129I in Swedish rivers: distribution and sources

We analyzed the concentration of 129I in the water of 26 rivers covering most of the runoff from Sweden, with the aim of assessing current contamination levels, distribution patterns and potential sources in freshwater systems of northern Europe. The results show relatively high values (up to 1.4 x 10(9) atoms l(-1)), steeply decreasing levels with increasing latitude and a positive correlation with Cl concentration and other chemical parameters. The 129I concentrations observed in south Sweden are probably the highest ever recorded in rivers without any direct discharge from a nuclear installation. The strong latitudinal dependence suggests a northward dilution and possibly depletion of the isotope and a transport from a source located to the south. The most plausible source of the 129I in the studied rivers is atmospheric fallout of 129I emitted either by atmospheric discharges from the nuclear reprocessing facilities at Sellafield (England) and La Hague (France) or by volatilization from seawater contaminated by the same sources. The question is now whether and at what rate the 129I concentration in Nordic watersheds will increase further if discharges from nuclear reprocessing continue.     

Records and sources of metal pollutants in a dated Loch Lomond sediment core

Lead, zinc, copper, chromium, arsenic and cadmium were measured in a sediment core from southern Loch Lomond for which ²¹⁰Pb dating indicated a sedimentation rate of 22±2 mg/cm²/yr corresponding to a mean accumulation rate of 0.36 mm/yr.While copper and chromium were enriched to only a minor extent, the lead, zinc, arsenic and cadmium concentrations were markedly enhanced in upper sections. Increasing anthropogenic input associated with industrial activity centred on Glasgow seems responsible for the vertical distribution of lead, zinc and cadmium but a high 0–1 cm level of arsenic (474 μg/g), strongly correlated with enhanced iron content in the surface oxidising layer of sediment, appears attributable to post-depositional diagenetic mobilisation and upward migration in the reducing zone of the sediment column.Leaching, using CH₃CO₂H/NH₂OH·HCl, released over 90% and 80% of the common metal pollutants, lead and zinc, from surface sediment. Onset of an approximately tenfold increase in lead and zinc concentrations above “background” levels of 13±2 μg/g and 47±13 μg/g to upper section levels of 140–170 μg/g and 450–460 μg/g respectively was placed at late-18th century, in accord with the records of the commencement of significant industrial activity in the Glasgow area. Current anthropogenic fluxes (μg/cm² /yr) of lead (2.51±0.34) and zinc (8.84±1.20) to the sediment are in agreement with recent atmospheric deposition data for the adjoining Clyde Sea Area.The general concordance between anthropogenic metal fluxes to Loch Lomond sediment and atmospheric deposition fluxes endorses the potential usefulness of Loch Lomond sediment data to the resolution of pollution sources in the adjoining sea lochs and firth of the Clyde Sea Area, illustrated here through consideration of the comparative distribution of chromium in relation to its historical use.     

129I measurements in lake water for an estimate of regional 129I depositions

Estimates of (129)I depositions from (129)I releases of reprocessing plants are so far based on measurements of soil and rain water samples. Because (129)I concentrations in these samples show a highly temporal and spatial variability, the (129)I deposition values deduced from single measurements cannot be seen as representative for a larger area. Here it is proposed to use lake water as an archive for former (129)I depositions, to overcome these limitations. If the limnological parameters of any lake are known, the local (129)I deposition flux can be deduced which is temporally averaged over the flushing time, and spatially averaged over the catchment area of the lake. Samples were collected from various European lakes and from Lake Baikal (Russia). The (129)I concentration in these samples was measured by means of accelerator mass spectrometry, and values between 0.3 and 8.1x10(8) at/l were obtained. Deduced (129)I deposition fluxes averaged over the flushing times of the lakes range from 0.3 to 9.3x10(12) at/m(2) y. The (129)I deposition fluence measured for Lake Baikal is attributed predominantly to releases from the former Soviet reprocessing facilities Chelyabinsk, Tomsk and Krasnoyarsk, while the (129)I deposition fluxes deduced for all other lakes are attributed to releases from the European reprocessing activities at Sellafield, Marcoule and La Hague.     

