Scientific visualization for the study and use of forest stand simulators

In this concept paper, a case is made for incorporating visualization capabilities into forest stand simulators to increase understanding of forest stand dynamics and improve management decisions. Forest management decisions are predicated on information about both current and future resource conditions. Forests are dynamic biological systems that are continuously changing and it is necessary to project these changes to obtain relevant information for prudent decision making.     

The importance of biomass net uptake for a trace metal budget in a forest stand in north-eastern France

The trace metal (TM: Cd, Cu, Ni, Pb and Zn) budget (stocks and annual fluxes) was evaluated in a forest stand (silver fir, Abies alba Miller) in north-eastern France. Trace metal concentrations were measured in different tree compartments in order to assess TM partitioning and dynamics in the trees. Inputs included bulk deposition, estimated dry deposition and weathering. Outputs were leaching and biomass exportation. Atmospheric deposition was the main input flux. The estimated dry deposition accounted for about 40% of the total trace metal deposition. The relative importance of leaching (estimated by a lumped parameter water balance model, BILJOU) and net biomass uptake (harvesting) for ecosystem exportation depended on the element. Trace metal distribution between tree compartments (stem wood and bark, branches and needles) indicated that Pb was mainly stored in the stem, whereas Zn and Ni, and to a lesser extent Cd and Cu, were translocated to aerial parts of the trees and cycled in the ecosystem. For Zn and Ni, leaching was the main output flux (> 95% of the total output) and the plot budget (input-output) was negative, whereas for Pb the biomass net exportation represented 60% of the outputs and the budget was balanced. Cadmium and Cu had intermediate behaviours, with 18% and 30% of the total output relative to biomass exportation, respectively, and the budgets were negative. The net uptake by biomass was particularly important for Pb budgets, less so for Cd and Cu and not very important for Zn and Ni in such forest stands.     

Fluxes of radiocaesium in selected rural study sites in Russia and Ukraine.

Food production and food harvesting systems common in the areas contaminated by the Chernobyl accident in Russia and Ukraine can be grouped into three major categories: collective farm produce, private farming produce and foods collected from natural ecosystems. The contribution of each of these sources to radiocaesium intake by people living in rural settlements in the mid 1990s has been estimated at two major study sites, one in each country. The collective farm system provided the smallest contribution (7-14%) to the intake of radiocaesium at both sites. Natural food was the major contributor to intake at the Russian site (83%). Whereas private farm produce was the major contributor (68%) at the Ukrainian study site. The difference between the two sites was mainly because private milk production was stopped at the Russian site due to the contamination in 1986. A retrospective assessment of the situation 1 year after the accident shows that collective farming could have been a minor contributor to radiocaesium intake (8%), whilst private farming would have been the major contributor wherever private milk production and consumption continued. The extent to which inhabitants consume natural foods from forests has a considerable effect on their radiocaesium intake. The comparative importance of food products from natural ecosystems increases with time due to the long effective ecological half-lives of radiocaesium in unimproved pastures and forests. Estimation of the fluxes of radiocaesium from the different production and harvesting systems showed that the contribution from private farming and food harvesting from natural ecosystems may be significant, contributing 14-30% to the total fluxes of radiocaesium from an area even if the quantity of food produced in these systems is small. However, the major contributor to the flux exported from an area was the collective farming system, accounting for about 70-86% of the total.     

Application of potassium chloride to a Chernobyl-contaminated lake: modelling the dynamics of radiocaesium in an aquatic ecosystem and decontamination of fish

This study tests a whole-lake experiment to reduce the bioaccumulation of radiocaesium (137Cs) in fish in lakes contaminated by the Chernobyl accident. In many lakes in the Chernobyl contaminated areas, radiocaesium activity concentrations in fish are still significantly higher (up to 100 times in some species) than acceptable limits for human consumption. Estimates of the long-term rate of decline of 137Cs in fish in these regions, in the absence of countermeasures, show that radioactivity in fish in some lakes may remain above acceptable consumption limits for a further 50-100 years from the present date. In February 1998 we applied 15 t of potassium chloride to Lake Svyatoe, Kostiukovichy. The addition of potassium chloride fertilizer to the lake resulted in a decrease in activity concentration of 137Cs to approximately 40% of pre-countermeasure values in a number of different fish species. In contrast to Lake Svyatoe, 137Cs activity concentrations in fish from four control lakes showed no systematic decrease over the study period. Simplified models for transfers of 137Cs in lakes successfully 'blind' predicted the changes in 137Cs in water and fish resulting from this major alteration of the potassium concentration of the lake. The experiment represents the first test of a predictive model for the dynamics of radiocaesium in response to a major perturbation in potassium (its major competitor ion) in a whole lake ecosystem.     

