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1.
Five provinces located in the five main rice-growing regions in China were selected as study areas, which were Jiangsu, Heilongjiang, Sichuan, Guangdong and Hunan province respectively in the middle and lower reaches of the Yangtze River, northern, southwest, southern and central rice districts. Carbon footprints of rice production in these five provinces were calculated through the life cycle assessment method using governmental statistical data, industrial standards and relevant technical data separately. Material and energy consumptions were estimated, key stages of energy consumptions and carbon emissions were identified as well. Moreover, improving measurements had been suggested correspondingly. The results indicated that: the energy consumptions of rice production in these five provinces ranked as following (high to low): Guangdong, Heilongjiang, Hunan, Sichuan and Jiangsu. The carbon footprints of rice production were 2504.20 kg carbon dioxide equation per ton rice (kgCO2-eq./t) (Guangdong province), 2326.47 kgCO2-eq./t (Hunan province), 1889.97 kgCO2-eq./t (Heilongjiang province), 1538.90 kgCO2-eq./t (Sichuan province) and 1344.92 kgCO2-eq./t (Jiangsu province) respectively. Reducing the quantities of urea and using the intermittent irrigation method could decrease energy consumption as well as carbon footprint.  相似文献   

2.
A water footprint considers both the water volumes involved in production processes and the resulting waste water generated. The grey water (GW) footprint represents the volume of fresh water required to assimilate pollutants to acceptable concentrations—a concept proposed by the water footprint network—but it faces several difficulties when applied to agricultural production systems. Crop production cannot be fully controlled and it is weather-dependent, which greatly affects the year-to-year GW calculations.In this study, we examined the effect of time step on the calculation of annual GW footprints by utilizing 30 years of daily average nitrate-nitrogen (NO3-N) concentrations in drainage water (both leachate and runoff water derived from a process-based model) from corn and soybean production systems. For each crop year, the volume of water required to assimilate NO3-N to an acceptable threshold concentration (i.e. <10 mg L−1) was calculated over different time steps (daily, weekly, monthly, seasonally and yearly), and each case was summed to an annual GW value. Daily average NO3-N concentrations in the effluent water were generally below the acceptable threshold concentrations, with intermittent exceedances. Thus, the fields often provided their own ‘dilution’ water, and annual average concentrations were only 2.0 mg L−1 and 0.4 mg L−1 for corn and soybean, respectively.The GW footprint varied significantly when calculated for different time steps. The greatest annual footprint occurred when calculated daily (shortest time step). The GW footprint for corn ranged from 2.7 × 103 m3 ha−1, or 2700 mm of water, when estimated daily to zero for the yearly time step. For soybean it ranged from 0.5 × 103 m3 ha−1, or 500 mm of water, to zero. The GW footprint results are therefore highly dependent on the time step of calculation. The effect of this issue extends beyond crop production as it is exported and amplified through feed rations to affect the GW footprint from animal production. To be able to reconcile these problems, the GW calculation pathways should be reconsidered and standardized.  相似文献   

3.
Water and energy are closely connected and both are very important for human development. Wastewater treatment plants (WWTPs) are central to water–energy interactions as they consume energy to remove pollutants and thus reduce the human gray water footprint on the natural water environment. In this work, we quantified energy consumption in 9 different WWTPs in south China, with different treatment processes, objects, and capacities. The energy intensity in most of these WWTPs is in the range of 0.4–0.5 kWh/m3 in 2014. Footprint methodologies were used in this paper to provide insight into the environmental changes that result from WWTPs. A new indicator “gray water footprint reduction” is proposed based on the notion of gray water footprint to better assess the role of WWTPs in reducing human impacts on water resources. We find that higher capacity and appropriate technology of the WWTPs will result in higher gray water footprint reduction. On average, 6.78 m3 gray water footprint is reduced when 1 m3 domestic sewage is treated in WWTPs in China. 13.38 L freshwater are required to produce the 0.4 kWh electrical input needed for treating 1 m3 domestic wastewater, and 0.23 kg CO2 is emitted during this process. The wastewater characteristics, treatment technologies as well as management systems have a major impact on the efficiency of energy utilization in reducing gray water footprint via these WWTPs. The additional climate impact associated with wastewater treatment should be considered in China due to the enormous annual wastewater discharge. Policy suggestions are provided based on results in this work and the features of China's energy and water distribution.  相似文献   

