Auswaschung von Nährstoffen durch sauren Nebel aus jungen intakten Fichten (Picea abies)

Leaching of nutrients out of young intact spruce (Picea abies) by acid fog The effect of acid fog on the leaching of minerals and carbohydrates out of needles of five year old spruce trees (Picea abies) was studied. The fogs were prepared from H₂SO₄ and HNO₃ (2:1) with a pH of 2.75 (acid treatment) and 5 (control treatment). The acid fog leached significantly higher amounts of K, Ca, Mg, Mn, and Zn as well as carbohydrates as compared with the control fog. The absolute quantities of minerals leached, however, were low and amounted to only some percent of the minerals generally present in needles. Except Zn, of which the quantity leached was about as high as the Zn needle content. Nevertheless the Zn concentration in the needles treated with acid fog was not lower than the Zn concentration in the control needles suggesting that the lost Zn was quickly compensated by Zn uptake. In the treatments with acid fog damage symptoms appeared at the end of the experimental period. In the older needles a weak chlorosis occurred; from the needles of the 1^st year some turned redish brown. In the acid fog treatments all needles lacked brightness while the control needles looked bright. These symptoms were similar to those under field conditions of older spruce trees with the ?lametta syndrom”?. Electron microscopic investigation revealed that the wax layer of the needles treated with acid fog was badly damaged.     

Acid fog and ozone: Their possible role in birch deterioration around the Bay of Fundy,Canada

The area of deterioration in white birch stands adjacent to the Bay of Fundy overlaps with the area intercepting the often acidic “Fundy Fog” (mean pH 3.6 April to October). The fogs deposit substantial, and previously undetected, amounts of acidity (0.1 – 0.5 keq ha^?1) which rival and may exceed the input by rain to the stands. Preliminary data (1987) suggest a relationship between fog acidity, nitrate levels (P<0.01 and P<0.05 respectively), and foliar browning occurring at each site. Acidity tends to increase inland, which may indicate rapid conversion of dissolved SO₂ in fog droplets to SO₄. The relationship with O₂ was not significant at the 0.05 level. Browning is more extensive on older leaves, suggesting cumulative damage and increasing susceptibility to secondary attack by leaf spot fungus. Although the direct effect of ozone on browning is unresolved, its role in controlling fog chemistry warrants further investigation.     

Nitrate removal from ground water — use of a nitrate selective resin and a low concentrated regenerant

A new, strong base, macro-porous anion exchange resin, Amberlite IRA 996, appeared to be more nitrate selective than sulfate selective in treating high nitrate concentrations (18 mg NO _inf3 ^sup? -N L^?1) in potable water. When regeneration is carried out in a closed circuit in which a biological denitrification reactor is incorporated to remove nitrate from the regenerant, regeneration salt requirement and brine production can be minimized. In this combination of ion exchange and biological denitrification, regeneration with 30 g NaHCO₃ L^?1) is possible in 6 hr at a flow rate of 11 BV hr^?1. Accumulation of sulfate in the closed regeneration circuit does not affect the nitrate capacity of the resin.     

Effect of municipal landfill leachate on mercury movement through soils

The effect of solution composition on the movement of Hg ions through soils was studied. Three solutions spiked with HgC1₂ were passed through four different soils. The solutions were 0.25 mM Na₂ EDTA, simulated sanitary landfill effluent, and deionized water. The Hg ions were found to be more mobile in the effluent from the simulated landfill than in the other solutions. The formation of mercurous ions and the presence of organic matter seem to be the major contributing factors for Hg; movement through soils in simulated landfill effluent.     

Effect of simulated acid precipitation on nitrogen mineralization and nitrification in forest soils

