共查询到20条相似文献,搜索用时 31 毫秒
1.
The proportion of total sulphur lost during combustion (600 °C) of Douglas-fir (Pseudotsuga menziesii) foliage is reduced from> 90% to 65–70% as the SO4-S concentration increases from 10% to 45–50% of the total S content. Foliar SO4-S content is decreased by improvement of plant nitrogen status, suggesting that alterations to soil N availability may influence S transfer to the atmosphere during biomass burning. 相似文献
2.
The hypothesis that SO4 desorption can explain apparent long term net SO4-S losses (5 kg·ha–1·yr–1 on average) at the Lake Laflamme catchment from 1982 to 1991 is examined. Field observations show that SO4 concentrations in the soil solution are strongly buffered during percolation through the Bf horizon. In the Bf horizon, SO4 exchange reactions between the adsorbed and aqueous compartments are rapid (hours). Most (60%) of the adsorbed SO4 may be readily desorbed with deionized water. These observations and the presence of an important adsorbed SO4-S reservoir in the Bf horizon (113 kg·ha–1) as compared with annual wet SO4-S deposition (7 kg·ha–1), suggest that on the short-term, adsorption and desorption reactions can control dissolved SO4 concentration in the Bf horizon. To examine whether SO4 adsorption/desorption could explain long-term SO4-S losses by the catchment, an aggregated Langmuir isotherm for the Bf horizon was used to calculate the catchment's resilience to changing SO4-S loads. The results indicate that the soil should adjust rapidly (within 4 years) to changing SO4-S loads and that SO4 desorption alone cannot explain long-term net SO4-S losses. Other possibilities, such as an underestimation of dry deposition or the weathering of S-bearing minerals also appear unlikely. Our results suggest a net release of SO4-S from the soil organic S reservoirs (1230 kg·ha–1) present in the catchment. 相似文献
3.
In the Netherlands, permanent damming of sulphate (SO4 2–)-rich surface water, in order to rewet desiccated wetlands, has resulted in stagnation and eutrophication of surface water. Permanent damming of surface water prevents periodic drought during summer and leads to suppressed iron (Fe)-rich groundwater input and to stimulated SO4 2– reduction, all likely stimulating depletion of reducible Fe in the sediment. A laboratory experiment was conducted to assess the importance of temporary desiccation, its differential effects on various sediment types and the consequences for water table management. Permanent high SO4 2–-rich surface water tables above sediments that are indirectly affected by shallow groundwater flows, resulted in severe eutrophication. The effect of temporary desiccation on phosphorus (P) mobilization and immobilization strongly depended on the sediment Fe and P pools in combination with the buffering capacity of the sediment. Desiccation of sediment that is indirectly affected by shallow groundwater flows, led to a long-lasting reduction in phosphate (o-PO4 3–) release from the sediment because a reduced Fe pool is present, resulting in the release of Fe upon oxidation. Formerly dry sediments that have not been influenced by groundwater for a long time do not possess such a reduced Fe pool and desiccation did not reduce P-release from these sediments resulting in considerable eutrophication of the water layer immediately after rewetting. In sediment of seepage zones that are directly and permanently influenced by deeper groundwater, reduced Fe and calcium levels are so high that o-PO4 3– was effectively immobilized under oxidized as well as reduced conditions. The results indicate that restoration of desiccated wetlands can not be achieved by simply retaining water by means of constructed dams. If water retention is artificially increased, temporary drops in water level during the summer are necessary to recharge the reducible P-binding Fe pool in large zones of the wetlands in order to prevent eutrophication. 相似文献
4.
