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.     

Stable lead isotopic characterisation of the historical record of environmental lead contamination in dated freshwater lake sediment cores from northern and central Scotland

Sediment cores from three Scottish freshwater lakes, Loch Ness in the remote north and Loch Lomond and the Lake of Menteith, much closer to the heavily populated and industrialised central belt were analysed for 210Pb, 137Cs, Pb and stable Pb isotopic composition (206Pb/207Pb). The radionuclide data were used to establish chronologies for the Loch Ness and Loch Lomond cores, but a chronology could not be developed for the Lake of Menteith core, in which the surface sediment had been subject to intense mixing. Although Pb concentrations generally started increasing during the mid-17th Century, a small peak occurred for Loch Ness in the early 16th Century, perhaps attributable to the influence of medieval mining and smelting in mainland Europe. Temporal trends in the pattern of Pb accumulation were similar for Loch Ness and both sites in Loch Lomond, with 40-50% of the anthropogenic Pb deposited prior to the 20th Century. Fluxes of anthropogenic Pb to the lake sediments peaked during the 1950s at all locations where chronologies could be established. The 5-fold increase in anthropogenic Pb inventory for the southern basin of Loch Lomond relative to Loch Ness reflected geographical proximity to the main polluting sources. The 206Pb/207Pb data for anthropogenic Pb in the sediments from Loch Ness and Loch Lomond exhibited largely similar trends related to five different time periods. Pre-1820, the 206Pb/207Pb ratio was close to that for coal (1.181). From 1820 to 1900, a fairly constant 206Pb/207Pb ratio of approximately 1.17 probably resulted from a combination of emissions from the smelting of indigenous Pb ore (1.170) and coal burning (1.181) in Scotland, and industrial activity to the south in England, where Australian Pb of characteristically low 206Pb/207Pb ratio (1.04) was already in use. From 1901 to 1930, the 206Pb/207Pb ratio declined by <0.01, due to the increasing influence of Australian Pb. From 1931 to 1975/1985, the 206Pb/207Pb ratio of anthropogenic Pb declined by a further 0.03 to 0.04, to minimum values from approximately 1975 to 1985, primarily a consequence of car-exhaust emissions of Pb arising from the introduction of alkyl Pb petrol additives (206Pb/207Pb approximately 1.06-1.09). From 1975/1985 to the mid-1990s, the 206Pb/207Pb ratio of anthropogenic Pb increased by up to 0.015, a consequence of a reduction in car-exhaust emissions of Pb, resulting from reductions in the maximum permitted concentration of Pb in petrol, and the introduction and increasing uptake of unleaded petrol. Source apportionment calculations, on the basis of 206Pb/207Pb values in surface sediment, suggested that the contribution of Pb emissions from the use of leaded petrol was 27-40% of the atmospheric burden by the mid-1990s, in line with estimates from rainwater 206Pb/207Pb data.     

Relative influence of 129I sources in a sediment core from the Kattegat area

The depth profiles of the (129)I concentration and the (129)I/(127)I ratio in a surface sediment core from the Kattegat area have been analyzed in order to obtain information about the different sources of (129)I in that core. Therefore, a mathematical model that relates the measured values to the available emission data from the nuclear fuel reprocessing plants and nuclear weapons tests has been applied. Results show that the reprocessing plants at La Hague and Sellafield are the main sources of (129)I in the sediment. Results about the transfer from the release points at the reprocessing plants to the sampling zone agree with other literature data. The model calculates quite fast the sedimentation of (129)I in the sampling place, probably attached to organic matter. Finally, an estimation of approximately 89 kg of (129)I released by Sellafield between 1952 and 1968 has been obtained from the model.     