4.
春玉米-晚稻与早稻-晚稻种植模式碳足迹比较   总被引:2,自引:0,他引:2  
量化作物生产的碳足迹有助于为农业生态系统温室气体减排提供理论依据。利用生命周期法研究了我国南方地区稻田春玉米-晚稻水旱轮作种植模式和早稻-晚稻连作种植模式下粮食生产的碳足迹,并定量分析粮食生产过程中各种碳排放源的相对贡献。结果表明,与早稻-晚稻的连作模式相比,春玉米-晚稻轮作模式的单位面积碳排放降低了6724 kg CO2-eq/hm2,单位产量的碳足迹降低了0.56 kg CO2-eq/kg。春玉米比早稻少排放6228 kg CO2-eq/hm2;与早稻-晚稻模式中晚稻碳排放相比,春玉米-晚稻轮作模式晚稻碳排放降低了497 kg CO2-eq/hm2。早稻-晚稻种植模式的碳足迹主要来源于甲烷(CH4),其碳排放为9776 kg CO2-eq/hm2(54.8%),氮肥生产和施用的碳排放为2871 kg CO2-eq/hm2(16.1%),灌溉电力消耗的碳排放2849 kg CO2-eq/hm2(16.0%)。春玉米-晚稻轮作模式的碳足迹主要来源于CH4的碳排放4442 kg CO2-eq/hm2(39.9%),氮肥生产和施用的碳排放2871 kg CO2-eq/hm2(25.8%),灌溉电力消耗的碳排放1508 kg CO2-eq/hm2(13.6%)。该模式中晚稻的碳足迹组成情况与春玉米-晚稻模式的碳足迹相似。但是,对于春玉米而言,其碳足迹主要来源氮肥生产和施用的碳排放1436 CO2-eq/hm2(50.1%),氧化亚氮(N2O)的碳排放为579 kg CO2-eq/hm2(20.2%),CH4的碳排放为378 CO2-eq/hm2(13.2%)。同时,相比于早稻-晚稻中晚稻的产量(6333 kg/hm2),春玉米-晚稻轮作模式下的晚稻产量(7270 kg/hm2)提高了14.8%。因此,引入春玉米-晚稻轮作模式有利于提升稻田生产力,降低稻田连作系统碳排放和碳足迹。  相似文献   

5.
《Mammalian Biology》2014,79(1):1-8
Western grey kangaroos (Macropus fuliginosus melanops) are large, foregut fermenting herbivores common to Australia's southern woodlands and shrublands, but they extend well into semiarid habitats at the north-eastern edge of their range. At this range boundary, western grey kangaroos occupy open chenopod (saltbush) shrubland, along with Australia's other large native kangaroos, as well as with extensive pastoral stock, primarily the wool-breed merino sheep. In this habitat, within a large naturally vegetated enclosure (16 ha), western grey kangaroos grazing sympatrically with merino sheep spent much of the day resting under shade trees, and fed mainly during the evening and early morning, mainly on grasses and flat-leaved chenopods. On this diet, western grey kangaroos had water turnovers similar to those of red kangaroos, at 1.1 L d−1. Sheep, however, used 7.7 L of water each day. Thus, although the sheep were twice the average body mass of kangaroos, the sheep used more than seven times as much water. This level of water use by sheep was almost half that previously reported for sheep at the same site feeding mainly on salt-laden chenopods (ca. 12 L d−1), but was consistent with other studies showing lower water usage by sheep feeding on trees and low-salt shrubs; foregut (rumen) contents of our sheep comprised 35% tree browse. Overall, our data do not support suggestions that western grey kangaroos are limited mainly by water at this arid range-boundary. Notably, the western grey kangaroos’ feeding behaviours were consistent with those of other arid-zone kangaroos, highlighting distinctive differences in the ecological physiology of the foregut fermenting kangaroos and the ruminant sheep.  相似文献   