Distribution of polycyclic aromatic hydrocarbons in riverine waters after Mediterranean forest fires

On the basis of a large-scale survey with 269 sampling sites and a field experiment with 12 cultivars grown at 3 ecologically different locations, Cadmium (Cd) and lead (Pb) contamination in milled rice grains and its variation among different locations were investigated in the area of southeast China. The objective of this study was mainly to assess the present situation of Cd and Pb contamination in rice grains harvested locally and find out the variation of Cd and Pb background levels in rice grains among the diverse regional locations. The results showed that: a) Cd concentrations in milled rice grains ranged from trace (below 10 ng/g) to 340 ng/g, with the means of 81.4 ng/g (AM) and 55.2 ng/g (GM) for the 269 samples, whereas Pb concentrations ranged from trace (below 10 ng/g) to 1136 ng/g, with the means of 113.5 ng/g (AM) and 51.0 ng/g (GM), respectively. High frequency was observed for both the Cd and Pb concentrations ranging from trace to 200 ng/g, with 95.9% for Cd and 84.8% for Pb, respectively. b) ANOVA for the AMs and GMs among 269 sampling sites indicated that there were significant differences among the different spatial locations in Cd or Pb concentrations. c) The Cd concentrations in milled rice grains were poorly correlated with Pb concentration among the 269 sampling sites surveyed, and no significant difference (P>0.05) in the AMs or GMs of Cd and Pb concentration was observed among different cities within a range of the same provinces, only with an exception for 1-2 provinces. d) Variance analysis of Cd, Pb concentrations for 12 rice cultivars grown in three locations showed that the great difference in coefficients of variation (CV) was observed both among cultivars grown in the same location and among locations of cultivars planted, in which locations showed much more contribution to the variation of Cd or Pb concentration in milled rice grains as compared with cultivars.     

Investigation of timber harvesting impacts on herbaceous cover,forest floor and surface soil properties on skid road in an oak (Quercus petrea L.) stand

In this study, we investigated the timber harvesting effects on some soil properties (sand, silt, clay, pH, electrical conductivity, fine soil <2 mm, coarse soil >2 mm, root mass, organic carbon, moisture equivalent, total porosity, bulk density, moisture and compaction) at soil depths (0–5 and 5–10 cm), herbaceous cover and forest floor (unit mass, organic matter and moisture) on skid road of an oak (Quercus petrea L.) stand in Istanbul Belgrad Forest of Turkey.     

Influence of zeolite on the availability of radiocaesium in soil to plants.

Plant availability of radiocaesium is usually high immediately after incorporation in a soil. However, for some Swedish soils, e.g, peat soils, a high radiocaesium uptake in plants has also been observed during a second growth period after contamination. For these soils the reduction in the plant availability of the nuclide seems to be a slow process. In the last two years the mineral zeolite has become of interest and has been tested as a caesium binding agent in both animal and in soil-plant systems. The aim of this study was to evaluate the time dependency and the effect of zeolite on the plant availability of radiocaesium in a peat soil-plant system. The pot experiments designed for this purpose were carried out in a climate chamber, using winter wheat as the test crop. A significant reduction of the uptake of 134Cs was obtained in wheat when increasing amounts of zeolite were added. This reduction in plant uptake, up to a factor of 8, might depend on two factors. One is that zeolite has reduced the activity concentration of radiocaesium in the soil solution available to the plant roots. The other is that the potassium added with the natural zeolite increased the degree of dilution of caesium in the soil solution. Also, increasing equilibration time for caesium in soil before sowing brought about an effective reduction in the caesium uptake.     

