Cd~(2+)、Pb~(2+)在湘江流域河床表层沉积物上的吸附特性研究

以湘江流域河床表层沉积物为吸附剂,用于去除水中Cd~(2+)、Pb~(2+),系统研究了沉积物对Cd~(2+)、Pb~(2+)的吸附规律,并探讨了其吸附Cd~(2+)、Pb~(2+)后的化学稳定性。结果表明,当2种离子单独存在时,沉积物对Cd~(2+)、Pb~(2+)均具有较好的吸附效果;当2种离子同时存在时,由于竞争作用,沉积物对Cd~(2+)和Pb~(2+)的吸附量分别减小了约40%和16%。对吸附平衡的溶液进行曝气和用双蒸水清洗吸附饱和的沉积物后,Cd~(2+)、Pb~(2+)的释放比例较小,说明湘江流域河床表层沉积物吸附Cd~(2+)、Pb~(2+)后,其化学稳定性较好。沉积物的SEM、FTIR和XRD分析发现,沉积物结构多孔,表面含有大量—OH、—NH,这些基团在吸附重金属阳离子过程中起重要作用。研究结果表明,湘江流域河床表层沉积物对去除水中的Cd~(2+)、Pb~(2+)有较好的效果,该成果对湘江流域重金属污染控制具有重要参考价值。     

Hydrologic and Morphologic Variability of Streams With Different Cranberry Agriculture Histories,Southern New Jersey,United States1

Procopio, Nicholas A., 2010. Hydrologic and Morphologic Variability of Streams With Different Cranberry Agriculture Histories, Southern New Jersey, United States. Journal of the American Water Resources Association (JAWRA) 46(3):527-540. DOI: 10.1111/j.1752-1688.2010.00432.x Abstract: The creation of reservoirs and the modification of stream channels are common practices used to facilitate the efficient production of cranberries. The potential impacts to hydrologic and geomorphic aspects of streamflow and channel structure have not been adequately assessed. In this study, the streamflow regime of 12 streams and the channel morphologies of 11 streams were compared for study sites in the Pinelands region of New Jersey with upstream active-cranberry bogs, upstream abandoned-cranberry bogs, and basins with no apparent agricultural history. Flow regime metrics included measures of low-flow, median-flow, and bankfull discharge, two measures of streamflow variability (spread and a modified Richards-Baker Flashiness index), and the frequency of overbank flooding. Stream-channel morphology metrics included average bank slope, average bankfull width, average bankfull depth, average bankfull width-to-depth ratio, and average bankfull area. No significant differences between stream types were apparent for any of the metrics. Basin-area normalized streamflow values of all 12 study sites were highly correlated to each other. Significant relationships existed between some of the flow-regime and channel-morphology metrics. Due to the lack of significant differences between stream types, it appears that neither historic nor current cranberry agricultural practices considerably influence flow regimes or the channel morphology of streams in the New Jersey Pinelands.     

载硫活性炭微观结构和表面形态研究

为了增强活性炭脱除燃煤电厂烟气中汞的能力，利用汞和硫可以生成稳定的HgS的性质，研究了通过热沉淀增加了活性炭中的硫含量的改性方法，并以SEM、BET、TGA等方法，研究了改性对活性炭表面形貌、硫在活性炭中的分布、活性炭比表面积等性能的影响。结果表明，热沉淀改性方法可以增加活性炭中的硫含量；硫粘附在活性炭的炭链上量较多，孔壁较少；改性工艺降低了活性炭的比表面积，且改性活性炭的比表面积随着温度的升高而增大；载硫后，活性炭中元素硫和炭的结合被增强。     

Influence of foliar morphology and crown geometry on insecticide deposition and dissipation following an aerial spray over a mixed forest

Abstract

Deposition and dissipation of aerially sprayed phosphamidon insecticide over a mixed forest consisting of different species of coniferous and deciduous trees were studied. The data showed that the chemical deposited more and dissipated slower from deciduous foliage than from conifer needles. Differences in deposits and persistence were also found within each of the two foliar types. Leaf shape and orientation, crown geometry and foliar morphology appear to have played a role. No correlation was found between initial deposit levels and cuticular wax content of different foliar species. A controlled laboratory study showed that surface area/mass ratio played a more important role on initial deposits than pubescence/serrations present on foliar surfaces.     

Growth, leaf traits and litter decomposition of roadside hybrid aspen (Populus tremula L.× P. tremuloides Michx.) clones

Road traffic contributes considerably to ground-level air pollution and is therefore likely to affect roadside ecosystems. Differences in growth and leaf traits among 13 hybrid aspen (Populus tremula × P. tremuloides) clones were studied in relation to distance from a motorway. The trees sampled were growing 15 and 30 m from a motorway and at a background rural site in southern Finland. Litter decomposition was also measured at both the roadside and rural sites. Height and diameter growth rate and specific leaf area were lowest, and epicuticular wax amount highest in trees growing 15 m from the motorway. Although no significant distance × clone interactions were detected, clone-based analyses indicated differences in genotypic responses to motorway proximity. Leaf N concentration did not differ with distance from the motorway for any of the clones. Leaf litter decomposition was only temporarily retarded in the roadside environment, suggesting minor effects on nutrient cycling.     