Total S concentration in the top 35 cm of Big Run Bog peat averaged 9.7 mol·g — wet mass–1 (123 mol·g dry mass–1). Of that total, an average of 80.8% was carbon bonded S, 10.4% was ester sulfate S, 4.5% was FeS2S, 2.7% was FeSS, 1.2% was elemental S, and 0.4% was SO4
2–S. In peat collected in March 1986, injected with35SSO4
2– and incubated at 4 °C, mean rates of dissimilatory sulfate reduction (formation of H2S + S0 + FeS + FeS2), carbon bonded S formation, and ester sulfate S formation averaged 3.22, 0.53, and 0.36 nmol·g wet mass–1·h–1, respectively. Measured rates of sulfide oxidation were comparable to rates of sulfate reduction. Although dissolved SO4
2– concentrations in Big Run Bog interstitial water (< 200 µM) are low enough to theoretically limit sulfate reducing bacteria, rates of sulfate reduction integrated throughout the top 30–35 cm of peat of 9 and 34 mmol·m–2·d–1 (at 4 °C are greater than or comparable to rates in coastal marine sediments. We suggest that sulfate reduction was supported by a rapid turnover of the dissolved SO4
2– pool (average turnover time of 1.1 days). Although over 90% of the total S in Big Run Bog peat was organic S, cycling of S was dominated by fluxes through the inorganic S pools. 相似文献
5.
Summary The study was conducted in a greenhouse and under field conditions. In the greenoouse, barley was grown to maturity in pots on a sandy soil which contained 80 and 120 meq/l of chloride and sulphate dominant salts in its saturation extract, to which 0, 10, 25 and 50 ppm P were added. In the field study, wheat was grown on loamy sand soils having 0, 25, 50 and 75 kg/ha added P levels and irrigated with either Cl- or SO4-dominant saline waters (EC=15–19 mmhos/cm). The results of the greenhouse study indicated that at maturity barley straw and grain yield was significantly increased by 50 ppm of added P both on the non-saline control and the Cl-treatments. However, 25 ppm P was optimal on the SO4-treatments. The Cl content of plants was significantly decreased and S was increased with the increase in the P content of soil. A synergistic relation between the S and P content of barley shoots was observed. In the field study wheat grain yield responded significantly to P applications upto 50 kg/ha level on the Cl-site and there was no response to applied P on the SO4-site, although the former contained more Olsen's P than the latter. The results suggested that P requirement of wheat and barley was greater on Cl- than on SO4-salinity. 相似文献
6.
Summary The replacement of carboxy-proton of IAA, plays an important role in the process of growth under saline conditions. Appreciable changes in pH have ben observed in the presence of CO3
–2 and HCO3
–, and increase in pH appears to be caused owing to the formation of unstable complex of IAA, which soon hydrolyzes and gives alkalinity. The pH change thus achieved favours IAA oxidase activity; therefore, suppression of growth is resulted in CO3
–2 and HCO3
– medium. In the presence of SO4
–2 and Cl– salts slight lowering of pH takes place which does not favour IAA oxidase activity. It is therefore, presumed that anion (CO3
–2, HCO3
–, SO4
–2 and Cl–) controls the process of growth and development through the alteration of pH of the medium. 相似文献
7.
Sulphur fractionation and availability to plants are poorly understood in calcareous soils. Sixty-four calcareous soils containing varying amounts of CaCO3 were collected from ten provinces in China and their S fractions determined. Organic S was the predominant fraction of S, accounting for on average 77% of the soil total S. The amounts of adsorbed sulphate were found to be negligible. 1 M HCl extracted substantially more sulphate than either 0.01 M CaCl2 or 0.016 M KH2PO4, indicating the existence of water-insoluble but acid-soluble sulphate, probably in the form of sulphate co-precipitated with CaCO3. The concentrations of water-insoluble sulphate correlated positively with the contents of CaCO3 and accounted for 0.03–40.3% (mean 11.7%) of soil total S. To test the bioavailability of water-insoluble sulphate, a sulphate-CaCO3 co-precipitate labelled with 35S was prepared and added to a calcareous soil in a pot experiment with either NH4+ or NO3– as the N source. In 29 days, wheat plants took up 10.6% and 3.0% of the 35S added to the soil in the NH4+ and NO3– treatments, respectively. At the end of the pot experiment, the decrease of water-insoluble, acid-soluble, sulphate was more apparent in the NH4+ than in the NO3– treatment. The results indicate that sulphate co-precipitated with CaCO3 in calcareous soils may become partly available for plant uptake, depending on rhizosphere pH, if the field precipitate is similar to the laboratory prepared sample studied. 相似文献
8.
