Regional NOx emission inversion through a four-dimensional variational approach using SCIAMACHY tropospheric NO2 column observations

In this paper, the NOx emission scaling factors applied over the 2001 National Emissions Inventory (NEI) are estimated through a four-dimensional variational (4D-Var) approach using SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY) tropospheric NO₂ columns measured during summer 2004. In the “top-down” approach, two-month average NO₂ columns are assimilated into a regional chemical transport model (CTM), STEM, using different assimilation setups. In a basic setup, NOx emissions are adjusted by assimilating the NO₂ columns. A more general setup of emission inversion allows the initial O₃ concentrations be adjusted along with the NOx emissions. A final case is set up to assimilate both the NO₂ columns and O₃ measurement from various platforms while allowing adjustments of both the NOx emissions and the initial O₃ concentrations. It is found that the addition of O₃ measurements did not improve the NOx emission inversion. With the NOx emission at surface and upper levels being adjusted separately, results from four cases show that the elevated NOx emission reduction ranges from 8.9% to 11.4%, and the surface NOx emission reduction is up to 6.6%. All the cases show NOx emission reduction in Ohio valley and Washington, District of Columbia areas.     

Conservation on private land: a review of global strategies with a proposed classification system

With parks and protected areas insufficient to sustain global biodiversity, the role of private land in biodiversity conservation is becoming increasingly significant. This paper reviews global voluntary and involuntary strategies for private land conservation. Involuntary strategies can achieve effective conservation outcomes, but often lack social acceptability. In contrast, voluntary strategies enjoy greater social acceptance but may not achieve sufficient uptake to have meaningful conservation objectives. Based on the review, we propose a classification system for private land conservation as a complement to the International Union for Conservation of Nature's (IUCN's) classification of global protected areas. The classification system provides a framework for identifying and describing conservation strategies on private land on the dimension of tenure and security. It also identifies opportunities and vulnerabilities in achieving conservation on private land while emphasising the need for systematic data collection similar to IUCN's efforts for protected areas.     

A Geospatial Methodology to Identify Locations of Concentrated Runoff from Agricultural Fields

A geospatial methodology has been developed that utilizes high resolution lidar‐derived DEMs to help track runoff from agricultural fields and identify areas of potential concentrated flow through vegetated riparian areas in the Coastal Plain of Virginia. Points of concentrated flow are identified across 74 agricultural fields within the Virginia portion of the Chesapeake Bay watershed. On average, 70% of the surface area of the agricultural fields analyzed drains through less than 20 m of the field margin, and on average 81% of the field surface area drains through 1% or less of the field margin. Within the riparian buffer, locations that were predicted by the geospatial model to have high levels of concentrated flow were found to exhibit evidence of channelization. Results indicate that flow concentration and channelized flow through vegetated riparian areas may be common along the margin of agricultural fields, resulting in vegetated riparian areas that are less effective at sediment trapping than assumed. Additional results suggest that the regulations governing the location and width of vegetated riparian may not be sufficient to achieve goals for reducing sediment and nutrient runoff from nonpoint agricultural sources. Combined with the increasing availability of lidar‐derived DEMs, the geospatial model presented has the potential to advance management practices aimed at reducing nonpoint source pollution leaving agricultural fields.     

多种聚氧乙烯牛脂胺混合物MON 0818的水生环境危害评估：脉冲暴露后沉积物、温度和恢复能力的影响

我们对一种商业表面活性剂混合物(多种聚氧乙烯牛脂胺)MON 0818进行了一系列毒性测试：1. 测定底栖无脊椎动物和鱼类在沉积物存在的情况下受到的毒性;2.测定大型蚤(Daphnia magna)和4种初级生产者经过24 h的脉冲暴露之后的恢复能力;3.鉴定水体温度上升对于2种冷水鱼类所受到MON 0818毒性的潜在影响。在沉积物存在的情况下,5种生物中有3种在最高10 mg/L的浓度下短期(24 h)死亡率为零。其余2种物种的中位有效浓度则显著高于仅对水体进行测试的结果。15 ℃下北极红点鲑(Salvelinus alpinus)的半数有效浓度统计上低于10 ℃下。绿藻(Rhabdocelis subcapitata)和普通小球藻(Chlorella vulgaris)在经过24 h 1 mg/L的暴露后的恢复期中显示出生长延迟的状况,表明该暴露可能存在潜在影响。尽管如此,2个物种的最大绝对生长速率并未改变,表明其均可恢复。1.5 mg/L下的蝾螈共生藻(Oophila sp.)和100 mg/L下的浮萍(Lemna minor)经过24 h的暴露并未显示显著反应。24 h 5 mg/L暴露之后的恢复期中,大型蚤显示出潜在的死亡率。然而存活个体的生殖终端指标并未受到影响。结果表明在沉积物的存在下MON 0818的快速损耗可以减轻对于被暴露生物的效果,在不小于环境中可能出现的MON 0818浓度情况下,24 h暴露以后的生物的完全恢复是可能的。
精选自Jose L. Rodriguez-Gil, Ryan Prosser, Gregory Hanta, David Poirier, Linda Lissemore, Mark Hanson, Keith R. Solomon. Aquatic hazard assessment of MON 0818, a commercial mixture of alkylamine ethoxylates commonly used in glyphosate-containing herbicide formulations. Part 2: Roles of sediment, temperature, and capacity for recovery following a pulsed exposure. Environmental Toxicology and Chemistry: Volume 36, Issue 2, pages 512–521, July 2017. DOI: 10.1002/etc.3558
详情请见http://onlinelibrary.wiley.com/wol1/doi/10.1002/etc.3558/full
     

