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1.
Jean-Michel Harmand Hector Ávila Etienne Dambrine Ute Skiba Sergio de Miguel Reina Vanessa Renderos Robert Oliver Francisco Jiménez John Beer 《Biogeochemistry》2007,85(2):125-139
Nitrogen fertilization is a key factor for coffee production but creates a risk of water contamination through nitrate (NO3−) leaching in heavily fertilized plantations under high rainfall. The inclusion of fast growing timber trees in these coffee
plantations may increase total biomass and reduce nutrient leaching. Potential controls of N loss were measured in an unshaded
coffee (Coffea arabica L.) plot and in an adjacent coffee plot shaded with the timber species Eucalyptus deglupta Blume (110 trees ha−1), established on an Acrisol that received 180 kg N ha−1 as ammonium-nitrate and 2,700 mm yr−1 rainfall. Results of the one year study showed that these trees had little effect on the N budget although some N fluxes
were modified. Soil N mineralization and nitrification rates in the 0–20 cm soil layer were similar in both systems (≈280 kg N ha−1 yr−1). N export in coffee harvest (2002) was 34 and 25 kg N ha−1 yr−1 in unshaded and shaded coffee, and N accumulation in permanent biomass and litter was 25 and 45 kg N ha−1 yr−1, respectively. The losses in surface runoff (≈0.8 kg mineral N ha−1 yr−1) and N2O emissions (1.9 kg N ha−1 yr−1) were low in both cases. Lysimeters located at 60, 120, and 200 cm depths in shaded coffee, detected average concentrations
of 12.9, 6.1 and 1.2 mg NO3−-N l−1, respectively. Drainage was slightly reduced in the coffee-timber plantation. NO3− leaching at 200 cm depth was about 27 ± 10 and 16 ± 7 kg N ha−1 yr−1 in unshaded and shaded coffee, respectively. In both plots, very low NO3− concentrations in soil solution at 200 cm depth (and in groundwater) were apparently due to NO3− adsorption in the subsoil but the duration of this process is not presently known. In these conventional coffee plantations,
fertilization and agroforestry practices must be refined to match plant needs and limit potential NO3− contamination of subsoil and shallow soil water. 相似文献
2.
Late-successional forests in the upper Great Lakes region are susceptible to nitrogen (N) saturation and subsequent nitrate
(NO3−) leaching loss. Endemic wind disturbances (i.e., treefall gaps) alter tree uptake and soil N dynamics; and, gaps are particular
susceptible to NO3− leaching loss. Inorganic N was measured throughout two snow-free periods in throughfall, forest floor leachates, and mineral
soil leachates in gaps (300–2,000 m2, 6–9 years old), gap-edges, and closed forest plots in late-successional northern hardwood, hemlock, and northern hardwood–hemlock
stands. Differences in forest water inorganic N among gaps, edges, and closed forest plots were consistent across these cover
types: NO3− inputs in throughfall were significantly greater in undisturbed forest plots compared with gaps and edges; forest floor leachate
NO3− was significantly greater in gaps compared to edges and closed forest plots; and soil leachate NO3− was significantly greater in gaps compared to the closed forest. Significant differences in forest water ammonium and pH
were not detected. Compared to suspected N-saturated forests with high soil NO3− leaching, undisturbed forest plots in these late-successional forests are not losing NO3− (net annual gain of 2.8 kg ha−1) and are likely not N-saturated. Net annual NO3− losses were observed in gaps (1.3 kg ha−1) and gap-edges (0.2 kg ha−1), but we suspect these N leaching losses are a result of decreased plant uptake and increased soil N mineralization associated
with disturbance, and not N-saturation. 相似文献
3.
Relationship between river water quality and land use in a small river basin running through the urbanizing area of Central Japan 总被引:9,自引:0,他引:9
In this study, the relationship between water quality (as represented by major inorganic ion concentrations) and land use
characteristics is examined for a small river basin which runs through the urbanizing area of central Japan. Water samples
were taken from 24 sites at base flow and analyzed, and the proportions of the various land uses associated with the respective
drainage basins were calculated using a digital land-use map (scale: 1:25000). The electrical conductivity (EC) of the water
ranged from 84.5 to 600 μS cm−1. Ca2+ and Na+ were the major cations, accounting for 77% of all cations. Among the anions, HCO3
− was dominant (56%), followed by Cl− (24%), SO4
2− (13%) and NO3
− (7%). Applying principal component analysis to land use in the drainage basin yielded three principal components. The first
principal component expressed the degree of occupation by residential areas, the second indicated the degree of urban developing
area (i.e., fast-developing and industrial areas), and the third showed the degree of coverage with farmland and green space.