6.
Complex changes in carbon sources and sinks caused by rapid urbanization have been observed with extensive changes in the quantity, structure, and spatial pattern of land use types. Based on the modified Carnegie-Ames-Stanford Approach model and on gray relational analysis, we analyzed the influence of land use changes on carbon sinks and emissions in Guangzhou from 2000 to 2012. The aim was to identify suitable options for built-up land expansion that would allow for minimal carbon losses. The key results were as follows: (1) Built-up land increased by 118.91% in Guangzhou city over the study period, with this expansion taking the form of concentric circles extending around the old Yuexiu district. (2) Carbon emissions over the period of analysis significantly exceeded carbon sink capabilities. The total carbon sink decreased by 30.02%, from 535.40 × 103 t to 374.6 × 103 t. Total carbon emissions increased by 1.89 times, from 13.73 × 106 t to 39.67 × 106 t; 80% of carbon emissions were derived from energy consumption. (3) There were large differences in the extent of carbon sink losses at different scales of built-up land expansion and land use change. In Guangzhou, the loss of carbon sink is small when cultivated land (though not prime farmland) and water bodies are converted to built-up land on a small scale. The loss of carbon sink is much smaller when grasslands are converted to built-up land on a large scale. However, forested land, which has excellent carbon sink functions, should not be converted. (4) Changes in carbon sinks were mainly affected by natural factors and land urbanization. Changes in carbon emissions were mainly affected by population urbanization, economic urbanization, and land urbanization. (5) To achieve “economical and intensive use of land”, “urban growth boundary” and “ecological red lines” should be determined for government policies on land use management. These factors have great significance for “increasing carbon sinks and reducing carbon emissions” in urban ecological systems.  相似文献   

7.
The influence of whole, crushed and ground barley and oats on intake, performance and carcass characteristics of lambs was examined. A comparison of diets was conducted with individually-fed male and female lambs in six groups. The study was repeated in three successive years (1995–1997) using the same experimental design. A total of 192 lambs of a mean initial age of 74 days (SD 13.0) and live weight 20.6 kg (SD 4.54) were daily fed their respective concentrates, 72 g dry matter (DM)/kg metabolic live weight (kgW0.75), for 98 days from weaning to slaughter. Hay was provided ad libitum.The lambs adapted more quickly to diets containing barley than to those containing oats. Compared to oats, the total daily DM intake was higher on barley (1162 vs. 990 g DM/lamb, 89 vs. 78 g DM/kgW0.75, P < 0.001). Hay consumption was significantly lower on oats than on barley (182 vs. 344 g DM/day, P < 0.001). On oats the lambs experienced energy and protein deficiencies with their energy and protein intakes being 20% below feeding recommendations. On the barley diets the energy and protein requirements of the lambs were satisfied. When processed cereals were offered, there was no increase in the total DM, energy or protein intakes. Processing did not improve the organic matter digestibility of barley or oats.The growth rate (P < 0.01), carcass weight (P < 0.001) and slaughter percentage (P < 0.001) were higher on a barley diet than on oats. A barley diet resulted in more kidney fat (P < 0.01) and fattier carcasses. Processing had no positive influence on the live weight gain. On the contrary, lambs receiving crushed or ground barley or oats had a lower final live weight than those receiving whole grains (P < 0.001). The utilisation of whole grain was more efficient than that of processed grain. There were no advantages in processing barley and oats for the feeding of lambs.  相似文献   

