芦苇植株对湿地温室气体排放的影响及其日变化特征

利用静态箱-气相色谱法对夏季(7月、8月和9月)长江河口湿地芦苇植被CO_2、CH_4和N_2O的叶面通量、茎秆扩散速率以及沉积物通量的日变化进行研究。结果显示,通过芦苇叶片排放的N_2O与CH_4的量分别为2.99μg/(m~2·h)和15.36μg/(m~2·h),CO_2则呈现白天吸收(-120.86 mg/(m~2·h))、夜间排放(69.39 mg/(m~2·h))的特点。芦苇茎秆N_2O、CH_4和CO_2平均扩散速率分别为1.96μg/h、142.45μg/h和10.69 mg/h,沉积物平均排放通量为N_2O 8.18μg/(m~2·h)、CH_41.58 mg/(m~2·h)、CO_2169.66 mg/(m~2·h)。芦苇茎秆和沉积物界面CH_4和CO_2的排放均呈现出明显的"单峰型"昼夜变化规律,其排放峰值集中在日照及温度最高的9:00至15:00。芦苇植株是影响温室气体排放变化的因素之一。芦苇植株在光合作用下吸收CO_2并促进CH_4的排放,而芦苇发达的根系及茎秆是温室气体排放的主要途径。同时,Pearson相关性分析表明温度对芦苇群落CH_4和NO2的排放影响显著,但与CO_2通量的相关性不明显。土壤氧化还原电位对3种气体的排放均有显著影响。     

2003年夏秋季大气环流异常对西北地区降水的影响

根据2003年6～10月西北地区118站逐日降水资料,对该地区、该时段的大气环流及其对该地区降水的影响进行了分析研究.     

再生水补给城市河湖水生态系统构建及管护技术体系研究应用—以圆明园为例

提出了"再生水水源补给城市河湖水生态系统构建及管护技术体系",并在圆明园开展了推广应用,设计建设了近70 hm2再生水水源补给城市河湖水生态系统构建及管护示范区.结果表明,该技术可有效改善水体景观、水质及水生态状况:浊度明显降低,示范区浊度大多小于3NTU(饮用水浊度国家标准1NTU),感官效果明显优于修复前;总磷平均...     

再生水补给型景观水体微生物健康风险评价——以圆明园为例

再生水作为景观水体的非常规补给水源被全球各个国家广泛使用,而其内病原微生物的存在可能会通过不同传输途径对人体健康产生一定的威胁.因此,本文以粪大肠菌群（Fecal Coliform,FC）、大肠杆菌（Escherichia coli,EC）、肠球菌（Enterococcus,ENT）为研究对象,系统调查了圆明园景观水体中这3种指示微生物的污染特征,并运用定量微生物风险评价模型（Quantitative Microbial Risk Assessment,QMRA）量化了其对人体健康造成的潜在风险.研究结果显示,沿着园区内水体的流动方向,3种指示菌的浓度与入水时相比均出现了明显的增长,其中ENT和FC浓度最高值分别达到了入水时的14.3倍和17.6倍,增长情况最为明显.采用不同剂量-A反应方程表征的FC、EC、ENT单次暴露的健康风险值皆低于1.7×10^-2,处于风险可接受的范围;在年健康风险方面,职业人群的年健康风险远高于非职业人群;经过人工湿地工程的生态修复区域能够显著削减指示微生物浓度,同时在一定程度上降低病原微生物带来的健康风险,因此扩大生态修复范围可以进一步降低风险.     

Concentrations of (137)Cs in summer pasture plants that reindeer feed on in the reindeer management area of Finland

Samples of summer pasture plants that reindeer feed on were collected in order to study ¹³⁷Cs concentrations in different plant species and in species nested in certain site types, and to study the regional distribution of ¹³⁷Cs in the Finnish reindeer management area. Plant species were categorized by the site types of mineral soil forest (xeric heath forest and mesic heath forest) and peatland. A third category called ’other plant species’ included plants with various site types, poorly determined species and species with poor statistics. The ¹³⁷Cs concentrations in different site types differed significantly. The mean ¹³⁷Cs concentrations of the whole reindeer management area in the xeric heath forest plant species was 44 ± 27 Bq/kg dw, in the mesic heath forest plant species 75 ± 59 Bq/kg dw and in the peatland plant species 219 ± 150 Bq/kg dw. The peatland species uptake ¹³⁷Cs more efficiently than plant species of mineral soil forests. A particularly efficient collector of ¹³⁷Cs was Trichophorum sp. It is suggested that Trichophorum sp. could be used as an indicator species for reindeer summer fodder plants. The highest concentrations of ¹³⁷Cs were found in Southern Lapland and the lowest in Northern Lapland. Today, the concentrations of ¹³⁷Cs in summer pasture plants that reindeer feed on in Finland are at such a level that there is no need to avoid any plant species. In the case of future nuclear fallout, reindeer grazing in peatlands would increase concentrations of ¹³⁷Cs in reindeer meat.     