Historical changes in the concentrations of selenium in soil and wheat grain from the Broadbalk experiment over the last 160 years

Selenium (Se) intake has decreased substantially in the UK population since 1970s. To investigate whether Se concentration in wheat grain has changed as a result of yield improvement or environmental changes, we analyzed archived wheat grain from the Broadbalk Wheat Experiment at Rothamsted, England, which has been run continuously for over 160 years. Wheat grain and soil samples were selected from plots receiving different fertilizer or manure treatments. Grain Se concentration varied from 11 to 236 ng g(-1), with a mean and median of 44 and 32 ng g(-1), respectively. Grain samples from the unfertilized control plot had significantly higher concentrations of Se than those from fertilized or manured plots; the latter received various amounts of S and also had higher grain yield. No significant trends in grain Se concentrations were detected in the fertilized or manured plots, in spite of a dramatic increase in grain yield since the introduction of modern short-straw cultivars in the mid 1960s. In the control plot, grain samples had higher Se concentrations in the periods before 1920 or after 1970 than those during 1920-1970. This temporal pattern mirrored that of SO(2) emissions and atmospheric S deposition. Soil Se concentrations showed an increasing trend in all plots over 160 years. The results show that the Se concentration of wheat grain from the Broadbalk experiment was influenced by S inputs from fertilizers and atmospheric deposition, and that improving grain yield through plant breeding has not resulted in a significant decrease in grain Se concentration in the fertilized plots.     

Changes in stable isotopes, lignin-derived phenols, and fossil pigments in sediments of Lake Biwa, Japan: implications for anthropogenic effects over the last 100 years

We measured stable nitrogen (N) and carbon (C) isotope ratios, lignin-derived phenols, and fossil pigments in sediments of known ages to elucidate the historical changes in the ecosystem status of Lake Biwa, Japan, over the last 100 years. Stable N isotope ratios and algal pigments in the sediments increased rapidly from the early 1960s to the 1980s, and then remained relatively constant, indicating that eutrophication occurred in the early 1960s but ceased in the 1980s. Stable C isotope ratios of the sediment increased from the 1960s, but decreased after the 1980s to the present. This decrease in stable C isotope ratios after the 1980s could not be explained by annual changes in either terrestrial input or algal production. However, when the C isotope ratios were corrected for the Suess effect, the shift to more negative isotopic value in atmospheric CO(2) by fossil fuel burning, the isotopic value showed a trend, which is consistent with the other biomarkers and the monitoring data. The trend was also mirrored by the relative abundance of lignin-derived phenols, a unique organic tracer of material that originated from terrestrial plants, which decreased in the early 1960s and recovered to some degree in the 1980s. We detected no notable difference in the composition of lignin phenols, suggesting that the terrestrial plant composition did not change markedly. However, we found that lignin accumulation rate increased around the 1980s. These results suggest that although eutrophication has stabilized since the 1980s, allochthonous organic matter input has changed in Lake Biwa over the past 25 years.     

Review and feedback of experience gained over the last fifty years in design and construction of natural-draught cooling towers

A review of natural-draught cooling towers and their development from the early 1930s to the present is given. Experience gained with these older towers, some of which are still in operation, is described and attention is drawn to aspects of construction and design that have proved to be unsatisfactory. Examples of towers with structural defects that have led to current design philosophy are described. Observations on other aspects of design of natural-draught cooling towers, such as foundations, packing, packing supports and lightning protection are given.     

Possible impacts of Hg and PAH contamination on benthic foraminiferal assemblages: an example from the Sicilian coast, central Mediterranean

The Palermo and Augusta urban/industrial areas (Sicily) are examples of contaminated coastal environments with a relatively high influx of unregulated industrial and domestic effluents. Three sediment box-cores were collected offshore of these urban/industrial areas in water depths of 60-150 m during two cruises (summers 2003/2004), dated by (210)Pb and (137)Cs, and analysed for total mercury concentration and total polycyclic aromatic hydrocarbon (PAH) concentration. Benthic foraminiferal assemblages were also examined (in terms of their distribution and morphology) to assess the potential use of benthic foraminifera as bioindicators of pollutant input and environmental change in these Mediterranean shelf environments. The Hg and PAHs vs depth profiles show a clear increase in concentration with decreasing depth. Most of the sediments are highly enriched in mercury and show concentrations more than 20 times the background mercury value estimated for sediments from the Sicily Strait. The Hg and PAH concentrations appear to be potentially hazardous, grossly exceeding national and international regulatory guidelines. A reduction in abundance of benthic foraminifera, increasing percentages of tests with various morphological deformities, and the dominance of opportunistic species in more recent sediments can be correlated to anthropogenic impact.     