Sulfate reduction and S-oxidation in a moorland pool sediment 总被引:3,自引:2,他引:1
In an oligotrophic moorland pool in The Netherlands, S cycling near the sediment/water boundary was investigated by measuring (1) SO4
2– reduction rates in the sediment, (2) depletion of SO4
2– in the overlying water column and (3) release of35S from the sediment into the water column. Two locations differing in sediment type (highly organic and sandy) were compared, with respect to reduction rates and depletion of SO4
2– in the overlying water.Sulfate reduction rates in sediments of an oligotrophic moorland pool were estimated by diagenetic modelling and whole core35SO4
2– injection. Rates of SO4
2– consumption in the overlying water were estimated by changes in SO4
2– concentration over time in in situ enclosures. Reduction rates ranged from 0.27–11.2 mmol m–2 d–1. Rates of SO4
2– uptake from the enclosed water column varied from –0.5, –0.3 mmol m–2 d–1 (November) to 0.43–1.81 mmol m–2 d–1 (July, August and April). Maximum rates of oxidation to SO4
2– in July 1990 estimated by combination of SO4
2– reduction rates and rates of in situ SO4
2– uptake in the enclosed water column were 10.3 and 10.5 mmol m–2 d–1 at an organic rich and at a sandy site respectively.Experiments with35S2– and35SO4
2– tracer suggested (1) a rapid formation of organically bound S from dissimilatory reduced SO4
2– and (2) the presence of mainly non SO4
2–-S derived from reduced S transported from the sediment into the overlying water. A35S2– tracer experiment showed that about 7% of35S2– injected at 1 cm depth in a sediment core was recovered in the overlying water column.Sulfate reduction rates in sediments with higher volumetric mass fraction of organic matter did not significantly differ from those in sediments with a lower mass fraction of organic matter.Corresponding author 相似文献
9.
The biogeochemistry of sulfur at Hubbard Brook 总被引:8,自引:8,他引:0
G.E. Likens C.T. Driscoll D.C. Buso M.J. Mitchell G.M. Lovett S.W. Bailey T.G. Siccama W.A. Reiners C. Alewell 《Biogeochemistry》2002,60(3):235-316
A synthesis of the biogeochemistry of S was done during 34 yr(1964–1965 to 1997–1998) in reference and human-manipulated forestecosystems of the Hubbard Brook Experimental Forest (HBEF), NH. There have beensignificant declines in concentration (–0.44µmol/liter-yr) and input (–5.44mol/ha-yr)of SO4
2– in atmospheric bulk wet deposition, and inconcentration(–0.64 µmol/liter-yr) an d output (–3.74mol/ha-yr) of SO4
2– in stream water ofthe HBEF since 1964. These changes arestrongly correlated with concurrent decreases in emissions of SO2from the source area for the HBEF. The concentration and input ofSO4
2– in bulk deposition ranged from a low of 13.1µmol/liter (1983–1984) and 211 mol/ha-yr(1997–1998) to a high of 34.7 µmol/liter(1965–1966) and 479 mol/ha-yr (1967–1968), with along-term mean of 23.9 µmol/liter and 336mol/ha-yr during 1964–1965 to 1997–1998. Despiterecentdeclines in concentrations, SO4
2– is the dominantanion in both bulk deposition and streamwater at HBEF. Dry deposition is difficult to measure, especially inmountainousterrain, but was estimated at 21% of bulk deposition. Thus, average totalatmospheric deposition was 491 and 323 mol/ha-yr during1964–1969 and 1993–1998, respectively. Based on the long-term34S pattern associated with anthropogenic emissions,SO4
2– deposition at HBEF is influenced by numerousSO2sources, but biogenic sources appear to be small. Annual throughfall plusstemflow in 1993–1994 was estimated at 346 molSO4
2–/ha. Aboveground litterfall, for thewatershed-ecosystemaveraged about 180 mol S/ha-yr, with highest inputs (190 molS/ha-yr) in the lower elevation, more deciduous forest zone. Weatheringrelease was calculated at a maximum of 50 mol S/ha-yr. Theconcentration and output of SO4
2– in stream waterranged from a low of 42.3µmol/liter (1996–1997) and 309 mol/ha-yr(1964–1965), to a high of 66.1 µmol/liter(1970–1971) and 849 mol/ha-yr (1973–1974), with along-term mean of 55.5 µmol/liter and 496mol/ha-yr during the 34 yrs of study. Gross outputs ofSO4
2– in stream water consistently exceeded inputsin bulkdeposition and were positively and significantly related to annualprecipitationand streamflow. The relation between gross SO4
