Soil moisture determines the effectiveness of two urease inhibitors to decrease N<Subscript>2</Subscript>O emission

Among the mitigation strategies to prevent nitrogen (N) losses from ureic fertilizers, urease inhibitors (UIs) have been demonstrated to promote high N use efficiency by reducing ammonia (NH₃) volatilization. In the last few years, some field experiments have also shown its effectiveness in reducing nitrous oxide (N₂O) losses from fertilized soils under conditions of low soil moisture. An incubation experiment was carried out with the aim of assessing the main biotic mechanisms behind N₂O emissions once that the UIs N-(n-butyl) thiophosphoric triamid (NBPT) and phenil phosphorodiamidate (PPDA) were applied with Urea (U) under different soil moisture conditions (40, 60 and 80 % water-filled pore space, WFPS). In the same study we tried to analyze to what extent soil WFPS regulates the effect of these inhibitors on N₂O emissions. The use of PPDA in our study allowed us to compare the effect of NBPT with that of another commercially available urease inhibitor, aiming to see if the results were inhibitor-specific or not. Based on the results from this experiment, a WFPS (i.e. 60 %) was chosen for a second study (i.e. mesocosm experiment) aiming to assess the efficiency of the UIs to indirectly affect N₂O emissions through influencing the pool of soil mineral N. The N₂O emissions at 40 % WFPS were almost negligible, being significantly lower from all fertilized treatments than that produced at 60 and 80 % WFPS. When compared to U alone, NBPT+U reduced the N₂O emissions at 60 % WFPS but had no effect at 80 % WFPS. The application of PPDA significantly increased the emissions with respect to U at 80 % WFPS whereas no significant effect was found at 60 %. At 80 % WFPS, denitrification was the main source of N₂O emissions for all treatments. In the mesocosm study, the application of NBPT+U was an effective strategy to reduce N₂O emissions (75 % reduction compared to U alone), due to a lower soil ammonium (NH₄ ⁺) content induced by the inhibitor. These results suggest that adequate management of the UI NBPT could provide, under certain soil conditions, an opportunity for mitigation of N₂O emissions from fertilized soils.     

Using activated biochar for greenhouse gas mitigation and industrial water treatment

This study explored the feasibility of using residual biomass to both mitigate greenhouse gas (GHG) emissions and remediate water contaminated by hydrocarbons. Using produced (process-affected) water from Canada’s oil sands operations as a case study, activated biochar (ACB) was found to have a higher affinity to organics than activated coal and removed 75 % of total organic carbon (TOC) from produced water in steam-assisted gravity drainage (SAGD) operations or 90 % of the TOC from synthetic tailings (ST) water sample. Up to 6 Tg dry biomass year^?1 would be required to treat the waters associated with the 93?×?10⁶-m³ of bitumen recovered per year. Landfilling the spent ACB and flaring any biogas produced were estimated to provide a greater GHG benefit than the combustion of the biochar + organics for heat to offset natural gas demand. Net costs for the ACB were about 13.84?$?m^?3 bitumen for SAGD operations and 1.76?$?m^?3 bitumen for mining operations. The values for mining operations justify further work to create a value chain that will integrate bioprocesses into the fossil fuel industry.     

CO<Subscript>2</Subscript>-fertilization and potential future terrestrial carbon uptake in India

There is huge knowledge gap in our understanding of many terrestrial carbon cycle processes. In this paper, we investigate the bounds on terrestrial carbon uptake over India that arises solely due to CO ₂ -fertilization. For this purpose, we use a terrestrial carbon cycle model and consider two extreme scenarios: unlimited CO₂-fertilization is allowed for the terrestrial vegetation with CO₂ concentration level at 735 ppm in one case, and CO₂-fertilization is capped at year 1975 levels for another simulation. Our simulations show that, under equilibrium conditions, modeled carbon stocks in natural potential vegetation increase by 17 Gt-C with unlimited fertilization for CO₂ levels and climate change corresponding to the end of 21st century but they decline by 5.5 Gt-C if fertilization is limited at 1975 levels of CO₂ concentration. The carbon stock changes are dominated by forests. The area covered by natural potential forests increases by about 36% in the unlimited fertilization case but decreases by 15% in the fertilization-capped case. Thus, the assumption regarding CO₂-fertilization has the potential to alter the sign of terrestrial carbon uptake over India. Our model simulations also imply that the maximum potential terrestrial sequestration over India, under equilibrium conditions and best case scenario of unlimited CO₂-fertilization, is only 18% of the 21st century SRES A2 scenarios emissions from India. The limited uptake potential of the natural potential vegetation suggests that reduction of CO₂ emissions and afforestation programs should be top priorities.     