The residential area showed significant positive correlations with K+, Mg2+, Ca2+, NO3
−, HCO3
−, EC and TMI (total major ions). Urban developing area showed significant positive correlations with Ca2+, Cl−, HCO3
−, EC and TMI as well as weak negative correlations with NO3
− and SO4
2−. Industrial area showed weak positive correlations with Na+ and Cl− and a moderate negative correlation with NO3
−. Farmland showed significant positive correlations with NO3
− and SO4
2−; these ions are present due to fertilizers and the biological activity of plants. Forest area is inversely related to almost
all ions, indicating the need for this form of land use in order to maintain river water quality. 相似文献
4.
Problems of estimating population parameters and production of fish in a tropical rain forest stream,North Venezuela 总被引:1,自引:1,他引:0
The River Todasana is a small rain tropical forest stream emptying to the Caribbean Sea (Venezuela). Fish were sampled by
electrofishing at three contiguous sites (pool, riffle, raceway). Nine species were recorded. Their mean biomass and production
were: 43.72 kg ha−1 and 36.94 kg ha−1 yr−1, maximum: 55.47 kg ha−1 and 42.33 kg ha−1 yr−1, respectively. 相似文献
5.
Spatial and Temporal Variability in Sediment Denitrification Within an Agriculturally Influenced Reservoir 总被引:2,自引:1,他引:1
Reservoirs are intrinsically linked to the rivers that feed them, creating a river–reservoir continuum in which water and
sediment inputs are a function of the surrounding watershed land use. We examined the spatial and temporal variability of
sediment denitrification rates by sampling longitudinally along an agriculturally influenced river–reservoir continuum monthly
for 13 months. Sediment denitrification rates ranged from 0 to 63 μg N2O g ash free dry mass of sediments (AFDM)−1 h−1 or 0–2.7 μg N2O g dry mass of sediments (DM)−1 h−1 at reservoir sites, vs. 0–12 μg N2O gAFDM−1 h−1 or 0–0.27 μg N2O gDM−1 h−1 at riverine sites. Temporally, highest denitrification activity traveled through the reservoir from upper reservoir sites
to the dam, following the load of high nitrate (NO3−-N) water associated with spring runoff. Annual mean sediment denitrification rates at different reservoir sites were consistently
higher than at riverine sites, yet significant relationships among theses sites differed when denitrification rates were expressed
per gDM vs. per gAFDM. There was a significant positive relationship between sediment denitrification rates and NO3−-N concentration up to a threshold of 0.88 mg NO3− -N l−1, above which it appeared NO3−-N was no longer limiting. Denitrification assays were amended seasonally with NO3−-N and an organic carbon source (glucose) to determine nutrient limitation of sediment denitrification. While organic carbon
never limited sediment denitrification, all sites were significantly limited by NO3−-N during fall and winter when ambient NO
3−-N was low. 相似文献
6.
We examined the hydrologic controls on nitrogen biogeochemistry in the hyporheic zone of the Tanana River, a glacially-fed
river, in interior Alaska. We measured hyporheic solute concentrations, gas partial pressures, water table height, and flow
rates along subsurface flowpaths on two islands for three summers. Denitrification was quantified using an in situ 15NO3− push–pull technique. Hyporheic water level responded rapidly to change in river stage, with the sites flooding periodically
in mid−July to early−August. Nitrate concentration was nearly 3-fold greater in river (ca. 100 μg NO3−–N l−1) than hyporheic water (ca. 38 μg NO3−–N l−1), but approximately 60–80% of river nitrate was removed during the first 50 m of hyporheic flowpath. Denitrification during
high river stage ranged from 1.9 to 29.4 mg N kg sediment−1 day−1. Hotspots of methane partial pressure, averaging 50,000 ppmv, occurred in densely vegetated sites in conjunction with mean
oxygen concentration below 0.5 mgO2 l−1. Hyporheic flow was an important mechanism of nitrogen supply to microbes and plant roots, transporting on average 0.41 gNO3−–N m−2 day−1, 0.22 g NH4+–N m−2 day−1, and 3.6 g DON m−2 day−1 through surface sediment (top 2 m). Our results suggest that denitrification can be a major sink for river nitrate in boreal
forest floodplain soils, particularly at the river-sediment interface. The stability of the river hydrograph and the resulting
duration of soil saturation are key factors regulating the redox environment and anaerobic metabolism in the hyporheic zone. 相似文献
7.