Distribution and sources of polycyclic aromatic hydrocarbons in the sediment of a sub-tropical coastal wetland

Sediment cores (0-35cm below surface) from twelve sampling stations in the Mai Po and Inner Deep Bay Ramsar Site of Hong Kong were retrieved in the period March-December 1999. Vertical profiles of 15 priority polycyclic aromatic hydrocarbons (PAHs) in each sediment core were determined. Ranges of total PAH concentration, [sigmaPAH], in the wetland sediment were 0.18-0.83 (N = 0.36) microg/g dried sediment (mudflats) and 0.63-0.96 (x = 0.77) microg/g dried sediment (mangroves). A decreasing trend in depth averaged [sigmaPAH] was observed from the landward end towards the seaward end of the Marshes. On the mudflats, vertical profiles of the PAHs were quite uniform. At the fringe of the Mai Po mangroves, significantly higher concentration of all PAHs was observed at the upper 0 to -8 cm layer. No significant difference in the distribution patterns of the 15 priority PAHs in summer and winter was observed. This indicates that distribution of PAHs in the sediment of the Mai Po Marshes is not very sensitive to sub-tropical climatic changes of the region. Two PAH isomer ratios, [Phen]/([Phen] + [Anthra]) and [Pyrene]/([Pyrene] + [Fluoran]), were used to identify potential sources of PAH contamination in the wetland. Results revealed that local deposition is a more important source than long-range atmospheric transportation.     

考虑孔道及核心面积影响的混凝土局部受压承载力试验研究

为了深入考察预留孔道、间接钢筋内表面范围内混凝土核心面积和局部受压面积比等关键参数对局部受压承载力的影响,完成了12个素混凝土试件、9个配置网片式间接钢筋的混凝土试件和9个配置螺旋式间接钢筋的混凝土试件的轴心局部受压承载力试验。获得了间接钢筋的应变分布、楔形体特征及破坏形态等试验资料。试验结果表明:预留孔道的存在将使混凝土局部受压承载力提高系数降低,其降低幅度随孔道直径的增大而增大;当网片式间接钢筋的种类、直径、根数、网片间距不变或螺旋式间接钢筋的种类、直径及螺旋间距不变时,局部受压承载力随混凝土核心面积的增加而线性提高。建立了基于试验结果的考虑预留孔道直径和核心面积大小影响的混凝土局部受压承载力计算公式,可供相关设计标准修订时参考。     

A comparison of phosphorus retention in lakes determined from mass balance and sediment core calculations

Phosphorus retention (TP_acc) was determined in 7 lakes in Ontario, Canada from mass balances and from the direct measurement of phosphorus accumulation in the sediments. Phosphorus retentions determined using the mass balance technique ranged between 20 ± 4.0 and 95 ± 23 mg/m²/yr and were slightly lower than those calculated by multiplying sediment total phosphorus (TP) concentrations by sediment accumulation rates (49 ± 14 to 148 ± 37 mg/m²/yr). The lower TP_acc values measured using the mass balance approach may result from the underestimation of external TP inputs. Alternatively, it is suggested that in the more acidic lakes, a decrease in TP concentrations in the lakewaters and/or a decrease in TP export from the catchment may have resulted in a decrease in TP_acc through time. Thus, relatively higher TP_acc values would be calculated using the sediment approach (since TP_acc values calculated from the sediment data are averaged over a greater number of years than those calculated from the mass balance data).Provided several cores are collected from the lake, the direct measurement of sediment TP and sediment accumulation rates for estimating TP_acc may be a suitable alternative to mass balances, especially in situations where it is not possible to measure all inputs of TP to the lake.     

Innovative use of a sediment dumping area by the port as a car yard

The Port of Kotka is situated by the Baltic Sea and the river Kymi. The river transports into the estuary sediments containing pollutants. The dredging and dumping of the polluted sediments are challenging tasks, which are strictly monitored by the environmental authorities. In this study, we show how a former dumping area was converted into a car storage area in an innovative way. The construction on wetland base was extremely challenging. The field was built by using tyre scrap, which weighs only a quarter of the stone material's weight. The advantage of frost season was used during the construction phase, which reduces the costs. The Port of Kotka's solution to use polluted dredged material and waste material, in order to economically reclaim new land, sets a good example that can be used in other ports as well.     

