The relationship between salmonid fish densities and critical ANC at exceeded and non-exceeded stream sites in Scotland

The critical load concept is now accepted throughout Europe as a means of estimating the sensitivity of key components of aquatic and terrestrial ecosystems to atmospheric inputs of sulphur (S) and nitrogen (N). Current UK freshwater maps, based on steady-state water chemistry, are derived using a critical acid neutralising capacity (ANC_LIM) value of zero eql^–1, which is based on the probability of occurrence of salmonid fish in lakes. In practice most acidification damage to salmonid fish occurs in nursery streams at the emergence and first feeding stages. In general a clear relationship exists between salmon (Salmo salar L.) and trout (S. trutta L.) densities in Scottish streams and ANC values. However, differences between sites depend on which ANC value is used (eg maximum, minimum or mean). By contrast, when the exceedance of critical loads is compared with salmonid densities the relationship is less clear because many exceeded sites have good salmonid densities. Many of these latter sites are found in north-west Scotland where sea-salt inputs are high and ANC is usually greater than zero eql^–1, although diatom-based studies indicated slight acidification of these waters, with a point of change in diatom flora close to ANC=20 eql^–1. These false exceedances are probably due to preferential adsorption of acidic SO₄ deposition which results in an overestimate of exceedance values. All sites with a mean ANC 0 are fishless but some sites with negative minimum ANC values had normal salmonid densities. Consequently a mean ANC_LIM value of zero in the critical load equations for UK freshwaters appears to be too low to protect salmonid stocks. Values between 20–50 eql^–1 represent a more realistic range if prevention of long term damage to salmonid stocks is to be achieved.     

Surface ozone concentrations and exposures during growing season at the Lithuanian rural site

The surface ozone (O₃) data show an increase by 2.6 % per year during the period 1982–1994 at the rural site of Lithuania. WHO (World Health Organization), UN-ECE (United Nations Economic Commission for Europe), CES (Commission of the European Communities) guideline values for the protection of vegetation from adverse effects are exceeded during the growing season at the Preila coastal station. Ozone exposures for different concentration threshold are estimated during daylight hours in April-September. These values above 60 g/m³ varied between 10 000 and 43 000 (g/m³) ·h, above 80 g/m³ — between 1700 and 15 000 (g/m³) ·h, above 100 g/m³ — between 130 and 3700 (g/m³) ·h during separate years. Maximum hourly ozone values were observed from 116 to 228 g/m³ during this period.     

Ionic composition of rainwater and atmospheric aerosols in Sardinia,southern Mediterranean

The ionic composition of 55 aerosol samples and 31 precipitation events collected in a coastal site in southern Sardinia (Capo Carbonara, 39°06 N; 09°31 E) were compared. The samples were collected during one year period (Oct'90/Oct'91) and showed high variability in composition according to meteorological conditions. Rain and soluble part of aerosol showed a strikingly similar ionic composition: most significant anions were chlorine and sulphate, and sodium is the principal cations, followed by magnesium and calcium. The acid events are associated with N-NW trajectories (anthropogenic influxes from N. Europe) with avg. pH=4.65, non sea salt (nss) Ca=60 eq/l and NO₃/_nssSO₄=0.6. Southern precipitations are influenced by Saharan dust alkaline effects, with avg. pH=6.75,_nssCa=271 eq/l and NO₃/_nssSO₄=0.4. Na/Cl ratio in rain is similar to sea water (0.87), whilst in aerosols there is a Cl loss (Na/Cl=1.10), probably due to reaction with nitric acid. Total fluxes of Ca, Mg, NO₃ and SO₄ were 104, 9, 64 and 113 g/cm², and wet deposition exceeded (65–90%) dry deposition. Scavenging ratios (SR) as defined by the equation:SR=[(Ci)rain/(Ci)air] ^*d, (d=1200g/m³) were calculated, using geometric means (Ci) of precipitation and aerosols collected concurrently during the period (a total of 23 samples). The SR values are Ca=3400, Cl=2400, Na, K, SO₄=1700, Mg=1000 and NO₃=750. These numbers could be useful to infer total fluxes by using simply rainwater ionic composition in Mediterranean semi-arid sites like Sardinia.     

