共查询到20条相似文献,搜索用时 187 毫秒
1.
Great efforts have been devoted to assessing the effects of straw managements on greenhouse gas (GHG) emissions, global warming potential (GWP), and net economic budget in rice monoculture (RM). However, few studies have evaluated the effects of straw managements on GHG emissions and net ecosystem economic budget (NEEB) in integrated rice-crayfish farming (RC). Here, a randomized block field experiment was performed to comprehensively evaluate the effects of aquatic breeding practices (feeding or no feeding of forage) and straw managements (rice straw returning or removal) on soil NH4+–N and NO?3–N contents, redox potential (Eh), CH4 and N2O emissions, GWP, and NEEB of fluvo-aquic paddy soil in a rice-crayfish co-culture system in Jianghan Plain of China. We also compared the differences in CH4 and N2O emissions, GWP, and NEEB between RM and RC. Straw returning significantly increased CH4 and N2O emissions by 34.9–46.1% and 6.2–23.1% respectively compared with straw removal. Feeding of forage decreased CH4 emissions by 13.9–18.7% but enhanced N2O emissions by 24.4–33.2% relative to no feeding. Compared with RM treatment, RC treatment decreased CH4 emissions by 18.1–19.6% but increased N2O emissions by 16.8–21.0%. Moreover, RC treatment decreased GWP by 16.8–22.0% while increased NEEB by 26.9–75.6% relative to RM treatment, suggesting that the RC model may be a promising option for mitigating GWP and increasing economic benefits of paddy fields. However, the RC model resulted in a lower grain yield compared with the RM model, indicating that more efforts are needed to simultaneously increase grain yield and NEEB and decrease GWP under RC model. 相似文献
2.
Land use conversion and fertilization have been widely reported to be important managements affecting the exchanges of greenhouse gases between soil and atmosphere. For comprehensive assessment of methane (CH 4) and nitrous oxide (N 2O) fluxes from hilly red soil induced by land use conversion and fertilization, a 14-month continuous field measurement was conducted on the newly converted citrus orchard plots with fertilization (OF) and without fertilization (ONF) and the conventional paddy plots with fertilization (PF) and without fertilization (PNF). Our results showed that land use conversion from paddy to orchard reduced the CH 4 fluxes at the expense of increasing the N 2O fluxes. Furthermore, fertilization significantly decreased the CH 4 fluxes from paddy soils in the second stage after conversion, but it failed to affect the CH 4 fluxes from orchard soils, whereas fertilizer applied to orchard and paddy increased soil N 2O emissions by 68 and 113.9 %, respectively. Thus, cumulative CH 4 emissions from the OF were 100 % lower, and N 2O emissions were 421 % higher than those from the PF. Although cumulative N 2O emissions were stimulated in the newly converted orchard, the strong reduction of CH 4 led to lower global warming potentials (GWPs) as compared to the paddy. Besides, fertilization in orchard increased GWPs but decreased GWPs of paddy soils. In addition, measurement of soil moisture, temperature, dissolved carbon contents (DOCs), and ammonia (NH 4 +-N) and nitrate (NO 3 ?-N) contents indicated a significant variation in soil properties and contributed to variations in soil CH 4 and N 2O fluxes. Results of this study suggest that land use conversion from paddy to orchard would benefit for reconciling greenhouse gas mitigation and citrus orchard cultivation would be a better agricultural system in the hilly red soils in terms of greenhouse gas emission. Moreover, selected fertilizer rate applied to paddy would lead to lower GWPs of CH 4 and N 2O. Nevertheless, more field measurements from newly converted orchard are highly needed to gain an insight into national and global accounting of CH 4 and N 2O emissions. 相似文献
3.