PAH fluxes in the Laja Lake of south central Chile Andes over the last 50 years: evidence from a dated sediment core

This paper reports the occurrence of polyaromatic hydrocarbons (PAHs) deposition inferred from a sediment core of an Andean lake in south central Chile. Sediments were carefully collected from one of the deepest section of the lake and sliced every 1 cm. The samples were analyzed for PAHs, (137)Cs, (210)Pb, organic carbon and grain-size. The stratigraphic chronology and the sedimentation rates were estimated using the sedimentary signature left by the (137)Cs and (210)Pb fallout as temporal markers. PAHs were quantified by HPLC-fluorescence detection (HPLC-Fluorescence). 15 priority EPA PAHs were analyzed in this study. Based on these results, PAH deposition over the last 50 years was estimated (a period characterized by an important intervention in the area). PAH concentration ranged from 226 to 620 ng g(-1) d.w. The highest concentrations of PAHs were found in the core's bottom. The PAH profile is dominated by the presence of perylene indicating a natural source of PAH. In addition, two clear PAH deposition periods could be determined: the most recent with two-four rings PAHs, the older one with five-seven rings predomination. Determined fluxes where 71 to 972 microg m(-2) year(-1), dominated by perylene deposition. PAH levels and fluxes are lower compared to the levels found in sediments from remote lakes in Europe and North America. It is concluded that the main source of PAHs into the Laja Lake sediments are of natural origin.     

Innovative use of a sediment dumping area by the port as a car yard

The Port of Kotka is situated by the Baltic Sea and the river Kymi. The river transports into the estuary sediments containing pollutants. The dredging and dumping of the polluted sediments are challenging tasks, which are strictly monitored by the environmental authorities. In this study, we show how a former dumping area was converted into a car storage area in an innovative way. The construction on wetland base was extremely challenging. The field was built by using tyre scrap, which weighs only a quarter of the stone material's weight. The advantage of frost season was used during the construction phase, which reduces the costs. The Port of Kotka's solution to use polluted dredged material and waste material, in order to economically reclaim new land, sets a good example that can be used in other ports as well.     

Infrared spectroscopy tracing of sediment sources in a small rural watershed (French Alps)

The present article describes a first attempt to use infrared spectroscopy to trace the origin of suspended river sediments. Fifty samples of the main potential sediment sources within a small catchment area (990 ha) in the French Alps were collected and compared with samples of suspended sediment from the river, collected on various dates during 2006 and 2007 using sediment traps. Two major categories of sediment source were identified: topsoils and river channel sediments. For the qualitative part of the study, each of these two main categories was divided into two sub-categories, that is to say, cultivated and pastureland topsoils, and riverbed and riverbank sediments. Discriminant analysis on the source samples showed that Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy can be used to differentiate between the four potential source materials. To determine whether or not immersion in the river altered the infrared spectra of these source materials, we measured the infrared spectra of samples that had been immersed in the river, in litter bags, for periods of up to 24 days. Immersion did not cause any major changes in the infrared spectra. The contribution of each type of source material to the suspended sediment in the river was quantified using partial least squares (PLS) analyses of DRIFT spectra to compare actual river sediment samples with an experimental model. This model was produced from the DRIFT spectra of a range of calibration samples produced by mixing source material samples in different ratios. The predictions of the model were valid and fell within the confidence interval calculated for the calibration set. Comparisons between suspended sediment samples and the model indicate that the predominant source of the sediment is riverbank erosion, which, in this case, is probably due to trampling by cattle.     

太原市城市核心区街道景观改造漫谈

通过对太原市城市核心区街道景观改造的具体实践,分析了太原市核心区老街道存在的问题,并遵循制定的改造原则,提出了改造的具体内容和方法,从而为如何创造一种地域特色、整体意向、功能环境、休闲生活相互交融的城市提供了依据。     