Identification of ergosterol in vesicular-arbuscular mycorrhizae

Summary Ergosta-5,7,22-tri-3-enol (ergosterol) was identified by gas chromatography-mass spectrometry in roots of berseem (Trifolium alexandrinum L., cv. Landsorte) and sweet corn (Zea mays L., cv. Honeycomb-F1) infected with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus intraradices. The fungal-derived compound ergosterol was determined quantitatively in root extracts using reverse-phase high performance liquid chromatography. The concentrations of ergosterol in VAM-infected roots reached 72 g^-1 dry material in berseem and 52 g^-1 in sweet corn after 80 days of growth, whereas concentrations in non-infected roots remained below 8 g^-1 dry weight. Additionally, phytosterols such as -sitosterol, campesterol, and stigmasterol were detected in both infected and non-infected roots. Ergosterol, as a characteristic fungal substance, is proposed as an indicator of fungal biomass in the early stages of VAM infection.     

Disturbance effects on soil solution chemistry due to heating cable installation

Installation of heating cables for warming soil was used to evaluate the effect of disturbance on soil solution chemistry within a northern hardwood forest (Adirondack Mountains, New York). Differences in response among treatments suggested the importance of both the depth and timing of cable installation. There were increases (p>0.05) in many solutes within pilot study plots in which surrogate cable was installed at 15 cm depth. Most notably, mean nitrate concentrations for the 1st year following disturbance were 744 eq l^-1 at 15 cm depth compared to 7 eq l^-1 for the non-disturbed control. A comparison of pilot plots with 5 cm cable depth and an unheated soil-warming control plot with the same cable disturbance showed that the seasonality of soil disturbance may have a key role in response to disturbance. The soil solution response was diminished if installation occurred during the spring, a period of rapid uptake of nitrogen by vegetation. Mean nitrate concentrations were 176 eq l^-1 for 5-cm pilot plots (installed in fall 1991) versus 6 eq l^-1 for 5-cm, unheated soil-warming control plots (installed in spring 1992). Disturbance effects were attenuated over time and not generally apparent 1 year after installation.     

Molybdenum reserves of seed,and growth and N2 fixation by Phaseolus vulgaris L.

Summary Plants grown from seed with high (1.5–7.3 g Mo seed^-1) and low (0.07–1.4 g Mo seed^-1) Mo contents were grown in the presence and absence of Mo in growth media (perlite) or in a flowing-solution culture, in a controlled environment. Neither the high (1.5 g Mo seed^-1) nor the low (0.1 g Mo seed^-1) Mo content in seed from a small-seeded genotype (BAT 1297) was able to prevent Mo deficiency (reduced shoot, root and nodule dry weight, N₂ fixation and seed production) in growth media without an external supply of Mo, whereas both the high (7.3 g Mo seed^-1) and the low (0.07 g Mo seed^-1) contents in seed were able to prevent Mo deficiency in a large-seeded genotype (Canadian Wonder). Responses to Mo treatment by the Two genotypes were inconsistent between the growth media and solution culture experiments. Seed with a large Mo content (3.5 g Mo seed^-1) from the Canadian Wonder genotype was unable to prevent Mo deficiency (reduced shoot and nodule dry weight and N₂-fixation) in a solution culture without an external source of Mo, whereas both the large (1.7 g Mo seed^-1) and the small (0.13 g Mo seed^-1) contents in seed prevented a deficiency in BAT 1297. Growing plants from seed with a small Mo content, without additional Mo, reduced the seed Mo content by 83–85% and seed production by up to 38% in both genotypes. Changes in seed size and increases in shoot, root and nodule dry weight occurred, but varied with the genotype and growth conditions. These effects were also observed in some cases where plants were grown with additional Mo, demonstrating that the amount of Mo in the seed sown can influence plant nutrition irrespective of the external Mo supply. Nodule dry weight, total N content of shoots and seed production were improved by using seed with a small Mo content (1.64–3.57 g Mo seed^-1) on acid tropical soils in Northern Zambia. Plants of both the large- and small-seeded genotypes grown from seed with a small Mo content (<1.41 g Mo seed^-1) had a smaller nodule weight, accumulated less N and produced less seed. The viability of seed with a small Mo content was lower (germination up to 50% less) than that of seed with a large Mo content.     

