Ion Leaching Before and After Clear-Cutting in a Norway Spruce Stand - Effects of Long-Term Application of Ammonium Nitrate and Superphosphate

Soil solution chemistry was measured in a Haplic Podzol in a Norway spruce (Picea abies, L.Karst) site in central Sweden that had received frequent low-dose applications of nitrogen (N) asammonium nitrate (30-120 kg N/ha yr) and phosphorus (P) as superphosphate (20-40 kg P/haabout every third year) over a long period (22 yr). The aim was to investigate effects of added Non the ion leaching before and after clear-cutting. The N load corresponded well with actual loadsin central Europe. Prior to clear-cutting, fertilization increased concentrations of several ions inthe soil solution. Total losses of NO ₃ ^- , Al andH⁺ increased with the intensity of fertilization. However, since fertilization enhanced tree growthand nutrient uptake, differences between the total losses of several other ions tended to beequalized. After clear-cutting, the pH in the soil solution decreased, and the losses of Mn and Alincreased with fertilizer load, probably because of increased N mineralization and nitrification. Inthe N treatments the concentration of SO ₄ ^2- in the soil solution decreased, probably owing toincreased adsorption in the B horizon in response to the pH decrease. The effects ofanthropogenic N deposition are discussed in the light of our findings and possible causes oftemporal and spatial variation in soil solution chemistry and ion fluxes are suggested.     

The role of weathering and forestry in determining the acidity of Lakes in Sweden

The long term acidity level of a lake is determined by the balance between acidity input to the catchment and the generation of alkalinity in the catchment. If the input of acidity through biomass net production and the production of alkalinity through weathering of minerals can be estimated, then the steady-state acidity level can be calculated for the lake under a certain acid deposition rate. Such a calculation has been carried out for 8 lakes ranging from acid to neutral. For lakes with the most sensitive soils in the catchment, the critical acid deposition load that will permit the lake to stay neutral, may be less than zero acidity, indicating that the forest growth is contributing to the acidification of very sensitive system under the present forest managements methods.     

Aluminium sulphate solubility in acid forest soils in Denmark

Ion leaching in 3 sandy spruce forest soils of different origin and pH was investigated in the laboratory. Zero-tension lysimeters containing undisturbed soil columns of varying soil depth were subjected to H₂SO₄ loadings for a period of 9 weeks. The analysis of the resulting leachate supports the hypothesis that Al-sulphate minerals may form in acidic soils when exposed to acid (H₂SO₄) deposition. In the B horizon of a glaciofluvial sandy soil (pH 4.2), both H⁺ and sulphate ions were retained to maintain 2pH + PSO₄ = 11.9 in the leachate solutions. This relation between H⁺ and sulphate activity may be due to an adsorption mechanism or a precipitation mechanism. The precipitation mechanism is favored by the good fit of leachate composition to the conditions for jurbanite [AlOHSO₄] formation from gibbsite [Al(OH)₃]. In the B horizon of a sandy till at pH 3.7, the Al in soil solution (0.5 mmol L^?1) was leached with sulphate. As the sulphate load was increased, some sulphate was retained. This may also be due to the dissolution and precipitation of an Al-sulphate mineral. The ion activity products of leachate solutions from the B horizon of this soil were close to the pK_s reported for jurbanite. The conditions for the possible existence and/or formation of Al-sulphate minerals in acidic soils are discussed.     

Nutrient and persistent pollutant deposition on the Bothnian Bay ice and snow fields

A study of atmospheric deposited nutrients and some persistent pollutants has been carried out on the ice and snow fields of the subarctic Bothnian Bay, the northernmost basin of the Baltic Sea. Total amounts of 600, 500 and 400 tons NO₃-N, NH₄-N and N_org-N, respectively are deposited in the snow while the corresponding amounts for P_tot-P is 40 tons. The corresponding amount for PCB and lindane are 1.0 and 0.2 kg, respectively. The measurements were carried out on the snow-covered ice four to six weeks old. A part of the deposited snow has been incorporated -into the snow-ice and an attempt to estimate its mean thickness and its amount of nutrients has been made. The total amounts now reach 1700, 1300 and 1100 tons of NO₃-N and NH₄-N and N_org-N, respectively in the snow and ice together. The results obtained support the use of land-based stations in estimates of seasonal atmospheric nutrient deposition to the Bothnian Bay. The observed concentrations of chloroorganic compounds correspond to those land-based observations reported from the same latitude in the northern hemisphere and reported in literature.     