After exposure of samples of three forest soils (pH 3.4 to 3.9) from the Adirondacks region of New York to 60, 230, or 400 cm of simulated rain of pH 3.5 or 5.6 in 4, 14, or 24 weeks, respectively, the soil samples were separated into the 0 to 2 and 2 to 5 cm organic layers and further incubated. The rates of N mineralization in Woods soil exposed to the simulated precipitation were less for rain at pH 3.5 than at pH 5.6, but the inhibition decreased with increasing exposure of the 0 to 2 cm layer. In Panther soil, the rates of mineralization were usually not affected by the acidity of the simulated rain. In the upper layer of Sagamore soil, mineralization was not influenced by pH of the simulated rain, but the transformation was faster in the bottom layer of soil after prolonged exposure to simulated rain at pH 3.5 than at pH 5.6. The rate of nitrate formation in Panther and Woods soil amended with ammonium was inhibited by the more acid rain. Studies with ¹⁵NH₄ indicated that ammonium was oxidized to nitrate even though ammonium levels did not decline or declined only slightly after prolonged exposure of Panther or Woods soil to rain at pH 3.5. The growth of orchardgrass in Panther and Woods soil was inhibited by the more acid simulated rain.     

Der Nitratgehalt in der Halmbasis als Maßstab für den Stickstoffdüngerbedarf bei Wintergetreide

The nitrate content of the basal internode of the stems as an indicator of the nitrogen fertilizer requirement of winter cereals In fertilizer experiments on loess soils in the southern part of Lower Saxony (FRG) the possibility was tested if the nitrate content of the basal internode of the stems can be used in the determination of the N-fertilizer requirement between stem elongation and ear emergence. The nitrate concentration was determined by a plant sap test. The following results were obtained:

• 1 Nitrate concentrations in the fresh matter between 200 and 2000 ppm can be determined by the reagent ?Diphenylaminesulphuric acid”?. This method is easily applicable and can be done by farmers.
• 1 Winter wheat and winter barley have different nitrate concentrations in the basal internode of the stems between stem elongation and ear emergence. As the N-supply in spring (N_min + N-fertilizer) was the same in all fields, the different nitrate concentrations in the stems are due to the preceding crop and to different organic manuring.
• 1 There is a close relationship between the nitrate content in stems (basal internode) and the nitrate content of the soil.
• 1 The required amount of nitrogen fertilizer between stem elongation and ear emergence was significantly correlated with the nitrate content in the stems (basal intenode). Therefore, a recommendation of N-top dressings to winter wheat and winter barley was made on this basis. The method is suitable for determining the necessary amount and timing of N-fertilization.

     

Spatial-temporal variations in snowfall chemistry in the montreal region

Snowfall was collected on an event basis for 6 winter storms in 1980 at 10 locations around the greater Montreal region. Six sites were urban, 2 suburban and 2 rural (small town). For all storms, 4 of the urban stations had the highest pH of the 10 locations, with the 6 Montreal Island sites having the highest chemical concentrations. Employing principal component analysis, two chemical species associations are apparent: (1) an alkaline/fly ash factor and (2) an ‘acid snow’ factor. The former indicates the possible effects of local emissions. Generally, the storms produced individual chemical concentrations patterns enabling five of the storms to be separated into distinct events. Three storms were designated as ‘type’ storms in which pH, sulphates, and nitrates varied according to individual storm characteristics and air trajectories. If the air trajectory passed over SO_x and NO_x sources to the west and south-west (Ontario-Great Lakes region) pH values were lower and sulphate and nitrate concentrations in the snowfall higher.     

Response surface methodology to understand the anaerobic biodegradation of organochlorine pesticides (OCPs) in contaminated soil—significance of nitrate concentration and bioaccessibility

Purpose

Problems associated with Organochlorine pesticide (OCP)-contaminated soils have received wide attention. To understand the anaerobic biodegradation process constraints, innovative mathematical analysis methods are effective.

Materials and methods

Response surface methodology (RSM) and Tenax TA extraction method combined with the first-three-compartment model were employed to systematically investigate the role of nitrate concentration and bioaccessibility enhancer (methyl-β-cyclodextrin, MCD) in the anaerobic biodegradation of OCPs in contaminated soil.

Results and discussion

The sole addition of either KNO₃ or MCD could facilitate the anaerobic biodegradation of OCPs. The highest biodegradation for total OCPs, hexachlorocyclohexanes, endosulfans, and chlordanes were 71.6, 82.1, 68.3, and 55.6 %, respectively, when 20 mM KNO₃ and 3.0 % (w/w) MCD were applied simultaneously. As predicted by RSM, the theoretical maximum biodegradation for total OCPs ranged from 60 to 80 % when 20 to 25 mM KNO₃ and >2.5 % (w/w) MCD were applied simultaneously. Tenax TA extraction method demonstrated the enhancement of OCP bioaccessibility caused by MCD addition. Changes in the soil microbial activities also suggested the positive effects of adding suitable amounts of KNO₃ as a cosubstrate to facilitate the anaerobic biodegradation of OCPs.

