Biomonitoring of metal deposition in northern Spain by moss analysis

The results of the first survey carried out in northern Spain to determine atmospheric deposition of metals by analysis of terrestrial mosses, are described. Samples of different mosses, mainly Hypnum cupressiforme and Scleropodium purum, were collected from 134 sampling sites, between 1995 and 1996. Levels of Al, As, Cr, Cu, Fe, Hg, Ni, Pb and Zn, were determined by flame atomic absorption or atomic fluorescence spectrophotometry. Regression analysis was used to compare the capacity of the selected moss species to accumulate the elements, and intercalibration of accumulation in these species was carried out where necessary. Distribution maps were prepared to allow the zones most affected by metal deposition to be identified and to relate this to known sources of contamination: electricity power stations and other industries (e.g. Hg and Ni), edaphic contamination (e.g. Al and Cr) and road traffic (Pb). Background levels of metals in each species were also determined for the study area.     

Temporal and spatial trends of mercury in fish collected in the English-Wabigoon river system in Ontario, Canada

The First Nations communities of Grassy Narrows and Wabaseemong (Ontario, Canada) have been impacted by mercury pollution since the 1960s. This study was implemented with the objective of providing these communities with information on current mercury concentrations in their catch, in order to make appropriate fish consumption choices. A total of 851 fish samples, including Walleye, Northern Pike, Large-mouth Bass, and Whitefish, were collected from thirteen lakes and rivers. Total mercury was measured and the relationship between fish length, mercury concentration, and lake of origin were assessed. It was found that fish from most of the lakes exhibit a positive relationship between length and mercury accumulation. Mercury concentrations in fish collected from Clay Lake, closest to the original source of contamination, are higher than those from other lakes. Mercury concentrations have declined over the last 25 years but the gradient of contamination was still observed. Results were communicated to the communities for public health purposes.     

Temporal trends of cadmium and mercury in Greenland marine biota

Data for cadmium and mercury in Greenland marine biota (blue mussels, polar cod, shorthorn sculpin, glaucous gull and ringed seals) over a period of 20 years has been analysed in order to assess temporal changes. Most of the comparisons were conducted between tissue samples collected in the mid-1980s and mid-1990s. Cadmium data from a few time series obtained at reference sites during monitoring of mining activities were also included. No overall temporal trends in cadmium or mercury concentrations were found within the 20-year period assessed. However, cadmium concentrations in ringed seals tended to increase in the period from late-1970s to the mid-1980s. From the mid-1980s to the mid-1990s cadmium concentrations in ringed seals decreased again, whilst mercury concentrations showed a tendency to increase in the same period. The observed changes may reflect natural fluctuations caused by factors such as a shift in feeding behaviour, rather than changes in anthropogenic exposure.     

The spatial and temporal trends of Cd, Cu, Hg, Pb and Zn in Seine River floodplain deposits (1994-2000)

Fresh floodplain deposits (FD), from 11 key stations, covering the Seine mainstem and its major tributaries (Yonne, Marne and Oise Rivers), were sampled from 1994 to 2000. Background levels for Cd, Cu, Hg, Pb, and Zn were established using prehistoric FD and actual bed sediments collected in small forested sub-basins in the most upstream part of the basin. Throughout the Seine River Basin, FD contain elevated concentrations of Cd, Cu, Hg, Pb and Zn compared to local background values (by factors>twofold). In the Seine River Basin, trace element concentrations display substantial downstream increases as a result of increasing population densities, particularly from Greater Paris (10 million inhabitants), and reach their maxima at the river mouth (Poses). These elevated levels make the Seine one of the most heavily impacted rivers in the world. On the other hand, floodplain-associated trace element levels have declined over the past 7 years. This mirrors results from contemporaneous suspended sediment surveys at the river mouth for the 1984-1999 period. Most of these temporal declines appear to reflect reductions in industrial and domestic solid wastes discharged from the main Parisian sewage plant (Seine Aval).     