Comparing Deterministic and Probabilistic Risk Assessments. A case study at a closed steel mill in southern Sweden (7 pp)

Background, Aims and Scope   Contaminated land is a high priority environmental problem in most of Europe and North-America. Sweden is no exception and generic guideline values have been developed for the initial assessment, but site-specific assessments are also needed. The generic guideline values are not applicable when the exposure conditions are different from the typical Swedish conditions or when the site contains a particularly sensitive ecosystem. The Swedish guideline values have, like in many other countries, been set by using deterministic point estimates for all variables and constants in the used multimedia model. The same approach is common also for site-specific assessments, and a limitation is that it fails to quantify variability and uncertainty. Probabilistic risk assessment provided a method to deal with this problem. Variability and uncertainty in the input parameters (variables or constants) are described by probability distributions, and likewise the output (risk or exposure) is presented as a probability distribution. A substantial number of probabilistic risk assessments for contaminated land at sites in North America, Europe and Asia have been published. However, an extensive review of the literature did not identify any study where probabilistic risk assessment was applied to a site contaminated by an iron or steel industry. Here we will describe such a case, where we have compared a deterministic point estimate with a probabilistic risk assessment for six elements and benzo[a]pyrene. Methods   The site had different metallurgical plants in operation for more than 100 years. Most parts of the steel mill were closed by the mid 1980s, and today the site is used by small-sized enterprises. The soil is contaminated with metals from the previous industrial operations. The present owner plans to develop the site and has therefore initiated extensive investigations of soil contamination. Sixty-two soil samples collected between 1997 and 2000 provided a good coverage of the whole site, and were analyzed for the content of different elements and polycyclic aromatic hydrocarbons (PAH). The exposure assessments were focused on six elements with high concentrations compared to the generic guideline values; arsenic (As), lead (Pb), cadmium (Cd), chromium (Cr), copper (Cu) and zinc (Zn). In addition, benzo[a]pyrene was included due to the high toxicity and comparatively high concentrations. Variability and uncertainty were characterized in a Monte Carlo simulation of exposures (10 000 iterations), and the exposures were evaluated with two land use scenarios; less sensitive use and sensitive use. Results and Discussion   The deterministic point estimates and the probabilistic estimates of the 95th percentile are in approximately the same ranges in the scenario of less sensitive land use. It is only the exposure for arsenic that is slightly above the toxicological reference value (TRV) in the deterministic assessment. In the probabilistic assessment, the exposure for all elements is below the TRV. The results for sensitive land use are applicable to a scenario where the site is developed for general housing. The deterministic point estimates and the probabilistic estimates of the 95th percentile are also here in approximately the same ranges, but the exposure exceeds the TRV for arsenic, cadmium and lead. Drinking water, vegetables grown on site and soil ingestion are the major exposure pathways for this scenario. In this assessment, the estimated intake distributions are applicable to a randomly selected individual. The probability distributions used here to characterize the different soil parameters are typically representing both variability and uncertainty, and the same is true the majority of the exposure variables. We therefore decided not to attempt to separate variability and uncertainty at this stage, but with additional data from a more in-depth site investigation it might be possible to achieve this. Conclusions and Outlook   To the best of our knowledge, this study is the first report on a probabilistic risk assessment on a former iron and steel works site. The materials handled by this industry were less toxic than for many other metallurgical operations, but contaminants may still severely limit the options for future land use. This case study shows that probabilistic exposure estimates for a set of soil contaminants can be quite similar to deterministic point estimates. The main difference is instead to be found in the additional information obtained with the probabilistic assessment. The sensitivity analyses show pathways and input variables that contribute most to variations in the total intake of each contaminant, e.g. dermal contact and ingestion of soil, vegetables and drinking water. This information can be used both in the planning of future land use and for active measures to reduce current exposure. The probabilistic assessment also provides information on the magnitude of exposure and the margin of safety. This information may facilitate risk communication between decision-makers and stakeholders. The presentation of results from probabilistic risk assessments is only briefly discussed in the literature and here we see a need for research and opportunities for enhancement. The choice of data analytical tools may then be of importance, since more complex multimedia models are rather difficult to decipher when implemented within traditional spreadsheet software. Some of the research needs are identified here and in a previous review article in this journal.     

