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Peatland restoration via rewetting aims to recover biological communities and biogeochemical processes typical to pristine peatlands. While rewetting promotes recovery of C accumulation favorable for climate mitigation, it also promotes methane (CH4) emissions. The potential for exceptionally high emissions after rewetting has been measured for Central European peatland sites previously grazed by cattle. We addressed the hypothesis that these exceptionally high CH4 emissions result from the previous land use. We analyzed the effects of cattle dung application to peat soils in a short- (2 weeks), a medium- (1 year) and a long-term (grazing) approach. We measured the CH4 production potentials, determined the numbers of methanogens by mcrA qPCR, and analyzed the methanogen community by mcrA T-RFLP-cloning-sequencing. Dung application significantly increased the CH4 production potential in the short- and the medium-term approach and non-significantly at the cattle-grazed site. The number of methanogens correlated with the CH4 production in the short- and the long-term approach. At all three time horizons, we found a shift in methanogen community due to dung application and a transfer of rumen methanogen sequences (Methanobrevibacter spp.) to the peatland soil that seemed related to increased CH4 production potential. Our findings indicate that cattle grazing of drained peatlands changes their methanogenic microbial community, may introduce rumen-associated methanogens and leads to increased CH4 production. Consequently, rewetting of previously cattle-grazed peatlands has the potential to lead to increased CH4 emissions. Careful consideration of land use history is crucial for successful climate mitigation with peatland rewetting.  相似文献   

4.
Soil characteristics regulate various belowground microbial processes including methanogenesis and, consequently, affect the structure and function of methanogenic archaeal communities due to change in soil type which in turn influences the CH4 production potential of soils. Thus, five different soil orders (Alfisol, Entisol, Inceptisol, Podzol and Vertisol) were studied to assess their CH4 production potential and also the methanogenic archaeal community structure in dryland irrigated Indian paddy soils. Soil incubation experiments revealed CH4 production to range from 178.4 to 431.2 μg CH4 g-1 dws in all soil orders as: Vertisol<Inceptisol<Entisol<Podzol<Alfisol. The numbers of methanogens as quantified using real-time quantitative polymerase chain reaction (qPCR) targeting mcrA genes varied between 0.06 and 72.97 (×106 copies g-1 dws) and were the highest in Vertisol soil and the least in Alfisol soil. PCR-denaturing gradient gel electrophoresis (DGGE)-based approach targeting 16S rRNA genes revealed diverse methanogenic archaeal communities across all soils. A total of 43 DGGE bands sequenced showed the closely related groups to Methanomicrobiaceae, Methanobacteriaceae, Methanocellales, Methanosarcinaceae, Methanosaetaceae and Crenarchaeota. The composition of methanogenic groups differed among all soils and only the Methanocellales group was common and dominant in all types of soils. The highest diversity of methanogens was found in Inceptisol and Vertisol soils. Methane production potential varied significantly in different soil orders with a positive relationship (p?<?0.05) with methanogens population size, permanganate oxidizable C (POXC) and CO2 production. The present study suggested that CH4 production potential of different soils depends on physicochemical properties, methanogenic archaeal community composition and the population size.  相似文献   

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6.
The effect of different stages of sewage sludge treatment on phosphorus (P) dynamics in amended soils was determined using samples of undigested liquid (UL), anaerobically digested liquid (AD) and dewatered anaerobically digested (DC) sludge. Sludges were taken from three points in the same treatment stream and applied to a sandy loam soil in field-based mesocosms at 4, 8 and 16 t ha−1 dry solids. Mesocosms were sown with perennial ryegrass (Lolium perenne cv. Melle), and the sward was harvested after 35 and 70 days to determine yield and foliar P concentration. Soils were also sampled during this period to measure P transformations and the activities of acid phosphomonoesterase and phosphodiesterase. Data show that the AD amended soils had the greatest plant-available and foliar P content up to the second harvest, but the UL amended soils had the greatest enzyme activity. Characterisation of control and 16 t ha−1 soils and sludge using solution 31P nuclear magnetic resonance (NMR) spectroscopy after NaOH–EDTA extraction revealed that P was predominantly in the inorganic pool in all three sludge samples, with the highest proportion (of the total extracted P) as inorganic P in the anaerobically digested liquid sludge. After sludge incorporation, P was immobilised to organic species. The majority of organic P was in monoester-P forms, while the remainder of organic P (diester P and phosphonate P) was more susceptible to transformations through time and showed variation with sludge type. These results show that application of sewage sludge at rates as low as 4 t ha−1 can have a significant nutritional benefit to ryegrass over an initial 35-day growth and subsequent 35-day re-growth periods. Differences in P transformation, and hence nutritional benefit, between sludge types were evident throughout the experiment. Thus, differences in sludge treatment process alter the edaphic mineralisation characteristics of biosolids derived from the same source material.  相似文献   