2–output and annual streamflow changed with time asatmospheric inputs declined. In contrast to the pattern for bulk depositionconcentration, there was no seasonal pattern for streamSO4
2– concentration. Nevertheless, stream outputs ofSO4
2– were highly seasonal, peaking during springsnowmelt, andproducing a monthly cross-over pattern where net hydrologic flux (NHF) ispositive during summer and negative during the remainder of the year. Nosignificant elevational pattern in streamwaterSO4
2– concentration was observed. Mean annual,volume-weightedsoil water SO4
2– concentrations were relativelyuniform by soil horizon andacross landscape position. Based upon isotopic evidence, much of theSO4
2– entering HBEF in atmospheric depositioncycles throughvegetation and microbial biomass before being released to the soil solution andstream water. Gaseous emissions of S from watershed-ecosystems at HBEF areunquantified, but estimated to be very small. Organic S (carbon bonded andestersulfates) represents some 89% of the total S in soil at HBEF. Some 6% exists asphosphate extractable SO4
2– (PSO4).About 73% of the total S in the soilprofile at HBEF occurs in the Bs2 horizon, and some 9% occurs in the forestfloor. The residence time for S in the soil was calculated to be 9 yr, butonly a small portion of the total organic soil pool turns over relativelyquickly. The S content of above- and belowground biomass is about 2885mol/ha, of which some 3–5% is in standing dead trees. Yellowbirch, American beech and sugar maple accounted for 89% of the S in trees, with31% in branches, 27% in roots and 25% in the lightwood of boles. The pool of Sin living biomass increased from 1965 to 1982 due to biomass accretion, andremained relatively constant thereafter. Of current inputs to the availablenutrient compartment of the forest ecosystem, 50% is from atmospheric bulkdeposition, 24% from net soil release, 11% from dry deposition, 11% from rootexudates and 4% is from canopy leaching. Comparing ecosystem processes for Sfrom 1964–1969 to 1993–1998, atmospheric bulk deposition decreasedby 34%, stream output decreased by 10%, net annual biomass storage decreased by92%, and net soil release increased by 184% compared to the 1964–1969values. These changes are correlated with decreased emissions of SO2from the source area for the HBEF. Average, annual bulk deposition inputsexceeded streamwater outputs by 160.0 ± 75.3 SD molS/ha-yr,but average annual net ecosystem fluxes (NEF) were much smaller, mostlynegativeand highly variable during the 34 yr period (–54.3 ± 72.9 SDmol S/ha-yr; NEF range, +86.8 to –229.5). While severalmechanisms may explain this small discrepancy, the most likely are netdesorption of S and net mineralization of organic S largely associated with theforest floor. Our best estimates indicate that additional S from dry depositionand weathering release is probably small and that desorption accounts for about37% of the NEF imbalance and net mineralization probably accounts for theremainder (60%). Additional inputs from dry deposition would result fromunmeasured inputs of gaseous and particulate deposition directly to the forestfloor. The source of any unmeasured S input has important implications for therecovery of soils and streams in response to decreases in inputs of acidicdeposition. Sulfate is a dominant contributor to acid deposition at HBEF,seriously degrading aquatic and terrestrial ecosystems. Because of the strongrelation between SO2 emissions and concentrations ofSO4
2– in both atmospheric deposition and streamwater at HBEF,further reductions in SO2 emissions will be required to allowsignificant ecosystem recovery from the effects of acidic deposition. Thedestruction or removal of vegetation on experimental watershed-ecosystems atHBEF resulted in increased rates of organic matter decomposition andnitrification, a lowering of soil and streamwater pH, enhancedSO4
2– adsorption on mineral soil and smallerconcentrations andlosses of SO4
2– in stream water. With vegetationregrowth, this adsorbedSO4
2– is released from the soil, increasingconcentrations andfluxes of SO4
2– in drainage water. Streamwaterconcentration ofSO4
2– and gross annual output ofSO4
2–/ha are essentially the same throughout theHubbard BrookValley in watersheds varying in size by about 4 orders of magnitude, from 3 to3000 ha. 相似文献
10.
