Observed cold season changes in a Fennoscandian fell area over the past three decades

We studied trends and variability in snow and climate characteristics in 1978–2012 in the Värriötunturit fell area, northern Finland. Cold season changes were examined using long-term observational data on snow depths, meteorological data, large-scale climate indices, and reindeer herders’ experiences with difficult snow conditions. Snow depths declined, and temperatures increased significantly over the study period, with the largest changes observed in October–December and in April. Snow depths decreased particularly in forests at lower altitudes but not in treeless areas at higher altitudes. Interannual variability (but not the trends) in snow depths could be partially linked to large-scale climate indices. A majority of difficult reindeer grazing conditions were related to deep snow in the winter or spring. Our observations suggest that shortened duration of snow cover may facilitate reindeer grazing, whereas potentially more frequent formation of ice layers and mold growth on pastures in the future is disadvantageous for reindeer husbandry.     

Linking fine-scale sub-arctic vegetation distribution in complex topography with surface-air-temperature modelled at 50-m resolution

Recent studies have shown that the complexities of the surface features in mountainous terrain require a re-assessment of climate impacts at the local level. We explored the importance of surface-air-temperature based on a recently published 50-m-gridded dataset, versus soil variables for explaining vegetation distribution in Swedish Lapland using generalised linear models (GLMs). The results demonstrated that the current distribution of the birch forest and snowbed community strongly relied on the surface-air-temperature. However, temperature alone is a poor predictor of many plant communities (wetland, meadow). Because of diminishing sample representation with increasing altitude, the snowbed community was under-sampled at higher altitudes. This results in underestimation of the current distribution of the snowbed community around the mountain summits. The analysis suggests that caution is warranted when applying GLMs at the local level.     

Evaluation of SO2 dry deposition over short vegetation in Portugal

SO₂ dry deposition was studied over short vegetation, in Portugal, by means of the concentration gradient method. The experimental study involved one first phase of long-term measurements carried out in a grassland and, subsequently, a second period of several 1997 intensive field campaigns performed in three places representing different climate and surface conditions. Temporal and spatial patterns of dry deposition parameters show that downward fluxes of SO₂ are by some extent affected by surface processes. Median R_c varied from 140 s cm⁻¹ to values around 200 s cm⁻¹, in a wide range of environmental conditions. Stomatal uptake is an important sink when vegetation is biologically active, but its contribution is effectively low when compared with non-stomatal mechanisms, especially when the surface is wet. Under dry conditions R_c increases by a factor of two, but SO₂ deposition rates then still are significant. The parameterisation of the surface resistance for SO₂ proved to be difficult, but V_d derived with the Erisman parameterisation (Erisman et al., Atmos. Environ. 28 (16) (1994) 2595) compared best with measured values, at low time resolution scale and especially under moisture conditions.     

Assessing heavy metal pollution in the surface soils of a region that had undergone three decades of intense industrialization and urbanization

Heavy metals in the surface soils from lands of six different use types in one of the world’s most densely populated regions, which is also a major global manufacturing base, were analyzed to assess the impact of urbanization and industrialization on soil pollution. A total of 227 surface soil samples were collected and analyzed for major heavy metals (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) by using microwave-assisted acid digestion and inductively coupled plasma–mass spectrometry (ICP-MS). Multivariate analysis combined with enrichment factors showed that surface soils from the region (>7.2?×?10⁴ km²) had mean Cd, Cu, Zn, and As concentrations that were over two times higher than the background values, with Cd, Cu, and Zn clearly contributed by anthropogenic sources. Soil pollution by Pb was more widespread than the other heavy metals, which was contributed mostly by anthropogenic sources. The results also indicate that Mn, Co, Fe, Cr, and Ni in the surface soils were primarily derived from lithogenic sources, while Hg and As contents in the surface soils were controlled by both natural and anthropogenic sources. The pollution level and potential ecological risk of the surface soils both decreased in the order of: urban areas?>?waste disposal/treatment sites?～?industrial areas?>?agricultural lands?～?forest lands?>?water source protection areas. These results indicate the significant need for the development of pollution prevention and reduction strategies to reduce heavy metal pollution for regions undergoing fast industrialization and urbanization.     

Research trends and hotspots of aquatic biofilms in freshwater environment during the last three decades: a critical review and bibliometric analysis

Environmental Science and Pollution Research - Freshwater periphytic biofilms (FPBs), existing widely in various aquatic environments, have attracted extensive attention for many years. In the...     