Atmospheric metal deposition in a moss data correlation study with mortality and disease in the Netherlands

The present paper addresses the correlations between moss metal concentrations and epidemiological data on health and mortality rates in The Netherlands. Attention was given to both total and fractionated metal concentrations in the moss tissues, the latter by factor-analytical (mathematical) approaches, and to both grouped and specific diseases. Better than 95% probability correlations were found both for total moss elements and mortality due to specific diseases and for fractionated moss elements and mortality rates summed for grouped diseases. Overall, the presented data suggest that correlation studies between biomonitoring data on metal air pollution and (epidemiological) health data may prove valuable in turning attention to specific metal-health issues and in directing further study into possible dose-response mechanisms in air-associated metal epidemiology.     

Atmospheric deposition of arsenic and selenium across Canada using Sphagnum moss as a biomonitor

A biomonitoring study was made of the atmospheric deposition of arsenic and selenium across northern Canada utilizing Sphagnum fuscum moss. Intensive sampling was carried out adjacent to the smelter at Rouyn-Noranda, Quebec. An average background concentration of arsenic in the moss of 0.66 mg kg-1 was determined, while most selenium concentrations were below the detection limit of 0.2 mg kg-1. Elevated arsenic concentrations were found in the vicinity of the mining and smelting areas of Flin Flon, Manitoba, and Atikokan, Ontario. High concentrations of selenium were detected only near Rouyn-Noranda. Both arsenic and selenium occurred in moss at concentrations lower than found in Canadian soils.     

Temporal trends of Cd, Cu, Hg, Pb and Zn in mussel (Mytilus galloprovincialis) from the Spanish North-Atlantic coast 1991-1999

Temporal trends for heavy metals (Cd, Cu, Hg, Pb and Zn) in mussel (Mytilus galloprovincialis) from the Galician and Cantabrian areas in Spain, where samples were yearly collected from 1991 to 1999, are presented. This study was carried out by the Centro Oceanográfico de Vigo of the Instituto Espa?ol de Oceanografia (I.E.O.) as part of the Spanish contribution to the Joint Assessment and Monitoring Programme (JAMP) of the OSPAR Convention. The experimental work and subsequent statistical treatment, following OSPAR procedures and guidelines, are described. In order to carry out the statistical treatment of the data, median values of the different shell length classes were used for each contaminant, year and area. The Kendall T-b correlation coefficient was used with the purpose of demonstrating the existence of a downward significant temporal trend in the pollution levels, according to the advice of ICES Working Group on Statistical Aspects of Environmental Monitoring. A decrease of copper levels was detected in Vigo, Pontevedra and Arosa, of mercury in Pontevedra and A Coru?a, of lead in Vigo, Pontevedra, A Coru?a and Bilbao and of zinc in Pontevedra and A Coru?a. However, a cadmium positive trend was registered at Ria de Vigo. No significant trends were detected in the other cases.     

Temporal and spatial variations of the Vienna aerosol

For several intensive sampling periods the mass concentration, light extinction, light scattering and light absorption coefficients, and the mass size distribution of the aerosol have been determined at up to eleven location in the non-industrial town of Vienna. Obviously, large variations of the measured values have been found. The following factors influenced the aerosol markedly: wind speed, wind direction, increased aerosol production such as by space heating or traffic and resuspension. Most of the variations in aerosol were found to be caused by these factors. A comparison of the mass concentration and light absorption of the aerosol upwind and downwind of Vienna permitted the estimation of locally produced aerosols: about 50% of the mass of the aerosol and 75% of the light-absorbing aerosol appears to be produced locally.     

Temporal trends in gaseous mercury evasion from the Mediterranean seawaters

Mercury evasion from seawaters is considered to be one of the main natural sources of mercury released to the atmosphere. The temporal evolution of this mechanism is related to biotic and abiotic processes that produce mercury in its elemental form and as DGM. The efficiency of these processes depends upon the intensity of the solar radiation, the ambient temperature of the air parcel above the seawater, and the water temperature. In the Mediterranean region, the magnitude of these mechanisms are particularly significant, due to favorable climate conditions and to the presence of large cinnabar deposits that cross the whole region; all these synergic factors yield significant evasional fluxes of mercury from the surface water during most of the annual period. In this work, mercury fluxes were measured by using a floating flux chamber connected to an atomic absorption analyzer. Photosynthetic active radiation (PAR) and UV components of the solar radiation were measured using the same system adopted in the EC 'ELDONet project'. The measurements of the mercury evasional fluxes were carried out at three sites of the northern Tyrrhenian Sea during 1998. Two sites were located at unpolluted and polluted coastal areas, and the third was an offshore site. The evasional flux showed a typical daily trend, highest at midday when the ambient temperature and solar radiation were at the maximum, and lowest, near to zero, during the night. Besides the day-night behavior, a seasonal trend was also observed, with minimum values during the winter period (0.7-2.0 ng/m2 h) and maximum values during the summer (10-13 ng/m2 h).     