Summary Moorland pools are shallow oligotrophic soft water lakes on poorly buffered sandy soils. Diatom assemblages of samples from 16 pools taken in 1920 and 1978 were compared by analysis of pH-spectra, diversity, dissimilarity and multivariate statistical techniques.The pH-spectra of pools in the southern (S) and central (C) part of the country indicate a fall in pH from 4.5–6.0 in the old samples to 3.7–4.6 in the recent ones. The pH-spectra of the northern pools (N) do not indicate a significant shift from the original pH (ca 4.5).The number of species in the count and the diversity (indices of Simpson and Shannon) decreased significantly in S+C, and that goes also for the dissimilarity index of Dyer. No changes were found in N.The first component (PC 1) of the principal component analysis explains 61% of total variance. PC 1 is correlated with log [SO4] (r=0.83, p<0.001) and even better (r=0.95, p<0.001) with the relative sulphate concentration,i.e. the ratio of sulphate to all major anions (sulphate, chloride, bicarbonate). All old samples have low scores on PC 1, recent samples have low scores on the second (PC 2) and third (PC 3) principal component. Old samples have high scores on PC 2 and PC 3, explaining 9 and 6% of total variance, respectively.The orginal variation, caused by regional factors, is replaced by a SO4
2– controlled variation. PC 1 is nearly completely determined by the relative abundance ofEunotia exigua. This species, which is known to be very resistant to pollution by sulphur, aluminium and heavy metals, increased largely from 1920 to 1978.In spite of the rather homogeneous distribution of wet sulphate deposition in the Netherlands, substantial differences in SO4
2– content in the pools are observed, being lowest in N (0.13–0.48 meq.l–1) and highest in S+C (0.38–1.65 meq.l–1). Sulphate is positively correlated with calcium, aluminum and magnesium but negatively with factors that characterize humic acid waters (e.g. permanganate-consumption, iron and the ratio of univalent to divalent cations). Sulphate concentration depends on the intensity of sulphate reduction, accumulation by dry deposition in surrounding forests of Scots pine, drought and atmospheric deposition. 相似文献
11.
Water relations and xylem transport of nutrients in pepper plants grown under two different salts stress regimes 总被引:4,自引:0,他引:4
Josefa M. Navarro Consuelo Garrido Vicente Martínez Micaela Carvajal 《Plant Growth Regulation》2003,41(3):237-245
Two iso-osmotic concentrations of NaCl and Na2SO4 were used for discriminating between the effects of specific ion toxicities of salt stress on pepper plants (Capsicum annuum L.) grown in hydroponic conditions, in a controlled-environment greenhouse. The two salts were applied to plants at different electrical conductivities, and leaf water relations, osmotic adjustment and root hydraulic conductance were measured. Leaf water potential (w), leaf osmotic potential (o) and leaf turgor potential (p) decreased significantly when EC increased, but the decrease was less for NaCl- than for Na2SO4-treated plants. The reduction in stomatal conductance was higher for NaCl-treated plants. There were no differences in the effect of both treatments on the osmotic adjustment, and a reduction in root hydraulic conductance and the flux of solutes into the xylem was observed, except for the saline ions (Na+, Cl– and SO4
2–). Therefore, pepper growth decreased with increasing salinity because the plants were unable to adjust osmotically or because of the toxic effects of Cl–, SO4
2– and/or Na+. However, turgor of NaCl-treated plants was maintained at low EC (3 and 4 dS m–1) probably due to the maintenance of water transport into the plant (decrease of stomatal conductance), which, together with the lower concentration of Na+ in the plant tissues compared with the Na2SO4 treatment, could be the cause of the smaller decrease in growth. 相似文献
12.
Response of sugarcane to different types of salt stress 总被引:2,自引:0,他引:2
Summary Due to climatic conditions and prevailing water regime the yield and sucrose recovery in sugarcane are high in South Western India. However, excessive irrigation, poor drainage and luxuriant use of fertilizers have resulted in conversion of large fertile areas into saline lands. The salinity is due to the excess of Na+, Ca++, Mg++, SO4
– and Cl– ions. Individual salts of NaCl, Na2SO4, MgCl2 and MgSO4 were employed in culture experiments to study salt stress effect on sugarcane variety Co 740. It was observed that sulphate salinity was more toxic to sugarcane than the chloride one. Sulphate salts caused more inhibition of growth, chlorophyll synthesis, PEPCase activity, decreased the uptake of K+ and Ca++ ions but stimulated nitrate reductase. The stress did not result in proline accumulation in the sugarcane cultivar Co 740. The degree of toxicity of different ions in decreasing order in sugarcane cultivar Co 740 is SO4
–>Na+>Cl–>Mg++. 相似文献
13.