Effects of nitrification inhibitors on denitrification of nitrate in soil

Summary The influence of 28 nitrification inhibitors on denitrification of nitrate in soil was studied by determining the effects of different amounts of each inhibitor on the amounts of nitrate lost and the amounts of nitrite, N₂O and N₂ produced when soil samples were incubated anaerobically after treatment with nitrate or with nitrate and mannitol. The inhibitors used included nitrapyrin (N-Serve), etridiazole (Dwell), potassium azide, 2-amino-4-chloro-6-methylpyrimidine (AM), sulfathiazole (ST), 4-amino-1,2,4-triazole(ATC),2,4-diamino-6-trichloromethyl-s-triazine (CL-1580), potassium ethylxanthate, guanylthiourea (ASU), 4-nitrobenzotrichloride, 4-mesylbenzotrichloride, sodium thiocarbonate (STC), phenylmercuric acetate (PMA), and dicyandiamide (DCD).Only one of the nitrification inhibitors studied (potassium azide) retarded denitrification when applied at the rate of 10 g g^–1 soil, and only two (potassium azide and 2,4-diamino-6-trichloromethyl-s-triazine) inhibited denitrification when applied at the rate of 50 g g^–1 soil. The other inhibitors either had no appreciable effect on denitrification, or enhanced denitrification, when applied at the rate of 10 or 50 g g^–1 soil, enhancement being most marked with 3-mercapto-1,2,4-triazole. Seven of the inhibitors (potassium azide, sulfathiazole, potassium ethylxanthate, sodium isopropylxanthate, 4-nitrobenzotrichloride, sodium thiocarbonate, and phenylmercuric acetate) retarded denitrification when applied at the rate of 50 g g^–1 soil to soil that had been amended with mannitol to promote microbial activity.Reports that nitrapyrin (N-Serve) and etridiazole (Dwell) inhibit denitrification when applied at rates as low as 0.5 g g^–1 soil could not be confirmed. No inhibition of denitrification was observed when these compounds were applied at the rate of 10 g g^–1 soil, and enhancement of denitrification was observed when they were applied at the rate of 50 or 100 g g^–1 soil.     

The “shenandoah national park: Fish in sensitive habitats” (SNP: FISH) project. An integrated assessment of fish community responses to stream acidification

The Shenandoah National Park: Fish in Sensitive Habitats (SNP:FISH) project is a response to declining pH and acid neutralizing capacity in Shenandoah National Park (SNP) streams. SNP receives more atmospheric sulfate than any other USA national park, and pH had decreased to the point where early negative effects on fish were expected. SNP provides the opportunity to study the early stages of acidification effects on fish. Three different classes of geological formations yield streams with low-ANC (0 Eq/L), intermediate-ANC (60–100 Eq/L) or high-ANC (150–200 Eq/L) waters in SNP. This allows a comparison of responses across a water quality gradient in a small geographic area receiving similar deposition. Both chronic and episodic acidification occur in SNP streams. Biological effects are apparent in fish species richness, population density, condition factor, age, size, and bioassay survival. A primary project objective was to provide the necessary data for development and testing models for forecasting changes in fish communities resulting from changes in stream chemistry. Monitored variables include several which are predictive of acidification effects on SNP fish communities.     

Condition factor and whole-body sodium concentrations in a freshwater fish: Evidence for acidification stress and possible ionoregulatory over-compensation

Condition factor, K, was measured for 1202 blacknose dace (Rhinichthys atratulus) from three streams in Shenandoah National Park (USA) of different acid neutralizing capacities (ANCs). K is a ratio of weight standardized to length; it is an indication of the health of the individuals in a population. R. atratulus condition factor in the low-ANC stream was found to be significantly lower (11%) than that of dace measured for fish from the intermediate- and high-ANC streams. This difference, according to the results of related investigations, is likely to be biologically significant. Whole-body sodium concentrations were measured as an additional test of sublethal stress in these streams. During summer base flow conditions, mean whole-body sodium concentrations of adult R. atratulus maintained in cages were found to be highest in the low-ANC stream and lowest in the high-ANC stream. The lower condition factor of dace in the low-ANC stream may be related to whole-body sodium concentration and ion regulation. Ion regulation in the low-ANC stream may be more metabolically costly because of chronic sublethal pH stress. R. atratulus may maintain high body Na⁺ concentrations in low ANC- and ionic strength waters in order to provide a buffer against large episodic pH depressions. The metabolic cost of this ionoregulatory over-compensation may necessitate the diversion of energy from somatic growth and explain the poorer condition of fish from such waters.     

