Acidification of soils and surface waters caused by acid deposition is still a major problem in southern Scandinavia, despite clear signs of recovery. Besides emission control, liming of lakes, streams, and wetlands is currently used to ameliorate acidification in Sweden. An alternative strategy is forest soil liming to restore the acidified upland soils from which much acidified runoff originates. This cost-benefit analysis compared these liming strategies with a special emphasis on the time perspective for expected benefits. Benefits transfer was used to estimate use values for sport ffishing and nonuse values in terms of existence values. The results show that large-scale forest soil liming is not socioeconomically profitable, while lake liming is, if it is done efficiently-in other words, if only acidified surface waters are treated. The beguiling logic of "solving" an environmental problem at its source (soils), rather than continuing to treat the symptoms (surface waters), is thus misleading.
Cites: Nature. 2007 Nov 22;450(7169):537-4018033294
The reuse of municipal sewage for agricultural purposes is becoming more prevalent. The literature concerning the impact of this practice is reviewed. It is readily apparent that agricultural reuse of municipal sewage is preferable to other common methods of disposal both from the point of view of ecological influence and economical waste utilization. There is a need to establish guidelines for the agricultural use of municipal sewage which will serve the variable conditions found in Canada and meet the public health concerns associated with an extensive agricultural use.
Gastric cancer mortality incidence data registered in two different areas of Eastern Transylvania (Roumania) were reported related to 325,000 inhabitants from the period of 1951-1972. The findings were compared to some geographical environmental factors deriving from an area of 13,300 km with 905,700 inhabitants. A 2-3.5 times larger incidence of gastric cancer (75-140 per 100,000/year) was found in some selected geographical areas of the intermontane depressions of Gheorgheni and Ciuc in comparison to hilly area of Transylvanian Tableland. The difference might be explained by some unknown environmental gastric cancer risk factors. Of the natural factors, the presence of magmatic substrata shows a significant degree of correlation. The main pedological factor seems to be badly drained pseudoglyied podzolic and peaty soils of low pH and high content of organic matter. Sofs drinking waters also may be involved as risk factor. High altitude, cold climate determining a restricted assortiment of cultivated plants, the successive production of vegetal and animal food on the same soil for livelong periods and several generations, especially in isolated rural areas, seem to represent gastric cancer risk factors. According to authors' opinion a survey of the high-risk population selected on the basis of the environmental factors, especially of the persons suffering from gastric disorders considered today possible precursors of gastric cancer, may offer some progress in detecting early gastric malignancy in the future.
Iodine deficiency disorders continue to be a severe problem in many parts of Central Asia, causing delayed mental development and cretinism in indigenous populations. In some areas, iodized salt has not succeeded in controlling this problem. In southern Xinjiang Province of China, we tried a new method of supplying iodine to rural populations by dripping potassium iodate into irrigation water canals. By this means iodine was distributed into soil, crops, animals and people. This proved feasible and cost effective; it reached all the people, required no medical expertise, required no continuing effort after the initial dripping, and had the important added benefit of improving livestock production.
We serially monitored iodine concentrations in soil, crops, animal products and human urine for several years after the last dripping. In a similar project in Inner Mongolia, total soil iodine was determined in addition. Here, iodine concentrations in soil, crops, animals and people have been monitored for 4 years after supplementation.
After dripping, total iodine increased two-fold, while soluble iodine increased 4-5-fold. Iodine added to soil is available for more than 4 years after a single application.
Potassium iodate added to soil appears to increase soluble iodine out of proportion to the amount added. This effect and the long persistence of dripped iodate in soil contribute to the efficacy and cost effectiveness of this method of iodine supplementation.
Mosses dominate many northern ecosystems and their presence is integral to soil thermal and hydrological regimes which, in turn, dictate important ecological processes. Drivers, such as climate change and increasing herbivore pressure, affect the moss layer thus, assessment of the functional role of mosses in determining soil characteristics is essential. Field manipulations conducted in high arctic Spitsbergen (78 degrees N), creating shallow (3 cm), intermediate (6 cm) and deep (12 cm) moss layers over the soil surface, had an immediate impact on soil temperature in terms of both average temperatures and amplitude of fluctuations. In soil under deep moss, temperature was substantially lower and organic layer thaw occurred 4 weeks later than in other treatment plots; the growing season for vascular plants was thereby reduced by 40%. Soil moisture was also reduced under deep moss, reflecting the influence of local heterogeneity in moss depth, over and above the landscape-scale topographic control of soil moisture. Data from field and laboratory experiments show that moss-mediated effects on the soil environment influenced microbial biomass and activity, resulting in warmer and wetter soil under thinner moss layers containing more plant-available nitrogen. In arctic ecosystems, which are limited by soil temperature, growing season length and nutrient availability, spatial and temporal variation in the depth of the moss layer has significant repercussions for ecosystem function. Evidence from our mesic tundra site shows that any disturbance causing reduction in the depth of the moss layer will alleviate temperature and moisture constraints and therefore profoundly influence a wide range of ecosystem processes, including nutrient cycling and energy transfer.