Accumulation of organic carbon over the past 150 years in five freshwater peatlands in western and central Europe

Under predicted scenarios of global climate change, peatlands may become a net source of greenhouse gases which will accelerate warming of the atmosphere. Comparative studies of peat bogs along present climatic gradients may provide an insight into the future response of boreal and subarctic peatlands to changing temperature and moisture. Three maritime peat bogs in the British Isles, and two high-elevation peatlands in the Czech Republic were studied. All sites were relatively wet, the mean annual temperatures were higher by up to 6 degrees C at the British/Irish sites than at the Czech sites. Cumulative carbon content in (210)Pb-dated Sphagnum-dominated vertical peat cores increased from the warmer to the colder sites when evaluated for the most recent decades (since ca. 1950). That would correspond to formation of thinner, more highly decomposed peat deposits over the long-term in warmer conditions, and deeper peat bogs in colder conditions. However, when cumulative carbon content was evaluated for the last ca. 150 years, no relationship was found between mean annual temperature and the carbon pool size. Even along broad present-day climatic gradients, site-specific factors controlled organic carbon preservation in peat. Pollen analysis was instrumental in corroborating the (210)Pb dates, identifying wet and dry periods in the past, and it also provided evidence for increasing nitrogen loads in wetland areas.     

Modern and historical fluxes of halogenated organic contaminants to a lake in the Canadian arctic, as determined from annually laminated sediment cores

Two annually laminated cores collected from Lake DV09 on Devon Island in May 1999 were dated using 210Pb and 137Cs, and analyzed for a variety of halogenated organic contaminants (HOCs), including polychlorinated biphenyls (PCBs), organochlorine pesticides, short-chain polychlorinated n-alkanes (sPCAs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs). Dry weight HOC concentrations in Lake DV09 sediments were generally similar to other remote Arctic lakes. Maximum HOC fluxes often agreed well with production maxima, although many compound groups exhibited maxima at or near the sediment surface, much later than peak production. The lower than expected HOC concentrations in older sediment slices may be due to anaerobic degradation and possibly to dilution resulting from a temporary increase in sedimentation rate observed between the mid-1960s and 1970s. Indeed, temporal trends were more readily apparent for those compound classes when anaerobic metabolites were also analyzed, such as for DDT and toxaphene. However, it is postulated here for the first time that the maximum or increasing HOC surface fluxes observed for many of the major compound classes in DV09 sediments may be influenced by climate variation and the resulting increase in algal primary productivity which could drive an increasing rate of HOC scavenging from the water column. Both the fraction (F(TC)) and enantiomer fraction (EF) of trans-chlordane (TC) decreased significantly between 1957 and 1997, suggesting that recent inputs to the lake are from weathered chlordane sources. PCDD/Fs showed a change in sources from pentachlorophenol (PeCP) in the 1950s and 1960s to combustion sources into the 1990s. Improvements in combustion technology may be responsible for the reducing the proportion of TCDF relative to OCDD in the most recent slice.     

Environmental response to climate and human impact during the last 400 years in Taibai Lake catchment, middle reach of Yangtze River, China

Element content, grain size, pollen and 210Pb dating analysis were performed on 80 cm sediment core from Taibai Lake, a shallow lake in the middle reach of Yangtze River in China, to reveal the response of catchment environment to climate changes and human activities during the past four centuries. The 210Pb dating suggests that 0-39.5 cm of the core represents the past 163 years and bottom of the core is at ca. 1590 AD. Major changes showed in the core are compared with the records from historical documents, including population, cultivation and climate etc. 1700-1810 AD was the period with intensive human activities in Taibai Lake catchment, behaving as deforestation and cereal cultivation expansion, signaled in the sediments by low percentage of pinus pollen and high percentage of Gramineae pollen, high content of <16 microm fraction. Another period with intensive human activities was since 1928 AD, behaving as deforestation, reservoir construction, land reclamation, soil loss. The high sedimentation flux epochs, such as 1900-1920 AD, 1931 AD, 1938-1939 AD and 1954 AD, were correlated with high precipitation; nevertheless, the high sedimentation flux epochs in 1958-1970 AD and 1983-1993 AD were correlated with the land reclamation around Taibai Lake and soil loss due to intensive cultivation development respectively. The two coldest stages during the "Little Ice Age" were in 1650-1700 AD and 1810-1900 AD, consistent with the historical records generally, characterized by weak weathering, high forest coverage and weak human activities in Taibai Lake catchment.     