During 1999–2001 the chemical composition and fluxes were measured in rainfall, throughfall, soil solution and stream water
in a remote forested site in the Italian Alps. The analysis of temporal patterns revealed the differential behaviour of nitrogen
and sulphur and suggested that different mechanisms controlled their flux. No important changes in sulphate concentration
and fluxes emerged as the solution passed through the various components of the forest ecosystem, and temporal variations
of SO4 in the soil solution and stream were likely driven by the physical process of dilution. The availability of nitrate and ammonia,
by contrast, was drastically reduced as throughfall water entered the soil and passed through the mineral layers, irrespective
of season. The calculated hydrochemical budget based on throughfall and soil solution N fluxes revealed that ~80% N retention
in the forest soil, corresponding to 12 kg ha−1 yr−1, despite a relatively high N deposition loading (15 kg ha−1 yr−1). Most of the leached nitrogen (90%) was in the organic form. Indicators of the N status of this ecosystem, such as C/N ratio
in solid and solution phase of the soil and N foliage content as well as land use history were examined. Despite the strong
N retention in the forested part of the catchment, the stream water N–NO3 levels were consistently above 10 μg l−1 suggesting that the Val Masino catchment as a whole was less efficient in processing atmospheric N inputs. This contrasting
N behaviour illustrates the role of landscape features, such as the soil cover and vegetation type, that is characteristic
of an alpine catchment. 相似文献
8.
Acidification of Soil in a Dry Land Winter Wheat-sorghum/corn-fallow Rotation in the Semiarid U.S. Great Plains 总被引:4,自引:0,他引:4
David D. Tarkalson José O. Payero Gary W. Hergert Kenneth G. Cassman 《Plant and Soil》2006,283(1-2):367-379
Soil pH is decreasing in many soils in the semiarid Great Plains of the United States under dry land no-till (NT) cropping
systems. This study was conducted to determine the rate of acidification and the causes of the acidification of a soil cropped
to a winter wheat (Triticum aestivum L.)-grain sorghum [Sorghum bicolor (L.) Moench]/corn (Zea mays L.)-fallow rotation (W-S/C-F) under NT. The study was conducted from 1989 to 2003 on soil with a long-term history of either
continuous NT management [NT(LT)] (1962–2003) or conventional tillage (CT) (1962–1988) then converted to NT [NT(C)] (1989–2003).
Nitrogen was applied as ammonium nitrate (AN) at a rate of 23 kg N ha−1 in 1989 and as urea ammonium nitrate (UAN) at an average annual rate of 50 kg N ha−1 from 1990 to 2003 for both NT treatments. Soil samples were collected at depth increments of 0–5, 5–10, 10–15, and 15–30 cm
in the spring of 1989 and 2003. Acidification rates for the NT(LT) and NT(C) treatments were 1.13 and 1.48 kmol H+ ha−1 yr−1 in the 0–30 cm depth, respectively. The amount of CaCO3 needed to neutralize the acidification is 57 and 74 kg ha−1 yr−1 for the NT(LT) and NT(C) treatments, respectively. A proton budget estimated by the Helyar and Porter [1989, Soil Acidity
and Plant Growth, Academic Press] method indicated that NO3− leaching from the 30 cm depth was a primary cause of long-term acidification in this soil. Nitrate leaching accounted for
59 and 66% of the H+ from the acid causing factors for NT(LT) and NT(C) treatments, respectively. The addition of crop residues to the soil neutralized
62 and 47% of the acidity produced from the leaching of NO3−, and 37 and 31% of the acid resulting from NO3− leaching and the other acid-causing constituents for the NT(LT) and NT(C) treatments, respectively. These results document
that surface soils in dry land W-S/C-F rotations under NT are acidifying under current management practices. Improved management
to increase nitrogen uptake efficiency from applied fertilizer would help reduce the rate of acidification. The addition of
lime materials to prevent negative impacts on grain yields may be necessary in the future under current management practices.