Intensive beef production has increased during recent decades in Brazil and may substantially increase both methane (CH 4) and nitrous oxide (N 2O) emissions from manure management. However, the quantification of these gases and methods for extrapolating them are scarce in Brazil. A case study examines CH 4 and N 2O emissions from one typical beef cattle feedlot manure management continuum in Brazil and the applicability of Manure-DNDC model in predicting these emissions for better understand fluxes and mitigation options. Measurements track CH 4 and N 2O emissions from manure excreted in one housing floor holding 21 animals for 78 days, stockpiled for 73 days and field spread (360 kg N ha ?1). We found total emissions (CH 4 + N 2O) of 0.19 ± 0.10 kg CO 2eq per kg of animal live weight gain; mostly coming from field application (73%), followed housing (25%) and storage (2%). The Manure-DNDC simulations were generally within the statistical deviation ranges of the field data, differing in ?28% in total emission. Large uncertainties in measurements showed the model was more accurate estimating the magnitude of gases emissions than replicate results at daily basis. Modeled results suggested increasing the frequency of manure removal from housing, splitting the field application and adopting no-tillage system is the most efficient management for reducing emissions from manure (up to about 75%). Since this work consists in the first assessment under Brazilian conditions, more and continuous field measurements are required for decreasing uncertainties and improving model validations. However, this paper reports promising results and scientific perceptions for the design of further integrated work on farm-scale measurements and Manure-DNDC model development for Brazilian conditions. 相似文献
4.
Manure-based soil amendments (herein “amendments”) are important fertility sources, but differences among amendment types and management can significantly affect their nutrient value and environmental impacts. A 6-month in situ decomposition experiment was conducted to determine how protection from wintertime rainfall affected nutrient losses and greenhouse gas (GHG) emissions in poultry (broiler chicken and turkey) and horse amendments. Changes in total nutrient concentration were measured every 3 months, changes in ammonium (NH 4+) and nitrate (NO 3?) concentrations every month, and GHG emissions of carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2O) every 7–14 days. Poultry amendments maintained higher nutrient concentrations (except for K), higher emissions of CO 2 and N 2O, and lower CH 4 emissions than horse amendments. Exposing amendments to rainfall increased total N and NH 4+ losses in poultry amendments, P losses in turkey and horse amendments, and K losses and cumulative N 2O emissions for all amendments. However, it did not affect CO 2 or CH 4 emissions. Overall, rainfall exposure would decrease total N inputs by 37% (horse), 59% (broiler chicken), or 74% (turkey) for a given application rate (wet weight basis) after 6 months of decomposition, with similar losses for NH 4+ (69–96%), P (41–73%), and K (91–97%). This study confirms the benefits of facilities protected from rainfall to reduce nutrient losses and GHG emissions during amendment decomposition. Implications: The impact of rainfall protection on nutrient losses and GHG emissions was monitored during the decomposition of broiler chicken, turkey, and horse manure-based soil amendments. Amendments exposed to rainfall had large ammonium and potassium losses, resulting in a 37–74% decrease in N inputs when compared with amendments protected from rainfall. Nitrous oxide emissions were also higher with rainfall exposure, although it had no effect on carbon dioxide and methane emissions. Overall, this work highlights the benefits of rainfall protection during amendment decomposition to reduce nutrient losses and GHG emissions. 相似文献
5.