Adjustment behaviour of capital structure over the business cycles: evidence from the construction industry of Taiwan

Prior studies have found that firms may deviate from the target capital structure in the short run and adjust towards the target in the long run. However, little attention has been given to the adjustment behaviour of capital structure in the construction industry over the business cycles, in particular within the context of emerging markets. The partial adjustment model with the GMM (i.e. generalized method of moments) estimation is used to examine the adjustment behaviour of capital structure in the construction industry within the context of Taiwan during the period 1982 to 2007. The results suggest that, first, the average rate of adjustment is 26.3% of the adjustment gap between the target debt ratios and the previous debt ratios for firms in the construction industry of Taiwan. However, the average rate of adjustment towards the target debt ratios has slowed down after the Asian financial crisis of 1997. Secondly, firms with the financial constraint of over‐leverage relative to the target debt ratios have lower debt ratios than those firms with the financial constraint of under‐leverage. In addition, the difference in debt ratios between firms with the financial constraint of over‐leverage and under‐leverage has become narrower after the Asian financial crisis. Lastly, the findings suggest that macroeconomic conditions do not have a significant, negative effect on debt ratios.     

Variability in the geotechnical properties of a lateritic soil from south western Nigeria

Four bulk soil samples of lateritic soil from the subgrade of the stable flexible highway pavement at Awosun village, near Ile-Ife, Nigeria, were investigated to determine the variation in geotechnical properties within a horizontal distance of 39 m. The California bearing ratio and uniaxial compressive strength were found to vary significantly over this short length. The importance of detailed and thorough sampling of lateritic soils is emphasized for proper evaluation of highway subgrade soils.      

Phosphate exchange characteristics of wet and dried sediment samples from a hypertrophic reservoir: Implications for the measurements of sediment phosphorus status

This paper examines changes in the phosphate exchange characteristics induced in sediment samples by drying during preparation for analysis. Comparison of selected sediment parameters measured in wet and dried subsamples of a range of sediments from hypertrophic Hartbeespoort Dam showed that air drying resulted in major changes in their physical and chemical composition. Particle size distribution in the dried sediments showed a shift towards larger particles, particularly in samples in which smaller particles were abundant, indicative of irreversible aggregation of finer particles. Drying decreased the bioavailable phosphorus (NTA-extractable) content of sediments but reduced the phosphate buffering capacity and increased the phosphate equilibrium concentrations by a factor of 3, thereby increasing the phosphate release potential of dried sediments. Since sediment phosphorus status is often studied with a view to assessing the role of sediments in phosphorus cycling and eutrophication control, it is concluded that inappropriate decisions could result from the use of dried samples for analysis. The implications of these results in the marginal zones of lakes, which experience natural dehydration during periods of draw-down, are discussed.     

Mercury contamination in the vicinity of a derelict chlor-alkali plant. Part I: sediment and water contamination of Lake Balkyldak and the River Irtysh

A mercury-cell chlor-alkali plant operated in Pavlodar, Northern Kazakhstan, for 18 years and caused widespread contamination of the surrounding environment. Untreated wastewater from the plant was discharged to Lake Balkyldak, a shallow impounded lake without an outlet. The nearby River Irtysh was also suspected to be impacted by mercury (Hg) via the transport of contaminated groundwater. We took sediment and water samples from both aquatic systems, and also sampled soils along the shoreline of the lake and in the Irtysh flood plain. Sediments from Lake Balkyldak were found to be very heavily contaminated, with Hg concentrations in the surface layer reaching up to approximately 1500 mg kg(-1) near the wastewater outfall pipe. The contaminated lake sediments are prone to wind-driven resuspension and are acting as a strong source of Hg to the water column. Unfiltered lake water samples taken in shallow areas within 10-15 m from the shoreline contained from 0.11 microg Hg L(-1) in the less contaminated northern part of the lake to 1.39 microg L(-1) near the pollutant outfall in the south (up to 7.3 microg L(-1) on windy days). Sediments from the River Irtysh were only slightly impacted, with maximum Hg concentrations of 0.046 mg kg(-1) in the old river channel and 0.36 mg kg(-1) in floodplain oxbow lakes. In water samples from the River Irtysh, Hg was generally not detected, although trace concentrations (3 to 9 ng L(-1)) were found in some samples taken from oxbow lakes. We conclude that the river is not significantly impacted by Hg, but the highly contaminated Lake Balkyldak poses a threat and is in need of remediation. Potential remediation options for the lake are reviewed and are discussed in the context of experiences made at other Hg-contaminated sites.     