Drought-induced sulphate release from a wetland in south-central Ontario

Increased sulphate (SO₄) export from wetlands following summer droughts in central Ontario, Canada has been associated with the delayed chemical recovery of downstream surface waters following decreased sulphur (S) emissions. Prolonged summer droughts result in a decrease or cessation of stream flow, declines in wetland water table level and oxidation of reduced S compounds to SO₄, which is subsequently flushed into drainage streams when stream flow resumes. Sulphate input-output budget calculations (1983–1995 and 1999–2001) at a conifer Sphagnum swamp in the Plastic Lake catchment, indicate that SO₄ is retained in most years but is exported on a net basis following particularly severe summer droughts that result in the cessation of stream flow for more than 54 days (95% CI: 41–72 days). Hindcast calculations using long-term (1916–2000) stream discharge records from a nearby station indicate that while droughts occurred frequently in south-central Ontario over the past 85 years, sufficiently dry conditions to cause net SO₄ export occurred in only18 of the past 85 years, and indicate a cumulative positive SO₄ balance for the swamp (i.e. net SO₄ retention). Furthermore, the S pool at the Plastic Lake swamp has been estimated to be ∼1500 kg S/ha in the upper 40 cm peat layer, which is large compared to the amount of net SO₄ export that occurs even in years with particularly dry summers (e.g. −43 kg S/ha in 1987/88). Together, these data suggest that the wetland S pool at Plastic Lake has not been depleted by previous droughts and will continue to sustain episodic drought-related SO₄ export for the foreseeable future.     

Seasonal to sub-seasonal variations of the Asian Tropopause Aerosols Layer affected by the deep convection, surface pollutants and precipitation

The Asian Tropopause Aerosols Layer (ATAL) refers to an accumulation of aerosols in the upper troposphere and lower stratosphere during boreal summer over Asia, which has a fundamental impact on the monsoon system and climate change. In this study, we primarily analyze the seasonal to sub-seasonal variations of the ATAL and the factors potentially influencing those variations based on MERRA2 reanalysis. The ability of the reanalysis to reproduce the ATAL is well validated by CALIPSO observations from May to October 2016. The results reveal that the ATAL has a synchronous spatiotemporal pattern with the development and movement of the Asian Summer Monsoon. Significant enhancement of ATAL intensity is found during the prevailing monsoon period of July–August, with two maxima centered over South Asia and the Arabian Peninsula. Owing to the fluctuations of deep convection, the ATAL shows an episodic variation on a timescale of 7–12 days. Attribution analysis indicates that deep convection dominates the variability of the ATAL with a contribution of 62.7%, followed by a contribution of 36.6% from surface pollutants. The impact of precipitation is limited. The ATAL further shows a clear diurnal variation: the peak of ATAL intensity occurs from 17:30 to 23:30 local time (LT), when the deep convection becomes strongest; the minimum ATAL intensity occurs around 8:30 LT owing to the weakened deep convection and photochemical reactions in clouds. The aerosol components of the ATAL show different spatiotemporal patterns and imply that black carbon and organic carbon come mainly from India, whereas sulfate comes mainly from China during the prevailing monsoon period.     

Training future experts in “biodiversity and ecosystem services”: a progress report

Biodiversity is essential for multiple aspects of human life and well-being, but many current assessments of the functioning of biodiversity and ecosystems, understanding of risks posed by environmental change and the best practice of their management of ecosystems are lacking a unified scientific and conceptual basis. Methods such as scenario analysis, and terms such as ecosystem services, are widely used, but their meaning is understood in many different ways depending on context, user needs and experience of researchers. In order to advance the conceptual basis for ecosystem analysis and management in a rapidly changing world, as well as the ability of young scientists to reflect upon these concepts, we have organised five 2-week-long summer schools in Peyresq, a remote village in the Southern French Alps. In total 173 participants have worked intensively with 69 experienced researchers and a team of conveners and tutors in order to discuss a broad range of views on topics on ecosystem analysis and functioning. Topics ranged from conditions of and threats to various ecosystems due to environmental change, models and scenarios for assessment, stakeholder perceptions and needs for information, to the social and economic contexts for biodiversity. We report our experience from these schools, present the training concept which has emerged from them and suggest lines of further development.

蚌埠市夏季大气细颗粒物在线源解析

为了解蚌埠市环境空气中PM_(2.5)的来源,于2017年8月18日—9月18日,在百货大楼和高新区站点,利用单颗粒物气溶胶飞行时间质谱仪开展PM_(2.5)在线源解析。结果表明,百货大楼点位ρ(PM_(2.5))高于高新区点位,轻度污染比例(4.2%)明显高于高新区点位(0.8%),出现了中度污染(0.3%);SPAMS的PM_(2.5)质谱图显示百货大楼点位PM_(2.5)中K~+、Na~+特征明显,高新区点位HSO_4~-、NO_3~-、NO_2~-等无机信号较为明显;2个点位NO_3~-、NO_2~-、NH_4~+离子颗粒数占总颗粒数的百分比明显较高,且高新区点位NO_3~-、HSO_4~-离子数占比要明显高于百货大楼点位,燃料燃烧、工业工艺源、农田氮肥施用是其主要的人为污染源;2个点位PM_(2.5)成分主要为元素碳,分别占比42.4%,40.6%;污染时段,ρ(PM_(2.5))快速上升,除受本地机动车尾气源和燃煤源累积影响外,百货大楼点位扬尘源排放增加,高新区点位扬尘源和工业工艺排放源增加;2个点位机动车尾气源均为首要污染源,分别占比29.5%和30.9%,其次为燃煤源(24.3%和24.7%),扬尘源占比分别为22.9%和20.8%。     

香港石岗——小溪磷、氮浓度的变化及影响因素

研究香港石岗一条小溪在1991年夏雨季溪流中氮和磷的浓度及其在暴雨过程中的变化。结果表明:在基本径流中的氮、磷浓度很低,而在暴雨期间,溪流的氮、磷浓度随水文过程线的上升而增加,但随着暴雨时间的延长,氮、磷浓度随水文过程线增加的趋势会逐渐减弱。与小溪下游汇入的河流比较来看,人为活动对河流的氮、磷浓度影响较大,如不加以控制,将会引起水质恶化。