Comparing in situ distribution coefficients and exchangeability of radiocaesium in freshwater sediments with laboratory predictions

Two short-term (24 h) laboratory procedures, based on measurement of the affinity and capacity of the specific binding sites for radiocaesium on illitic clay minerals, are used to predict the in situ 137Cs distribution coefficients (KD) in two Dutch freshwater sediments. Differences in the measured amount of specific binding sites between the sediments are shown to be related to differences in the particle size and illite content. A procedure based on measurement of the combined parameter KD[NH4+] predicts the measured in situ 137Cs distribution in both sediments very well. This is remarkable because the in situ data are based on 137Cs/sediment contact times of > 1 year, while previous experiments have shown that increasing contact times between Cs+ and sediments decreases the short-term exchangeability of caesium, as measured by extraction with a high ammonium concentration. The good predictions of the 37Cs solid/water distribution by short-term ion-exchange experiments, therefore, indicate that more 137Cs in the sediments is exchangeable than is measured by the commonly used extraction with high ammonium concentrations.     

Effects of nitrogen deposition on nitrogen cycling in an Aleppo pine stand in Athens, Greece

High levels of nitrogen deposition measured in throughfall fluxes in 2002, reaching 38 kg ha(-1) year(-1), affected the biogeochemical cycle of N in an Aleppo pine (Pinus halepensis) stand situated in Athens, the capital of Greece. The N fluxes in bulk deposition were far lower than those in throughfall indicating high levels of dry deposition in the city of Athens. The amounts of N in litterfall and those stored in the forest floor and mineral soil were not high, while the mean residence time of N in the forest floor, derived from fluxes equations, decreased considerably due to the high levels of N fluxes in throughfall deposition. Nitrogen concentration in needle tissues was high and this resulted in a high ratio of N/Zn. Zinc availability was low due to the alkaline nature of soil in the study area. Fast N cycling may affect the living status of Aleppo pine, which is an oligotrophic plant species capable of occupying poor soil sites. Nitrogen eutrophication may adversely affect forests grown on calcareous soils by developing nutrition imbalances between N and micronutrients, the solubility of which depends on soil pH values.     

Dry deposition of gaseous radioiodine and particulate radiocaesium onto leafy vegetables

Radionuclides released to the atmosphere during dry weather (e.g. after a nuclear accident) may contaminate vegetable foods and cause exposure to humans via the food chain. To obtain experimental data for an appropriate assessment of this exposure path, dry deposition of radionuclides to leafy vegetables was studied under homogeneous and controlled greenhouse conditions. Gaseous ¹³¹I-tracer in predominant elemental form and particulate ¹³⁴Cs-tracer at about 1 μm diameter were used to identify susceptible vegetable species with regard to contamination by these radionuclides. The persistence was examined by washing the harvested product with water. The vegetables tested were spinach (Spinacia oleracea), butterhead lettuce (Lactuca sativa var. capitata), endive (Cichorium endivia), leaf lettuce (Lactuca sativa var. crispa), curly kale (Brassica oleracea convar. acephala) and white cabbage (Brassica oleracea convar. capitata). The variation of radionuclides deposited onto each vegetable was evaluated statistically using the non-parametric Kruskal-Wallis Test and the U-test of Mann-Whitney. Significant differences in deposited ¹³¹I and ¹³⁴Cs activity concentration were found among the vegetable species.For ¹³¹I, the deposition velocity to spinach normalized to the biomass of the vegetation was 0.5-0.9 cm³ g^− 1 s^− 1 which was the highest among all species. The particulate ¹³⁴Cs deposition velocity of 0.09 cm³ g^− 1 s^− 1 was the highest for curly kale, which has rough and structured leaves. The lowest deposition velocity was onto white cabbage: 0.02 cm³ g^− 1 s^− 1 (iodine) and 0.003 cm³ g^− 1 s^− 1 (caesium). For all species, the gaseous iodine deposition was significantly higher compared to the particulate caesium deposition. The deposition depends on the sensitive parameters leaf area, stomatal aperture, and plant morphology. Decontamination by washing with water was very limited for iodine but up to a factor of two for caesium.     

