英国Culm河河漫滩沉积物中磷素时空变化研究

河漫滩上沉积物的沉积伴随着与沉积物相结合的营养和污染物质的沉积。已有研究表明,河漫滩是与沉积物相结合的磷的沉积地。采用137Cs技术,并结合河漫滩沉积物中全磷(TP)含量的剖面信息,可以调查近年河漫滩沉积物中的TP含量,计算TP储量。本文根据英国Devon郡Culm河8个河漫滩采样环沉积物中的数据,重建了在过去40～50年内TP储量和含量的变化。结果表明,在Culm河河漫滩沉积物中,在1963～2000年间TP平均含量为0.60～1.96gkg-1,该值自河流上游向下游和自过去到现在有逐渐增加的趋势;在相同的河漫滩沉积物中,在相同的时期内TP储量为18.62～435.48gm-2,即0.49～11.46gm-2a-1,最大值出现在河流的中游。     

Gully erosion and environmental change: importance and research needs

Assessing the impacts of climatic and, in particular, land use changes on rates of soil erosion by water is the objective of many national and international research projects. However, over the last decades, most research dealing with soil erosion by water has concentrated on sheet (interrill) and rill erosion processes operating at the (runoff) plot scale. Relatively few studies have been conducted on gully erosion operating at larger spatial scales.Recent studies indicate that (1) gully erosion represents an important sediment source in a range of environments and (2) gullies are effective links for transferring runoff and sediment from uplands to valley bottoms and permanent channels where they aggravate off site effects of water erosion. In other words, once gullies develop, they increase the connectivity in the landscape. Many cases of damage (sediment and chemical) to watercourses and properties by runoff from agricultural land relate to (ephemeral) gullying. Consequently, there is a need for monitoring, experimental and modelling studies of gully erosion as a basis for predicting the effects of environmental change (climatic and land use changes) on gully erosion rates.In this respect, various research questions can be identified. The most important ones are:

What is the contribution of gully erosion to overall soil loss and sediment production at various temporal and spatial scales and under different climatic and land use conditions?

What are appropriate measuring techniques for monitoring and experimental studies of the initiation and development of various gully types at various temporal and spatial scales?

Can we identify critical thresholds for the initiation, development and infilling of gullies in different environments in terms of flow hydraulics, rain, topography, soils and land use?

How does gully erosion interact with hydrological processes as well as with other soil degradation processes?

What are appropriate models of gully erosion, capable of predicting (a) erosion rates at various temporal and spatial scales and (b) the impact of gully development on hydrology, sediment yield and landscape evolution?

What are efficient gully prevention and gully control measures? What can be learned from failures and successes of gully erosion control programmes?

These questions need to be answered first if we want to improve our insights into the impacts of environmental change on gully erosion. This paper highlights some of these issues by reviewing recent examples taken from various environments.     

长江口潮滩植物根际沉积物磷的累积及其生物有效性

通过对长江口潮滩植物生物量及根际沉积物中磷的赋存形态和含量的研究,结果表明各个采样点的海三棱草从春季开始生长并一直延续到初夏,到7月其生物量基本上都达到一个峰值。海三棱草根际沉积物中磷的赋存形态包括弱吸附态磷(Ad-P)、铁结合态磷(Fe-P)、自生磷灰石及钙结合态磷[(Ap+Ca)-P]、碎屑态磷(De-P)和有机磷(OP),它们都具有较好的季节性变化,在一定程度上都受到氧化还原状态的控制。文中还研究了根际沉积物孔隙水中的磷酸盐含量,发现其有效性受到了氧化还原状态及沉积物中铁的影响。     

潋水流域产水产沙自然过程的计算机模拟Ⅰ.数学模型体系与参数输入

使用流域尺度土壤和水资源管理模拟模型SWRRB（包括198个数学方程）,对面积为579.3km2的江西潋水河流域的产水量、产沙量等自然过程进行了计算机模拟,获得了较好的模拟结果.模拟成功的关键是：（1）将流域划分为多个亚区;（2）精心而周到地准备输入参数;（3）按各输入参数对各输出参数影响大小的顺序进行充分的实验和参数调整以达最佳结果.文中对亚区划分和地形要素、气温、降雨、土壤特性和径流曲线系数的赋值给予了较多的注意.     

Salt marsh rhizosphere affects microbial biotransformation of the widespread halogenated contaminant tetrabromobisphenol-A (TBBPA)