Endogenous market structures in non-cooperative international emissions trading

The literature on cost-effective international emissions trading (IET) assumes exogenous market structures. This paper develops a game-theoretical model along with numerical simulations for the world economy in order to analyze the equilibrium market structures of an IET scheme. Countries’ decisions regarding the exercise of market power and their initial permit endowments are made non-cooperatively, being guided by their national self-interest. The theoretical results show that both price-influencing and price-taking countries choose an optimal permit endowment in light of their damage costs. Low-damage (high-damage) countries choose more emission permits and act as permit sellers (buyers). The numerical results further suggest that an imperfectly competitive IET market with all price-influencing countries being permit buyers (sellers) has lower (higher) emissions than a perfectly competitive IET market. Finally, the IET scheme has an equilibrium market structure of imperfect competition where the high-damage European Union acts as a unique price maker. This equilibrium imperfectly competitive IET has the lowest global emissions.     

论地方水污染防治立法的创新——以北京市为例

2008年国家颁布了新的《水污染防治法》,但是国家的法律往往是对全国主要水污染问题的总体规定,地方的具体问题还需相应的地方法规予以保障。针对北京市水污染防治的主要问题,《北京市水污染防治条例》在完善管理体制、明确政府部门职责、保障生态环境用水等方面细化了国家法律的相关条款,在污泥处理处置、污水资源化等方面填补了法律空白,体现了地方立法的创新,对其他地方政府的立法工作具有一定借鉴作用。     

Metal accumulation in sediments and benthic invertebrates in lakes of Latvia

The concentrations of cadmium, lead, nickel and copper in waters, sediments (total metal concentrations and their speciation forms) and benthic macroinvertebrates in 11 lakes of Latvia were determined using atomic absorption spectroscopy. Metal concentrations in lake waters, sediments and biota were compared with water chemistry. Compared to total concentrations, metal speciation forms in sediments were better correlated with respective metal concentrations in invertebrates. Therefore, the evaluation of potential metal bioaccumulation should consider metal speciation. The mean concentrations of trace metals in benthic invertebrates in Latvia were much lower than in other countries, which can be explained by comparatively lower anthropogenic loads. However, local areas of anthropogenic impacts were evident.     

基于合成孔径雷达的城市建筑地震受损分析

汶川地震灾区位于青藏高原东缘,该地区云雨天气较多,光学遥感受制约较大,而微波能够穿透云、雾、小雨等,且不受太阳光线的影响,雷达遥感具有全天时、全天候的特点,因而可以弥补光学遥感的不足。根据房屋受地震破坏后影响雷达回波强度,在雷达影像上表现为亮度及纹理不同的原理,本论文利用不同分辨率的COSMO-SkyMed和Radarsat等SAR数据,将其与震前的SPOT影像进行配准后,通过纹理分析等处理,对都江堰市区、北川县城曲山镇等受灾较为严重的城镇进行分析解译,利用雷达影像判读出倒塌房屋的信息,以及地震次生山地灾害对城镇的破坏。     

转炉烟气净化系统中烟气的分析和量的计算

转炉煤气干法净化回收技术已被认定为转炉煤气处理技术的今后发展方向。我国在转炉煤气干法净化回收技术方面已经做了全面深入的研究,并于2006年创新性地开发出了完全适合我国转炉炼钢的转炉煤气干法净化回收系统。设计转炉煤气干法净化回收系统的第一步也是最关键的一步,就是转炉烟气的分析和烟气量的准确计算。