7.
Summary We evaluated potential NO inf3 sup- losses from organic and inorganic N sources applied to improve the growth of cotton (Gossypium hirsutum) on a Pima clay loam soil (Typic Torrifluvent). An initial set of soil cores (April 1989) was collected to a depth of 270 cm from sites in a cotton field previously amended with anaerobically digested sewage sludge or an inorganic N fertilizer. The denitrification potential was estimated in all soil samples by measuring N2O with gas chromatography. Soils amended with a low or high rate of sludge showed increased denitrification activity over soil samples amended with a low rate or inorganic N fertilizer. All amended samples showed greater denitrification activity than control soils. The denitrification decreased with soil depth in all treatments, and was only evident as deep as 90 cm in the soils treated with the high sludge rate. However, when soils collected from depths greater than 90 cm were amended with a C substrate, significant denitrification activity occurred. These date imply that organisms capable of denitrification were present in all soil samples, even those at depths far beneath the root zone. Hence, denitrification was C-substrate limited. A second series of soil cores taken later in the growing season (July 1989) confirmed these data. Denitrification losses (under laboratory conditions) to a soil depth of 270 cm represented 1–4% of total soil N depending on treatment, when the activity was C-substrate limited. With additional C substrate, the denitrification losses increased to 15–22% of the total soil N.  相似文献   

8.
The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) has owned and operated a 6320 ha Dedicated Beneficial Sludge Utilization Site in Fulton County, Illinois since 1971. The site consists of calcareous strip mine spoil intermingled with placed land. Sewage sludge from Chicago is barged to the site, located approximately 185 miles southwest of the city, and utilized to reclaim the strip mined soils and to fertilize the corn and wheat crops grown on them. Fields have received as much as 1317 dry Mg ha?1 of sewage sludge since 1971. Sludge Hg concentrations have ranged from 1.1 to 8.5 mg Hg kg?1 with mean concentration of 3.31 mg Hg kg?1, and maximum cumulative Hg loading rates are approximately 4 kg ha?1. Sludge applications have significantly increased extractable soil Hg concentrations, and regression analysis indicates that from 80 to 100% of the Hg applied to soils in sewage sludge since 1971 still resides in the top 15 cm of soil. Since 1985 the MWRDGC has been monitoring Hg concentration in corn leaf and grain, wheat grain and soils at the Fulton County site. Monitoring data indicate that 98.8% of the corn grain samples, 93.0% of the wheat samples and 50.7% of the corn leaf samples collected from 1985 through 1992 had Hg concentrations below detectable limits (<25μg kg?1). Cumulative Hg loading rates are utilized along with crop tissue concentrations to compute crop uptake response slopes (UC) for Hg into plant tissues at the Fulton County site. The UC for corn and wheat grain was zero and for corn leaf was ?0.0014 (mg Hg/kg tissue)/(kg Hg/ha soil), which indicate that sewage sludge additions did not increase plant tissue Hg concentrations at the Fulton County site. The negative UC obtained for corn leaf may actually indicate that sewage sludge applications decreased Hg uptake from mined soils possibly due to organic carbon and sulfides in the anaerobically digested sludge binding native Hg. The United States Environmental Protection Agency (U. S. EPA) has recently promulgated their 40 CFR Part 503 regulation for sewage sludge use and disposal. The rule sets risk based limits on ten metals, including Hg, in sludges that are land applied. Exposure pathways involving plant uptake of Hg are briefly discussed and it is shown that the UC used in U. S. EPA's risk assessment models for these pathways overpredict uptake of Hg by crops when compared with the UC derived from the MWRDGC's monitoring data at Fulton County.  相似文献   