Biogeochemistry of aluminum in a forest catchment in the Czech Republic impacted by atmospheric inputs of strong acids

The Lysina catchment in the Czech Republic was studied to investigate the biogeochemical response of Al to high loadings of acidic deposition. The catchment supports Norway spruce plantations and is underlain by granite and podzolic soil. Atmospheric deposition to the site was characterized by high H⁺ and SO₄ ^2– fluxes in throughfall. The volume-weighted average concentration of total Al (Al_t) was 28 mol L^–1 in the O horizon soil solution. About 50% of Al_t in the O horizon was in the form of potentially-toxic inorganic monomeric Al (Al_i). In the E horizon, Al_t increased to 71 mol L^–1, and Al_i comprised 80% of Al_t. The concentration of Al_t (120 mol L^–1) and the fraction of Al_i (85%) increased in the lower mineral soil due to increases in Al_i and decreases in organic monomeric Al (Al_o). Shallow ground water was less acidic and had lower Al_t concentration (29 mol L^–1). The volume-weighted average concentration of Al_t was extremely high in stream water (60 mol L^–1) with Al_i accounting for about 60% of Al_t. The major species of Al_i in stream water were fluorocomplexes (Al-F) and aquo Al³⁺. Soil solutions in the root zone were undersaturated with respect to all Al-bearing mineral phases. However, stream water exhibited Al_i concentrations close to solubility with jurbanite. Acidic waters and elevated Al concentrations reflected the limited supply of basic cations on the soil exchange complex and slow weathering, which was unable to neutralize atmospheric inputs of strong acids.     

Mercury Content of Illinois Soils

For a survey of Illinois soils, 101 cores had been collected and analyzed to determine the current and background elemental compositions of Illinois soils. Mercury and other elements were determined in six samples per core, including a surface sample from each core. The mean mercury content in the surface samples was 33 ± 20 g/kg soil, and the background content was 20 ± 9 g/kg. The most probable sources of mercury in these soils were the parent material, and wet and dry deposition of Hg⁰ and Hg²⁺ derived from coal-burning power plants, other industrial plants, and medical and municipal waste incinerators. Mercury-bearing sewage sludge or other fertilizers applied to agricultural fields could have been the local sources of mercury. Although the mercury content correlated with organic carbon content or clay content in individual cores, when all the data were considered, there was no strong correlation between mercury and either the organic carbon or the clay-size content.     

Measurements of atmospheric particulate carbon in Lithuania

During 1985–1989 particulate carbon concentrations were determined at suburban and rural sites in Lithuania. The main part of the continuous measurements was conducted at Preila background station (Curonian spit). Daily samples of airborne particulate matter were collected on glass fiber filters or by impactors and analysed for total carbon (TC), benzene extractable organic carbon (BEOC) and elemental carbon (EC) using combustion and optical techniques. Monthly median concentrations of total particulate carbon varied in the range 2–22 g/m³ during the period of measurements. For all the forms of particulate carbon the strong seasonal dependence was observed. The very regular seasonal cycle is characteristic for the ratio EC/TC: 0.10–0.15 and 0.30–0.35 for warm and cold periods respectively. Size distribution measurements shows that the main part of TC is in the sub-micron particle fraction — about 80–90 % in summer and even 92–98 % in winter. The concentrations of TC in size fraction <1.2>m have sharp winter peaks and summer minima. Very low concentrations and summer maxima for TC in the fraction >3.5 m have been observed. The concentrations of EC in precipitation varied from 0.02 to 0.7 mg/l and average wet deposition flux of EC was 5–7 and maximum 15–20 mg/m² per month.     

