A novel approach to studying the effects of temperature on soil biogeochemistry using a thermal gradient bar

The temperature dependence of chemical reaction rates and microbial metabolism mean that temperature is a key factor regulating soil trace gas emissions and hydrochemistry. Here we evaluated a novel approach for studying the thermal response of soils, by examining the effects of temperature on gas emissions and hydrochemistry in (a) peat and (b) soil from a Sitka spruce plantation. A thermal gradient was applied along an aluminium bar, allowing soil to be incubated contemporaneously from 2 to 18 °C. The approach demonstrated clear differences in the biogeochemical responses of the two soil types to warming. The peat showed no significant emission of CH₄ at temperatures below 6 °C, while above 6 °C, a marked increase in the rate of release was apparent up to 15 °C (Q₁₀ = 2.5) with emissions being similar between 15 and 18 °C. Conversely, CH₄ emissions from the forest soil did not respond to warming. Nitrate availability in the peat decreased by 90% between 2 and 18 °C (P < 0.01), whereas concentrations in the forest soil did not respond. Sulphate availability in the peat decreased significantly with warming (60%, P < 0.01), while the forest soil showed the opposite response (a 30% increase, P < 0.01). Conventionally, thermal responses are studied by incubating individual soil samples at different temperatures, involving lengthy preparation and facilities to incubate samples at different temperatures simultaneously. Data collected on a given thermal response is usually limited and thus interpolated or extrapolated. The thermal gradient method overcomes these problems, is simple and flexible, and can be adapted for a wide range of sample types (not confined to soil). Such apparatus may prove useful in the optimization of management practices to mitigate the effects of climate change, as thermal responses will differ depending on land use and soil type.     

Carbon storage by urban tree cultivars, in roots and above-ground

Urban trees can favorably affect factors underlying global warming by storing carbon and by reducing energy needs for cooling and heating buildings. To estimate carbon stored in roots and above-ground portions of trees, data was collected consisting of whole tree sampling of Amelanchier, Malus, Pyrus, and Syringa cultivars. Roots were excavated using an Air-Spade^™. Regression analysis resulted in two equations for predicting total carbon storage based on height and diameter of trees up to 20 cm dbh: Y = 0.05836 (dbh²) for root carbon storage, and Y = 0.0305 (dbh² × h)^0.9499 for above-ground carbon storage, explaining 97% and 96% of the variation, respectively. Average carbon stored in roots of various cultivars ranged from 0.3 to 1.0 kg for smaller trees, those 3.8 to 6.4 cm dbh, to more than 10.4 kg for trees 14.0 cm to 19.7 cm dbh. Average total carbon stored by cultivars ranged from 1.7 to 3.6 kg for trees less than 6.4 cm dbh to 54.5 kg for trees larger than 14.0 cm. The data from these equations apply mainly to trees in nurseries and recently transplanted trees. Comparisons showed that above-ground estimates from previous studies using a sampling technique overestimated values obtained from actual above-ground weights.     

全球气候暖干化对秦岭南北河流径流泥沙的影响研究

以秦岭南侧汉江和北侧渭河多年的径流泥沙观测资料，分析了全球气候暖干化对秦岭南北径流泥沙的变化。分析指出在80年代后，由于全球气候变化的影响，秦岭南北河流年均径流量均减少，与1935－1980年相比，汉江河流年均径流量减少1.9%，渭河河流年均径流量减少27.4%；同时汉江河流泥沙含量明显减少，但渭河河流泥沙含量呈增加趋势，是汉江河流泥沙含量133倍，表明了秦岭南北两侧在全球气候暖干化表现出明显的区域响应性。     

菌株Bacillus sp.CLb芽孢漆酶对染料、模拟染料废水脱色的研究

[目的]研究芽孢杆菌菌株CLb的芽孢漆酶在介体的互作下对不同类型的染料及模拟染料废水的脱色效果。[方法]制备芽孢粗酶液,在介体的互作下,测定具有漆酶活性的粗酶液对活性亮蓝、活性黑、靛红和结晶紫的脱色效果,筛选出对染料脱色有促进作用的漆酶介体,并且研究芽孢漆酶在不同pH条件下对染料和模拟染料废水脱色的影响。[结果]菌株CLb的芽孢漆酶在无介体参与下只能使活性亮蓝和结晶紫脱色。在介体乙酰丁香酮（ACE）的作用下,芽孢漆酶对4种染料的脱色率均超过70%。在pH 7.0条件下,芽孢漆酶浓度为44.74 U/L和介体ACE浓度为1 mmol/L时对模拟染料废水的脱色效果最好,6 h脱色率超过80%。在介体乙酰丁香酮存在,pH 7.0的条件下,菌株CLb的芽孢漆酶对合成染料脱色效率高于pH 9.0时的脱色率。[结论]在介体乙酰丁香酮的存在下,芽孢漆酶对染料和模拟染料废水均具有较好的脱色效果。     