Acrylate esters are α,β-unsaturated esters that contain vinyl groups directly attached to the carbonyl carbon. These compounds are widely used in the production of plastics and resins. Atmospheric degradation processes of these compounds are currently not well understood. The kinetics of the gas phase reactions of OH radicals with methyl 3-methylacrylate and methyl 3,3-dimethylacrylate were determined using the relative rate technique in a 50 L Pyrex photoreactor using in situ FTIR spectroscopy at room temperature (298?±?2 K) and atmospheric pressure (708?±?8 Torr) with air as the bath gas. Rate coefficients obtained were (in units cm 3 molecule ?1 s ?1): (3.27?±?0.33)?×?10 ?11 and (4.43?±?0.42)?×?10 ?11, for CH 3CH═CHC(O)OCH 3 and (CH 3) 2CH═CHC(O)OCH 3, respectively. The same technique was used to study the gas phase reactions of hexyl acrylate and ethyl hexyl acrylate with OH radicals and Cl atoms. In the experiments with Cl, N 2 and air were used as the bath gases. The following rate coefficients were obtained (in cm 3 molecule ?1 s ?1): k 3 (CH 2═CHC(O)O(CH 2) 5CH 3?+?Cl)?=?(3.31?±?0.31)?×?10 ?10, k 4(CH 2═CHC(O)OCH 2CH(CH 2CH 3)(CH 2) 3CH 3?+?Cl)?=?(3.46?±?0.31)?×?10 ?10, k 5(CH 2═CHC(O)O(CH 2) 5CH 3?+?OH)?=?(2.28?±?0.23)?×?10 ?11, and k 6(CH 2═CHC(O)OCH 2CH(CH 2CH 3)(CH 2) 3CH 3?+?OH)?=?(2.74?±?0.26)?×?10 ?11. The reactivity increased with the number of methyl substituents on the double bond and with the chain length of the alkyl group in –C(O)OR. Estimations of the atmospheric lifetimes clearly indicate that the dominant atmospheric loss process for these compounds is their daytime reaction with the hydroxyl radical. In coastal areas and in some polluted environments, Cl atom-initiated degradation of these compounds can be significant, if not dominant. Maximum Incremental Reactivity (MIR) index and global warming potential (GWP) were also calculated, and it was concluded that these compounds have significant MIR values, but they do not influence global warming. 相似文献
6.
In this research, in order to develop technology/country-specific emission factors of methane (CH 4) and nitrous oxide (N 2O), a total of 585 samples from eight gas-fired turbine combined cycle (GTCC) power plants were measured and analyzed. The research found that the emission factor for CH 4 stood at “0.82 kg/TJ”, which was an 18 % lower than the emission factor for liquefied natural gas (LNG) GTCC “1 kg/TJ” presented by Intergovernmental Panel on Climate Change (IPCC). The result was 8 % up when compared with the emission factor of Japan which stands at “0.75 kg/TJ”. The emission factor for N 2O was “0.65 kg/TJ”, which is significantly lower than “3 kg/TJ” of the emission factor for LNG GTCC presented by IPCC, but over six times higher than the default N 2O emission factor of LNG. The evaluation of uncertainty was conducted based on the estimated non-CO 2 emission factors, and the ranges of uncertainty for CH 4 and N 2O were between ?12.96 and +13.89 %, and ?11.43 and +12.86 %, respectively, which is significantly lower than uncertainties presented by IPCC. These differences proved that non-CO 2 emissions can change depending on combustion technologies; therefore, it is vital to establish country/technology-specific emission factors. 相似文献
7.
In this paper the authors have estimated for 1990 and 1995 the inventory of greenhouse gases CO 2, CH 4 and N 2O for India at a national and sub-regional district level. The district level estimates are important for improving the national inventories as well as for developing sound mitigation strategies at manageable smaller scales. Our estimates indicate that the total CO 2, CH 4 and N 2O emissions from India were 592.5, 17, 0.2 and 778, 18, 0.3 Tg in 1990 and 1995, respectively. The compounded annual growth rate (CAGR) of these gases over this period were 6.3, 1.2 and 3.3%, respectively. The districts have been ranked according to their order of emissions and the relatively large emitters are termed as hotspots. A direct correlation between coal consumption and districts with high CO 2 emission was observed. CO 2 emission from the largest 10% emitters increased by 8.1% in 1995 with respect to 1990 and emissions from rest of the districts decreased over the same period, thereby indicating a skewed primary energy consumption pattern for the country. Livestock followed by rice cultivation were the dominant CH 4 emitting sources. The waste sector though a large CH 4 emitter in the developed countries, only contributed about 10% the total CH 4 emission from all sources as most of the waste generated in India is allowed to decompose aerobically. N 2O emissions from the use of nitrogen fertilizer were maximum in both the years (more than 60% of the total N 2O). High emission intensities, in terms of CO 2 equivalent, are in districts of Gangetic plains, delta areas, and the southern part of the country. These overlap with districts with large coal mines, mega power plants, intensive paddy cultivation and high fertilizer use. The study indicates that the 25 highest emitting districts account for more than 37% of all India CO 2 equivalent GHG emissions. Electric power generation has emerged as the dominant source of GHG emissions, followed by emissions from steel and cement plants. It is therefore suggested, to target for GHG mitigation, the 40 largest coal-based thermal plants, five largest steel plants and 15 largest cement plants in India as the first step. 相似文献
8.