Acidic deposition,ecosystem processes,and nitrogen saturation in a high elevation Southern Appalachian watershed

High-elevation red spruce-Fraser fir forests in the Southern Appalachian mountains: 1) receive among the highest rates of atmospheric deposition measured in North America, 2) contain old-growth forests, 3) have shown declines in forest health, 4) have sustained high insect-caused fir mortality, and 5) contain poorly buffered soils and stream systems. High rates of nitrogen and sulphur deposition (1900 and 2200 Eq·ha^–1·yr^–1, respectively) are dominated by dry and cloud deposition processes. Large leaching fluxes of nitrate-nitrogen (100–1400 Eq·ha^–1·yr^–1) occur within the soil profile. We have expanded the study to the watershed scale with monitoring of: precipitation, throughfall, stream hydrology, and stream chemistry. Two streamlets drain the 17.4 ha Noland Divide Watershed (1676–1920m) located in the Great Smoky Mountains National Park. A network of 50 20x20 m plots is being used to assess stand structure, biomass, and soil nutrient pools. Nitrate is the predominant anion in the streamlets (weighted concentrations: 47 and 54 eq·L^–1 NO₃ ^–; 31 and 43 eq·L^–1 SO₄ ^2–). Watershed nitrate export is extremely high (1000 Eq·ha^–1 yr^–1), facilitating significant base cation exports. Stream acid neutralizing capacity values are extremely low (–10 to 20 eq·L^–1) and episodic acidifications (pH declines of a full unit in days or weeks time) occur. Annual streamwater sulfate export is on the order of 770 Eq·ha^–1yr^–1 or about one-third of total annual inputs, indicating there is net watershed sulfate retention. The system is highly nitrogen saturated (Stage 2, Stoddard, 1994) and this condition promotes both chronic and episodic stream acidification.     

The spatial distribution of soil microbial biomass in a permanent row crop

The effects of soil texture (silt loam or sandy loam) and cultivation practice (green manure) on the size and spatial distribution of the microbial biomass and its metabolic quotient were investigated in soils planted with a permanent row crop of hops (Humulus lupulus). The soil both between and in the plant rows was sampled at three different depths (0–10, 10–20, and 20–30 cm). The silt loam had a higher overall microbial biomass C concentration (260 g g^-1) than the sandy loam (185 g g^-1), whereas the sandy loam had a higher (3.1 g CO₂-C mg^-1 microbial Ch^-1) metabolic quotient than the silt loam (2.6 g CO₂-C mg^-1 microbial C h^-1), on average over depth (0–30 cm) and over all treatments. There was a sharp decrease in the microbial biomass with increasing depth for all plots. However, this was more pronounced in the silt loam than in the sandy loam. There was no distinct influence of sampling depth on the metabolic quotient. The microbial biomass was considerably higher in the rows than between the rows, especially in the silt loam plots. There was no significant difference between plots without green manure and plots with green manure for either the microbial biomass or the metabolic quotient.     

Uptake and toxicity of copper and zinc for the African earthworm,Eudrilus eugeniae (Oligochaeta)

Growth rate change in earthworms is considered to be a suitable endpoint when determining sublethal effects. In this study we evaluated growth and maturation in the vermicomposting earthworm speciesEudrilus eugeniae as marker of sublethal toxicity of copper and zinc. We also compared routes of uptake. Apart from exposing worms experimentally for 73 days to contaminated food, a series of contact filter paper tests was also performed to determine LD₅₀ for copper and zinc. Both copper and zinc at sublethal concentrations affected growth and maturation in worms exposed to contaminated food. These worms had a copper content of 34.5 g g^–1 after 73 days and a zinc content of 184.9 g g^–1, showing a differential uptake. Copper was more toxic than zinc. Also in the contact test worms did take up more zinc than copper and the LD₅₀ (48 h) for copper was 0.011 mg cm^–2 and for zinc 0.066 mg cm^–2, which translated to body burdens of 6 g g^–1 for copper and 131 g g^–1 for zinc. Indications were that a regulatory mechanism existed for both metals. Both metals were taken up through the body wall at a relatively fast rate. This study indicated that the skin was the major route of metal uptake. This study also showed a poor relation between the two types of tests for purposes of evaluating lethality of zinc and copper.     