A contribution of the university of Nebraska Agricultural Research Division, Lincoln, NE 68583. Journal series No. 15120 相似文献
9.
The bioerosive potential of the intertidal chiton Acanthopleura gemmata on One Tree Reef was determined by quantification of CaCO3 in daily faecal pellet production of individuals transplanted into mesocosms after nocturnal-feeding forays. Mean bioerosive
potential was estimated at 0.16 kg CaCO3 chiton−1 yr−1. Bioerosion rates were estimated for populations on two distinct chiton habitats, reef margin (0.013 kg CaCO3 m−2 yr−1) and beachrock platform (0.25 kg CaCO3 m−2 yr−1). Chiton density on the platform was orders of magnitude greater than on the reef margin. The surface-lowering rate (0.16
mm m−2 yr) due to bioerosion by the beachrock population is a substantial contribution to the total surface-lowering rate of 2 mm
m−2 yr−1 previously reported for One Tree Reef across all erosive agents. At high densities, the contribution of A. gemmata to coral reef bioerosion budgets may be comparable to other important bioeroders such as echinoids and fish. 相似文献
10.
Shi-Han Zhang Ling-Lin Cai Yun Liu Yao Shi Wei Li 《Applied microbiology and biotechnology》2009,82(3):557-563
The biological reduction of Fe(III) ethylenediaminetetraacetic acid (EDTA) is a key step for NO removal in a chemical absorption–biological
reduction integrated process. Since typical flue gas contain oxygen, NO2
− and NO3
− would be present in the absorption solution after NO absorption. In this paper, the interaction of NO2
−, NO3
−, and Fe(III)EDTA reduction was investigated. The experimental results indicate that the Fe(III)EDTA reduction rate decrease
with the increase of NO2
− or NO3
− addition. In the presence of 10 mM NO2
− or NO3
−, the average reduction rate of Fe(III)EDTA during the first 6-h reaction was 0.076 and 0.17 mM h−1, respectively, compared with 1.07 mM h−1 in the absence of NO2
− and NO3
−. Fe(III)EDTA and either NO2
− or NO3
− reduction occurred simultaneously. Interestingly, the reduction rate of NO2
− or NO3
− was enhanced in presence of Fe(III)EDTA. The inhibition patterns observed during the effect of NO2
− and NO3
− on the Fe(III)EDTA reduction experiments suggest that Escherichia coli can utilize NO2
−, NO3
−, and Fe(III)EDTA as terminal electron acceptors. 相似文献
11.
Nitrogen relations of natural and disturbed tropical plant communities in northern Australia (Kakadu National Park) were
studied. Plant and soil N characteristics suggested that differences in N source utilisation occur at community and species
level. Leaf and xylem sap N concentrations of plants in different communities were correlated with the availability of inorganic
soil N (NH+
4 and NO−
3). In general, rates of leaf NO−
3 assimilation were low. Even in communities with a higher N status, including deciduous monsoon forest, disturbed wetland,
and a revegetated mine waste rock dump, levels of leaf nitrate reductase, xylem and leaf NO−
3 levels were considerably lower than those that have been reported for eutrophic communities. Although NO−
3 assimilation in escarpment and eucalypt woodlands, and wetland, was generally low, within these communities there was a suite
of species that exhibited a greater capacity for NO−
3 assimilation. These “high- NO−
3 species” were mainly annuals, resprouting herbs or deciduous trees that had leaves with high N contents. Ficus, a high-NO−
3 species, was associated with soil exhibiting higher rates of net mineralisation and net nitrification. “Low-NO−
3 species” were evergreen perennials with low leaf N concentrations. A third group of plants, which assimilated NO−
3 (albeit at lower rates than the high-NO−
3 species), and had high-N leaves, were leguminous species. Acacia species, common in woodlands, had the highest leaf N contents of all woody species. Acacia species appeared to have the greatest potential to utilise the entire spectrum of available N sources. This versatility in
N source utilisation may be important in relation to their high tissue N status and comparatively short life cycle. Differences
in N utilisation are discussed in the context of species life strategies and mycorrhizal associations.
Received: 5 July 1997 / Accepted: 13 July 1998 相似文献
12.