Estuarine sediments are the repository for a wide range of contaminants. Anthropogenic impacts and variations in the belowground biomass of salt marsh plants potentially select for different sediment microbial communities with different functional capabilities, including the ability to biotransform anthropogenic contaminants. There are large differences in both root morphology and the amount of fine root biomass of Spartina alterniflora and Phragmites australis; Spartina is the species commonly used to replace Phragmites in northeastern US salt marsh restoration projects. Our study compared the effect of these two macrophyte species on sediment microbial communities responsible for the biotransformation of the halogenated flame retardant tetrabromobisphenol A (TBBPA). Sediments were obtained from contaminated and uncontaminated salt marsh field sites in New Jersey. Anaerobic methanogenic sediment microcosms were established and incubated for up to 130 days. TBBPA was reductively dehalogenated resulting in the transient formation of two intermediates, identified as tribromobisphenol A and dibromobisphenol A, and the formation and accumulation of bisphenol A (BPA) as the end product. Spartina sediments from both sites were found to dehalogenate TBBPA more rapidly than the Phragmites or unvegetated sediments, resulting in greater production of BPA. Microbial community diversity as measured by in situ sediment phospholipid fatty acid (PLFA) composition prior to TBBPA exposure, was found to be higher in the uncontaminated sediments; differences in microbial PLFA diversity were not seen in contaminated sediments associated with either the different plant species or unvegetated sediment. The results of this study demonstrate that these two plant species affected sediment microbial community function with respect to dehalogenation capabilities, even though the disturbed and undisturbed sediments varied in microbial community composition.     

苹果浑汁贮藏期间沉淀物的研究

采用HPLC和SDS-PAGE以及GC等技术分析了贮藏120 d后的果汁沉淀物的成分,沉淀物中酚类物质和蛋白质的性质。结果表明:果汁沉淀物以蛋白质为主,还含有碳水化合物、酚类(表儿茶素、绿原酸、单宁等)、5-羟甲基糠醛(5-HMF)等Vc降解产物,成分很复杂。沉淀物主要是由果汁中原有的颗粒聚集长大下沉产生。     

香溪河沉积物中碳氮元素的分布特征研究

[目的]研究靠近三峡大坝的第一支流香溪河沉积物中碳氮元素分布特征.[方法]在2015年春季,从分布于三峡水库典型支流香溪河入河口河段的三个采样点,用柱状沉积物采样法采集样品,研究该区域碳、氮等生源要素的分布特征.[结果]所调查河段的沉积物中总碳含量为1.74％-3.52％,总氮含量为0.1％-0.3％.总碳含量的沿程变化表现为靠近河口的沉积物中总碳平均含量低于上游,深度变化是靠近河口采样点的表层沉积物中总碳含量显著高于底层.而总氮含量的沿程变化和深度变化没有总碳变化明显.δ13C值随深度的增加而增加,靠近河口的沉积物中δ13C值小于上游采样点.[结论]该研究为认识香溪河沉积物中生源要素的分布特征及水生生态系统的演变过程提供了科学依据.     

花岗岩地区坡耕地径流泥沙观测试验研究

本文总结分析了三年来对花岗岩地区坡耕地径流泥沙的观测试验资料, 得出以下结论: 1.荒坡地的泥沙流失量大于作物地; 2.作物地覆盖度低于30%以下则比荒坡地的泥沙流失量要大; 3.大于25°的坡耕地, 头两年产量虽然较好, 但第3年以后产量大幅度下降, 并造成大量的泥沙流失, 故种多年生植物为佳。 同时通过试验研究表明: 在花岗岩地区, 泥沙流失量多数来源于坡耕地。 因此搞好坡耕地的综合治理, 是防治水土流失提高单位面积产量的关键措施。     

上海市老港垃圾填埋场潮滩重金属污染及评价研究

以上海市老港垃圾填埋场潮滩为例,研究了沉积物中重金属的分布特征,并采用化学法和潜在生态危害指数法评价了潮滩重金属的污染状况及其潜在生态危害,以期为保护潮滩环境以及利用潮滩进行垃圾渗滤液的净化提供科学依据。结果表明,受垃圾渗滤液排放和生物活动影响,老港潮滩表层沉积物中重金属(除Cu外)的含量在向海向上均表现为:高潮滩>低潮滩>中潮滩;Cr和Zn的含量在氧化池排污口处明显高于其它排污口,而Pb的含量在自然排污口处最高;老港潮滩沉积物受到一定程度的重金属污染,以Zn的污染最为严重,由这4种元素造成的潜在生态危害是中等的,其中,Cu和Pb的毒性贡献最大。     

Runoff and sediment losses from rough and smooth soil surfaces in a laboratory experiment

Soil surface roughness may significantly impact runoff and erosion under rainfall. A common perception is that runoff and erosion are decreased as a function of roughness because of surface ponding and increased hydraulic roughness that reduces effective flow shear stress. The objective of this study was to measure the effects of initial surface roughness on runoff and erosion under controlled laboratory conditions. Initially, rough and smooth surfaces were exposed to five simulated rainfall applications at 5% and 20% slopes. In all cases, runoff was delayed for the case of the initially rough surface; however, this effect was temporary. Overall, no statistical differences in either total runoff or erosion were measured on the 20% slope. At 5% slope, runoff was less on the rough surface for the first rainfall application but greater on the final three, probably due to the formation of a depositional seal in that case. This resulted in an overall insignificant difference in runoff for the sum of the five rainfall applications. Erosion was greater on the rougher slope at 5% steepness, probably due to concentration of flow as it moved around the roughness elements on the rougher slope. These results indicate that commonly held perceptions of the impact of soil surface roughness on runoff and erosion may not be entirely correct in all cases.