How the capital structure of firms is determined over business cycles: further evidence from the construction industry of Taiwan

This paper uses the panel data regression model to study the Taiwanese construction industry during the period 1982–1995 because during this period, Taiwan’s gross domestic product shows a structural change in economic growth trends over three business cycles. This design allows us to examine whether the effects of firm characteristics and economic growth on capital structure vary with macroeconomic conditions and across periods with changing economic growth trends. First, the results show that the effect of macroeconomic conditions on capital structure is counter-cyclical. Second, the effects of firm characteristics on capital structure can vary with macroeconomic conditions, although firm characteristics do not have a direct effect on capital structure. Third, the effects of firm characteristics on capital structure can vary across periods with changing economic growth trends. Finally, economic growth does not have a direct effect on capital structure. However, the effect of economic growth on capital structure can vary with macroeconomic conditions and across periods with changing economic growth trends. The findings of this study can be a helpful reference for financial managers, creditors, investors and government policy-makers in emerging countries.     

中部中心城市发展的战略思考--以湖北省宜昌市为例

“促进中部崛起”战略的提出．为中部地区城市带来了发展机遇。如何在科学发展观的指导下。正确认识和把握这一机遇．探索符合地方实际的发展模式。是这些城市在规划中面临的重要课题。     

Occupational segregation in a country of recent mass immigration: evidence from Spain

The aim of this paper is to study the occupational segregation of immigrants in Spain. It analyzes whether age, educational level, gender, region of origin, and years of residence in Spain affect the distribution of immigrants across occupations. In addition, given the remarkable increase of immigrants in the last few years and the adjustments that have occurred in the Spanish labor market from the current economic crisis, the evolution of the occupational segregation of immigrants between 1996 and 2009 is addressed. For these purposes, several measures recently proposed in the literature are used.     

Reconstruction of summer temperatures in East Siberia (Russia) for the last 850 years,inferred from records in lake sediments of non-biting midges (Diptera: Chironomidae)

We analysed a 42-cm-long sediment record from Lake Mountain located in East Siberia (Russia) for the reconstruction of summer temperature for the last 850 years. The high latitude of East Siberia at 52°N is probably sensitive to variation in insolation and solar activity. According to our reconstruction, clear decrease in summer temperatures occurred in East Siberia after ca. 1400 and we linked this temperature drop with the beginning of the Little Ice Age. The coldest summer occurred about ca. 1570–1700 and 1830–1900.     

Use of 222radon as a simple tool for surface water–groundwater connectivity assessment: a case study in the arid Limarí basin,north‐central Chile

We report the results from a pilot study on the use of ²²²Rn (²²²radon) for river–aquifer interaction assessment in the Limarí watershed, north‐central Chile. Previous studies on this tool for such applications are not abundant at international level, and no records exist for Chile. The lowest ²²²Rn levels (less than 1000 Bq/m³) were found in water reservoirs, thus indicating that this isotope is easily lost (and therefore usually absent) in surface waters. Conversely, the highest levels of ²²²Rn were found in groundwater, with maxima activities around 20 000 Bq/m³. This remarkable contrast allowed clear identification of zones of surface water–groundwater connectivity in the searched watershed domain.     

The multidimensional structure of subjective well-being: evidence from a rural area in Sicily

The paper looks at subjective well-being, defined in terms of individuals’ self-reported satisfaction with life, investigating nine dimensions (domains). The combination of the selected domains is obtained by applying methodologies known as composite indices. Compared to what is already known, this study explores well-being in a rural area with the aim to analyse if phenomena such as depopulation, abandonment of agricultural activities, economic crises and migration affect the well-being of the population. In particular, changes in subjective well-being are assessed for a rural community in the South of Italy (Sicily) and the interactions are analysed between changes in subjective well-being and changes in the other factors. This study finds, through the construction of a composite index, that well-being is a complex and multidimensional phenomenon in which there are numerous interacting factors.