Characterization of fine particle sources in the Great Smoky Mountains area

A source apportionment study to characterize sources of fine particles in the Great Smoky Mountains area was conducted analyzing ambient PM(2.5) (particulate matter< or =2.5 microm in aerodynamic diameter) speciation data collected at a Interagency Monitoring of Protected Visual Environments (IMPROVE) monitoring site. A total of 1442 samples collected between March 1988 and December 2003 analyzed for 30 elemental species were analyzed with the application of the positive matrix factorization (PMF). Eight major sources were extracted: summer-high secondary sulfate (55%), carbon-rich secondary sulfate (16%), summer-low secondary sulfate (2%), gasoline vehicle emissions (13%), diesel emissions (1%), airborne soil (6%), industry (5%), and secondary nitrate (2%). The contributions from the carbon-rich secondary sulfate particles are likely a combination of local and regional influences of the biogenic as well as anthropogenic secondary particles. The compositional profiles for gasoline vehicle and diesel emissions are similar to those identified in other US areas. Backward trajectories indicate that the high impacts of airborne soil were likely caused by Asian and Saharan dust storms. This study would assist in the implementation plan development for attaining the air quality standards for PM(2.5), regional haze rule planning, and source-specific community epidemiology.     

Vulnerability of hand-dug wells in the core area of Akure,Nigeria

Hand-dug wells (HDWs) are a major source of water supply in developing nations. This is consequent upon the failure of government to provide safe water to the people. This paper looks at the vulnerability of HDWs in the core area of Akure, Nigeria. The study area is made up of 11 residential quarters with 1149 buildings; 10% of buildings and five wells in each quarter were randomly selected for the study. Data were collected using structured questionnaires and laboratory examinations. Water quality assessment showed that most parameters fall within WHO permissible limits for drinking water. However, microbial examinations indicated that drinking water quality was compromised in two residential quarters as there was evidence of coliform and e-coli. The study also identified other possible sources of water contamination in the study area. This paper recommends regular treatment of wells and the adoption of pipe-borne water supply systems in the city and other similar cities in developing countries.     

天通苑核心区规划设计

1998年，北京市政府确定天通苑地区作为北京市经济适用住房建设的重点地区之一。之后该地区陆续建设了天通苑一期、二期、三期，目前正在准备建设四期——天通苑核心区。建成后天通苑经济适用住房总建筑面积可达500万m^2。天通苑居住区在建设过程中，暴露出交通拥堵，配套医疗、教育设施不全，辅助的金融，办公功能不中等问题，引起市领导、人大政协代表、居民和社会媒体的广泛关注。本次规划在定一程度上对相关问题的解决做出了努力。     

Factors controlling mobility of 127I and 129I species in an acidic groundwater plume at the Savannah River Site

In order to quantify changes in iodine speciation and to assess factors controlling the distribution and mobility of iodine at an iodine-129 (¹²⁹I) contaminated site located at the U.S. Department of Energy's Savannah River Site (SRS), spatial distributions and transformation of ¹²⁹I and stable iodine (¹²⁷I) species in groundwater were investigated along a gradient in redox potential (654 to 360 mV), organic carbon concentration (5 to 60 μmol L^− 1), and pH (pH 3.2 to 6.8). Total ¹²⁹I concentration in groundwater was 8.6 ± 2.8 Bq L^− 1 immediately downstream of a former waste seepage basin (well FSB-95DR), and decreased with distance from the seepage basin. ¹²⁷I concentration decreased similarly to that of ¹²⁹I. Elevated concentrations of ¹²⁷I or ¹²⁹I were not detected in groundwater collected from wells located outside of the mixed waste plume of this area. At FSB-95DR, the majority (55-86%) of iodine existed as iodide for both ¹²⁷I and ¹²⁹I. Then, as the iodide move down gradient, some of it transformed into iodate and organo-iodine. Considering that iodate has a higher K_d value than iodide, we hypothesize that the production of iodate in groundwater resulted in the removal of iodine from the groundwater and consequently decreased concentrations of ¹²⁷I and ¹²⁹I in downstream areas. Significant amounts of organo-iodine species (30-82% of the total iodine) were also observed at upstream wells, including those outside the mixed waste plume. Concentrations of groundwater iodide decreased at a faster rate than organo-iodine along the transect from the seepage basin. We concluded that removal of iodine from the groundwater through the formation of high molecular weight organo-iodine species is complicated by the release of other more mobile organo-iodine species in the groundwater.     