ORDER CLASSIFICATION OF URBAN CATCHMENTS1

ABSTRACT: Stream order systems provide useful classification methods according to the number of tributaries collected. In urban catchments, sewer line order is a concepot concept providing for the same type of classification. Horton's stream order system is used to classify sewers beginning with the smallest lines as first order to the largest main sewer which is sixth order for two catchments studied. Average tributary area, average length and number of lines are shown as functions of order. The bifurcation ratios are also presented. They can be used for finding the number of sewer lines in the next order. The number of first order lines depend on lot size and the bifurcation ratios vary widely.     

STREAM TYPES IN THE DES MOINES RIVER BASIN1

Stream tributaries in the Des Moines River basin have been classified according to the glacial terrain through which they flow. Three stream types were categorized as follows: (1) streams that flow entirely on Wisconsin drift, (2) streams that flow entirely on Kansan drift, and (3) streams that have their headwaters located on new drift but have their lower reaches flowing on older drift. Selected channel and valley characteristics were measured and used to verify the stream type classification. Five variables were chosen for use in a multiple linear discriminatory analysis, which is a statistical technique developed for the purpose of classifying observations into one of several categories which have been predetermined. The streams in each group were verified with the exception of three anomalies based on the probability associated with the largest linear discriminant function. The rationale for the three anomalous streams is not easily determined. But, they are considered to be associated with pre-glacial drainage or at least pre-Wisconsin age drainage. Otherwise, the analysis shows that the major channels and valleys in the Des Moines River basin tend to reflect the glaciated upland surface.     

Morphological Study on Hydrolytic Degradation of Poly(tetramethylene succinate) Single Crystals and Spherulites

The morphological changes of Poly(tetramethylene succinate) single crystal lamellae by hydrolysis are investigated, using TEM, WAXD and SAXS. And the morphology of PTMS spherulites was also observed by optical microscopy after treatments as well as single crystal lamellae. The edge region of single crystal lamella can be most easily affected in the initial stage of hydrolysis. As the hydrolysis time increases, the lamellae are separated into small fragments which may be started from the uneven or irregular parts of the surface. The WAXD results showed that crystallinity were increased with increasing of treatment time. The lamellar thickness decreased at the initial stage of hydrolysis and increased again. There were cracks on the surface of spherulites after hydrolysis and the direction of cracks were tangential direction of spherulites. This result was thought to be from the uniformity of molecular arrangement in the crystallographic unit cell.     

Morphology of a Wetland Stream

/ Little attention has been paid to wetland stream morphology in the geomorphological and environmental literature, and in the recently expanding wetland reconstruction field, stream design has been based primarily on stream morphologies typical of nonwetland alluvial environments. Field investigation of a wetland reach of Roaring Brook, Stafford, Connecticut, USA, revealed several significant differences between the morphology of this stream and the typical morphology of nonwetland alluvial streams. Six morphological features of the study reach were examined: bankfull flow, meanders, pools and riffles, thalweg location, straight reaches, and cross-sectional shape. It was found that bankfull flow definitions originating from streams in nonwetland environments did not apply. Unusual features observed in the wetland reach include tight bends and a large axial wavelength to width ratio. A lengthy straight reach exists that exceeds what is typically found in nonwetland alluvial streams. The lack of convex bank point bars in the bends, a greater channel width at riffle locations, an unusual thalweg location, and small form ratios (a deep and narrow channel) were also differences identified. Further study is needed on wetland streams of various regions to determine if differences in morphology between alluvial and wetland environments can be applied in order to improve future designs of wetland channels.KEY WORDS: Stream morphology; Wetland restoration; Wetland creation; Bankfull; Pools and riffles; Meanders; Thalweg     

INFLUENCES OF INCREASED SAND DELIVERY ON THE MORPHOLOGY OF SAND AND GRAVEL CHANNELS1

ABSTRACT A flume study was conducted to examine (1)changes in the particle-size distribution of sediments in riffles due to the proportion of sand in transport and the total rate of bedload transport at the time the riffle is deposited and (2) the effect of high sand transport rates on the stability of gravel riffles. The median particle size of sediment deposited in the riffle was larger than that of the sediment in transport. Small but significant (a = 0.05) decreases in the median particle size of riffle sediments resulted as the sand-to-gravel ratio. Increased concentrations of sand in transport caused previously stable gravel riffles to undergo scour. These results, in combination with information from other studies, suggest that an alluvial channel with pool-riffle sequences and with sand and gravel beds may respond to an increased delivery of sand by reducing form roughness. Form roughness can be reduced by degrading riffles and filling pools. Subsequent responses may be increases in width-to-depth ratio and slope.