between ecosystems as integrated elements of the landscape structure. This strategy aims at environmental protection, restoration and development of values ?where they must be?. Re-establishment of gradients by e.g. re-introducing tidal influence and by restoring salt marshes should contribute to sustainable development.     

Effects of Buffer-Strip Retention and Clearcutting on Land Snails in Boreal Riparian Forests

Abstract:  We investigated the short-term effects of forest clearcutting on land snails (terrestrial gastropods) in 15 forest stands along small streams in Sweden. Two different silvicultural treatments were applied at each site: clearcutting across the stream channel and buffer strips 10 m wide on each side of the stream. Additionally, we studied 10 reference sites in unlogged riparian forests along similar-sized streams. All sites were studied before logging and then 2.5 years after logging. After clearcutting the number of individuals in a 0.5-m² sample from each site decreased on average from 107 to 87, and the mean number of species per sample decreased from 9.9 to 7.7. Most species were negatively affected, but there were also clear differences in sensitivity. There were correlations between species survival and ground moisture. At the wettest clearcut sites with an almost intact bryophyte cover, the land snails were unaffected by clearcutting. This result suggests that wet or moist forest floors can serve as refugia even at very small spatial scales (e.g., shallow hollows, crevices). If this is an important mechanism, the spatial distribution of small habitats could be important for the long-term survival of the snail fauna or other small, dispersal-limited organisms at clearcut sites. In the buffer strips, the number of individuals decreased but not the number of species, indicating that buffer-strip retention is a good practice for protecting land snails in riparian forests. The varying effectiveness of the buffer strip could partly be explained by the proportion of the remaining basal area, emphasizing that buffer strips could be even more effective if efforts are made to avoid heavy damage by windthrows.     

缺氧-好氧连续流亚硝化颗粒污泥反应器的启动及稳定运行

在室温下(17~19℃),通过接种成熟的亚硝化颗粒污泥于缺氧-好氧连续流反应器中,研究连续流亚硝化颗粒污泥的启动及稳定运行.结果表明,在启动阶段,颗粒污泥系统的亚硝态氮积累率(NAR)平均超过95%,成功启动了缺氧-好氧连续流亚硝化颗粒污泥系统.将好氧区溶解氧(DO)由(3±0.2) mg·L~(-1)提高到(4.5±0.2) mg·L~(-1),探究DO对于该连续流系统的影响.结果表明,在较高DO下,缺氧-好氧连续流亚硝化颗粒污泥系统仍能保持良好的亚硝化性能,平均NAR大于95%.另外,通过改变进水的水力停留时间(HRT),探究HRT对于该连续流系统的影响.较短的水力停留时间(8.4 h)会加快污泥颗粒在系统中的循环,使破碎的颗粒污泥不能及时重组,致使污泥颗粒沉淀性变差,造成污泥颗粒的流失.HRT增加到12.2h时,颗粒污泥系统得到了恢复,并且可以稳定运行.在运行末(166 d),氨氮去除率和NAR分别为86.7%和96.2%.     

ABR-MBR反硝化除磷工艺的启动及稳定运行

以低C/N值生活污水为处理对象,重点考察了以厌氧/缺氧(A/A)运行的ABR耦合好氧MBR系统启动过程中脱氮除磷特性及系统长期运行的稳定性.结果表明,控制ABR容积负荷(VLR)为0. 8 kg·(m3·d)-1,污泥回流比为80%,硝化液回流比从150%逐步提升稳定至300%,反硝化除磷功能区污泥停留时间(sludge retention time,SRT)为25 d,MBR溶解氧(DO)为1～2 mg·L~(-1),温度为30℃±2℃,于46 d成功富集了反硝化聚磷菌(denitrifying phosphorus bacteria,DPBs),净释磷量为20. 56 mg·L~(-1),净吸磷量达到27. 74 mg·L~(-1),批次实验表明约84. 8%的聚磷菌(PAOs)能够利用NO-3-N作为电子受体进行反硝化除磷.启动成功后稳定运行50 d,对COD、NH+4-N、TN和PO_4~(3-)-P的平均去除率分别为91. 8%、99. 0%、71. 5%和94. 2%,系统缺氧反硝化除磷去除1 mg·L~(-1)的PO_4~(3-)-P,同步消耗约0. 83 mg·L~(-1)的NO-3-N,满足同步脱氮除磷的要求.     

Functional traits of poplar leaves and fine roots responses to ozone pollution under soil nitrogen addition

Concurrent ground-level ozone（O₃） pollution and anthropogenic nitrogen（N） deposition can markedly influence dynamics and productivity in forests.Most studies evaluating the functional traits responses of rapid-turnover organs to O₃ have specifically examined leaves,despite fine roots are another major source of soil carbon and nutrient input in forest ecosystems.How elevated O₃ levels impact fine root biomass and biochemistry remains to be resolved.This study was...     

氮污染在地下水中迁移、转化规律的研究

氮及其化合物是目前地表水和地下水的一个重要污染源。本文选取不同土质作为渗透介质,通过室内土柱实验,得出不同深度的土层对不同浓度的NH4+-N和NO3--N的去除率,及不同土层对同一浓度NH4+-N和NO3--N的去除率。同时得出,无论哪种地下土质对氨和硝酸盐的阻截能力都较弱,对突发污染恢复力也同样较弱。     

好氧颗粒污泥降解邻苯二甲酸二甲酯的影响因素研究

本文研究了好氧颗粒污泥系统中,温度、pH、曝气强度、邻苯二酸(Phthalic Acid,PA)及氨氮(NH3-N)对邻苯二甲酸二甲酯(Dimethyl Phthahte,DMP)降解效果的影响,结果表明:好氧颗粒污泥降解DMP的最佳温度、最佳PH值范围、最佳曝气强度分别为25℃～45℃、7.0 ～9.0、1.38 cm/s.当PA浓度为100 mg/L、300 mg/L,PA对DMP降解起促进作用;当PA浓度为500 mg/L、800 mg/L,PA对DMP降解起抑制作用.进水中50 mg/L的氨氮浓度对DMP降解的影响不大.本研究中采用的19种运行工况条件中,除曝气强度为0.33 cm/s以外,其他18种运行工况条件下,当运行时间达到300 min时,DMP的浓度都小于1.0 mg/L,因此,当水力停留时间达到5h以上时,温度、pH、PA、氨氮对DMP降解速率的影响基本上可以忽略不计.     

A preliminary model of nutrient cycling in sediments of a Mediterranean lagoon

A model of nitrogen and phosphorus cycles in the sediment of a lagoon has been developed. This model was applied to the Thau lagoon (southern France). Sediment was sliced in three layers to reproduce the oxygen profile, which is simulated within the model. Following an equilibrium hypothesis, the model was calibrated against field data. State variables and fluxes were estimated in the sediment and across the sediment-water interface. A Monte Carlo sensitivity analysis was performed to determine the most sensitive parameters and sediment state variables. A dynamic simulation with varying oxygen concentrations then showed the influence of anoxia on the phosphorus and nitrogen fluxes between water and sediment.