The wetlands play an important role in global carbon and nitrogen storage, and they are also natural sources of greenhouse gases such as methane (CH 4) and nitrous oxide (N 2O). Land-use change is an important factor affecting the exchange of greenhouse gases between wetlands and the atmosphere. However, few studies have investigated the effect of land-use change on CH 4 and N 2O emissions from freshwater marsh in China. Therefore, a field study was carried out over a year to investigate the seasonal changes of the emissions of CH 4 and N 2O at three sites ( Deyeuxia angustifolia marsh, dryland and rice field) in the Sanjiang Plain of Northeast China. Marsh was the source of CH 4 showing a distinct temporal variation. Maximum fluxes occurred in June and the highest value was 20.69 ± 2.57 mg CH 4 m ?2 h ?1. The seasonal change of N 2O fluxes from marsh was not obvious, consisted of a series of emission pulses. The marsh acted as a N 2O sink during winter, while became a N 2O source in the growing season. The results showed that gas exchange between soil/snow and the atmosphere in the winter season contributed greatly to the annual budgets. The winter season CH 4 flux was about 3.24% of the annual flux and the winter uptake of N 2O accounted for 13.70% of the growing-season emission. Conversion marsh to dryland resulted in a shift from a strong CH 4 source to a weak sink (from 199.12 ± 39.04 to ?1.37 ± 0.68 kg CH 4 ha ?1 yr ?1), while increased N 2O emissions somewhat (from 4.07 ± 1.72 to 4.90 ± 1.52 kg N 2O ha ?1 yr ?1). Conversion marsh to rice field significantly decreased CH 4 emission from 199.12 ± 39.04 to 94.82 ± 9.86 kg CH 4 ha ?1 yr ?1 and N 2O emission from 4.07 ± 1.72 to 2.09 ± 0.79 kg N 2O ha ?1 yr ?1. 相似文献
9.
Pakistan is facing problem of deforestation. Pakistan lost 14.7% of its forest habitat between 1990 and 2005 interval. This paper assesses the present forest wood consumption rate by 6000 brick kilns established in the country and its implications in terms of deforestation and emission of greenhouse gases. Information regarding consumption of forest wood by the brick kilns was collected during a manual survey of 180 brick kiln units conducted in eighteen provincial divisions of country. Considering annual emission contributions of three primary GHGs i.e., CO 2, CH 4 and N 2O, due to burning of forest wood in brick kiln units in Pakistan and using IPCC recommended GWP indices, the combined CO 2-equivalent has been estimated to be 533019 t y −1. 相似文献
10.
An increasing nitrogen deposition experiment (2 g N m ?2 year ?1) was initiated in an alpine meadow on the Qinghai-Tibetan Plateau in May 2007. The greenhouse gases (GHGs), including CO 2, CH 4 and N 2O, was observed in the growing season (from May to September) of 2008 using static chamber and gas chromatography techniques. The CO 2 emission and CH 4 uptake rate showed a seasonal fluctuation, reaching the maximum in the middle of July. We found soil temperature and water-filled pore space (WFPS) were the dominant factors that controlled seasonal variation of CO 2 and CH 4 respectively and lacks of correlation between N 2O fluxes and environmental variables. The temperature sensitivity ( Q10) of CO 2 emission and CH 4 uptake were relatively higher (3.79 for CO 2, 3.29 for CH 4) than that of warmer region ecosystems, indicating the increase of temperature in the future will exert great impacts on CO 2 emission and CH 4 uptake in the alpine meadow. In the entire growing season, nitrogen deposition tended to increase N 2O emission, to reduce CH 4 uptake and to decrease CO 2 emission, and the differences caused by nitrogen deposition were all not significant ( p < 0.05). However, we still found significant difference ( p < 0.05) between the control and nitrogen deposition treatment at some observation dates for CH 4 rather than for CO 2 and N 2O, implying CH 4 is most susceptible in response to increased nitrogen availability among the three greenhouse gases. In addition, we found short-term nitrogen deposition treatment had very limited impacts on net global warming potential (GWP) of the three GHGs together in term of CO 2-equivalents. Overall, the research suggests that longer study periods are needed to verify the cumulative effects of increasing nitrogen deposition on GHG fluxes in the alpine meadow. 相似文献
11.
