Effects of collector types in sampling of atmospheric depositional fluxes

The bulk gross alpha, gross beta and ⁷Be depositional fluxes were measured in Málaga (36.7°N, 4.5°W), a coastal Mediterranean station in the south of Spain for one whole year. In order to quantify the local variation of deposition rates, we have analysed the monthly results from two deposition collectors: a “pot “collector with a continuous water-covered surface and a “funnel” collector. In general, the alpha and beta depositional fluxes from the funnel collector were approximately two times lower than the pot collector. Whereas for the cosmogenic ⁷Be, the depositional flux of ⁷Be from funnel collector was also approximately two times lower than the pot collector. A good correlation of the depositional flux of ⁷Be has been obtained from both collectors.     

Comparison of seasonal variations of ozone exposure and fluxes in a Mediterranean Holm oak forest between the exceptionally dry 2003 and the following year

Ozone and energy fluxes have been measured using the eddy covariance technique, from June to December 2004 in Castelporziano near Rome (Italy), and compared to similar measurements made in the previous year. The studied ecosystem consisted in a typical Mediterranean Holm oak forest. Stomatal fluxes have been calculated using the resistance analogy and by inverting the Penmann-Monteith equation. Results showed that the average stomatal contribution accounts for 42.6% of the total fluxes. Non-stomatal deposition proved to be enhanced by increasing leaf wetness and air humidity during the autumnal months. From a comparison of the two years, it can be inferred that water supply is the most important limiting factor for ozone uptake and that prolonged droughts alter significantly the stomatal conductance, even 2 months after the soil water content is replenished. Ozone exposure, expressed as AOT40, behaves similarly to the cumulated stomatal flux in dry conditions whereas a different behaviour for the two indices appears in wet autumnal conditions. A difference also occurs between the two years.     

MBR的临界膜通量及其影响研究

采用通量阶梯式递增法测定了MBR的临界膜通量,研究了膜面气液两相流流速对临界膜通量影响,并考察次临界膜通量下MBR处理垃圾渗滤液的运行特性。试验结果表明,膜面气液两相流流速对临界膜通量影响较大,膜面气液两相流流速由0.9 m/s增至1.8 m/s,临界膜通量由12～14 L/(m²·h)增加至16～18 L/(m²·h),两者呈显著正相关关系,相关系数为0.997。次临界膜通量下运行时,膜污染包括不可逆污染和可逆污染2个阶段：不可逆污染阶段以凝胶层污染为主,占总量的72%,而可逆污染阶段以滤饼层形成的阻力为主,占总阻力的68.5%。     

基于改进混合遗传-支持向量机的CMF产水预测研究

将模拟退火思想和加速遗传特性相结合,改进选择策略和遗传算子,建立加速遗传模拟退火算法（AGSA）;基于支持向量机（SVM）的非线性回归和改进混合遗传算法的因子筛选,构造了支持向量机模型参数的自适应优化算法,提出连续微滤系统（CMF）产水预测模型;通过实测中试规模连续微滤系统产水量变化对模型进行验证,结果表明：该模型较好...     

Temporal signatures of advective versus diffusive radon transport at a geothermal zone in Central Nepal

Temporal variation of radon-222 concentration was studied at the Syabru-Bensi hot springs, located on the Main Central Thrust zone in Central Nepal. This site is characterized by several carbon dioxide discharges having maximum fluxes larger than 10 kg m⁻² d⁻¹. Radon concentration was monitored with autonomous Barasol™ probes between January 2008 and November 2009 in two small natural cavities with high CO₂ concentration and at six locations in the soil: four points having a high flux, and two background reference points. At the reference points, dominated by radon diffusion, radon concentration was stable from January to May, with mean values of 22 ± 6.9 and 37 ± 5.5 kBq m⁻³, but was affected by a large increase, of about a factor of 2 and 1.6, respectively, during the monsoon season from June to September. At the points dominated by CO₂ advection, by contrast, radon concentration showed higher mean values 39.0 ± 2.6 to 78 ± 1.4 kBq m⁻³, remarkably stable throughout the year with small long-term variation, including a possible modulation of period around 6 months. A significant difference between the diffusion dominated reference points and the advection-dominated points also emerged when studying the diurnal S₁ and semi-diurnal S₂ periodic components. At the advection-dominated points, radon concentration did not exhibit S₁ or S₂ components. At the reference points, however, the S₂ component, associated with barometric tide, could be identified during the dry season, but only when the probe was installed at shallow depth. The S₁ component, associated with thermal and possibly barometric diurnal forcing, was systematically observed, especially during monsoon season. The remarkable short-term and long-term temporal stability of the radon concentration at the advection-dominated points, which suggests a strong pressure source at depth, may be an important asset to detect possible temporal variations associated with the seismic cycle.     