Polychlorinated biphenyls (PCBs) in the atmosphere of sub-alpine northern Italy

The main objective of this work was to assess the atmospheric concentrations and seasonal variations of selected POPs in a sub-alpine location where few data are available. A monitoring and research station was set up at the JRC Ispra EMEP site (Italy). We present and discuss a one-year data set (2005-2006) on PCB air concentrations. ∑7PCBs monthly averaged concentration varied from 31 to 76 pg m⁻³. Concentrations in the gas phase (21-72 pg m⁻³) were higher than those in the particulate phase (3-10 pg m⁻³). Advection of air masses and re-volatilization from local sources seem to play a dominant role as drivers of PCB atmospheric concentrations in the area. Indications of seasonal variation affecting PCB congener patterns and the gas/particulate partitioning were found. Modeling calculations suggest a predominant importance of the wet deposition in this region (1 μg m⁻² yr⁻¹ ∑7PCBs yearly total wet deposition flux; 650-2400 pg L⁻¹ rainwater concentrations).     

Changes in concentration of lead and cadmium in water from three rivers in Derbyshire

River water from three sites in different streams in Derbyshire was sampled during different periods within 1 year to evaluate fluctuations in cadmium and lead concentration. The results indicate that most of the cadmium was in solution, while most of the lead was associated with particles at all sites. Period of sampling appeared to have a greater effect on the concentration of cadmium and lead than flow rate: metal levels were higher in spring than in autumn. Nevertheless, the total lead concentration increased with flow rate, presumably because more particles were then brought into suspension; however, the lead concentration in the filtrate was reduced at higher flow rates, presumably due to dilution in the greater water volume. Dissolved cadmium concentration increased with rising flow rate at relatively low flow rates and was diluted at high flow rates. The data suggest that particles with which most of the lead is associated remain in suspension for a considerable time even when flow rate decreases.     

Visibility trends in Korea during the past two decades

Temporal trends and spatial distributions of visibility measured by the human eye over 60 stations in Korea between 1980 and 2000 are analyzed and discussed. Generally, visibility is lowest on winter mornings and highest on summer afternoons throughout Korea. Visibility in Seoul is now in an increasing trend while it has decreased nationwide, especially in clean coastal areas. Spatial distribution of visibility in the 1990s was related negatively to that of relative humidity (RH). However, visibility generally decreased despite an overall decrease in RH throughout the country. Air pollutants should have played a role in this dissonant variation, particularly in relatively clean areas and on summer afternoons. It was interpreted that the visibility increase in major metropolitan areas, including the greater Seoul area, in the 1990s was caused mainly by the reduction in pollutant emissions by rigorous government policy. But the effect of the emission reduction was manifested with decreasing RH.     

Extractability and bioavailability of zinc over time in three tropical soils incubated with biosolids

Phytotoxicity of heavy metal is the primary concern in applying biosolids (sewage sludge) to agricultural land. This study evaluates the changes in chemical speciation of Zn in three tropical soils of Taiwan measured with sequential extraction over a one-year period. Biosolids were applied to the soils at application rates of 10, 50 and 100 Mg ha(-1), and correlated diethylene triamine pentaacetic acid (DTPA) and sequential extraction as extract for prediction of Zn bioavailability to Chinese cabbage (Brassica chinensis L.). Experimental results indicated that the exchangeable (F1) and Fe-Mn oxide (F3) fractions in the sequential extractions increased with application rate of biosolids in the soils over time. Large amounts of Zn in the soils following the cessation of biosolids application were identified as soluble and were adsorbed by Fe-Mn oxides. The organically bound Zn, which is associated with readily decomposable carbon, is in limited amounts in the biosolid-treated soils. The DTPA-extractable concentrations of Zn in all biosolid-treated soils decreased over the time. A positive and significant correlation (r(2) = 0.96) was found between the Zn concentrations extracted with DTPA and sum of F1 and carbonate-bound (F2) fractions in the sequential extractions. Additionally, the concentrations of Zn extracted with DTPA were strongly correlated with the concentrations of Zn in the shoots of Chinese cabbages, indicating that F1+F2 in the sequential extractions was reliable for predicting Zn bioavailability to Chinese cabbage in the biosolid-treated soils.     

Tundra in the rain: differential vegetation responses to three years of experimentally doubled summer precipitation in Siberian shrub and Swedish bog tundra

Precipitation amounts and patterns at high latitude sites have been predicted to change as a result of global climatic changes. We addressed vegetation responses to three years of experimentally increased summer precipitation in two previously unaddressed tundra types: Betula nana-dominated shrub tundra (northeast Siberia) and a dry Sphagnum fuscum-dominated bog (northern Sweden). Positive responses to approximately doubled ambient precipitation (an increase of 200 mm year(-1)) were observed at the Siberian site, for B. nana (30 % larger length increments), Salix pulchra (leaf size and length increments) and Arctagrostis latifolia (leaf size and specific leaf area), but none were observed at the Swedish site. Total biomass production did not increase at either of the study sites. This study corroborates studies in other tundra vegetation types and shows that despite regional differences at the plant level, total tundra plant productivity is, at least at the short or medium term, largely irresponsive to experimentally increased summer precipitation.     