Jirko Holst Chunyan Liu Nicolas Brüggemann Klaus Butterbach-Bahl Xunhua Zheng Yuesi Wang Shenghui Han Zhisheng Yao Jin Yue Xingguo Han 《Ecosystems》2007,10(4):623-634
Gross rates of N mineralization and nitrification, and soil–atmosphere fluxes of N2O, NO and NO2 were measured at differently grazed and ungrazed steppe grassland sites in the Xilin river catchment, Inner Mongolia, P. R.
China, during the 2004 and 2005 growing season. The experimental sites were a plot ungrazed since 1979 (UG79), a plot ungrazed
since 1999 (UG99), a plot moderately grazed in winter (WG), and an overgrazed plot (OG), all in close vicinity to each other.
Gross rates of N mineralization and nitrification determined at in situ soil moisture and soil temperature conditions were
in a range of 0.5–4.1 mg N kg−1 soil dry weight day−1. In 2005, gross N turnover rates were significantly higher at the UG79 plot than at the UG99 plot, which in turn had significantly
higher gross N turnover rates than the WG and OG plots. The WG and the OG plot were not significantly different in gross ammonification
and in gross nitrification rates. Site differences in SOC content, bulk density and texture could explain only less than 15%
of the observed site differences in gross N turnover rates. N2O and NO
x
flux rates were very low during both growing seasons. No significant differences in N trace gas fluxes were found between
plots. Mean values of N2O fluxes varied between 0.39 and 1.60 μg N2O-N m−2 h−1, equivalent to 0.03–0.14 kg N2O-N ha−1 y−1, and were considerably lower than previously reported for the same region. NO
x
flux rates ranged between 0.16 and 0.48 μg NO
x
-N m−2 h−1, equivalent to 0.01–0.04 kg NO
x
-N ha−1 y−1, respectively. N2O fluxes were significantly correlated with soil temperature and soil moisture. The correlations, however, explained only
less than 20% of the flux variance. 相似文献
13.
Nitrogen mineralization in high elevation forests of the Appalachians. I. Regional patterns in southern spruce-fir forests 总被引:4,自引:0,他引:4
Annual and seasonal rates of net nitrogen mineralization were determined for 19 sites in the spruce-fir forests of the Southern
Appalachian Mountains. These sites included high and low elevation stands of red spruce (Picea rubens Sarg.) and Fraser fir (Abies fraseri (Pursh.) Poir.) on east and west exposures on Whitetop Mountain, Virginia; Mt. Mitchell, North Carolina; and Clingman's Dome
in the Great Smoky Mountains National Park. Mineralization rates were determined using in situ soil incubations in PVC tubes
with ion exchange resin bags placed in the bottom of the tubes to collect leachate. Throughfall was collected in resin bags
placed in the top of the tubes. Average initial NH4-N + NO3-N ranged from 0.6 to 4.8 kg N/ha across all plots, and average mineralization rates ranged from 26 to 180 kg-N ha−1 yr−1. Throughfall ranged from 18 to 32 kg-N ha−1 yr−1 with NH4-N accounting for about two-thirds of the throughfall N across all sites. Throughfall and mineralization rates were not related
to elevation or exposure. The high rates of N mineralization and relatively high nitrate concentrations indicate that leaching
losses of nitrogen and associated cations could be substantial.
Requests for offprints 相似文献
14.
Water hyacinth productivity and detritus accumulation 总被引:2,自引:1,他引:1
Water hyacinth [Eichhornia crassipes (Mart) Solms] productivity and detritus accumulation were evaluated in eutrophic lake water with and without added nutrients
(fertilized and control reservoirs, respectively). Seasonal changes in plant productivity and detritus accumulation were determined
at monthly intervals for one year.
Significant differences were observed in plant productivity between seasons and nutrient additions. Seasonal plant productivity
ranged from 1.9 to 23.1 mg (dry wt) ha−1 for the fertilized reservoir and −0.2 to 10.2 mg ha−1 for the control reservoir. Detritus accumulation was not significantly different between seasons or nutrient additions. Seasonal
N assimilation by plants ranged from 34 to 242 kg N ha−1 for plants in the fertilized reservoir and < 0 to 104 kg N ha−1 for plants in the control reservoir. Annual net N recovered in detritus represented 21 and 28% of the total N removed by
plants in the fertilized and control reservoirs, respectively. Net N loading to the reservoirs from detritus was 92 to 148
kg N ha−1 yr−1. 相似文献
15.