Optothermistor as a breakthrough in the quantification of lycopene content of thermally processed tomato-based foods: verification versus absorption spectrophotometry and high-performance liquid chromatography

This study reports on the first use of the "optothermistor" as a novel, precise, fast, and low-cost detector of lycopene in a wide range of commercially available processed-tomato products. The quantitative performance of the new device was evaluated by comparing data obtained to that acquired by conventional methods, namely, absorption spectrophotometry and high-performance liquid chromatography (HPLC); the linear correlation was high (R = 0.98). The variation of data obtained with the optothermistor in a series of consecutive measurements performed with the same loading of the sample was better than 1%. However, the repeatability (RSD 0.5-9.0%, n = 3-5) achieved with the optothermistor by independent analyses (multiple loading) is comparable to that of HPLC and spectrophotometry. Results of the studies performed on the 19 products derived from tomatoes demonstrated that the optothermistor is suitable for selective, accurate, precise, and simple determination of lycopene (range = 7-75 mg/100 g of product weight) without the need for a sample pretreatment step. The estimated sensitivity of the present optothermistor is 2 mg of lycopene/100 g of product.     

Decreased levels of tobacco-specific N-nitrosamines in moist snuff on the Swedish market

Moist snuff, or snus, on the Swedish market in 2001 and 2002 was analyzed for tobacco-specific N-nitrosamines (TSNAs) using a recently developed LC-MS/MS method. All samples of moist snuff analyzed were found to contain detectable levels of N'-nitrosonornicotine (NNN), N'-nitrosoanatabine (NAT), N'-nitrosoanabasine (NAB), and 4-(N-methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In the survey in 2001, all samples except for one were produced by Swedish Match (n = 14), which is the dominating manufacturer on the Swedish snuff market. In the survey in 2002, samples from both Swedish Match (n = 7) and seven smaller manufacturers (n = 20) were analyzed. Total TSNA levels of between 0.15 and 3.0 microg/g wet weight were found. In the survey in 2001 and 2002, the mean level of the total TSNA content in moist snuff was 1.1 microg/g (n = 14) and 1.0 microg/g (n = 27), respectively. The result of the survey shows that the level of TSNAs in moist snuff on the Swedish market has been greatly reduced since the middle of the 1980s. Clearly, efforts have been made by the manufacturers to reduce the level of TSNAs in snuff.     

Testing the Aluminium Toxicity Hypothesis: A Field Manipulation Experiment in Mature Spruce Forest in Norway

Aluminium (Al) has been considered to be a central element for risk evaluation of forest damage due to acidification. It has been hypothesized that Al reduces root growth, nutrient uptake and forest vitality. However, forest monitoring studies fail to show correlations between soil acidification and forest health. In general, no direct relation between Al concentration and forest health has been established. Here, Al concentrations in soil solution were manipulated by weekly additions of dilute AlCl₃ to levels that are believed to be unfavorable for plant growth. Four treatments (in triplicate), including a reference and three Al addition levels, were established. Effects of enhanced Al concentrations on fine root growth, nutrient uptake and crown condition in a mature Norway spruce forest in Norway were tested (1996–1999). After three years of manipulation, crown condition, tree growth and fine root growth were not affected by potentially toxic Al concentrations. However, the Mg content in current year's needles decreased at the highest Al addition treatment. The Mg/Al ratio of fine roots of the same treatment had declined too, which suggests that Al blocked Mg uptake at the root surface. The manipulation will be continued for two more years.     

Modelling ”clean rain” treatments in acidified soils-EXMAN project results

The SAFE dynamic model was applied to a ”clean rain” roof experiment performed within the EXMAN project. In the experiment ambient throughfall was removed and replaced with artificial ”clean throughfall”. Input of S, N and H to the forest ecosystem was reduced by 75–100%. The results of the modelling show, that the time scales of model predictions and experiments are the same. The change in base cation flux was well reproduced, while the simulation of changes in aluminum flux was less successful. pH stayed constant in the experiment as well as in the calculations.     

Effect of gamma-irradiation on the lipid profile of nutmeg (Myristica fragrans Houtt.)

The effect of gamma-irradiation on the lipid constituents of nutmeg (Myristica fragrans) was examined at radiation doses between 2.5 and 10 kGy. The fatty acid composition of the triacylglycerol, the major lipid component, was found to be made up of myristic (90%), palmitic (6%), lauric (3%), petroselinic (0.13%), and stearic acids (0.5%) as determined by gas chromatography-mass spectrometry. A dose-dependent decrease in the triacylglycerol content and a concomitant increase in free fatty acids characterized the lipid profile of the irradiated spice. This suggested a breakdown of acylglycerols during radiation processing, resulting in the release of free fatty acids. These changes were found to be significant at doses above 5 kGy. The impact of the above changes on the flavor of the spice is discussed. These studies suggest that radiation processing of nutmeg should be limited to a dose of 5 kGy.