Changes in the wet precipitation of sodium and chloride over the continental United States, 1984–2006

Data on wet-only precipitation from the National Atmospheric Deposition Program/National Trends Network were analysed for trends in the sodium and chloride fluxes over the United States between 1 January 1984 and 31 December 2006. The data were first checked for consistency and for ionic balance. It was necessary to correct for changes in bicarbonate due to changes in atmospheric CO₂ levels over the study period, in order to obtain a balance. The fluxes were calculated and the trends determined by linear regression in the log domain. The significance of the trends was checked using both F- and t-tests. At 154 sites having reasonably continuous records over the assessment period, the sodium flux fell significantly at 139 and increased significantly at only one. The chloride flux similarly fell significantly at 140 and increased significantly at the same one as the sodium flux increased. At coastal sites the chloride to sodium ratio was the same as that in sea water, within experimental limits. Further from the coast the ratio changed apparently due to changes in the entire aerosol chemistry. The findings are discussed in terms of the simplicity and robustness of the methodology employed to determine the trends; the oceanic origin of most observable sodium even in the interior of the continent, probably because it occurs as a fine (<1 micron) aerosol which is poorly scavenged by precipitation; and the possibility that the drop in sodium and chloride fluxes might be driven by climate change.     

Comparison and significance of annual hydrochemical budgets in three small granitic catchments with contrasting vegetation (Mont-Lozere, France)

Chemical budgets are presented for three small granitic catchments in Southeastern France, with contrasting vegetation type: beech coppice; spruce forest; and grassland. The results show a small net loss of cations, and a large accumulation of sulphur in the soil, which acts as an additional proton sink. Significantly higher weathering rates are observed for the conifer catchment. Clearfelling of the spruce forest, late in the monitoring programme, increased net cation and nitrate losses. The importance of dry atmospheric deposition in the input-output budget, particularly for forests, is highlighted.     

Two decades of experimental manipulations of heaths and forest understory in the subarctic

Current atmospheric warming due to increase of greenhouse gases will have severe consequences for the structure and functioning of arctic ecosystems with changes that, in turn, may feed back on the global-scale composition of the atmosphere. During more than two decades, environmental controls on biological and biogeochemical processes and possible atmospheric feedbacks have been intensely investigated at Abisko, Sweden, by long-term ecosystem manipulations. The research has addressed questions like environmental regulation of plant and microbial community structure and biomass, carbon and nutrient pools and element cycling, including exchange of greenhouse gases and volatile organic compounds, with focus on fundamental processes in the interface between plants, soil and root-associated and free-living soil microorganisms. The ultimate goal has been to infer from these multi-decadal experiments how subarctic and arctic ecosystems will respond to likely environmental changes in the future. Here we give an overview of some of the experiments and main results.     

Study on the aerosol optical properties and their relationship with aerosol chemical compositions over three regional background stations in China

The special and temporal characteristics of aerosol optical depth (AOD) and Angstrom wavelength exponent (Alpha) and their relationship with aerosol chemical compositions were analyzed by using the data of CE318 sun-photometer and aerosol sampling instruments at Lin'an, Shangdianzi and Longfengshan regional atmospheric background stations. Having the highest AOD among the three stations, Lin'an shows two peaks in a year. The AOD at Shangdianzi station shows a single annual peak with an obvious seasonal variation. The AOD at Longfengshan station has obvious seasonal variation which peaks in spring. The Alpha analysis suggests that the aerosol sizes in Lin'an, Longfengshan and Shangdianzi change from fine to coarse categories. The relationship between the aerosol optical depths of the Lin'an and Longfengshan stations and their chemical compositions is not significant, which suggests that there is not a simple linear relationship between column aerosol optical depth and the near surface chemical compositions of atmospheric aerosols. The aerosol optical depth may be affected by the chemical composition, the particle size and the shape of aerosol as well as the water vapor in the atmosphere.     

Changes in soil microbial biomass and Zn extractability over time following zn addition to a paddy soil

A laboratory incubation study was conducted using a paddy soil spiked with two quantities of Zn as soluble Zn(NO3)2 and unamended controls. Three single extractants (1 M ammonium acetate (pH 7.0), 0.43 M acetic acid and 0.05 M EDTA) were used to assess the bioavailability of Zn. Biological community assessments were made microbial biomass (chloroform fumigation), soil basal respiration and dehydrogenase activity. During the 84-day period of the experiment, addition of Zn at both 500 and 1,000 mg kg(-1) had little detectable effect on soil pH. The concentration of NH4OAc-extractable Zn decreased rapidly within the initial six weeks. The concentration of HOAc-extractable Zn showed no decrease during 84 days incubation. EDTA-extractable Zn was greater than NH4OAc- and HOAc-extractable fractions, and showed a similar trend to NH4OAc-extractable after incubation. Microbial biomass, soil basal respiration and dehydrogenase activity all decreased over time during 84 days incubation. Addition of Zn resulted in a significant increase in specific respiration (qCO2). Microbial biomass and dehydrogenase activity did not appear to be influenced by added Zn, probably due to the strong buffering capacity of the soil. The Zn extracted by EDTA, HOAc and NH4OAc showed close relationships with each other (p < 0.001). Zinc extracted by 0.05 M EDTA and NH4OAc were highly correlated with soil basal respiration and specific respiration rate (p < 0.01). The results suggest that NH4OAc-extractable Zn combined with soil specific respiration could be used as parameters for risk assessment.     