放牧和模拟降水对短花针茅荒漠草原植物功能群多样性的影响

为探究放牧和降水变化对植物功能群的影响,本文以内蒙古短花针茅(Stipa breviflora)荒漠草原为研究对象,开展了野外控制试验。试验设置围封和适度放牧,分别进行模拟降水处理(减少降水量50%、自然降水、增加降水量50%、增加降水量100%),并在每年8月观测植物群落组成。结果表明：减水会降低植物功能群多样性、生物量和物种数量,增水有利于植物功能群多样性的提高。多年生丛生禾草多样性随降水量的增加而升高。同时,对降水梯度和功能群多样性进行拟合分析发现,降水量低于年降水量16%则不利于除灌木、半灌木外其他功能群植物的生长。围封草地增水67%～79%时,功能群的Simpson指数、Shannon-Wiener指数、Pielou指数值均较高,功能群多样性较高;由于放牧提高了植物的水分利用效率,放牧地各指数在增水26%～50%时较高,功能群多样性较高。综上,适度的放牧及水分补充有利于提高植物功能群多样性。     

基于模拟退火算法的减速器多目标优化设计

提出了采用模拟退火算法进行减速器参数的全局优化的方法;针对斜齿轮减速器优化设计的多参数、多目标、多约束特点,建立了多目标优化数学模型;应用层次分析法计算了各目标权重。仿真结果表明,优化参数比原设计参数的优化解要好,说明模拟退火算法用于减速器优化设计是有效、可行的。     

网吧火灾自动报警系统的上位机软件设计

介绍了一个采用VisualBasic6．0编写的、在网吧中实现自动报警系统的上位机软件。系统经过了测试和实际运行，工作稳定可靠，可以实现自动报警功能，具有较高的应用和推广价值。     

不同工艺对牛粪堆沤肥过程气体排放的影响

堆沤肥是中国畜禽粪便处理利用的最主要方式。为探究不同堆沤肥方式对温室气体和氨气排放规律和温室效应,在北京市密云区开展了为期71d的堆沤肥试验,以牛粪和玉米秸秆为原料,分析了静态堆沤 (T1)、堆沤+翻抛 (T2)、堆沤+覆膜 (T3)、翻抛+覆膜 (T4)等4种方式对堆沤肥过程中腐熟度、温室气体和氨气等指标的影响。结果表明,4个处理的种子发芽指数分别达到131.33%、134.49%、108.76%和136.24%,均满足堆肥产品的腐熟度要求（≥70%）。翻抛有利于CO₂、N₂O和NH₃的排放,而覆膜抑制了N₂O的生成,T2处理的增温潜势最高,T3处理的增温潜势最低,较对照组T1处理减排20.14%。因此,T3处理在能够保证堆肥产品的腐熟度要求的前提下,还可有效减少增温潜势。该研究可为中小养殖场户堆沤肥的工艺优化实践提供技术指导。     

气候变化对陇东冬小麦生态影响特征研究

对黄土高原比较有典型代表性的残塬"董志塬"的变暖及冬小麦生态响应特征进行研究,发现"董志塬"近35 a来年平均增温线性趋势达0.0505℃,增温表现出平均气温、最高气温、最低气温同时上升,且冬春季增温速度最快,秋季次之,夏季增温最平缓;增温对冬小麦的生态影响主要体现在全生育期(线性趋势0.91 d/a)、越冬期(线性趋势0.85 d/a)显著缩短,春季发育期普遍提前(返青期以0.57 d/a的线性趋势提前,拔节期以0.42 d/a的线性趋势提前,成熟期以0.48 d/a的线性趋势提前),而春季各发育期间间隔日数并未出现缩短的趋势.认为气候变暖对当地农业生产有利有弊,气候变暖,尤其冬春气温显著升高将导致越冬期土壤水分损耗增大,春旱加剧,不利于春季农业生产;另一方面冬小麦全生育期缩短,成熟期提前,能有效提高复种指数和土地利用率.