8.
Mycophenolic acid (MPA) was produced from Penicillium brevicompactum by solid-state fermentation (SSF) using pearl barley, and submerged fermentation (SmF) using mannitol. It was found that SSF was superior to SmF in terms of MPA concentration (1219 mg/L vs. 60 mg/L after 144 h fermentation), and the product yields were 6.1 mg/g pearl barley for SSF and 1.2 mg/g mannitol for SmF. The volumetric productivities were 8.5 and 0.42 mg/L h for SSF and SmF, respectively.The optimum solid substrate of SSF for MPA production was pearl barley, producing 5470 mg/kg compared with wheat bran (1601 mg/kg), oat (3717 mg/kg) and rice (2597 mg/kg). The optimum moisture content, incubation time and inoculum concentrations were 70%, 144 h and 6%, respectively. Neither the addition of mannitol or (NH4)2HPO4 nor adjustment of media pH within the range of 3–7 significantly enhanced MPA production.MPA production by SSF using a packed-bed bioreactor was performed and an increased maximum production of MPA 6.9 mg/g was achieved at 168 h incubation time. The higher volumetric productivity and concentrations makes SSF an attractive alternative to SmF for MPA production.  相似文献   

9.
The salinity problem is becoming increasingly widespread in arid countries. In semiarid Tunisia about 50% of the irrigated land is considered as highly sensitive to salinization. To avoid the risk of salinization, it is important to control the soil salinity and keep it below plant salinity tolerance thresholds. The objective of the present study was to provide farmers and rural development offices with a tool and methodology for predicting, monitoring of soil salinity for a better agronomical strategy. The experiments were carried out in the highly complex and heterogeneous semiarid Kalâat Landalous irrigated district of Tunisia. The field and laboratory measurements of soil and water properties were conducted in 1989 and 2006 at different observation scales (2900 ha, 1400 ha, 5200 m long transect, and soil profiles). Seventeen years of reclamation of a saline and waterlogged soil led to the reduction of average electrical conductivity of the soil saturated paste extract (ECe), measured at 5 soil depths (from 0 to 2 m) below the plant salt tolerance threshold and the dilution of groundwater salinity from 18.3 to 6.6 dS m−1. The variation in soil salt storage (ΔMss = Mss2006  Mss1989) in the vadose zone was negative, equal to about −145 × 103 ton (≈−50 ton ha−1). During the same period, the salt balance (Siw–Sdw) estimated from the input dissolved salt brought by irrigation water (Siw) and output salts exported by the drainage network (Sdw) was equal to −685 × 106 kg and the Sdw was 945 × 106 kg. Under irrigation and efficient drainage, the soil salinization could be considered as a reversible process. At the transect scale, the high clay content and the exchangeable sodium percentage was negatively correlated to saturated hydraulic conductivity. The textural stratification, observed at soil profile scale, favors accumulation of salt in the soil. Based on the findings related to the multiscale assessment of soil salinity and groundwater properties, soil salinization factors were identified and a soil salinization risk map (SRU) was elaborated. The shallow groundwater constitutes the main risk of soil salinization. This map can be used by both land planners and farmers to make appropriate decisions related to crop production, and soil and water management.  相似文献   

10.
Natural wetlands play an important role in the global carbon cycle, and loss of dissolved carbon through water has been indicated as one of the most important carbon sources for riverine ecosystems. During the last century, a large natural wetland area was reported to be converted to other land use types such as rice paddy land around the world. In this study, we explored the dynamics of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in two natural freshwater wetlands and a rice paddy field, which was reclaimed from the natural wetlands in the Sanjiang Plain, Northeastern China, during the growing season (May–October) of 2009. The DOC and DIC concentrations in the two ecosystems were significantly different (P < 0.05). The mean DOC concentrations during the growing season in the surface water of the Deyeuxia angustifolia and Carex lasiocarpa wetlands were 49.88 ± 5.44 and 27.97 ± 1.69 mg/L, respectively, while it was only 8.63 ± 2.54 mg/L in the rice paddy field. Specific ultra-violet light absorption at 254 nm (SUVA254) of DOC increased by an average of 19.54% in the surface water from the natural wetlands to rice paddy, suggesting that DOC mobilized in the natural wetlands was more aromatic than that in the rice paddy field. The mean DIC concentration in surface water of the rice paddy was 5.25 and 5.04 times higher than that in the natural D. angustifolia and C. lasiocarpa wetlands, respectively. The average ratio of DIC to dissolved total carbon (DTC) for the water sampled from the artificial drainage ditch in the rice paddy field was 61.82%, while it was 14.75% from the nearby channel of natural wetlands. The significant differences in dissolved carbon concentration in surface water and channels originating from different land use types suggested that reclamation of natural wetlands to rice paddy field would reduce DOC runoff and increase the DIC concentration to adjacent watersheds. Our study results for the changed pattern in dissolved carbon after the natural wetland was transformed to paddy field could have important implications for studying the impacts of the large-scale land use change to carbon cycle and management.  相似文献   