Hotspots and key periods of Greenland climate change during the past six decades

We investigated air temperature and pressure gradients and their trends for the period 1996–2014 in Greenland and compared these to other periods since 1958. Both latitudinal temperature and pressure gradients were strongest during winter. An overall temperature increase up to 0.15 °C year^?1 was observed for 1996–2014. The strongest warming happened during February at the West coast (up to 0.6 °C year^?1), weaker but consistent and significant warming occurred during summer months (up to 0.3 °C year^?1) both in West and East Greenland. Pressure trends on a monthly basis were mainly negative, but largely statistically non-significant. Compared with other time windows in the past six decades, the period 1996–2014 yielded an above-average warming trend. Northeast Greenland and the area around Zackenberg follow the general pattern but are on the lower boundary of observed significant trends in Greenland. We conclude that temperature-driven ecosystem changes as observed in Zackenberg may well be exceeded in other areas of Greenland.     

Exploring the spatial-temporal variations and policy-based driving force behind groundwater contamination and remediation research in past decades

Environmental Science and Pollution Research - Groundwater has been recognized as one of the most critical and vulnerable natural sources which is utilized in potable water supply, agricultural...     

Annual and seasonal trends of ambient ozone concentration and its impact on forest vegetation in Mercantour National Park (South-eastern France) over the 2000-2008 period

In the South-Eastern French Mediterranean region, high ozone concentrations were measured since many years and specific symptoms like chlorotic mottles were detected on Arolla pines. We presented results for the 2000-2008 period concerning the trend analysis for ambient ozone concentrations and related forest damages, with the Mann and seasonal Kendall tests. Ozone precursor’s emissions from Europe have been reduced over the last 20 years. Decreases in annual averages, median, 25th and 98th percentiles and maxima values were found. The seasonal trend analysis for the high-lying stations showed a decreasing trend for the warm season, when main ozone production is the photochemistry, and an increase for the cold period, caused by a reduced ozone titration. Statistics on Arolla Pine reveal strong correlations between mottling intensity and the high ozone concentrations. Finally, decreases for the ozone concentrations, and associated statistics, AOT40 values and for the mottling intensity on conifers needles were observed.     

Impact of cadmium and nickel on ion homeostasis in the yeast Schizosaccharomyces pombe

Abstract

Toxicity of heavy metals to living organisms is a worldwide research topic. Although, much has been discovered about cadmium and nickel impact on biological systems, a lot still remains unclear. We used inductively coupled plasma – optical emission spectroscopy to address the question of the effect of two different heavy metals nickel, and cadmium on intracellular ion balance. Increase or decrease of the content of several essential cations including Ca²⁺, Na⁺, K⁺, Mg²⁺, Cu²⁺, Fe³⁺ in the yeast Schizosaccharomyces pombe was determined. Our results revealed that the cell exposure to high nickel and cadmium concentrations led to significant elevation of Ca²⁺, Na⁺, Mg²⁺, Cu²⁺, Fe³⁺ levels in the yeast cell, while the content of K⁺ decreased. Correlation analyses showing in the presence of nickel and cadmium strong positive correlation among each tested element (Ca²⁺, Na⁺, Cu²⁺, Mg²⁺ and Fe³⁺) except for K⁺, demonstrate the significant impact of heavy metal treatment to ion homeostasis of the cell. Our data indicate that acute nickel and cadmium contamination leads to substantial ionome misbalance in yeast.     

Uncertainties in the role of land vegetation in the carbon cycle

Since the late 1950s the CO2 concentration of the atmosphere has been increasing by around 0.5-3 ppm per year. Understanding of carbon sinks is vital to understanding this trend and its future behaviour. Here we examine some of the factors which may affect the proportion of anthropogenic CO2 ending up in the atmosphere in the present and in the future, and variability in the CO2 increase from one year to another. We also examine the evidence for the potential of terrestrial ecosystem carbon sinks to take up or release CO2. In some cases, a careful re-examination of the research methods used to deduce present and future feedbacks may be necessary. The most advanced technology and the most complex models do not necessarily produce reliable results. They should be carefully checked against a general background knowledge of ecological processes before their results are accepted.