Conclusions

The amount of KNO₃ and MCD are crucial in influencing OCP biodegradation. RSM was demonstrated to be a powerful tool to estimate and predicting the optimal OCP biodegradation under KNO₃ and MCD application simultaneously.     

Removal of nitrates from potable water by ion exchange

The feasibility of removing nitrates from otherwise potable water by means of anion exchange was investigated. Candidate anion exchange resins had to demonstrate a higher affinity for nitrate ions than for the other ions present (Cl^?, HCO₃ ^?). The distribution factor between chloride and nitrate was investigated with the anion exchange resin Amberlite-400. In studies of column operation it was found that sea water was as effective as NaCl for regeneration. The nitrate ion capacity was proportional to the nitrate ion concentration and to the TDS in the feed. Nitrate ion leakage was greater with lower levels of regeneration. An operational capacity for nitrate of 0.3 to 0.4 me ml^?1 was found; this capacity was not significantly affected by the presence of sulfate ion in low concentration (2 me 1^?1).     

Seasonal pattern of nitrate losses from cultivated soil with subsurface drainage

Subsurface drainage systems have been installed in about 10000 ha of agricultural land in the flat part of the Emilia-Romagna Region in northern Italy. Nitrate loss in drainage water from a representative farm in this area was measured for three consecutive years (1986, 1987, 1988). During this period a total of 369 water samples were collected, filtered at 0.45 µm and analyzed. The nitrate concentration exceeded the limits for surface water set by Italian law regarding water pollution (90 mg NO₃ ^?L^?1 = 20 mg N L^?1) in 84% of the samples. The greatest nitrate loss was recorded during the winter and early spring when drainage was high. After this period loss of nitrate, via drainage water, progressively decreased. This was attributed to a decrease in the amount of drainage water and increase in crop uptake of N. The average annual nitrate loss via drainage water was around 200 kg of NO _inf3 ^sup? ha^?1. Annual nitrate losses of this order of magnitude (? 50 kg N ha^?1) indicate an urgent need for implementation of management practices directed towards achieving considerable reductions in these losses.     

Winterliche N-Mineralisation in sandigen Böden des ‘Fuhrberger Feldes’ (Hannover)

N mineralization in sandy soils of the ‘Fuhrberg well field’ (Hannover) during winter Net N mineralization was measured under field conditions during winter and spring 1991/92 in sandy arable soils (Gleyic Podzols, Mollic Gleysols, Gleyic Arenosols) of the ‘Fuhrberg well field’, a drinking water catchment north-east of Hannover. The aim was to assess leaching losses of nitrate from mineralization processes during the winter on soils formerly used as grassland. Two field procedures were used: the incubation of soil material in polyethylene bags at its original location and rain sheltered fallow plots. Between 6 and 40 (100) kg N ha^?1 were mineralized during 73 days from Dec., 17th to March, 2nd. Mineralisation rates were closely correlated to the organic N and C contents of the soils (r² ± 0.9). In the uncovered soils, the NO₃ was completely leached out. On five out of seven fields the process ‘N-mineralization during winter’ alone was sufficient to exceed the official limit for drinking water (50 mg 1^?1 NO₃^? ) in the uppermost groundwater. It is concluded that even 15 years after converting grassland into arable land the N_org and C_org levels in the soils had not reached a new equilibrium.     