Synopsis The age structures of brook charr (Salvelinus fontinalis) and ouananiche (Salmo salar) stocks inhabiting a large rapid the river Méo, tributary to the Caniapiscau River were used to compare population stability
and production of these species in north central Quebec. The brook chart stock was stable whereas ouananiche showed considerable
variation in year class strength. Stock estimates were not significantly different for the two species although the brook
charr estimate was 1.5 that of the ouananiche. Production estimates differed by a greater margin because of different growth
patterns. Brook chair production was estimated at 19.4 kg ha−1 yr−1. Above age 2+ it was 11.4 kg ha−1 yr−1 which compares with 4.8 kg ha−1 yr−1 for the same age groups of ouananiche. 相似文献
16.
A. Bryce Cooper 《Plant and Soil》1986,93(3):383-394
Summary Nitrate-N losses to stream waters and soil inorganic N pools, nitrifying potentials and NO3-N production rates were measured in 2 adjacent watersheds, one used as pasture and the other planted in exotic conifer forest
(Pinus radiata D. Don). Estimated NO3-N loss to stream waters draining the pine and pasture watersheds were 0.6kg ha−1 y−1 and 7.6 kg ha−1 y−1 respectively. Ammonium-N pool sizes were not significantly different between soils in the two watersheds but NO3−N pools and nitrifying potentials were always lower in the pine watershed soil samples. Laboratory incubation experiments
indicated that suppression of NO3−N formation in pine watershed soils required the presence of live tree roots and was not due to the direct action of allelopathic
chemicals on nitrifiers. 相似文献
17.
Nitrate and nitrite inhibition of methanogenesis during denitrification in granular biofilms and digested domestic sludges 总被引:4,自引:0,他引:4
Anaerobic bioreactors that can support simultaneous microbial processes of denitrification and methanogenesis are of interest
to nutrient nitrogen removal. However, an important concern is the potential toxicity of nitrate (NO3
−) and nitrite (NO2
−) to methanogenesis. The methanogenic toxicity of the NOx− compounds to anaerobic granular biofilms and municipal anaerobic digested sludge with two types of substrates, acetate and
hydrogen, was studied. The inhibition was the severest when the NOx− compounds were still present in the media (exposure period). During this period, 95% or greater inhibition of methanogenesis
was evident at the lowest concentrations of added NO2
− tested (7.6–10.2 mg NO2
−-N l−1) or 8.3–121 mg NO3
−-N l−1 of added NO3
−, depending on substrate and inoculum source. The inhibition imparted by NO3
− was not due directly to NO3
− itself, but instead due to reduced intermediates (e.g., NO2
−) formed during the denitrification process. The toxicity of NOx− was found to be reversible after the exposure period. The recovery of activity was nearly complete at low added NOx− concentrations; whereas the recovery was only partial at high added NOx− concentrations. The recovery is attributed to the metabolism of the NOx− compounds. The assay substrate had a large impact on the rate of NO2
− metabolism. Hydrogen reduced NO2
− slowly such that NO2
− accumulated more and as a result, the toxicity was greater compared to acetate as a substrate. The final methane yield was
inversely proportional to the amount of NOx− compounds added indicating that they were the preferred electron acceptors compared to methanogenesis. 相似文献
18.