11.
This paper quantifies and analyses the water footprint of Tunisia at national and sub-national level, assessing green, blue and grey water footprints for the period 1996–2005. It also assesses economic water and land productivities related to crop production for irrigated and rain-fed agriculture, and water scarcity. The water footprint of crop production gave the largest contribution (87%) to the total national water footprint. At national level, tomatoes and potatoes were the main crops with relatively high economic water productivity, while olives and barley were the main crops with relatively low productivity. In terms of economic land productivity, oranges had the highest productivity and barley the lowest. South Tunisia had the lowest economic water and land productivities. Economic land productivity was found to explain more of the current production patterns than economic water productivity, which may imply opportunities for water saving. The total blue water footprint of crop production represented 31% of the total renewable blue water resources, which means that Tunisia as a whole experienced significant water scarcity. The blue water footprint on groundwater represented 62% of the total renewable groundwater resources, which means that the country faced severe water scarcity related to groundwater.  相似文献   

12.
《Small Ruminant Research》2001,39(2):167-179
The voluntary intake, digestibility and mean retention time of six temperate forages differing in their chemical composition by 12 adult castrated male Scottish blackface sheep, aged 15 months, and fibre-producing castrated male goats, aged 27 months, and of similar live weight, 40 kg, were described. The creation of a range of chemical compositions was effected through the use of barley straw, and a low- and high-digestibility hay, and the use of ammonia treatment of these forages. A wide range of voluntary intakes (42–78 g DM/kg W0.75/day), digestibility of dry matter (0.46–0.60) and mean retention times of undigested residues (36–72 h) was achieved through feeding the six forages. Across all the forages fibre-producing goats had higher voluntary intakes, expressed on a metabolic live weight basis, and lower digestibility values than sheep, whereas the mean retention time of the undigested residues was similar for the two species. Within forages goats selected a diet of potentially higher nutritive value, as predicted from chemical composition, with a smaller particle size than sheep. It was concluded that the differences in intake and digestion of temperate forages between sheep and fibre-producing goats are broadly similar to those observed in other experiments between sheep and goats ingesting tropical forages.  相似文献   

13.
现代农业在带来粮食高产的同时也产生许多生态环境问题,这促使人们再次把目光转向传统农业系统。一些传统农业系统不仅具有突出的经济、社会和文化价值,还具有多种重要的生态功能,如温室气体减排。然而,已有研究缺乏对传统农业系统整个生命周期的固碳减排能力的测算及其环境影响的评价。为此,基于农户调研数据,运用生命周期评价法对青田稻鱼共生系统的碳足迹进行了测算,并与当地水稻单作系统进行比较。研究发现:(1)青田稻鱼共生系统和水稻单作系统碳足迹分别为6266.7 kgCO_2-eq/hm~2和7520.0 kgCO_2-eq/hm~2,单位产值碳足迹分别为0.12 kgCO_2-eq/元和0.21 kgCO_2-eq/元。与水稻单作系统相比,稻鱼共生系统排放的温室气体更少,环境影响更小,生态和经济效益更高。(2)农业生产过程中积累的CH_4是碳足迹的最主要来源,农业生产资料投入中的化肥是碳足迹的的第二大来源。农业生产资料投入中的饲料则是稻鱼共生系统碳足迹的另一重要来源。通过碳足迹的方法对青田稻鱼共生系统的环境影响进行量化,不仅丰富了碳足迹在实际应用中的适用类型,对于其他传统农业系统的环境影响评价也具有借鉴意义。  相似文献   