上海城市草坪CO2排放通量特征及其影响因子

草坪是城市绿地系统的重要组成部分,为量化其在城市碳平衡中的作用,采用静态箱 气相色谱法对上海结缕草草坪CO2排放通量进行了研究。结果表明：CO2排放通量具有明显的日变化和季节变化特征,日变化表现为昼高夜低的特点,最大排放通量一般出现在正午前后,最小在清晨,最大日较差为1 1877 mg/（m2·h）（7月1日）,最小892 mg/（m²·h）（1月3日）。CO₂排放通量的季节变化呈单峰型,夏季7月最大,春秋季次之,冬季1月最小,与温度的季节变化一致。观测期间年平均CO2排放通量为6194 mg/（m2·h）。对上海城市结缕草草坪观测期间,温度是CO2排放通量变化的主要影响因素。研究成果不仅可为城市草坪碳排放提供基础数据,也可为城市碳循环研究和管理提供参考.     

广州城市污泥中重金属的含量、排放通量及农用风险评价

分析了广州市中心城区5个主要的污水处理厂污泥的基本理化性质和7种重金属(Cr、Cu、Mn、Ni、Pb、Cd和Zn)在不同雨期的浓度变化,估算了广州市污水处理厂污泥重金属的年排放通量,并对其污泥农用做了潜在风险评价。结果表明,各污水厂污泥均达到《城镇污水处理厂污染物排放标准》(GB 18918-2002)对重金属的排放要求,污泥的基本理化性质满足《城镇污水处理厂污泥处置农用泥质》(CJ/T309-2009)标准,沥滘、猎德、京溪和大坦沙污水厂的污泥重金属满足CJ/T309-2009要求,而西朗污水处理厂2013年12月采集的污泥中Cu和Cd未达标。通过估算,广州市污水处理厂污泥中Cr、Cu、Mn、Ni、Pb、Cd和Zn的年排放通量分别为16.1、18.8、90.3、5.9、7.9、0.2和48.3 t。通过Hakanson生态风险评估,污泥在农用过程中除西朗污水处理厂污泥重金属危害为中等风险,其他厂污泥属于低风险。     

A fluorometric method to determine rainfastness,volatilization and photostability of glyphosate from glass slides,after application of vision® with two adjuvants

Abstract

A fluorometric method was developed to quantify glyphosate loss from glass surfaces after exposure to the natural forest environment. The method was based on the principle of converting glyphosate into glycine, followed by the fluorogenic labeling with o‐phthalaldehyde. A fluorometer (with λ _Ex = 360 nm / λ_Em =430 nm) was used to quantify the derivatized fluorogenic compound. Response was linear over the concentration range of 143, 286, 572, 858 and 1144 μg of glyphosate (acid equivalent, AE) per mL of the diluted Vision® formulation. Three end‐use mixtures of Vision® were prepared, each at a concentration of 28.6 g AE/L, without and with two adjuvants, Ethomeen® T/25 at 4.5 mL/L and Silwet^® L‐77 at 1.5 mL/L. Several dilutions of the end‐use mixtures were applied on glass slides without and with the coating of cuticular wax extracted from trembling aspen foliage. The slides were left for 5 days in a forest opening to determine rainfastness, volatilization and photostability of glyphosate. The residues were quantified using the method developed. Three calibration curves were required because Silwet decreased the fluorometric response of glyphosate, whereas Ethomeen increased it. The minimum detection limit was 143 μg of glyphosate/mL. Glyphosate was resistant to volatilization and sunlight‐mediated degradation, regardless of the presence of wax coating or the adjuvants. About 64% of the applied glyphosate was washed off after a 9.6 mm rainfall when no adjuvant was present. Both adjuvants provided some amount of rain‐protection to glyphosate, but Silwet reduced the washoff to a greater extent (46%) than Ethomeen (55%).     

陆地生态系统CO_2与水热通量的研究进展

陆地生态系统CO2和水热通量研究,一直是全球气候变化研究的热点与难点问题。它对认识生态系统变化规律,预测全球气候变化趋势,评价生态系统的碳固定具有重要的科学意义。涡度相关法被认为是目前测定CO2、水热通量的最可靠方法。国外学者应用此方法解决了均匀下垫面假设下不同类型生态系统的CO2、水热通量的计算问题。在查阅前人研究成果的基础上,分析了陆地生态系统用涡度相关法在能量通量研究中的地位和重要性,评述了生态系统水热平衡的研究意义,总结了我国包括森林、草地、荒漠、农田等不同类型生态系统CO2、水热通量方面最新的研究进展,并对我国生态系统通量未来的研究策略及数据管理提出了建议和展望。