Distribution of Pb and Po concentrations in wild berries and mushrooms in boreal forest ecosystems

The activity concentrations and distribution of ²¹⁰Pb and ²¹⁰Po in wild berries and edible mushrooms were investigated in Finnish forests. The main study areas were located in Scots pine (Pinus sylvestris L.) forests in southern and northern Finland. The activity concentrations of ²¹⁰Pb and ²¹⁰Po in blueberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) samples decreased in the order: stems > leaves > berries (i.e. fruits). The activity ratios of ²¹⁰Po/²¹⁰Pb in the wild berry samples were mainly higher than one, indicating elevated activity concentrations of polonium in the samples. In mushrooms the activity concentrations of ²¹⁰Pb and especially ²¹⁰Po were higher than in fruits of the wild berries. The highest activity concentration of ²¹⁰Pb was detected in Cortinarius armillatus L. (16.2 Bq kg^− 1 d.w.) and the lowest in Leccinum vulpinum L. (1.38 Bq kg^− 1 d.w.). The ²¹⁰Po activity concentrations of the whole fruiting bodies ranged from 7.14 Bq kg^− 1 d.w. (Russula paludosa L.) to 1174 Bq kg^− 1 d.w. (L. vulpinum L.). In general, the highest activity concentrations of ²¹⁰Po were recorded in boletes. The caps of mushrooms of the Boletaceae family showed higher activity concentrations of ²¹⁰Po compared to the stipes. In most of the mushrooms analyzed, the activity concentrations of ²¹⁰Po were higher than those of ²¹⁰Pb. ²¹⁰Po and ²¹⁰Pb dominate the radiation doses received via ingestion of wild berries and mushrooms in northern Finland, while in southern Finland the ingested dose is dominated by ¹³⁷Cs from the Chernobyl fallout.     

奥地利建筑全景

2007年11月．我有幸应奥地利文化、建筑和教育部之邀．赴奥地利对其当代建筑进行考察。在文化部官员们紧凑而高效的安排下．匆匆10日,不仅访问了维也纳、格拉兹（Graz）和因斯布鲁克（Innsbruck）等大城市．也深入到Egg这样鲜有国人知道的山区小镇,不仅亲身体验到Sezession House这样彪炳建筑史的名师之作．也进入乳品工厂、酒庄这类在建筑学上具有意义的小房子．本期奥地利建筑专辑的主要内容都取材于这次建筑之旅。     

Effect of clay content and wetting-and-drying on radiocaesium behaviour in a peat and a peaty podzol

The interaction of radiocaesium with peat under two moisture regimes was studied in laboratory experiments and by growing ryegrass in pot experiments to simulate changing field moisture conditions. A peat untreated and treated with 5% by weight of clay containing 46% illitic minerals, and a peaty podzol naturally containing 4.5% mineral matter on a dry weight basis were contaminated with (134)Cs and incubated. The soils were exposed to 8 wetting-and-drying cycles or kept constantly wet during 40 days. Extraction of the peat with 1 M CH(3)COONH(4) (pH 7) repeated after each wetting-and-drying cycle indicated increasing (134)Cs fixation with time of incubation. The peat treated with clay showed a much higher (134)Cs fixation than that without clay. The pot experiment with the incubated soils showed a (134)Cs transfer to ryegrass of the same order for the peaty podzol as for the peat treated with clay. For the peat untreated with clay the (134)Cs transfer to ryegrass was much greater. Wetting-and-drying the peat, with or without clay, increased the overall yield of grass and the concentration and uptake of (134)Cs over 5 consecutive harvests. K-fertilisation increased the yield of plant material (except for the peat with added clay), decreased the concentration of (134)Cs, but had no significant effect (p=0.05) on the resultant uptake of (134)Cs. Mixing clay with the surface layer of organic soils appears to be an effective means of decreasing radiocaesium transfer to field crops in fallout situations.     

Distribution of (210)Pb and (210)Po in boreal forest soil

Vertical distribution and activity contents of ²¹⁰Pb and ²¹⁰Po were investigated in forest soils of Scots pine-dominated (Pinus sylvestris L.) stands from seven different locations in Finland. The mean total inventory in the soil profile, up to 20 cm, of ²¹⁰Pb was 4.0 kBq m^− 2 (range 3.1-5.0 kBq m^− 2) and ²¹⁰Po 5.5 kBq m^− 2 (range 4.0-7.4 kBq m^− 2), the organic soil layer containing 45% of the total inventory of both nuclides. In both the organic and the mineral layers the ²¹⁰Po/²¹⁰Pb ratio was close to unity indicating a radioactive equilibrium between them. In the litter layer there was, however, a clear excess of ²¹⁰Po suggesting that polonium is recycled via root uptake from the root zone to the ground surface. The activity concentration (Bq kg^− 1) of ²¹⁰Pb clearly correlated with organic matter and the Fe, Al and Mn concentrations in soil indicating that radioactive lead is associated both with humic substances and the oxides of iron, aluminium and manganese. Radioactive lead was also seen to follow the behavior of stable lead. No systematic correlation between polonium and soil properties was seen.     