Trace element deposition and trends during a ten year period in Finland

The deposition of aluminium, arsenic, cadmium, chromium, copper, iron, lead, manganese, nickel, vanadium and zinc in bulk precipitation was examined at eight background stations in Finland during the last 10 years (1998-2007). The annual deposition was from the lowest values to the highest Cd < As < Cr < Ni < V < Cu and Pb < Mn < Zn < Al < Fe. Most of the elements had a south to north decreasing gradient mainly due to minor domestic emissions in the north, growing distance to the large European source areas and differences in the length of snow-cover period. Element enrichment factors divided the trace elements to the following categories: (1) slightly enriched Cr, Fe and Mn; (2) moderately enriched Cu, Ni and V; and (3) highly enriched As, Cd, Pb and Zn. Trend analysis of annual depositions showed that the established decreasing trend in As and Pb deposition continued during our study period while Cr, Cu and Fe depositions have lately increased. No statistically significant trends were detected for Cd, Mn, Ni, V and Zn during the studied years. Additionally, the measurement uncertainty of trace elements was evaluated for the whole measurement chain.     

Pesticides in groundwater: some observations on temporal and spatial trends

Following a monitoring programme of private shallow boreholes a total of 22 different pesticides were detected in 14 shallow boreholes in the Triassic Sherwood Sandstone aquifer of south Yorkshire, UK between January 2002 and November 2003. Of the 294 positive detections made, 34% were detected in excess of the permitted concentration value (PCV) (drinking water standard) for individual pesticides. Pesticides were detected in 11 (78%) of the boreholes, and in eight (57%) at concentrations exceeding the PCV on at least one occasion. These findings were complemented by data from deeper boreholes in which concentrations exceeding the PCV were also detected. Pesticide occurrence could be related to landuse; mecoprop and isoproturon were frequently detected at several locations reflecting the arable landuse, dicamba at a golf course, and atrazine, propazine and terbutryn near a railway. Temporal variations have emerged at individual sites and across the study area as the result of extended and frequent monitoring.     

Temporal and spatial distributions of phosphine in Taihu Lake, China

Phosphine is a natural gaseous carrier of phosphorus in its geochemical cycles, and it might be of importance to the phosphorus balance of eutrophic lakes. Phosphine concentration levels in Taihu Lake, a typical shallow eutrophic lake in China, were intensely investigated in this work. Results show that in the period of 2002 the variation of phosphine concentration in the atmosphere near Taihu Lake is significant, with a maximum value 2.85 pg/l. Concurrent sampling of phosphine in surface and bottom water of the lake had no distinct change. The mean concentration of phosphine in the water ranged from 1.92 to 3.01 pg/l. Approximately 84-90% of the phosphine was removed from lake water during passage of the sample through a 0.45 microm pore size filter, i.e. the average phosphine concentrations of filtered lake water in all sampling locations were from 0.37 to 0.40 pg/l with the highest value 0.73 pg/l and the lowest 0.08 pg/l, whereas phosphine concentrations in unfiltered samples were 5-9 times higher. Phosphine levels in lake sediments were positively correlated with different contamination of the samples. The concentration levels of phosphine were also higher in severe polluted sites. The local average values of the phosphine concentrations were from 21550 to 563,100 pg/kg. Its highest value was 919,238 pg/kg at 6# site (Zhihu harbor), a severely polluted sampling site.     

Temporal and spatial differences in the elemental composition of atmospheric aerosols

Proton induced X-ray emission has been applied to the analysis of various elements in 250 aerosol loaded filter samples collected daily over a period of up to 3 months at different sites: (1) city-center; (2) residential area; (3) recreation area 20 km off city; and (4) remote alpine resort areas. The time dependence of different element concentrations shows high correlation with meteorological parameters. The average concentration ratio between site 1 and site 4 amounts up to 100.     