9.
We studied the effects of applying different composts (urban organic waste, green waste, manure and sewage sludge), mineral fertilizer and compost plus mineral fertilizer on chemical, biological and soil microbiological parameters over a 12‐year period. The organic C and total N levels in soils were increased by all compost and compost + N treatments. Microbial biomass C was significantly (P ≤ 0.05) increased for some compost treatments. In addition, basal respiration and the metabolic quotient (qCO2) were significantly higher in all soils that had received sewage sludge compost. The Shannon diversity index (H), based on community level physiological profiling, showed a higher consumption of carbon sources in soils treated with compost and compost + N compared with the control. The utilization of different guilds of carbon sources varied amongst the treatments (compost, compost + N or mineral fertilizer). Cluster analysis of polymerase chain reaction‐denaturing gradient gel electrophoresis patterns showed two major clusters, the first containing the mineral fertilization and compost treatments, and the second, the composts + N treatments. No differences in bacterial community structure could be determined between the different types of compost. However, the results suggest that long‐term compost treatments do have effects on the soil biota. The results indicate that the effects on the qCO2 may be due to shifts in community composition. In this study, it was not possible to distinguish with certainty between the effects of different composts except for compost derived from sewage sludge.  相似文献   

10.

Purpose

This study aims to study the effect of sewage sludge amendment on crop yield and on microbial biomass and community structure in Swedish agricultural soils.

Materials and methods

Topsoil samples (0–0.20 m depth) from four sites where sewage sludge had been repeatedly applied during 14–53 years were analysed for total C, total N, pH and phospholipid fatty acids (PLFAs). Heavy metals were analysed in both soil and plant samples, and crop yields were recorded.

Results and discussion

At all four sites, sewage sludge application increased crop yield and soil organic carbon. Sludge addition also resulted in elevated concentrations of some heavy metals (mainly Cu and Zn) in soils, but high concentrations of metals (Ni and Zn) in plant materials were almost exclusively found in the oldest experiment, started in 1956. PLFA analysis showed that the microbial community structure was strongly affected by changes in soil pH. At those sites where sewage sludge had caused low pH, Gram-positive bacteria were more abundant. However, differences in community structure were larger between sites than between the treatments.

Conclusions

At all four sites, long-term sewage sludge application increased the soil organic carbon and nitrogen content, microbial biomass and crop yield. Long-term sewage sludge application led to a decrease in soil pH. Concentrations of some metals had increased significantly with sewage sludge application at all sites, but the amounts of metals added to soil with sewage sludge were found not to be toxic for microbes at any site.  相似文献   

11.
Sewage sludge treated with 15% bentonite, vermiculite or biochar was evaluated as a soil amendment in comparison to limed and untreated sludge. Seven treatments were established to two soils, an acid and an alkaline, in three replications, i.e. 2% addition of sludge treated with bentonite, vermiculite, biochar and lime and application of 2% untreated sludge, inorganic fertilization and no sludge or inorganic fertilizers (control). Then, the soil treatments were used in a pot experiment with perennial ryegrass (Lolium perenne L.) as a test plant. Sludge treated with the clay minerals or biochar improved pH of the acid soil and significantly increased organic matter and available nutrients of both soils compared to control. Although no salinity or sodicity hazard was evidenced, the initial salinity of acid and alkaline soil increased by four-eight and two-three times, respectively, upon addition of all sludge treatments, especially that of untreated sludge. Moreover, soil available zinc (Zn) increased by four-eight times. Soil application of sludge treated with the clay minerals or biochar increased the total aboveground biomass yield of ryegrass in the acid and alkaline soil by 133%–171% and 72%–88%, respectively, compared to control and enhanced nutrient uptake by plants. Furthermore the microbial metabolic quotient indicated lack of low pH and heavy metal stress with addition of sludge to the acid soil. After three harvests of ryegrass, the residual effect of sludge on pH of acid soil and salinity, available phosphorus (P), Zn and boron (B) of both soils still persisted. Thus sewage sludge treated with 15% bentonite, vermiculite or biochar could be applied to soils at a rate of 2% (≈80 Mg ha−1) to serve as soil amendment and fertilizer for grasses and pasture species; however, caution is needed regarding possible P build-up, Zn phytotoxicity and salinization risks.  相似文献   