Energy supply utilities release significant amounts of greenhouse gases (GHGs) into the atmosphere. It is essential to accurately estimate GHG emissions with their uncertainties, for reducing GHG emissions and mitigating climate change. GHG emissions can be calculated by an activity-based method (i.e., fuel consumption) and continuous emission measurement (CEM). In this study, GHG emissions such as CO 2, CH 4, and N 2O are estimated for a heat generation utility, which uses bituminous coal as fuel, by applying both the activity-based method and CEM. CO 2 emissions by the activity-based method are 12–19% less than that by the CEM, while N 2O and CH 4 emissions by the activity-based method are two orders of magnitude and 60% less than those by the CEM, respectively. Comparing GHG emissions (as CO 2 equivalent) from both methods, total GHG emissions by the activity-based methods are 12–27% lower than that by the CEM, as CO 2 and N 2O emissions are lower than those by the CEM. Results from uncertainty estimation show that uncertainties in the GHG emissions by the activity-based methods range from 3.4% to about 20%, from 67% to 900%, and from about 70% to about 200% for CO 2, N 2O, and CH 4, respectively, while uncertainties in the GHG emissions by the CEM range from 4% to 4.5%. For the activity-based methods, an uncertainty in the Intergovernmental Panel on Climate Change (IPCC) default net calorific value (NCV) is the major uncertainty contributor to CO 2 emissions, while an uncertainty in the IPCC default emission factor is the major uncertainty contributor to CH 4 and N 2O emissions. For the CEM, an uncertainty in volumetric flow measurement, especially for the distribution of the volumetric flow rate in a stack, is the major uncertainty contributor to all GHG emissions, while uncertainties in concentration measurements contribute a little to uncertainties in the GHG emissions. Implications:Energy supply utilities contribute a significant portion of the global greenhouse gas (GHG) emissions. It is important to accurately estimate GHG emissions with their uncertainties for reducing GHG emissions and mitigating climate change. GHG emissions can be estimated by an activity-based method and by continuous emission measurement (CEM), yet little study has been done to calculate GHG emissions with uncertainty analysis. This study estimates GHG emissions and their uncertainties, and also identifies major uncertainty contributors for each method. 相似文献
12.
Emissions of CH 4 and N 2O related to private pig farming under a tropical climate in Uvéa Island were studied in this paper. Physicochemical soil parameters such as nitrate, nitrite, ammonium, Kjeldahl nitrogen, total organic carbon, pH and moisture were measured. Gaseous soil emissions as well as physicochemical parameters were compared in two private pig farming strategies encountered on this island on two different soils (calcareous and ferralitic) in order to determine the best pig farming management: in small concrete pens or in large land pens. Ammonium levels were higher in control areas while nitrate and nitrite levels were higher in soils with pig slurry inputs, indicating that nitrification was the predominant process related to N 2O emissions. Nitrate contents in soils near concrete pens were important (≥55 μg N/g) and can thus be a threat for the groundwater. For both pig farming strategies, N 2O and CH 4 fluxes can reach high levels up to 1 mg N/m 2/h and 1 mg C/m 2/h, respectively. CH 4 emissions near concrete pens were very high (≥10.4 mg C/m 2/h). Former land pens converted into agricultural land recover low N 2O emission rates (≤0.03 mg N/m 2/h), and methane uptake dominates. N 2O emissions were related to nitrate content whereas CH 4 emissions were found to be moisture dependent. As a result relating to the physicochemical parameters as well as to the gaseous emissions, we demonstrate that pig farming in large land pens is the best strategy for sustainable family pig breeding in Uvéa Islands and therefore in similar small tropical islands. 相似文献
13.