14.
《Ecological Engineering》2006,26(3):266-271
Water supplies in the Middle East arid climate are a scarce commodity making treated wastewater an economically attractive source for increasing the limited existing water resources for agricultural purposes. In order to minimize water losses with the corresponding increased salinity and to reduce land demand, an integrated system based mainly on high-rate semi-intensive treatment units is being tested and demonstrated. The units include an upflow anaerobic sludge blanket (UASB) reactor and vertical and horizontal flow wetlands. The units are characterized by simple and low-cost maintenance with minimal energy input. Three years of pilot plant results from the combined system are presented in this paper. The results show a high organic removal rate for the combined system: 140 g COD/m2/day for the scheme, which included a UASB reactor followed by two PAVB units and subsurface horizontal flow CW. Even higher rates of 900 g COD/m2/day were achieved for the same scheme by replacing the final CWL with another PAVB unit. These high rates allow for a small treatment plant footprint equivalent to 0.13–0.9 m2 per person, assuming 125 g COD per person per day.  相似文献   

15.
Livestock husbandry in the dry areas of the Mediterranean basin is facing scarcity and fluctuation of feed supply and feed prices. At the same time the local agro-food industry is expanding and its by-products might be used as alternatives to traditional feed resources, but their nutritional value is not well known. Therefore, four by-products typical for the Mediterranean area were tested in vitro (n = 3 per diet or feed), in sacco (n = 6) and in vivo (n = 6) either individually or in a proportion of 0.34 of the total diet. The test feeds (broken lentils, sugar beet pulp, tomato pomace and crude olive cake) were compared to a barley–wheat bran mixture (control). Forage (barley straw) made up proportionately 0.5 of the diet. For all experiments either rumen canulated or intact castrated male Awassi sheep were employed. The thirty sheep used in the in vivo experiment weighed on average 42 kg. The animals were fed 1.1 kg dry matter (DM)/day and had free access to water. Large compositional differences (g/kg DM) between the batches of test feeds used in the present study were found in crude protein (from 79 to 245; for olive cake and broken lentils), neutral detergent fiber (aNDFom; from 283 to 584; for broken lentils and olive cake) and non-fiber carbohydrates (from 109 to 436 for tomato pomace and olive cake and to broken lentils). Two feeds (tomato pomace and olive cake) were rich in ether extract; sugar beet pulp was rich in calcium. Broken lentils had the highest effective degradabilities (ED). Olive cake was lowest in ED of OM and aNDFom (0.39 and 0.32, respectively). Olive cake caused refusals of concentrate (lower proportionate concentrate intake compared with the control, P<0.001). The apparent nutrient digestibility of broken lentils and sugar beet pulp was similar (P<0.001) to the control and lower (P<0.001) for tomato pomace and olive cake. Metabolizable energy (ME; MJ/kg DM) was determined by various ways and always showed a very low value for olive cake (1–2). Broken lentils and sugar beet pulp had ME contents higher (P<0.001) than that of tomato pomace. The study showed that some by-products were promising as alternatives to traditional concentrate ingredients, while others, especially olive cake, might be only used at low levels.  相似文献   