12.
The Phytotoxicity Changes of Sewage Sludge-Amended Soils   总被引：1，自引：0，他引：1  
The aim of the present study was the estimation of changes in the phytotoxicity of soils amended with sewage sludge with relation to Lepidium sativum, Sinapis alba and Sorghum saccharatum. The study was realised in the system of a plot experiment for a period of 29?months. Samples for analyses were taken at the beginning of the experiment, and then after 5, 17 and 29?months. Two kinds of sewage sludge, with varying properties, were added to a sandy soil (soil S) or a loamy soil (soil L) at the dose of 90?t/ha. The addition of sewage sludge to the soils at the start of the experiment caused a significant reduction of both seed germination capacity and root length of the test plants, the toxic effect being distinctly related to the test plant species. With the passage of time the negative effect of sewage sludge weakened, the extent of its reduction depending both of the kind of sewage sludge applied and on the type of soil. Phytotoxicity of the soils amended with the sewage sludges was significantly lower at the end of the experiment than at the beginning. The species of the plants grown on the soils also had a significant effect on their phytotoxicity. The greatest reduction of toxicity was observed in the soil on which no plants were grown (sandy soil) and in the soil under a culture of willow (loamy soil). Solid phase of sewage sludge-amended soils was characterised by higher toxicity than their extracts.  相似文献   

13.
The community structure of methanogenic archaea is relatively stable,i.e.,it is sustained at a high abundance with minimal changes in composition,in paddy field soils irrespective of submergence and drainage.In contrast,the abundance in non-methanogenic oxic soils is much lower than that in paddy field soils.This study aimed to describe methanogenic archaeal community development following the long-term submergence of non-methanogenic oxic upland field soils in pot and field experiments.In the pot experiment,a soil sample obtained from an upland field was incubated under submerged conditions for 275 d.Soil samples periodically collected were subjected to culture-dependent most probable number(MPN)enumeration,polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)analysis of archaeal 16 S r RNA gene,and quantitative PCR analysis of the methyl-coenzyme M reductase alpha subunit gene(mcr A)of methanogenic archaea.The abundance of methanogenic archaea increased from 102 to 103 cells g-1 dry soil and 104 to 107 copies of mcr A gene g-1 dry soil after submergence.Although no methanogenic archaeon was detected prior to incubation by the DGGE analysis,members from Methanocellales,Methanosarcinaceae,and Methanosaetaceae proliferated in the soils,and the community structure was relatively stable once established.In the field experiment,the number of viable methanogenic archaea in a rice paddy field converted from meadow(reclaimed paddy field)was monitored by MPN enumeration over five annual cycles of field operations.Viability was also determined simultaneously in a paddy field where the plow layer soil from a farmer’s paddy field was dressed onto the meadow(dressed paddy field)and an upland crop field converted from the meadow(reclaimed upland field).The number of viable methanogenic archaea in the reclaimed paddy field was below the detection limit before the first cultivation of rice and in the reclaimed upland field.Then,the number gradually increased over five years and finally reached 103–104 cells g-1 dry soil,which was comparable to that in the dressed paddy field.These findings showed that the low abundance of autochthonous methanogenic archaea in the non-methanogenic oxic upland field soils steadily proliferated,and the community structure was developed following repeated and long-term submergence.These results suggest that habitats suitable for methanogenic archaea were established in soil following repeated and long-term submergence.  相似文献   

14.
The present work investigates the behaviour of heavymetals accumulating in soils treated with urban sludge withrespect to untreated soils. Metal sorption during transportin the soils was evaluated by means of breakthrough curvesobtained via the soil column leaching test and the resultsof laboratory experiments were compared with those of fieldexperiments carried out on the same soil treated insitu with urban sludge. Soil column leaching tests showthat the amount of heavy metals retained in the soilincreases when the soil is treated with sludge both in situand in laboratory; the order of selectivity (Pb > Cu > Zn >Ni) remains similar for the two types of matrix.Experiments carried out both with soils treated with sludge in laboratory and in situ show a good agreementbetween the two sets of data as far as retention capacityis concerned; conversely, an increase in the soil resistance to pH change following acid input is observedwhen sludge treatments are carried out in situ.  相似文献   