ESBL-producing E. coli in Austrian sewage sludge

The aim of this study was to investigate the degree of contamination of sewage sludge with ESBL-producing Escherichia coli strains and the effectiveness of different sewage sludge treatment methods.Monthly sewage sludge samples were collected between January and September 2009 in 5 different sewage treatment plants and tested for the presence of ESBL E. coli. In addition, the number of colony forming units (CFU) of E. coli and coliform bacteria before and after the different sludge treatment methods (aerobic/anaerobic digestion, lime stabilization, and thermal treatment) was investigated.Of the 72 sewage sludge samples investigated, ESBL-positive E. coli were found in 44 (61.1%) sewage sludge samples. The classification of β-lactamase groups was carried out in 15 strains resulting in the detection of 2 different groups (CTX-M and TEM) of bla genes. All 15 of them had a CTX-M gene and 4 of these strains furthermore carried a TEM gene.With regard to the CFU of E. coli and coliform bacteria, thermal treatment and lime stabilization following dehydration sufficiently reduced pathogen concentrations. The plants using merely stabilization and dehydration showed an increase of E. coli and coliform bacteria and thus also an increase in ESBL-producing E. coli.     

A dynamic compartmental food chain model of radiocaesium transfer to Apodemus sylvaticus in woodland ecosystems

A study was undertaken to quantify the activity concentrations of 137Cs in Apodemus sylvaticus (the woodmouse) in two woodland sites, Lady Wood and Longrigg Wood, adjacent to British Nuclear Fuels Ltd. (BNFL) Sellafield, Cumbria, UK. A deterministic dynamic compartmental food chain model was also constructed to predict 137Cs activity concentration [Bq kg(-1) dry weight (dw)] in A. sylvaticus on a seasonal basis given the activity concentrations in its diet. Within the coniferous woodland site (Lady Wood), significant differences were found between seasons (P < 0.05, summer vs. autumn cohort; P < 0.001, spring vs. autumn cohort), with an autumn peak in activity concentration (geometric mean = 140 x/divided by 2.3 Bq kg(-1) dw) being attributed to mycophagy. Fungal concentrations ranged from 2-3213 Bq kg(-1) dw. The modelled activity concentrations fell between the confidence intervals of the observed data in four of the six seasonal cohorts sampled. Disparities between predicted and observed activity concentrations are attributed to uncertainties surrounding the fundamental feeding ecology of small mammals.     

Distribution and fate of nonylphenol in an aquatic microcosm

An aquatic microcosm consisting of four compartments, namely surface microlayer (SM), water sediment and biota (zebra fish), was developed to investigate the distribution and fate of nonylphenol (NP) in an aquatic environment. Level III and level IV fugacity-based multimedia models were used to calculate the distribution and fate of NP. Data obtained from model calculations were in good agreement with those of the experiments. Results of the model calculations showed that 86.50% of all NP input was removed by advective outflow, while 61.99% of the remainder was distributed to the sediment phase, 34.89% to the water phase, 2.50×10⁻²% to SM and 3.13% to the biotic phase. This finding demonstrates that sediment plays a key role in the fate of NP and acts as a sink in the aquatic environment. Bioconcentration factor (BCF) of NP in the zebra fish was high and varied in different parts of the fish. The highest BCF was 1440 in the viscera. After the uptake experiment, depuration of NP in clean water indicated that, the concentration of residue NP in the zebra fish was still high. This implies that NP in fish can pose a potential threat to human health due to its bioaccumulation in the food chain.     

新奥法隧道施工过程中的质量控制措施

随着科技的进步和工程技术的不断发展,新奥法施工技术在我国已经逐渐被隧道行业从业人员所理解并得到了广泛的应用。新奥法因其技术特点,在保证施工工期的基础上也能有效的保证施工的安全和质量。该文对新奥法的施工质量监控进行了详细的阐述,以期同广大同行共同提高认识,保证新奥法的施工质量。