The S cycle in the water column of a small, soft-water lake was studied for 9 years as part of an experimental study of the effects of acid rain on lakes. The two basins of the lake were artificially separated, and one basin was experimentally acidified with sulfuric acid while the other served as a reference or control. Spatial and seasonal patterns of sulfate uptake by plankton (53–70 mmol m–2 yr–1), deposition of sulfur to sediments in settling seston (53 mmol m–2 yr–1), and sulfate diffusion (0–39 mmol m–2 yr–1) into sediments were examined. Measurements of inputs (12–108 mmol m–2 yr–1) and outputs (5.5–25 mmol m–2 yr–1) allowed construction of a mass balance that was then compared with rates of S accumulation in sediments cores (10–28 mmol m–2 yr–1) and measured fluxes of S into the sediments. Because of the low SO4
2– concentrations (µmole L–1) in the lake, annual uptake by plankton (53–70 mmol m–2 yr–1) represented a large fraction (>50%) of the SO4
2– inventory in the lake. Despite this large flux through the plankton, only small seasonal fluctuations in SO4
2– concentrations (µmole L–1) were observed; rapid mineralization of organic matter (half-life <3 months) prevented sulfate depletion in the water column. The turnover time for sulfate in the water column is only 1.4 yr; much less than the 11-yr turnover time of a conservative ion in this seepage lake. Sulfate diffusion into and reduction in the sediments (0–160 µmole m–2 d–1) caused SO4
2– depletion in the hypolimnion. Modeling of seasonal changes in lake-water SO4
2– concentrations indicated that only 30–50% of the diffusive flux of sulfate to the sediments was permanently incorporated in solid phases, and about 15% of sulfur in settling seston was buried in the sediments. The utility of sulfur mass balances for seepage lakes would be enhanced if uncertainty about the deposition velocity for both sulfate aerosols and SO2, uncertainty in calculation of a lake-wide rate of S accumulation in sediments, and uncertainty in the measured diffusive fluxes could be further constrained. 相似文献
14.
Ten soils collected from the major arable areas in Britain were used to assess the availability of soil sulphur (S) to spring
wheat in a pot experiment. Soils were extracted with various reagents and the extractable inorganic SO4-S and total soluble S(SO4-S plus a fraction of organic S) were determined using ion chromatography (IC) or inductively-coupled plasma atomic emission
spectrometry (ICP-AES), respectively. Water, 0.016 M KH2PO4, 0.01 M CaCl2 and 0.01 M Ca(H2PO4)2 extracted similar amounts of SO4-S, as measured by IC, which were consistently smaller than the total extractable S as measured by ICP-AES. The amounts of
organic S extracted varied widely between different extractants, with 0.5 M NaHCO3 (pH 8.5) giving the largest amounts and 0.01 M CaCl2 the least. Organic S accounted for approximately 30–60% of total S extracted with 0.016 M KH2PO4 and the organic C:S ratios in this extract varied typically between 50 and 70. The concentrations of this S fraction decreased
in all soils without added S after two months growth of spring wheat, indicating a release of organic S through mineralisation.
All methods tested except 0.5 M NaHCO3-ICP-AES produced satisfactory results in the regression with plant dry matter response and S uptake in the pot experiment.
In general, 0.016 M KH2PO4 appeared to be the best extractant and this extraction followed by ICP-AES determination was considered to be a good method
to standardise on. 相似文献
15.