针对我国现在主流的城市污水污泥处置方法:填埋,焚烧,堆肥。用IPCC中推荐的方法和缺省值,对处置过程中产生的温室气体的直接排放、间接排放和替代排放做了计算和分析。填埋过程计算排放的温室气体有CH4,焚烧过程计算排放的有温室气体CO2和N2O,堆肥过程计算的排放的有温室气体CO2和N2O,最终比较的结果都折算成CO2的排放。结果表明,污泥填埋、焚烧、堆肥所产生的CO2的净排放量分别为695.847 kg CO2/t、443.643 kg CO2/t、511.817 kgCO2/t。由于考虑了堆肥以后的有机肥利用,从减排以及污泥资源化的角度分析,得出堆肥是相对好的污泥处置方式。 相似文献
14.
Extensive use of biochar to mitigate nitrous oxide (N 2O) emission is limited by the lack of understanding on the exact mechanisms altering N 2O emission from biochar-amended soil. Biochars produced from rice straw and dairy manure at 350 and 500 °C by oxygen-limited pyrolysis were used to investigate their influence on N 2O emission. A quadratic effect of biochar levels was observed on the N 2O emissions. The potential mechanisms were explored by terminal restriction fragment length polymorphism (T-RFLP) and real-time polymerase chain reaction (qPCR). A lower relative abundance of bacteria, which included ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), was observed at 4% biochar application rate. Reduced copy numbers of the ammonia monooxygenase gene amoA and the nitrite reductase gene nirS coincided with decreased N 2O emissions. Therefore, biochar may potentially alter N 2O emission by affecting ammonia-oxidizing and denitrification bacteria, which is determined by the application rate of biochar in soil. Implications:Biochar research has received increased interest in recent years because of the potential beneficial effects of biochar on soil properties. Recent research shows that biochar can alter the rates of nitrogen cycling in soil systems by influencing nitrification and denitrification, which are key sources of the greenhouse gas nitrous oxide (N 2O). However, there are still some controversial data. The purpose of this research was to (1) examine how applications of different dose of biochar to soil affect emission of N 2O and (2) improve the understanding of the underlying mechanisms. 相似文献
15.
Despite the many benefits of denitrifying phosphorus removal process, the significant generation of nitrous oxide (N 2O), a potent greenhouse gas, remains a problem for this innovative and promising process. To better understand and more effectively control N 2O generation in denitrifying phosphorus removal process, batch experiments were carried out to investigate the main causes of N 2O generation, based on which the control measures were subsequently proposed. The results showed that N 2O generation accounted for 0.41 % of the total nitrogen removal in denitrifying phosphorus removal process, whereas, in contrast, almost no N 2O was generated in conventional denitrification process. It was further demonstrated that the weak competition of N 2O reductase for electrons and the high nitrite accumulation were the two main causes for N 2O generation, evidenced by N 2O production and reduction rates under different conditions. Accordingly, the reduction of N 2O generation was successfully achieved via two control measures: (1) the use of continuous nitrate addition reducing N 2O generation by around 91.4 % and (2) the use of propionate as the carbon source reducing N 2O generation by around 69.8 %. 相似文献
16.