Available Nitrogen for Corn and Winter Cereal in Spanish Soils Measured by Electro‐ultrafiltration,Calcium Chloride,and Incubation Methods

Abstract

Comparison of methods is necessary to develop a quick and reliable test that can be used to determine soil‐available nitrogen (N) in an attempt to increase the efficiency of N fertilizers and reduce losses. The objectives of this research were to compare the fractions extracted by the calcium chloride (CaCl₂) and the electro‐ultrafiltration (EUF) methods and to correlate them to the mineralization rate (k) obtained from a 112‐d incubation of 61 soil samples. Thirty‐five soil samples were collected from cornfields and 26 from winter cereal fields. Subsamples were either aerobically incubated to calculate k or extracted by the EUF and CaCl₂ methods to identify three fractions: nitrate (NO₃ ^?)‐N, ammonium (NH₄ ⁺)‐N, and Norg‐N. The Norg‐N extracted by both methods was larger in soils from cornfields than in soils from winter cereal fields. In samples from cornfields, the Norg‐N fraction obtained by the EUF method was correlated to the Norg‐N measured by the CaCl₂ method (r=0.46). Soil N content was related to k in samples from cornfields (r=0.40) but not in samples from winter cereal fields. Also, k was correlated to inorganic N content extracted by both chemical methods. The CaCl₂ method was a reliable alternative for laboratories to determine soil‐available N for corn but not for winter cereal.     

Acidic precipitation at a site within the northeastern conurbation

Rain and snow were collected in plastic beakers either manually or with a Wong sampler during 58 precipitation events in 1974 at Yonkers, New York approximately 24 km north of the center of New York City. Determinations were made of total dissolved ionic species, free H ions, total H ions, sulfate, nitrate, chloride, and fluoride. Conductivity measurements ranged from 6.8 to 162 gmhos, pH from 3.4 to 4.9, total acidity from 36 to 557 μeq 1^?1 sulfate from less than 1 to 20 mg 1^?1, nitrate from less than 1 to 14 mg 1^?1, and chloride from less than 1 to 7 mg 1^?1. All fluoride concentrations were less than 0.1 mg 1^?1. The results indicate that precipitation at this suburban location adjacent to New York City is consistently acidic and contains concentrations of sulfate, nitrate, and chloride which are similar to values found for other locations in the northeastern United States. Positive correlations were found between nitrate and sulfate concentrations and acidity suggesting that the atmospheric contaminants, SO₂, and NO₂ are causally-related to the occurrence of acidic precipitation. Further research will be necessary to clarify the relative influence of natural and man-made sources of N and S compounds and the contributions of gaseous and particulate contaminants in the atmosphere to the acidity of precipitation at this location.     

Observations on Gaseous and Aerosols Components of the Atmosphere and Their Relationships

Measurements of sulphur dioxide, ozone, ammonia, and soluble inorganic components of the atmospheric aerosol were made at a site in central southern England. Ammonia, ozone, and nitrate aerosol in winter were shown to exhibit significant diurnal variation. Ozone showed a typical diurnal variability, the magnitude of which was dependent upon wind speed. The lower night-time ozone concentrations at lower wind speeds were attributed to depletion inside nocturnal boundary layers by dry deposition. Ammonia, in contrast, showed a different behaviour, whereby the diurnal cycle was more pronounced at higher wind speeds, indicating that the cycle was unlikely to be the result of dry deposition at night. Ammonia concentrations showed a temperature dependence and the diurnal cycle of ammonia at this site appears to be the result of a temperature-driven emission signal. Of the total reduced nitrogen, NH_x (NH_x = NH₃ + NH₄ ⁺ aerosol), the phase was dominant and it is likely that more than 60% of the boundary layer NH_x is in this phase. The loss term of ammonia by reaction with acid sulphate aerosol is likely to be greater than that by dry deposition on a UK scale. Nitrate aerosol showed a positive correlation with sodium aerosol, once the effect of mutual correlations with sulphate and ammonium were removed. This correlation effect, in combination with evidence of a marine-oriented directional dependence of nitrate aerosol, and negative non sea-salt chloride aerosol from the same ‘marine’ sector, shows the potential importance of the formation of sodium nitrate aerosol from reaction of dinitrogen pentoxide, or possibly nitric acid or nitrogen dioxide with sodium chloride aerosol. It is likely that this provides the major route of nitrate into rain, not the scavenging of nitric acid vapour. Aerosol sulphate, nitrate, and ammonium have been measured at Harwell since 1954. Sulphate aerosol increased up until 1976 and has declined subsequently. Nitrate aerosol has increased over the whole period, whereas ammonium aerosol follows a similar pattern to that of sulphate, but with an equivocal direction of trend after 1976. Sulphate, nitrate and ammonium aerosol all show a similar statistically significant seasonality. A historical inventory of ammonia emissions shows a clear correlation with ammonium aerosol.     