15.
There is conflicting evidence, and therefore continuing concern, as to whether metals in sewage sludge are deleterious to soil microbial processes and long-term agricultural productivity. Nine field experiments with sewage sludge cakes, three with metal-amended liquid sludges and three with inorganic metal salts were set up across Britain in 1994 to give individual metal dose–response treatments to try to answer this question. This study reports on the effects of Zn, Cu and Cd on the population size of Rhizobium leguminosarum biovar trifolii, a nitrogen fixing symbiont of white clover (Trifolium repens), in soils from these experiments over 11 years. Significant (P < 0.05) reductions in indigenous rhizobial numbers occurred on the Zn metal dose–response treatments at eight of the sludge cake sites in 2005, but few consistent effects were evident on the Cu or Cd metal dose–response treatments during the 11-year monitoring period. The soil total Zn concentrations where effects occurred were near to the UK statutory limit of 300 mg kg?1 for soils receiving sewage sludge. No significant reductions occurred in any treatments on the metal-amended liquid sludge or inorganic metal salt experiments in which the metals would be expected to be in a more bioavailable form, even after 11 years. The effects in the sludge cake experiments were related consistently with soil total Zn, with no recovery to date. The reductions in clover rhizobial numbers in the sludge cake experiments were due to Zn effects on free-living rhizobia in the soil, with gradual die-off over a long time with increasing soil total Zn concentrations. Currently, no consistent adverse effects on rhizobia have been seen at the UK limits for Cu and Cd of 135 and 3 mg kg?1, respectively.  相似文献   

16.
A greenhouse experiment was conducted to evaluate the availability of metals from sewage sludge and inorganic salts, and the effect of pH and soil type on yield and metal (Zn, Cu, Cd and Ni) uptake by wheat (Triticum aestivum L. var. ‘holly’). Soils used in this study were Hartsells sandy loam (fine-loamy, siliceous Thermic Typic Hapludult) and Decatur silty clay loam (Clayey, kaolinitic, Thermic Rhodic Paleudult). Two treatments of sewage sludge containing metals were applied at the rate of 20 and 100 mt ha?1. Inorganic Salts of Zn, Cu, Cd, and Ni were applied (as sulfate salts) at concentrations equivalent to those found in the 20 and 100 mt ha?1 sludge. One treatment consisted of inorganic metals plus sewage at the 20 Mg ha?1 rate. Two soil pH levels, one at field pH (below 6.0) and another pH adjusted between 6.5 and 7.0 were used. Wheat plants were harvested four weeks after germination. Two more subsequent harvests were made at four week intervals. For each harvest, dry matter yield increased as the rate of sludge application increased for both soil types. The soil pH also influenced the dry matter yield. High yield was observed when the pH was adjusted between 6.5 to 7.0 for both soils. An increase in yield was also observed at each subsequent harvest for most of the treatments. Inorganic salt treatments produced lower dry matter yields when compared with the sludge. Both sludge application and metal salts increased plant tissue concentration of Zn, Cu, Cd, and Ni at field pH for both soils. However, increasing the pH of the soil for both sludge and inorganic salt treatments generally decreased the tissue concentration of the above metals.  相似文献   

17.
The objective of this study was to evaluate the effect of sewage sludge on soil suppressiveness to the pathogens Fusarium oxysporum f. sp. lycopersici on tomato, Sclerotium rolfsii on bean, Sclerotinia sclerotiorum on tomato, Rhizoctonia solani on radish, Pythium spp. on cucumber, and Ralstonia solanacearum on tomato. Soil samples were collected from an experimental corn field in which sewage sludge had been incorporated once a year, since 1999. Sludge from two sewage treatment stations in Brazil (Franca and Barueri, SP) were applied at the rates of one (1N), two (2N), four (4N) and eight (8N) times the N recommended doses for the corn crop. Soil suppressiveness was evaluated by methods using indicator host plants, baits and mycelial growth. There was no effect of sewage sludge on soil suppressiveness to Fusarium oxysporum f. sp. lycopersici in tomato plants. For S. rolfsii, reduction of the disease in bean was inversely proportional to the dose of Franca sludge. The incidence of dead plants, caused by S. sclerotiorum, was directly proportional to sludge doses applied. For R. solani and R. solanacearum, there was a linear trend with reduction in plant death in soils treated with increasing amounts of sludge from Franca. There was an increase in the pathogen community of Pythium spp., proportional to the amounts of sewage applied. The effects of sewage sludge varied depending on the pathogen, methodology applied and on the time interval between the sewage sludge incorporation and soil sampling.  相似文献   