Various water management regimes, such as continuous flooding (F), flooding-midseason drainage-reflooding (F-D-F), and flooding-midseason drainage-reflooding-moist intermittent irrigation, but without water logging (F-D-F-M), are currently practiced in paddy rice production in mainland China. These water regimes have incurred a sensitive change in direct N 2O emission from rice paddy fields. We compiled and statistically analyzed field data on N 2O emission from paddy fields during the rice growing season (71 measurements from 17 field studies) that were published in peer-reviewed Chinese and English journals. Seasonal total N 2O was, on average, equivalent to 0.02% of the nitrogen applied in the continuous flooding rice paddies. Under the water regime of F-D-F or the F-D-F-M, seasonal N 2O emissions increased with N fertilizer applied in rice paddies. An ordinary least square (OLS) linear regression model produced the emission factor (EF) of nitrogen for N 2O averaged 0.42%, but background N 2O emission was not pronounced under the water regime of F-D-F. Under the F-D-F-M water regime, N 2O EF and background emission were estimated to be 0.73% and 0.79 kg N 2O-N ha −1, respectively, during the paddy rice growing season. Based on results of the present study and national rice production data, subsequently, direct N 2O emissions during the rice growing season amounted to 29.0 Gg N 2O-N with the uncertainty of 30.1%, which accounted for 7–11% of the reported estimates of annual total emission from croplands in mainland China. The results of this study suggest that paddy rice relative to upland crop production could have contributed to mitigating N 2O emissions from agriculture in mainland China. 相似文献
17.
Spent coffee grounds (SCG), poultry manure, and agricultural waste-derived biochar were used to manufacture functional composts through microbial bioaugmentation. The highest yield of tomato stalk-based biochar (40.7%) was obtained at 450°C with a surface area of 2.35 m 2 g ?1. Four pilot-scale composting reactors were established to perform composting for 45 days. The ratios of NH 4+–N/NO 3?–N, which served as an indicator of compost maturity, indicate rapid, and successful composting via microbial bioaugmentation and biochar amendment. Moreover, germination indices for radish also increased by 14–34% through augmentation and biochar amendment. Microbial diversity was also enhanced in the augmented and biochar-amended composts by 7.1–8.9%, where two species of Sphingobacteriaceae were dominant (29–43%). The scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH) were enhanced by 14.1% and 8.6% in the fruits of pepper plants grown in the presence of the TR-2 (augmentation applied only) and TR-3 (both augmentation and biochar amendment applied) composts, respectively. Total phenolic content was also enhanced by 68% in the fruits of the crops grown in TR-3. Moreover, the other compost, TR-L (augmentation applied only), boosted DPPH scavenging activity by 111% in leeks compared with commercial organic fertilizer, while TR-3 increased the phenolic content by 44.8%. Composting facilitated by microbial augmentation and biochar amendment shortened the composting time and enhanced the quality of the functional compost. These results indicate that functional compost has great potential to compete with commercially available organic fertilizers and that the novel composting technology could significantly contribute to the eco-friendly recycling of organic wastes such as spent coffee grounds, poultry manure, and agricultural wastes. 相似文献
18.
Micrometeorological flux-gradient and nocturnal boundary layer methods were combined with Fourier transform infrared (FTIR) spectroscopy for high-precision trace gas analysis to measure fluxes of the trace gases CO 2, CH 4 and N 2O between agricultural fields and the atmosphere. The FTIR measurements were fully automated and routinely obtained a precision of 0.1–0.2% for several weeks during a measurement campaign in October 1995. In flux-gradient measurements, vertical profiles of the trace gases were measured every 30 min from the ground to 22 m. When combined with independent micrometeorological measurements of water vapour fluxes, trace gas fluxes from the underlying surface could be determined. In the nocturnal boundary layer method the rate of change in mass storage in the 0–22 m layer was combined with fluxes measured at 22 m to estimate surface fluxes. Daytime fluxes for CO 2 were −0.78±0.40 (1 σ) mg CO 2 m −2 s −1. Daytime fluxes of N 2O and CH 4 were very small and difficult to measure reliably using the flux-gradient technique, despite the high precision of the concentration measurements. Mean daytime flux for N 2O was 17±48 ng N m −2 s −1, while the corresponding flux for CH 4 was 47±410 ng CH 4 m −2 s −1. The mean nighttime flux of CO 2 estimated using the nocturnal boundary layer method was +0.15±0.05 mg CO 2 m −2 s −1, in good agreement with chamber measurements of respiration rates. Nighttime fluxes of CH 4 and N 2O from the nocturnal boundary layer method were 109±69 ng CH 4 m −2 s −1 and 2±3.2 ng N m −2 s −1, respectively, in good agreement with chamber measurements and inventory estimates based on the sheep and cattle stocking rates in the region. The suitability of FTIR-based methods for long term monitoring of spatially and temporally averaged flux measurements is discussed. 相似文献
19.