Suppression of peatland methane emission by cumulative sulfate deposition in simulated acid rain 总被引:11,自引:3,他引:8
This field manipulation study tested the effect of weekly pulses of solutions of NH4NO3 and (NH4)2SO4 salts on the evolution of CH4 and N2O from peatland soils. Methane and nitrous oxide emission from a nutrient-poor fen in northern Minnesota USA was measured over a full growing season from plots receiving weekly additions of NH4NO3 or (NH4)2SO4. At this relatively pristine site, natural additions of N and S in precipitation occur at 8 and 5 kg ha–1 y–1, respectively. Nine weekly additions of the dissolved salts were made to increase this to a total deposition of 31 kg N ha–1 y–1 on the NH4NO3-amended plots and 30 and 29 kg ha–1 y–1 of N and S, respectively, in the (NH4)2SO4-amended plots. Methane flux was measured weekly from treatment and control plots and all data comparisons are made on plots measured on the same day.After the onset of the treatments, and over the course of the growing season, CH4 emission from the (NH4)2SO4-amended plots averaged 163 mg CH4 m–2 d–1, significantly lower than the same-day control plot mean of 259 mg CH4 m–2 d–1 (repeated measures ANOVA). Total CH4 flux from (NH4)2SO4 treatment plots was one third lower than from control plots, at 11.7 and 17.1 g CH4 m–2, respectively. Methane emission from the NH4NO3-amended plots (mean of 256 mg CH4 m–2 d–1) was not significantly different from that of controls measured on the same day (mean of 225 mg CH4 m–2 d–1). Total CH4 flux from NH4NO3 treatment plots and same-day controls was 16.9 and 15.1 g CH4 m–2, respectively. In general, stable, relatively warm and wet periods followed by environmental `triggers' such as rainfall or changes in water table or atmospheric pressure, which produced a CH4 `pulse' in the other plots, produced no observable peak in CH4 emission from the (NH4)2SO4-amended plots. Nitrous oxide emission from all of the plots was below the detection limit over the course of the experiment. 相似文献
16.
Nitrogen nutrition of rice plants under salinity 总被引:1,自引:0,他引:1
Two rice (Oryza sativa L.) cultivars, Koshihikari and Pokkali, were grown in solution culture at three concentrations of NaCl or Na2SO4 [0 (S0), 50 (S1), and 100 (S2) mmol dm–3] and three N contents [0.7 (N1), 7 (N2) and 14 (N3) mmol dm–3]. Salinity significantly decreased dry matter of both cultivars. Pokkali had better growth than Koshihikari under both saline and non-saline conditions. Applications of N enhanced development of shoot dry mass under S0 and S1 treatments up to N2. Under S2, N application had no effect on shoot dry mass of both cultivars. Root dry mass of both cultivars decreased with increasing N application at S1 and S2. Shoot and root NO3-N content in both rice cultivars increased with increasing N concentration in the nutrient solutions. The absorption of NO3-N was less in Koshihikari than Pokkali plants, and also was much less in Cl– than SO4
2– salinity suggesting the antagonism between Cl– and NO3
–. In addition a significant negative correlation between concentrations of NO3-N and Cl– in the shoots or roots was observed in both cultivars 相似文献
17.
Sulfur (S) deficiency in soils and plants has been increased in the recent decade which is reducing crop yield and quality. Unfortunately, no extensive study has been conducted on S nutritional status of plants in Turkey. In this study, soil and plant samples were collected from Çukurova, Central Anatolia and GAP regions where wheat is extensively cultivated. Plant samples either as flag leaf or the whole shoot were collected depending on growth stage of wheat crop at sample collection. Similarly, surface (0–20 cm) and sub-surface (20–40 cm) soil samples were collected from plant sampling sites and a total 963 plant and 1947 soil samples were collected during the study. The S concentration in flag leaf samples varied between 0.18 and 0.67%, 0.11–0.59% and 0.17–0.82% for central Anatolia, Çukurova and GAP regions, respectively. According to S concentration in flag leaf samples, 99% of the plants in Çukurova region were found sufficient in S nutrition. However, 49% of the samples collected from central Anatolia and GAP regions were deficient in S. Critical N:S ratio indicating S nutrition status of plants was lower than the widely accepted critical value of 17. This low N:S ratio was a consequence of deficient N nutrition rather than S nutrition. Moreover, it was observed that plant available SO4-S concentration of soils varied within and among sampled provinces with an average value of 20.6 and 31.6 mg kg−1 for surface and sub-surface samples, respectively. The SO4-S concentration increased with increasing soil depth. The results indicate a significantly positive correlation between S concentration in plant shoot and plant available SO4-S concentration in soils. In conclusion, S-containing fertilizer use in central Anatolia and GAP regions must be considered as an important approach for the prevention of yield and quality losses. Furthermore, rapid and sensitive plant and soil analysis methods are needed, which must also consider the local and site-specific conditions. 相似文献
18.