18.
A pulse of 13CO2 was added to the above ground vegetation in an upland grassland to determine the effects of faunal diversity on the flux of carbon to the surface horizons of the soil. Faunal diversity was manipulated by liming and biocide treatments for three years prior to the pulse addition. The relocation of 13C within roots and rhizosphere soil was determined by analysis of samples of bulk soil and of specific features identified on soil thin sections on four dates after the addition of the 13CO2 pulse. Analysis of bulk soils showed only a small enrichment in 13C and no significant effects of the treatments. Analysis by isotope ratio mass spectrometry of the products of in situ laser combustion of root material and aggregates formed from faunal excrement showed that the distribution of the newly photosynthesised 13C is very localised, with large spatial variability in soil and root δ13C at scales of less than 1 mm. δ13C values ranged from the natural abundance level of around −28‰ to −4.9‰ in roots and to −8.4‰ in aggregates. The small pulse and large spatial variability masked any effects of the liming and biocide treatments in these soils. However, the variability in the relocation of newly photosynthesised carbon may help to explain the large spatial variability found in bacterial numbers at the sub-mm scale within soils and emphasises the importance of the accessibility of substrates to decomposers in undisturbed structured soils.  相似文献   

19.
The influence of a single addition of sewage sludges to soils on the composition of fungal communities, soil pH (physical factor) and presence of Eschericha coli (sanitary factor) during 1 year was studied. Only the pH of soil treated with limed sewage sludge increased significantly from 7.01 to 7.58 after 3 months. E. coli was still present in soil 1 year after application of sewage sludge. Fungal numbers increased in the sewage-sludge-treated soil up to 6 months after application (maximum value was 7.5 times that of the control) and then decreased to reach values comparable to those of the control. Treated soils showed different fungal communities to the control with presence of keratinolytic fungi (Sporothrix schenckii, Microsporum sp.), yeasts (Geotrichum candidum, Candida sp., Rhodotorula sp. Cryptococcus sp.), and other potential pathogenic fungi (Aspergillus niger, Fusarium solani). The results indicate that fungi belonging to the genus Candida could be used as specific indicator organisms of the sanitary condition of soils treated with sewage sludge.  相似文献   

20.
The present study was conducted to assess the suitability of sewage sludge amendment in soil for Beta vulgaris var. saccharifera (sugar beet) and Triticum aestivum (wheat) by evaluating the arsenic and selenium accumulation and physiological responses of plants grown at 10%, 25%, and 50% sewage sludge amendment rate. Sewage sludge amendment was modified by the physicochemical properties of soil, thus increasing the availability of heavy metals in the soil and consequently with higher accumulation in plant parts. The chlorophyll contents increased after the sewage sludge treatments except for 50%. The sewage sludge amendment led to a significant increase in arsenic and selenium concentrations of the soil. The heavy metal accumulation in the soil after the treatments did not exceed the limits for the land application of sewage sludge recommended by the US Environmental Protection Agency. The increased concentration of heavy metals in the soil due to the sewage sludge amendment led to increases in heavy metal uptake in the leaves and root concentrations of arsenic and selenium in plants as compared to those grown on unamended soil. Accumulation was more in roots than shoots and leaves for most of the heavy metals. Concentrations of arsenic and selenium were more than the permissible limits of national standards in the edible portion of sugar beet and wheat grown on different sewage sludge amendments ratios. The study concludes that the sewage sludge amendment in the soil for growing sugar beet and wheat may not be a good option due to risk of contamination of arsenic and selenium.  相似文献   

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