Temporal trends of legacy POPs in Arctic biota, an update

A statistically robust method was applied to 316 time-series of ‘legacy’ persistent organic pollutants (POPs) in Arctic biota from marine, freshwater and terrestrial ecosystems with the purpose of generating a ‘meta-analysis’ of temporal trend data collected over the past two to three decades for locations from Alaska in the west to northern Scandinavian in the east. Information from recently published temporal trend studies was tabulated and comparisons were also drawn with trends in arctic air. Most of the analysed time-series of legacy POP compounds showed decreasing trends, with only a few time-series showing significantly increasing trends. Compounds such as α-HCH, γ-HCH and ΣDDT had a relatively high proportion of time-series showing significantly decreasing trends; ΣCHL had the lowest proportion. β-HCH was an exception, where long-range transport through the ocean, and not the atmosphere, may explain several increasing trends that were detected in the Canadian Arctic. Moving east from the Canadian Arctic there was a trend towards a greater proportion of significantly decreasing trends. Several time-series for DDE and ΣDDT showed significantly non-exponential trends, most often with a period of relative stability followed by a decrease. The median ‘minimum detectable annual change within a 10-year period’ for all of the time-series considered was 12% which did not meet the desirable level of statistical power capable of detecting a 5% annual change with a significance level of 5% within a 10-year period. The trends observed in the biota were consistent with decreasing trends of legacy POPs reported for Arctic air which appear to follow historic decreases in emissions. However, recent decreases in air are also starting to show signs of levelling off which may be an indication that atmospheric concentrations and, consequently those in the biota, are being less driven by primary sources and more by environmental processes and degradation.     

Water quality of Scottish rivers: spatial and temporal trends

The Harmonised Monitoring Scheme (HMS) was initiated in 1974 and represents the best-organised source of temporal and spatial data describing water quality for the major mainland rivers of Scotland, England and Wales. This paper presents the first detailed analysis of HMS data for Scotland, and identifies temporal changes in water quality from 1974 to 1995. From a concomitant analysis of catchment land cover characteristics, water quality indices have been linked with potential 'drivers' of change, influencing both point and diffuse sources. Nitrate concentrations between rivers are highly correlated with the amount of arable land, and relationships exist between grassland cover, orthphosphate-P and suspended solids concentrations. Similarly, urban catchments are highly correlated with ammonium-N, orthophosphate-P and suspended solids. Spatial and temporal trends in water quality for the rivers of Scotland are discussed.     

Temporal and spatial influences of flooding on dissolved mercury in boreal reservoirs

Dissolved total mercury and methylmercury concentrations ([HgT]D and [MeHg]D, respectively) in natural lakes and reservoirs of varying age (2 months to 69 years) were monitored between 1993 and 1997, during different times of the year and at several sites within the same reservoir. Both HgT-D and MeHgD in flooded environments were significantly greater (Student's t-test, P < 0.001) than those determined for neighbouring lakes, with average concentrations of 2.35+/-0.85 ng(-1) (n = 79) vs. 1.51+/-0.43 ng l(-1) (n = 70) for HgT-D and 0.28+/-0.10 ng Hg l(-1) (n = 87) vs. 0.05+/-0.025 ng Hg l(-1) (n = 30) for MeHgD. Furthermore, the proportion of HgT-D in the methylated form was, on average, nearly four times greater in the reservoir sites as compared with those of the lakes (12% vs. 3.6%). Simple linear regressions used to compare [MeHg]D with nine water quality parameters suggest that factors controlling the presence of MeHgD are not the same in all flooded environments. Overall, our results demonstrate that [MeHg]D are higher in reservoirs as compared with natural lakes and that up to 18 years after reservoir construction [MeHg]D remain elevated as compared with background levels.     