The effects of salt exclusion during ice formation on circulation in lakes

Laboratory experiments have been performed to investigate the effects of salt exclusion on the behaviour of lakes with salinities up to 8 g L^?1. At these salinities the freezing temperature is less than the temperature of maximum density and, unlike sea-ice, a reverse temperature stratification forms beneath the ice that can support at least some of the excluded salt. Temperature time series at four depths showed that salt exclusion drives cascades of localised overturning, while the persistence of reverse temperature stratification indicated that mixing was not complete. While our array of temperature sensors had insufficient spatial resolution to provide full details of the flow, we hypothesize that: at salinities of 1 and 2 g L^?1  salt is released relatively uniformly and forms a layer of elevated salinity immediately below the ice, which supports double-diffusive salt-fingering; and at salinities of 4 and 8 g L^?1, salt plumes penetrate the reverse stratification. After the ice melted, a relatively fresh surface layer formed above a more saline layer, sufficient to suppress spring turnover. Our measurements compare favourably with field observations from lakes, and highlight the importance of salt exclusion on biogeochemical processes in lakes.     

Prenatal diagnosis of xeroderma pigmentosum and cockayne syndrome

In a study of fetal cells from a series of 12 pregnancies in ten families at risk for the ultraviolet light-sensitive, DNA repair-deficient diseases xeroderma pigmentosum (XP) and Cockayne syndrome (CS), we detected one XP and two CS homozygote fetuses. The diagnoses were confirmed by analysis of fetal skin fibroblasts or second amniotic samples after termination of the pregnancies. The measurement of ultraviolet light sensitivity and DNA repair depended on properties common to the seven excision repair-deficient XP complementation groups (A-G) and the two CS complementation groups (A, B). No XP variant families were included in the study, because the variant requires different testing techniques. Reliable and rapid diagnosis proved possible in all but one of the 12 pregnancies, supporting the use of these methods until the spectrum of mutations in the various XP and CS genes of the U. S. population is fully characterized and a DNA sequence-based diagnostic procedure becomes available.     

Comprehensive primary particulate organic characterization of vehicular exhaust emissions in France

A study to characterize primary particulate matter (PM_2.5 and PM₁₀) from the French vehicular fleet was conducted during winter 2008, in a tunnel in Marseille, France. The carbonaceous fraction represents 70% of the aerosol mass and elemental carbon fraction (EC) represent 60% of the carbonaceous fraction. The organic carbon OC was characterized in term of its water soluble fraction, functionalization rate and HULIS content. Seventy trace organic compounds including alkanes, polycyclic aromatic hydrocarbons (PAH), petroleum biomarkers and carboxylic acids were also quantified, in order to determine an organic emission profile for chemical mass balance modeling studies. Such source profiles were still missing in Europe and particularly in France. The profile obtained in this study is consistent with profiles determined in tunnel or dynamometer studies performed in other countries during the last ten years. These results suggest that organic compounds profiles from vehicular exhaust emissions are not significantly influenced by the geographic area and are thus suitable for use in aerosol source apportionment modeling applied across extensive regions. The chemical profile determined here is very similar to those obtained for diesel emissions with high concentrations of EC relative to OC (EC/OC = 1.8) and low concentrations of the higher molecular weight PAH. These results are consistent with the high proportion of diesel vehicles in the French fleet (49%).     

The mobility of thiobencarb and fipronil in two flooded rice-growing soils

The mobility of the rice pesticides thiobencarb (S-[(4-chlorophenyl) methyl] diethylcarbamothioate) and fipronil ([5-amino-3-cyano-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]pyrazole) were investigated in the glasshouse under flooded conditions using two Australian rice-growing soils. When using leakage rates of 10 mm day(-1), less than 20% of applied thiobencarb and fipronil remained in the water column after 10 days due to rapid transfer to the soil phase. Up to 70% and 65% of the applied thiobencarb and fipronil, respectively, were recovered from the 0-1 cm layer of soils. Only 5-7% of each pesticide was recovered from the 1-2 cm layer, and less than 2% was recovered from each 1 cm layer in the 2-10 cm region of the soils. Analysis of the water leaking from the base of the soil cores showed between 5-10% of the applied thiobencarb and between 10-20% of the applied fipronil leaching from the soil cores. The high levels of pesticide in the effluent was attributed to preferential flow of pesticide-laden water via soil macropores resulting from the wetting and drying process, worm holes and root channels.