Anion‐exchange membranes used to assess management impacts on soil nitrate

Abstract

Our goal was to determine if anion‐exchange membranes (AEMs), which can be placed in situ in soils and act as anion exchangers, were better soil nitrate (NO₃‐) assessment tools than soil extraction. During winter 1993–1994 we compared NO₃‐ in the surface of tilled and non‐tilled soils that were subjected to rye cover crop and fallow winter coverage treatments. Estimates of soil solution concentrations of NO₃‐ based on KC1 extracts of the AEMs were between 1 to 5 fold higher than concentrations based on soil extracts. Both methods of NO₃‐ assessment documented a general decline in NO₃‐ availability during the winter; however, only the AEM NO₃‐ data produced statistically significant results. AEM data suggested that the combination of fall tillage and winter fallowing increased soil NO₃‐ contents and led to more potential for loss of NO₃‐ during the 1993–1994 winter than reduced tillage practices or planting a rye cover crop.     

Contrasting response of nitrification capacity in three agricultural soils to N addition during short-term incubation

Purpose

Human disturbance is a major culprit driving imbalances in the biological transformation of nitrogen from the nonreactive to the reactive pool and is therefore one of the greatest concerns for nitrogen (N) cycling. The objective of this study was to compare potential nitrification rates and the abundance of ammonia oxidizers responsible for nitrification, with the amendment of external N in different agricultural soils.

Materials and methods

Three typical Chinese agricultural soils, QiYang (QY) acid soil, ShenYang (SY) neutral soil, and FengQiu (FQ) alkaline soil, were amended with 0, 20, 150, and 300 μg NH₄ ⁺-N g^?1 soil and incubated for 40 days. The abundance of ammonia oxidizing bacteria (AOB) and archaea (AOA) at the end of incubation in the soil microcosms was determined using the real-time PCR.

Results and discussion

There was a significant decrease in ammonium concentration in the QY soil from the highest to the lowest N-loading treatments, while no significant difference in ammonium concentrations was detected among the different N-loading treatments for the SY and FQ soils. A significantly higher potential nitrification rate (PNR) was observed in the FQ soil while lowest PNR was found in the QY soil. Quantitative PCR analysis of AOB amoA genes demonstrated that AOB abundance was significantly higher in the high N-loading treatments than in the control for the QY soil only, while no significant difference among treatments in the SY and FQ soils. A significant positive correlation between PNR and AOB amoA abundance, however, was found for the SY and FQ soils, but not for the QY soil. Little difference in AOA amoA abundance between different N-loading treatments was observed for all the soils.

Conclusions

This study suggested that ammonia oxidation capacity in the FQ and SY soils was higher than those in the QY soil with the addition of ammonium fertilizer for a short-term. These findings indicated that understanding the differential responses of biological nitrification to varying input levels of ammonium fertilizer is important for maximizing N use efficiency and thereby improving agricultural fertilization management.     

A baseline study on trace metal elution from diverse soil types

Ten soils were leached with a dilute solution of AICI₃, and FeCl₂ adjusted with HCl to pH 3.0. The effluents were analyzed for eight trace metals as well as pH, to determine the maximum contribution of the soils to the trace metal burden of the soil solution. This contribution was correlated with various soil properties to evaluate the controlling factors on the elution of certain metals. Measurable quantities of Mn, Co, Zn, Ni, Cu, and Cr were found in the soil leachates; Cd and Pb were infrequently detected. The important soil properties describing the amounts of the elements leached were the total metal originally present, the total amount of Mn, and the percentage of free iron oxides.     