Vanadium, Cr, and Ni accumulating in a Swiss peat bog since 12 370 14C yr B.P. have been measured using inductively coupled plasma-mass spectrometry (ICP-MS) after acid dissolution in a microwave autoclave. Strict quality control schemes were applied to guarantee the accuracy of the applied analytical methodology. The concentration gradients in the peat column and comparison with Pb indicate that V, Cr, and Ni are effectively immobile in the ombrotrophic section of the peat profile but that Ni is added to the minerotrophic peat layers by chemical weathering of the underlying sediments. The lowest metal concentrations were found during the Holocene climate optimum (5320-8230 14C yr B.P.) when "natural background" values averaged 0.55 +/- 0.13 microg g(-1) V, 0.76 +/- 0.17 microg g(-1) Cr, and 0.46 +/- 0.09 microg g(-1) Ni (n = 18); given the average bulk density (0.05 g/cm3) and accumulation rate (0.05 cm/ yr) of peat in this zone, the corresponding atmospheric fluxes are approximately 14, 19, and 12 microg m(-2) yr(-1) for V, Cr, and Ni, respectively. The highest concentrations of V, Cr, and Ni were found during the Younger Dryas cold climate event (centered at 10 590 14C yr B.P.) when background values were exceeded by about 40 times. Elevated concentrations and accumulation rates were also found at 8230 and 5320 14C yr B.P., which are consistent with the elevated dust fluxes recorded by Greenland ice cores. By far the greatest contribution of the three elements to the peat inventory is atmospheric soil dust, and the metal fluxes vary not only with climate change but also land-use history (especially the beginning of forest clearing for agriculture ca. 6 millennia ago). The V/Sc, Cr/Sc, and Ni/ Sc ratios were remarkably similar to their corresponding ratios in the earth's crust until the onset of the Industrial Revolution (240 14C yr B.P.), which largely validates the use of crustal concentrations for calculating enrichment factors (EF) for these elements. In modern samples, the EFs of V, Cr, and Ni reach maximum values between 2.4 and 4.1, relative to background; anthropogenic emissions are a more likely explanation of the elevated EFs than either plant uptake or chemical diagenesis. This study demonstrates the usefulness of peat bogs as archives of atmospheric metal deposition and underpins the potential of peat cores to help distinguish between lithogenic and anthropogenic metal sources.
The environmental loadings of national Norwegian mercury emissions compared to the loadings of atmospheric long range transported mercury have been estimated using national emission data and EMEP model data. The results indicate that atmospheric long-range transport to Norway is somewhat larger than the national Norwegian emissions of mercury. Atmospheric deposition of mercury has been studied using data from Norwegian monitoring programs on mercury in precipitation, mosses, natural surface soils, and lake sediments. Precipitation data show no significant time trend during 1990-2002, whereas moss samples show similar concentrations from 1985 to 1995, but a 30% decrease from 1995 to 2000. Concentrations of mercury in peat cores and reference sediments indicate that the current mercury levels measured in surface sediments, surface soils and mosses at background sites in Norway are substantially affected by long-range atmospheric transport.
Fungal and bacterial community structure in tussock, intertussock and shrub organic and mineral soils at Toolik Lake, Alaska were evaluated. Community structure was examined by constructing clone libraries of partial 16S and 18S rRNA genes. The soil communities were sampled at the end of the growing season in August 2004 and just after the soils thawed in June 2005. The communities differed greatly between vegetation types, although tussock and intertussock soil communities were very similar at the phyla level. The communities were relatively stable between sample dates at the phyla and subphyla levels, but differed significantly at finer phylogenetic scales. Tussock and intertussock bacterial communities were dominated by Acidobacteria, while shrub soils were dominated by Proteobacteria. These results appear consistent with previous work demonstrating that shrub soils contain an active, bioavailable C fraction, while tussock soils are dominated by more recalcitrant substrates. Tussock fungi communities had higher proportions of Ascomycota than shrub soils, while Zygomycota were more abundant in shrub soils. Recent documentation of increasing shrub abundance in the Arctic suggests that soil microbial communities and their functioning are likely to be altered by climate change.
Arctic permafrost environments store large amounts of organic carbon. As a result of global warming, intensified permafrost degradation and release of significant quantities of the currently conserved organic matter is predicted for high latitudes. To improve our understanding of the present and future carbon dynamics in climate sensitive permafrost ecosystems, the present study investigates structure and carbon turnover of the bacterial community in a permafrost-affected soil of the Lena Delta (72 degrees 22'N, 126 degrees 28'E) in northeastern Siberia. 16S rRNA gene clone libraries revealed the presence of all major soil bacterial groups and of the canditate divisions OD1 and OP11. A shift within the bacterial community was observed along the soil profile indicated by the absence of Alphaproteobacteria and Betaproteobacteria and a simultaneous increase in abundance and diversity of fermenting bacteria like Firmicutes and Actinobacteria near the permafrost table. BIOLOG EcoPlates were used to describe the spectrum of utilized carbon sources of the bacterial community in different horizons under in situ temperature conditions in the presence and absence of oxygen. The results revealed distinct qualitative differences in the substrates used and the turnover rates under oxic and anoxic conditions. It can be concluded that constantly negative redox potentials as characteristic for the near permafrost table horizons of the investigated soil did effectively shape the structure of the indigenous bacterial community limiting its phylum-level diversity and carbon turnover capacity.