The effects of several silicates (talcum powder (TP), calcium silicate (CS), sodium silicate (SS), and potassium silicate (PS)), in comparison with other amendments (quicklime (QL) and potassium dihydrogen phosphate (PDP)) on cadmium (Cd) uptake by three dicotyledonous crops ( Amaranthus hypochondriacus L. Cv. ‘K112’, Amaranthus tricolor L., and Brassica oleracea var. albiflora Kuntze) were investigated in Cd–contaminated soil. The effects of both application methods of amendments (singly and combined) and timing of application were also evaluated. Sodium silicate was the most effective in reducing crop Cd uptake and translocation, which was diminished by 51 % in roots, 53 % in stems, and 72 % in leaves on average. Application of CS amendment showed greater efficiency than PDP amendment in decreasing Cd uptake by crops and resulted in increased biomass. Potassium silicate only slightly decreased shoot Cd concentration. Combination of PDP and SS was able to overcome the inhibitory effect of SS on crop yield while decreasing Cd concentrations in roots, stems and leaves of the tested crops by average rates of 52, 65, and 68 % respectively. Applications of SS and PS significantly reduced the root-to-shoot Cd transfer factor. We found that Si accumulation in crops was not associated with lower Cd concentration, indicating that Si in crops may play a major role in alleviating metal stress rather than inhibiting crop Cd accumulation. We suggested that the inhibitive effect of silicates on crops Cd uptake was majorly attributed to the properties of the silicates, those were their specific effects on soil pH and cations, which increased Cd adsorption by soil and suppressed Cd uptake from soil solution by increasing the relative dissolved concentrations of competing cations. 相似文献
20.
Patches of dung and urine are major contributors to the feedlot gas emissions. This study investigated the impacts of dung deposition frequency (partly reflecting animal stocking density of a feedlot), dairy feedlot floor conditions (old floor indicated with the presence of consolidated manure pad [CMP] vs. new floor with the absence of consolidated manure pad [CMPn]), and application of dicyandiamide (DCD) and hydroquinone (HQ) on nitrous oxide (N 2O) and methane (CH 4) emissions from patches in the laboratory, and the integrative impacts were expressed in terms of global warming potential (CO 2-equivalent). Dung deposition frequency, feedlot floor condition, and application of inhibitors showed inverse impacts on N 2O and CH 4 emissions from patches. Greenhouse gas (GHG) emissions from the dung, urine, and dung+urine patches on the CMP feedlot surface were approximately 7.48, 87.35, and 7.10 times those on the CMPn feedlot surface ( P < 0.05). Meanwhile, GHG emissions from CMP and CMPn feedlot surfaces under high deposition frequency condition were approximately 10 and 1.7 times those under low-frequency condition. Moreover, application of HQ slightly reduced the GHG emission from urine patches, by 14.9% ( P > 0.05), while applying DCD or DCD+HQ significantly reduced the GHG, by 60.3% and 65.0%, respectively ( P < 0.05). Overall, it is necessary to include feedlot management such as animal stocking density and feedlot floor condition to the process of determining emission factors for feedlots. In the future, field measurements to quantitatively evaluate the relative contribution of nitrification and denitrification to the N 2O emissions of feedlot surfaces are highly required for effective N 2O control. Implications: This study shows that feedlot CH4 and N2O emissions inversely respond to the dicyandiamide (DCD) application. Applying DCD significantly reduces GHG emissions of feedlot urine patches. Feedlot floor condition and stocking density strongly impact feedlot GHG emissions. Including feedlot floor condition and stocking density in the feedlot EF determining process is necessary. 相似文献
|