Sulphate fluxes in bulk deposition, throughfall and soil solution were monitored during two years, and integrated within a model describing the cycling of S in a chalk grassland ecosystem. Throughfall fluxes were strongly determined by interceptive properties of the grassland canopy. Seasonal variation in Leaf Area Index resulted in dry deposition velocities for SO2 varying between 0.1 cm.s–1 (snow cover, almost no aerodynamic resistance) to 0.9–1.8 cm.s–1 in periods with a fully developed canopy. On an annual basis net canopy exchange (assimilation of SO2 minus foliar leaching) was estimated to be –15% of net throughfall. Simulated soil solution concentrations, being the result of throughfall input, leaching, adsorption, biomass uptake and mineralization, closely fitted actual values (r > 0.92; p > 0.001). Actual and simulated leaching were 1.74 ± 0.03 and 2.00 keq.-ha–1.yr–1, respectively. Sulphur budgets for the soil showed net accumulation from April to October and net losses from October to April. Annual budgets for the ecosystem showed atmospheric input (2.02keq.ha–1.yr–1) and actual output (2.05keq.ha–1.yr–1) to be almost balanced. Apart from increased soil solution concentrations, additional input of sulphate (3.55 keq.ha–1.yr–1) to experimental plots resulted in additional accumulation in the ecosystem of 0.62 keq.ha–1.yr–1 相似文献
19.
Sulfate reduction in fine-grained sediments in the Eastern Scheldt,southwest Netherlands 总被引:2,自引:1,他引:1
Oene Oenema 《Biogeochemistry》1990,9(1):53-74
Sulfate reduction and sulfide accumulation were examined in fine-grained sediments from rapidly accreting abandoned channels and mussel culture areas in the Eastern Scheldt, which covered 4 and 5% of the total surface area, respectively.Reduction rates were measured in batch experiments in which the SO4
2– depletion was measured during anoxic incubation. The reduction rates in summer varied between 14–68 mmol SO4
2– m–2 day–1 and were related to the sedimentation rate. In the most rapidly accreting channels, SO4
2– was exhausted below 15–50 cm and methanogenesis became the terminal process of organic carbon oxidationOne-dimensional modelling of sulfate profiles in mussel banks indicated that the subsurface influx of SO4
2– was almost of the same order as the diffusive flux at the sediment-seawater interface, during the initial stages of the mussel bank accretion. The energy dissipation of waves and tidal currents on the mussel bank surface increased the apparent sediment diffusivity up to 3-fold, especially in the winterThe results indicate that acid volatile sulfide (AVS) was the major, in-situ reduced, sulfur compound in the sediment. The sulfidation of easily extractable iron was nearly complete. Pyrite concentrations (40–80 M S cm–3) were as high as the AVS concentrations, but there was apparently no in-situ transformation of AVS into pyrite. The detrital pyrite originated from eroding marine sediments elsewhere 相似文献
20.
Sulfur cycling in forests 总被引:6,自引:5,他引:1
D. W. Johnson 《Biogeochemistry》1984,1(1):29-43
Sulfur is essential for the production of certain amino acids in plants. As amino acid sulfur is the major form of sulfur in trees, there is a strong relationship between organic S and organic N in tree tissue. Sulfur deficiencies occur in parts of southeastern Australia and northwestern North America, remote from pollutant inputs. Since bilogical S requirements of forests are modest (< 5 kg · ha–1 yr–1 for net vegetative increment), however, atmospheric S inputs in polluted regions (10–80 kg · ha–1 yr–1 ) often exceed not only the forest ecosystem S requirement but also its ability to biologically accumulate S. There is some increase in the SO2–
4–S content of forest vegetation in response to elevated atmospheric S inputs, but this capacity is apparently easily saturated. Soil SO2–2
4adsorption is often the dominant feature of S cycling in polluted ecosystems and often accounts for net ecosytem S accumulations.Contribution from a symposium on the role of sulfur in ecosystem processes held August 10, 1983, at the annual meeting of the A.I.B.S., Grand Forks, ND; Myron Mitchell, convenor. 相似文献