Levels and spatial and temporal trends of contaminants in Greenland biota: an updated review

Knowledge of contaminant levels in Greenland biota has increased substantially in recent years, particularly for persistent organic pollutants. This paper reviews and updates knowledge of spatial and temporal trends of Cd, Hg and organochlorines (PCBs, DDTs, HCHs, HCB and chlordane-related compounds) in Greenland terrestrial, freshwater and marine biota. The most comprehensive studies of spatial trends of Cd and Hg in the terrestrial ecosystem concern lichens, with relatively complete coverage, and caribou (Rangifer tarandus), with coverage mainly in different regions of central West Greenland and Southwest Greenland. The Arctic char (Salvelinus alpinus) is the only freshwater organism for which studies of spatial trends of Hg levels have been completed. Information on spatial trends of Cd and Hg in the marine environment is available from studies of fish, seabirds, ringed seals (Phoca hispida) and polar bears (Ursus maritimus). Geographical patterns of Cd and Hg in Greenland biota were not always consistent among different species or different studies. In landlocked Arctic char the concentrations of Hg decreased from south to north. In marine animals levels of Hg tended to be higher in East Greenland than in West Greenland and Cd levels were highest in biota from Disko Island in central West Greenland. The observed regional differences are difficult to explain but in most cases the causes appear to be natural rather than anthropogenic. Only a few time series covering the last 20 years exist for Cd and Hg. The one time series indicating a temporal change is for ringed seals in Northwest Greenland, which shows an increasing trend of Hg and a decreasing trend of Cd since 1984. Whether the changes reflect anthropogenic inputs, seal behaviour or other environmental factors is unknown. The most significant new insights have concerned organochlorines. In general, levels of these compounds were very low in terrestrial biota compared to marine species. Concentrations in landlocked Arctic char were highest in Southeast Greenland and lowest in Northwest and Northeast Greenland. Marine species from East Greenland had consistently higher levels of SigmaPCB, SigmaDDT and SigmaHCH than marine species from West Greenland. Very few data exist to evaluate temporal changes of organochlorine levels in Greenland biota, and this is the most significant knowledge gap at present. The most pronounced change observed was a decrease of 78% in SigmaPCB levels in polar bears from East Greenland from 1990 to 2000. Levels of SigmaHCH in shorthorn sculpins (Myoxocephalus scorpius) and seals from both central West Greenland and central East Greenland appear to have decreased since 1994. Increasing trends of SigmaDDT from 1994 until now were found in both sexes of seals as well as in male sculpins from central West Greenland.     

Temporal and spatial inhibitory effects of zinc and copper on wastewater biofilms from oxygen concentration profiles determined by microelectrodes

To understand the temporal and spatial toxic effect of heavy metals on the microbial activities of biofilms, microelectrodes were used to measure the inhibitory oxygen (O₂) concentration profiles resulted from the effects of zinc (Zn²⁺) and copper (Cu²⁺). Using the O₂ microprofiles as bases, the spatial distributions of net specific O₂ respiration were determined in biofilms with and without treatment of 5 mg/L Zn²⁺ or 1 mg/L Cu²⁺. Results show that microbial activities were inhibited only in the outer layer (∼400 μm) of the biofilms and bacteria present in the deeper sections of the biofilms became even more active. The inhibition caused by the heavy metals was evaluated by two methods. One was derived from the oxygen influx at the interface and the other was based on the integral of the oxygen consumption calculated from the entire O₂ profile. The two methods yielded significantly different results. We argue that the integral method results in more accurate assessment of toxicity than the surface flux determination.     

挖掘机市场分析与发展趋势

液压挖掘机被誉为工程机械之王,广泛应用于土石方工程,市政工程、路面修复、农田改造、混凝土破碎、管道铺设、园林栽培及河沟清淤等基础建设和生产领域.从1997年以来,挖掘机市场以年均33.2%的速度增长,2007年产量超过6万台,近10年国内挖掘机行业取得了可喜的成绩(图1).     

Geographic information systems and spatial analysis

Geographical Information Systems (GIS) are capable of acquiring spatially indexed data from a variety of sources, changing the data into useful formats, storing the data, retrieving and manupulating the data for analysis, and then generating the output required by a given user. Their great strength is based on the ability to handle large, multilayered, heterogenous databases and to query about the existence, location and properties of a wide range of spatial objects in an interactive way. The lack of analytical and modelling functionality is, however, widely recognised as a major deficiency of current systems. There is a wide agreement in both the GIS community and the modelling community that the future success of GIS technology will depend to a large extent on incorporating more powerful analytical and modelling capabilities. This paper discusses some major directions and strategies to increase both the analytical and modelling capabilities and the level of intelligence of geographic information systems.