16.
Wetlands provide a large pool of organic matter and nutrients, and are important for maintaining material cycle balances in terrestrial ecosystems, and also help retard climate change. Land use changes in wetlands have greatly disturbed the natural evolution of wetland ecosystems. Wetland drainage and reclamation alters the physical, chemical and biological conditions of the wetland, thus significantly disturbing the material cycles, leading to significant changes in the biogeochemical processes of carbon, nitrogen and phosphorus in the wetland. The wetlands in the Sanjiang Plain are the largest area of fresh wetlands in China. However, the area has experienced major land uses changes since the 1950s; areas of the wetland have been drained and converted to arable land. Some studies have been conducted into the effects of land use change on material cycles in the Sanjiang Plain wetlands but few reports have discussed the C/N and C/P ratios and pH values as indicators of wetland degradation due to land use changes. We selected eight land uses: humus marsh (HM), marshy meadow (MM), drained humus marsh (DHM), drained marshy meadow (DMM), tillage land (TL), abandoned land (AL), natural secondary forest (NSF) and artificial forest (AF), in the Honghe area of the Sanjiang Plain. We studied changes in the total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), C/N and C/P ratios and pH values in topsoil (0–20 cm) of these eight different land uses. The possible mechanisms underlying the changes, and the significance of the C/N and C/P ratios as indicators of soil quality were also discussed. In the natural wetland, the TOC, TN and TP concentrations in the soil were high, with values of 203.5 g/kg, 20.2 g/kg and 1.44 g/kg, respectively, in HM; and 59.2 g/kg, 5.28 g/kg and 0.83 g/kg, respectively, in MM. Drainage of the HM has led to decreases in the TOC, TN and TP concentrations of about 50%. Significant decreases were also observed in TOC, TN and TP for NSF and AF compared to HM. Drained MM led to decreases in the TOC and TN of about 45%, but had little effect on TP. Marshy meadow that had been drained for more than 10 years experienced an exponential decline in TOC, TN and TP, with decreases of more than 60% for TOC and TN, and 20% for TP. However, after being abandoned for a short time (5 years), the TOC, TN and TP concentrations in soil experienced little change because poor water conditions combined with low productivity led to a large loss of soil organic matter. Land use change in the marsh areas has led to a decrease in C/N and C/P ratios of the soil, which are positively related to TOC and TN with different land uses (P < 0.05). Marsh reclamation has led to decreasing C/N and C/P ratios in soil and increasing pH values, which are negatively related to TOC, TN and TP (P < 0.05). Changes in carbon, nitrogen and phosphorus in soil with different land uses were mainly regulated by water-heat conditions and microbial activity, while the C/N and C/P ratios were mainly regulated by substrate availability. Our results suggest that C/N and C/P ratios and the pH value could be used as indicators to evaluate the quality and nutrient status of wetland soil under different land uses.  相似文献   

17.
《Small Ruminant Research》2008,76(2-3):185-191
General health, clinical-chemical blood analysis and copper (Cu), zinc (Zn), selenium (Se) and vitamin E concentrations in plasma and liver tissue (wet weight, ww) of two extensive grazing sheep flocks without mineral supply were compared to the status of local roe deer (Capreolus capreolus) populations (liver samples). Both sheep flocks were classified as healthy except for a remarkable variation in body weight and a slight foot rot infection in one flock. Hematology of sheep was normal, and total protein and creatinine as well as activities of creatin kinase, aspartat-amino-transferase, alkaline phosphatase and gamma-glutamyl-transferase in plasma were within reference levels. The mean of glutamate dehydrogenase (13.8 U/l) was slightly elevated in one flock. Mean liver concentrations of Zn (38.9 and 43.5 mg/kg ww) and Cu (111 and 87.5 mg/kg ww) in sheep flocks were higher compared to the respective roe deer populations (27.5 and 36.3 mg Zn/kg ww; 18.3 and 28.6 mg Cu/kg ww). This is supposed to be caused by differences in Cu and Zn metabolism in sheep and roe deer. Selenium deficiency was diagnosed in liver samples of both sheep flocks (0.21 and 0.23 mg/kg ww). There were neither significant differences compared to roe deer (0.21 and 0.27 mg Se/kg ww) nor differences depending on location. Correlations between plasma and liver concentrations of Cu, Zn and Se were not significant in sheep. Means of vitamin E in liver samples (30.6 and 41.8 mg/kg ww) were higher in roe deer populations. This may be caused by the opportunity of selective browsing for wild ruminants, which allows access to younger plants which are higher in vitamin E.  相似文献   