Do freeze‐thaw events enhance C and N losses from soils of different ecosystems? A review

Freezing and thawing of soils may affect the turnover of soil organic matter and thus the losses of C and N from soils. Here we review the literature with special focus on: (i) the mechanisms involved, (ii) the effects of freezing temperature and frequency, (iii) the differences between arable soils and soils under natural vegetation, and (iv) the hypothesis that freeze‐thaw events lead to significant C and N losses from soils at the annual scale. Changes in microbial biomass and populations, root turnover and soil structure might explain increased gaseous and solute fluxes of C and N following freeze‐thaw events, but these mechanisms have seldom been addressed in detail. Effects of freeze‐thaw events appear to increase with colder frost temperatures below 0°C, but a threshold value for specific soils and processes cannot be defined. The pool of C and N susceptible to freeze‐thaw events is rather limited, as indicated by decreasing losses with short‐term repeated events. Elevated nitrate losses from soils under alpine and/or arctic and forest vegetation occurred only in the year following exceptional soil frost, with greatest reported losses of about 13 kg N ha^?1. Nitrate losses are more likely caused by reduced root uptake rather than by increased N net mineralization. N₂O emissions from forest soils often increased after thawing, but this lasted only for a relatively short time (days to 1–2 months), with the greatest reported cumulative N₂O emissions of about 2 kg N₂O‐N ha^?1. The emissions of N₂O after freeze‐thaw events were in some cases substantially greater from arable soils than from forest soils. Thus, freeze‐thaw events might induce gaseous and/or solute losses of N from soils that are relevant at the annual time scale. While a burst of CO₂ after thawing of frozen soils is often found, there is strong evidence that, at the annual time scale, freeze‐thaw cycles either have little effect or will even reduce soil C losses as compared with unfrozen conditions. On the contrary, a milder winter climate with fewer periods of soil frost may result in greater losses of C from soils that are presently influenced by extended frost periods.     

Simulation des Nitrataustrags im Winterhalbjahr aus Intensiv genutzten Ackerböden in der Geest

Modeling nitrate leaching during the winter halfyear from sandy arable soils under intensive cultivation Three years (1989–91) of post harvest and winter nitrogen dynamics (August to March) were simulated in 20 arable sandy soils to quantify nitrate leaching during winter time. Easily accessible soil, weather and management data were used for a simple but deterministic model. The calculated mineral N (N_min) content and distribution in the soil (0–90 cm) were compared to more than 100 measurements from September to March each season. An overall agreement of approximately 50% between measured and simulated N_min values was obtained. The simulation over- or underestimated the measured N_min depending on the rainfall and temperature distribution which varied from year to year. Practically, the effect of fertilizer application was largely (60%) responsible for deviations greater than ±20 kgN ha^?1 from the 1:1-line. Ignoring these instances, 80% of the simulated N_min contents were within these “confidence limits” of ±20 kgN ha^?1. Considering the nitrogen distribution in the profile, the N_min content is underestimated in the top soil, but overestimated in the subsoil. Based on the 95% confidence intervals (measured versus simulated) the estimate was better for the lower (30–90 cm) than for the upper part of the profile (0–30 cm). It is concluded that winter leaching can be reduced from 130 kgN ha^?1 (corn, winter grain) to about 10 kgN ha^?1 growing winter hard forage crops. Two major processes were identified as reasons for the disagreement and are proposed for further model improvement: (1) The simulation underestimates the short term transport velocity on the basis of field capacity derived from survey data. (2) Nitrogen is mineralized quickly in sandy soils, especially after catch crops, and sometimes due to freeze-thaw effects. Furthermore, as ammonium remains in the surface, nitrification needs to be explicitly simulated.     

Influence of Different Substrates in Wetland Soils on Denitrification

Different substrates were evaluated to investigate their effect on nitrate removal and denitrifying bacterial community in soils obtained from wetland. Serial batch kinetic tests were conducted on soils obtained from wetland mixed with glucose and sawdust using KNO₃ solution. Column tests were also conducted on soils obtained from wetland mixed with three different substrates (glucose, sawdust, and scoria coated with zero-valent iron) using KNO₃ solution. For the batch tests, the nitrate removal efficiency for soil mixed with glucose was comparable to that for soil mixed with sawdust, but the nitrate removal rate for soil mixed with glucose (23.3 NO ₃ ^? -N mg/L-d) was approximately eight times higher than that for soil mixed with sawdust (2.8 NO ₃ ^? -N mg/L-d). For column tests among soil samples, nitrate removal efficiency was highest in soil mixed with glucose, which is an easily biodegradable carbon source. Removal efficiency increased with increasing incubation time for both soil samples with glucose and sawdust. A phylogenetic analysis based on nitrate reductase gene demonstrated that the different carbon sources affected both the diversity and compositions of the denitrifying bacterial in soil samples.