Historical trends of PCDD/Fs and CO-PCBs in a sediment core collected in Sendai Bay, Japan

The vertical distribution of dioxins in a sediment core was investigated to elucidate historical trends of dioxins discharged into Sendai Bay, Japan. The dioxin concentration was 410 pg/g dry weight (dw) in sediments deposited in the mid-1930s and 3870 pg/g dw in those deposited in the mid-1980s. Dioxin fluxes increased from the mid-1930s and then reached a maximum in the mid-1980s. 1,3,6,8-TeCDD+1,3,7,9-TeCDD, OCDD, and Co-PCB concentrations were 110, 140, and 26 pg/g dw, respectively, in mid-1930s sediments, and reached maximums of 1800, 1100, and 200 pg/g dw, respectively, in mid-1980s sediments. Shipments to Miyagi Prefecture of CNP and PCP products, the major sources of 1,3,6,8-TeCDD+1,3,7,9-TeCDD and OCDD, were highest in 1975 (4700t) and 1970 (3100t), respectively; and in Japan, the amount of PCBs, the major source of Co-PCB congeners, used was highest (11,100t) in 1970. Thus, the period for which the maximum concentrations of 1,3,6,8+1,3,7,9-TeCDD, OCDD, and Co-PCBs were measured in the sediment core (mid-1980s) did not correspond to the time of maximum use of CNP, PCP, or PCB products, but lagged behind by more than 10 years. We attributed this time lag to the time required for the movement of dioxins from Miyagi Prefecture to Sendai Bay.     

城市与水体、建筑与环境、历史与未来的结合——宁波市“核心滨水区城市设计及三江六岸概念规划”国际征集方案述评

1 概况 素有中国古代"海上丝绸之路”始发港之称的宁波,是我国东南沿海重要港口城市.余姚江、奉化江、甬江交汇,形成独具特色的三江口核心滨水地区.该地区既是城市商务、文化、旅游、信息等公共生活的中心,又是城市重要的历史性地段,更是集中体现城市风貌和形象的标志性地区. 为了完善三江口城市核心滨水区的中心功能,改善城市形象,实现城市与水体、建筑与环境、历史与未来的结合,塑造富有地方特色的为城市居民所喜爱的滨水空间和公共活动场所,2000年1月至4月,宁波市进行了"核心滨水区城市设计及三江六岸概念规划”方案征集工作,上海市城市规划设计研究院、美国龙安建筑规划设计顾问公司、清华大学城市规划设计研究院、株式会社日本设计四家单位应邀参加.     

Fine sediment influence on salmonid spawning habitat in a lowland agricultural stream: a preliminary assessment

Spawning habitat utilized by Atlantic Salmon (Salmo salar) and Sea Trout (Salmo trutta) was characterized in a 1.6-km reach of the Newmills Burn, a small, highly canalized tributary of the River Don in Aberdeenshire. The Newmills Burn is typical of the intensively farmed lower sub-catchments of the major salmon rivers on the east coast of Scotland. Such streams have substantial potential in providing spawning and juvenile habitat for salmonids, with high redd densities resulting in egg deposition rates of > 5 m2. However, in comparison with upland spawning tributaries draining less intensively managed catchments, canalization and intensive cultivation has seriously degraded the physical characteristics of aquatic habitats in many streams. In the Newmills Burn, spawning gravels have a relatively high (> 20% by mass) fine sediment (< 2 mm in size) content. The burn is characterized by hydraulic conditions that are suitable for salmonid spawning, with modal velocities of 0.50-0.65 m s(-1) and depths of 0.20-0.25 m. However, infiltration of fine sediments into gravels is rapid during hydrological events in the winter months. Thus, complete siltation of open gravel matrices (simulated redds) can occur within a week, and probably within a single moderate to large storm event. Appreciable, but small, deposition of organic and silt/clay particles can also affect spawning gravels. Egg mortalities in redds following spawning are variable, but can be as high as 86% in the Newmills Burn. This may be related to fine sediment infiltration, reduced permeability of spawning gravels and reduced oxygen supply to ova. It appears that the main cause of high influx is sediment loads mobilized from intensively managed land. It is suggested that fundamental changes to the management of agricultural land is required if fish habitats are to be improved and degraded streams are allowed to re-naturalize. The need for closely focused investigations of the causal relationships between fine sediment infiltration and egg survival is stressed.