Über die Anwendbarkeit der Liebermann-Burchard-Reaktion auf stickstoffhaltige SteroideSolanum-Alkaloide. XXXVIII. Mitteilung

Zusammenfassung Von 51 überprüften stickstoffhaltigen Steroiden mit bzw ohne ⁵-Doppelbindung (Solanum-Steroidalkaloide, N-haltige Cholestan- und Pregnan-Derivate) gaben lediglich 3 eine positive Liebermann-Burchard-Reaktion: N-Acetyltomatidadien, N-Acetyl-solasodien und Dihydrosolasodin A. Auch eine Anzahl ⁵-ungesättigter Steroidsapogenine und stickstofffreier Pregnan-Derivate zeigte eine nur schwache Farbreaktion.

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Summary To obtain information about the value and limitations of the Liebermann-Burchard reaction 51 nitrogenous steroids with or without ⁵ double bond have been tested. Only 3 of them show a positive colour reaction: the N-acetyl derivatives of tomatidadiene and solasodiene as well as the dihydrosolasodine A. Also some ⁵-unsaturated steroidal sapogenins and nitrogen-free pregnane derivatives produce colours of only slight intensity.

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am ¶rt;u 51 ⁵- ( Solanum, ) 3 -: N--, N-- . ⁵ - .

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XXXVII. Mitteil.: Schreiber, K., 1964. — Liebigs Ann. Chem.674, 168–175.     

Mercury in the Aquatic Environment of the Village of Caimito at the Mojana Region,North of Colombia

During May–September 1999, several aquatic environmental samples were collected from the village of Caimito, in the San Jorge River basin area, state of Sucre (Colombia), and analyzed for total mercury (T-Hg). Mean T-Hg concentration in sediments from surrounded marshes was 0.155 ± 0.016 g Hg/g. Low Hg concentrations were found in the phytoplanktivorous fish species Prochilodus magdalenae (0.087 ± 0.01 g Hg/g), while four-fold greater concentrations were found in all the carnivorous species. In average, T-Hg concentrations for fish samples did not exceed the limit consumption level (0.5 g Hg/g). However, risk assessment based on the hazard index suggested that the consumption of 0.1 kg per day of carnivorous fish could increase the risk of mercury poisoning in local population.     

Relation between sulphur concentrations in the Scots pine needles and the air in northernmost Europe

The SO₂ emissions from the Kola Peninsula in Arctic Russia (totalling around 600 Gg(SO₂) yr^–1 at the beginning of the 1990s) produce an atmospheric SO₂ concentration gradient to the northernmost Europe. This gradient covers the range from >50 g m^–3 in the vicinity of the sources to 1 g m^–3 in Finnish Lapland. In the present study, the measured sulphur concentrations in Scots pine needles were compared with the estimated distribution of atmospheric SO₂. The total sulphur concentrations in the needles ranged from 741 to 2017 mg kg^–1. Strongly elevated concentrations (> 1200 mg kg^–1) were found within 40 km from the smelters corresponding to an area where the annual mean atmospheric SO₂ concentration exceeded 10 g m^–3. The foliar sulphur concentrations (total, organic and inorganic) show a high correlation with the estimated mean SO₂ concentration distribution in the air. Consequently the foliar sulphur concentrations reflected the atmospheric sulphur load well. The data presented here show that uptake via stomata is an important deposition pathway also in the arctic conditions with a short growing season.     

Physiological and symbiotic characteristics of Rhizobium fredii isolated from subtropical-tropical soils

Summary Physiological and symbiotic characteristics were identified in Rhizobium fredii isolated from subtropical-tropical soils. The generation times of R. fredii Taiwan isolated-SB 357 and -SB 682 were 1.7 and 2.5 h, respectively. These strains were associated with acid production in yeast-extract mannitol medium. They were able to use hexoses, pentose, sucrose, trehalose and raffinose. Strain SB 357 can resist a high concentration of kanamycin (100 g ml^–1 and penicillin (400 g ml^–1). It can tolerate up to 2.34% NaCl and 1031.3 mosmol kg^–1 (23.4 bars). The growth rate of R. fredii SB 357 under the concentration of approximately 450 mosmol kg^–1 (10.2 bars) was not affected by salinity, but responded to osmotic pressure. Both strains (SB 357 and SB 682) isolated from subtropical-tropical soils were able to form an effective N₂-fixing symbiosis with the US soybean cv Clark lanceolate leaflet.