Due to a large reclamation (recultivation) demand in the Lusatian lignite mining district, efficient strategies for the rehabilitation
of abandoned mine sites are needed. A field study was conducted for comparing the effects of three different fertilizer treatments
(mineral fertilizer, sewage sludge and compost) on soil solution chemistry of both a lignite and pyrite containing spoil as
well as a lignite and pyrite free spoil. The lignite and pyrite containing spoil was ameliorated with fly ash from a lignite
power plant (17–21 t ha−1 CaO), whereas the lignite and pyrite free site received 7.5 t ha−1 CaO in form of limestone. Fertilizer application rates were: mineral fertilizer 120 N, 100 P and 80 K kg ha−1. 19 t ha−1 sewage sludge and 22 t ha−1 compost were applied. Soil solution was sampled in 20, 60 and 130 cm depth for the period of 16 months. Solution was collected
every fortnight and analysed for pH, EC, Ca2+, Mg2+, K+, Na+, Fen+, Aln+, Mn2+, Zn2+, NO3
−, NH4
+, SO4
2−, Cl−, PO4
3−, Cinorg and DOC. Lignite and pyrite containing spoil differed clearly from lignite and pyrite free spoil regarding soil solution
concentrations and composition. Acidity (H+) produced by pyrite oxidation led to an enhanced weathering of minerals and, therefore, to at least 10 fold higher soil solution
concentrations compared to the lignite and pyrite free site. Major ions in solution of the lignite and pyrite containing site
were Ca2+, Mg2+, Fen+, Aln+ and SO4
2−, whereas soil solution at the lignite and pyrite free site was dominated by Ca2+, Mg2+ and SO4
2−. At both sites application of mineral fertilizer led to an immediate but short term (about 1 month) increase of NO3
−, NH4
+ and K+ concentrations in soil solution down to a depth of 130 cm. Application of sewage sludge caused a long term (about
16 months) increase of NO3
3
− in the topsoil, whereas NO3
− concentrations in the subsoil were significantly lower compared to the mineral fertilizer plot. Compost application resulted
in a strong long-term increase of K+ in soil solution, whereas NO3
− concentrations did not increase. Concentrations of PO4
3− in soil solution depend on solution pH and were not correlated with any treatment.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
19.
Spatial variability of soil total nitrogen (N), available N (KCl extractable NH4+ and NO3−), and spatial patterns of N mineralization and nitrification at a stand scale were characterized with geostatistical and
univariate analysis. Two extensive soil spatial samplings were conducted in an evergreen broadleaf forest in Sichuan province,
southwestern China in June and August 2000. In a study area of 90 × 105 m2, three soil samples were collected from each 5 × 5 m2 plot (n = 378) in June and August, and were analyzed for total N and available N contents. Net N mineralization and nitrification
were measured by in situ core incubation and the rates were estimated based on the difference of NH4+ and NO3− contents between the two sampling dates. Total N, NH4+, and NO3− were all spatially structured with different semivariogram ranges (from high to low: NH4+, NO3−, and total N). The semivariograms of mineralization and nitrification were not as spatially structured as available N. NH4+ was the dominant soil inorganic N form in the system. Both NH4+ and NO3− affected spatial patterns of soil available N, but their relative importance switched in August, probably due to high nitrification
as indicated by greatly increased soil NO3− content. High spatial auto-correlations (>0.7) were found between available N and NH4+, available N and NO3− on both sampling dates, as well as total N measurements between both sampling dates. Although significant, the spatial auto-correlation
between NH4+ and NO3− were generally low. Topography had significant but low correlations with mineralization (r = −0.16) and nitrification (r = −0.14), while soil moisture did not. The large nugget values of the calculated semivariograms and high-semivariance values,
particularly for mineralization and nitrification, indicate that some fine scale (<5 m) variability may lie below the threshold
for detection in this study. 相似文献
20.
Temporal and spatial trends in nitrogen and phosphorus inputs to the watershed of the Altamaha River,Georgia, USA 总被引:4,自引:0,他引:4
The watershed of the Altamaha River, Georgia, is one of the largest in the southeastern U.S., draining 36,718 km2 (including parts of metro Atlanta). We calculated both nitrogen (fertilizer, net food and feed import, atmospheric deposition,
and biological N fixation in agricultural and forest lands) and phosphorus (fertilizer and net food and feed import) inputs
to the watershed for 6 time points between 1954 and 2002. Total nitrogen inputs rose from 1,952 kg N km−2 yr−1 in 1954 to a peak of 3,593 kg N km−2 yr−1 in 1982 and then declined to 2,582 kg N km−2 yr−1 by 2002. Phosphorus inputs rose from 409 kg P km−2 yr−1 in 1954 to 532 kg P km−2 yr−1 in 1974 before declining to 412 kg P km−2 yr−1 in 2002. Fertilizer tended to be the most important input of both N and P to the watershed, although net food and feed import
increased in importance over time and was the dominant source of N input by 2002. When considered on an individual basis,
fertilizer input tended to be highest in the middle portions of the watershed (Little and Lower Ocmulgee and Lower Oconee
sub-watersheds) whereas net food and feed imports were highest in the upper reaches (Upper Oconee and Upper Ocmulgee sub-watersheds).
Although the overall trend in recent years has been towards decreases in both N and P inputs, these trends may be offset due
to continuing increases in animal and human populations. 相似文献