Hydrologic Effects of Surface Coal Mining in Appalachia (U.S.)

Surface coal mining operations alter landscapes of the Appalachian Mountains, United States, by replacing bedrock with mine spoil, altering topography, removing native vegetation, and constructing mine soils with hydrologic properties that differ from those of native soils. Research has demonstrated hydrologic effects of mining and reclamation on Appalachian landscapes include increased peakflows at newly mined and reclaimed watersheds in response to strong storm events, increased subsurface void space, and increased base flows. We review these investigations with a focus on identifying changes to hydrologic flow paths caused by surface mining for coal in the Appalachian Mountains. We introduce two conceptual control points that govern hydrologic flow paths on mined lands, including the soil surface that partitions infiltration vs. surface runoff and a potential subsurface zone that partitions subsurface storm flow vs. deeper percolation. Investigations to improve knowledge of hydrologic pathways on reclaimed Appalachian mine sites are needed to identify effects of mining on hydrologic processes, aid development of reclamation methods to reduce hydrologic impacts, and direct environmental mitigation and public policy.     

中国大陆土壤中239+240Pu的来源与背景值研究

利用现有大量实测的¹³⁷Cs背景值数据,根据北半球大气沉降¹³⁷Cs/^239+240Pu活度比值32.5（¹³⁷Cs活度校正到2005年）,将中国大陆土壤中¹³⁷Cs转换成对应的^239+240Pu,类比中国大陆¹³⁷Cs-RI模型（¹³⁷Cs-RI MCM）,利用克里金插值方法模拟中国大陆土壤中Pu-RI的空间分布.目前中国大陆土壤中实测^239+240Pu的沉积通量范围在7.3~546 Bq/m²之间,模拟Pu-RI的范围在3~812 Bq/m²之间,并且最大值出现的地点与模拟最大Pu-RI可能出现的区域基本一致,¹³⁷Cs-RI MCM模型对中国大陆土壤中Pu-RI的模拟具有可行性.由于¹³⁷Cs与^239+240Pu沉降的不均匀性,根据中国土壤实测¹³⁷Cs/^239+240Pu的活度比可知,局部区域Pu-RI模拟值可能有偏差.为了更好的说明¹³⁷Cs-RI MCM模型的可行性,本研究利用30~40°N之间中国62个城市位点的^239+240Pu湿沉降通量（I_湿沉降）与相应Pu-RI的值（I_总沉降）进行了比较,发现I_湿沉降和I_总沉降的理论计算均是合理的.     

Calorimetric studies on the thermal stability of methyl ethyl ketone peroxide (MEKP) formulations

The energetic decomposition of methyl ethyl ketone peroxide (MEKP) and its formulations have long been known to present a significant risk. Indeed, MEKP has the highest number of reported decomposition incidents of all organic peroxides, many of which have led to significant numbers of fatalities, injuries and damage. It is noteworthy that incidents have been reported at all stages of the product lifecycle.This paper is derived from incident-investigation work and provides a summary of serious incidents involving MEKP, followed by details of calorimetric experiments performed to investigate thermal stability of representative MEKP formulations containing varying amounts of MEKP monomer. In particular we report the wide degree of variation that exists between commercial MEKP formulations, even between materials that are of the same nominal formulation. Such variations are detectable using differential scanning calorimetry (DSC).Follow-up studies performed on a representative MEKP formulation containing MEKP monomer indicate that a risk of decomposition exists at temperatures well below the reported self-accelerating decomposition temperature (SADT) of the products. As such, the experimental results reported here suggest that lower storage temperatures (commonly recommended by manufacturers to maximise shelf life) should be considered as being essential throughout the product lifecycle to reduce the risk of accidents in storage and transportation.     

The role of two distinct subunit types in the architecture of keyhole limpet hemocyanin (KLH)

The Science of Nature -     

Temporal variability of the elemental composition in urban street dust

Urban Street dust is recognized as a source of urban air and runoff degradation. This paper takes a preliminary step toward a better understanding of temporal variability in street dust chemistry and of the controlling mechanisms. Street dust samples, collected over four seasons in the city of Hamilton, Canada, show a variability dependent on element and source-anthropogenic sources exhibiting the greatest temporal variability. In addition, elements attributed to common sources exhibit similar temporal patterns. The use of generic or even one-time samples may seriously misrepresent the elemental make-up of urban street dust. Based on the samples collected in this study, a number of questions/insights are posed to further the study of street dust temporal variability.