18.
The purpose of this study was to investigate the reliability of surface electromyography (sEMG) measurements after submersion (swimming) for 90 min. Isometric maximal voluntary contractions (MVC) on land and in water were collected from eight muscles on the right side of the body in 12 healthy participants (6 women and 6 men). Repeated measures analyses of variance (general linear model ANOVA) showed no significant differences in the peak amplitude MVC scores between land pre and post measurements for all muscles, p > .05. The mean of the Intraclass correlation coefficient (1, 1) for land pre and land post was .985 with (95% Cl = .978–.990), for land pre and water pre .976 (95% Cl = .964–.984) and for land pre and post, water pre and post .981 (95% Cl = .974–.987). Measuring sEMG on land before and after a prolonged submersion is highly reliable without additional waterproofing when using electrodes with 57 mm diameter.  相似文献   

19.
A total of 120 commercial crossbred steer calves (284±1.9 kg) were allocated in a 2×2 arrangement to two barley processing methods; whole (W) or rolled (R) barley and two ammoniation treatments; ammoniated (A) or non-ammoniated (N) barley. Steers were randomly allocated to twelve pens with 10 steers per pen and 3 pens (replications) per diet. The study was divided into two stages, growing (0–84 day) and finishing (85–196 day). Average daily gain (ADG) for the overall 196 day period was affected by processing (p<0.01) averaging 1.10 and 1.20 kg day−1 for steers on W and R barley, respectively. Steers on the R barley gained 19.6% more than those on W barley during the growing stage and 0.8% more during the finishing stage. There was a trend towards an improvement (p=0.06) in overall ADG by ammoniation. The ADG of steers was significantly higher (p<0.01) during the finishing (1.22 kg day−1) than during the growing (1.06 kg day−1) stage. Feed efficiency was better with R than with W barley (6.8 vs. 7.7; p=0.02). Processing and ammoniation had no effect (p>0.05) on carcass traits or grades.  相似文献   

20.
Rapid and periodic assessment of the impact of land cover change and climate variability on ecosystem services at regional levels is essential to understanding services and sustainability of ecosystems. This study focused on quantifying and assessing the changes in multiple ecosystem services in the Three-River Headwaters Region (TRHR), China in 2000–2012. Based on the widely used biophysical models including Integrated Valuation of Ecosystem Services and Trade-Offs (InVEST), Revised Wind Erosion Equation (RWSQ), and Carnegie-Ames-Stanford Approach (CASA) models, this study assessed the historical flow of regulating services, including soil conservation, water yield, and carbon sequestration, and provisioning service food provision. The soil conservation function of ecosystem was slightly enhanced as a whole, and water yield increased sharply, with both the soil conservation and water yield showing an increasing spatial homogenization. The net primary productivity (NPP) and food production increased substantially from 2000 to 2012. Ecosystem services are closely and complexly interlinked. The correlation analyses indicated a trade-off between the water yield and carbon sequestration, however, a synergy between soil conservation and carbon sequestration. Congruence between the three different ecosystem provisioning services, including pasture, meat, and grain, was found. There was also a synergy between food production and ecosystem carbon sequestration in the TRHR. Climatic variability and vegetation restoration are important for the ecosystem services flow. Correlation analyses showed that the increase in precipitation significantly enhanced the water yield (P < 0.01) and soil erosion (P < 0.01), while the temperature increase influenced positively the NPP (P < 0.1). The experience of ecological rehabilitation and the change in key ecosystem services in the TRHR exemplified the positive effects of environmental policies and the necessity of adopting an adaptive management approach. Thus the ecological construction and policy making should take climate variability into account, and facilitate synergies on multiple ecosystem services in order to maximize human well-being and preserve its natural ecosystems.  相似文献   

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