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Gireesh Raghavan Chanjaplackal Kesavan Haridevi & Cherukara Purushothaman Gopinathan 《Aquaculture Research》2008,39(10):1053-1058
The marine diatom Chaetoceros calcitrans f. pumilus has been examined for its potential source as live feed in aquaculture. The present study investigated effects of temperature (20, 25 and 30 °C), salinity (25 and 35) and carbon dioxide addition (air+CO2 ) on the growth and proximate composition of C. calcitrans under laboratory conditions. The growth and biomass of C. calcitrans were primarily affected by carbon dioxide addition, and to a lesser extent by temperature and salinity. In general, lipid and carbohydrate contents were higher at lower temperatures (20 and 25 °C), while the protein content was unaffected. Carbon dioxide addition increased protein, while lowering carbohydrates, but had no effect on lipid content. Carbohydrates were increased while lipids and protein decreased at the highest salinity (35±0.9). These results should be taken into consideration when evaluating the dietary value of this micro alga for aquaculture. 相似文献
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为探究氮硫互作对大蒜植株生长的影响,以‘新疆白皮蒜’为试材,研究无机基质栽培条件下不同氮硫互作水平对大蒜农艺性状、叶绿素含量以及根系活力的影响。试验结果表明,不同生长阶段氮硫互作对大蒜株高、茎粗、植株鲜重、干重、鳞茎鲜重均有不同程度的增促效果,但氮或硫单一元素对其影响不一;大蒜生长过程中叶绿素含量与根系活力呈先升高后降低趋势,氮硫互作对其均有显著影响,且氮和硫素单一元素也显著影响大蒜根系活性。综合来看,大蒜生长过程中氮硫互作效果显著,在氮素20 mmol/L、硫素4 mmol/L条件下收获的鳞茎重量最大。 相似文献
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依据排放成因,初步建立了海水鱼养殖中二氧化碳排放负荷和排放强度的测算方法;依据竹内俊郎法并综合考虑生物滤池处理效率,初步建立了海水鱼养殖的氮、磷排放负荷和排放强度以及排放总量的测算方法;依据海上生活污水排放标准,初步建立了氮、磷瞬时排放浓度的测算方法;利用浓度限值法测算了黄海冷水团区域氮、磷的环境容量。以大西洋鲑养殖数据为基础,测算了6种养殖模式的碳、氮、磷排放负荷和排放强度,并将测算的氮、磷年排放量、瞬时排放浓度的结果与黄海冷水团区域的环境容量进行比较分析,初步评估了养殖活动对环境的影响。结果显示,网箱养殖模式的二氧化碳排放负荷和排放强度均显著低于其他模式,循环水养殖模式的氮排放负荷和排放强度均显著低于全流水养殖模式,而6种养殖模式之间,磷排放负荷和排放强度的差异不显著,磷排放是制约扩大养殖规模的主要因素。 相似文献
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E. C. Spiker R. P. Hosker Jr. V. C. Weintraub S. I. Sherwood 《Water, air, and soil pollution》1995,85(4):2679-2685
The dry deposition of gaseous air pollutants on stone and other materials is influenced by atmospheric processes and the chemical characteristics of the deposited gas species and of the specific receptor material. Previous studies have shown that relative humidity, surface moisture, and acid buffering capability of the receptor surface are very important factors. To better quantify this behavior, a special recirculating wind tunnel/environmental chamber was constructed, in which wind speed, turbulence, air temperature, relative humidity, and concentrations of several pollutants (SO2, O3, nitrogen oxides) can be held constant. An airfoil sample holder holds up to eight stone samples (3.8 cm in diameter and 1 cm thick) in nearly identical exposure conditions. SO2 deposition on limestone was found to increase exponentially with increasing relative humidity (RH). Marble behaves similarly, but with a much lower deposition rate. Trends indicate there is little deposition below 20% RH on clean limestone and below 60% RH on clean marble. This large difference is due to the limestone's greater porosity, surface roughness, and effective surface area. These results indicate surface variables generally limit SO2 deposition below about 70% RH on limestone and below at least 95% RH on marble. Aerodynamic variables generally limit deposition at higher relative humidity or when the surface is wet. 相似文献
38.
利用开放培养系统,分别在20℃和30℃,好气和淹水条件下研究了四种土壤(黑土、褐土、黄棕壤和红壤)有机硫矿化特征。结果表明,30℃条件下土壤有机硫累积矿化量显著高于20℃下的矿化量(P<0.01)。20℃和30℃好气条件下累积矿化量分别为17.53-24.35mg kg^-1和34.20-54.33mg kg^-1,分别占有机硫总量的2.5%-6.5%和5.-14.5%,20℃和30℃淹水条件下累积矿化量分别为18.14-21.15mg kg^-1和26.86-30.63mg kg^-1,分别占有机硫总量的2.6%-5.6%和4.0%-7.7%。好气和淹水下30℃与20℃的有机硫累积矿化量之比分别为1.85-2.23和1.28-1.71。用一级动力学方程和双倒数方程计算土壤有机硫矿化势(S0)表明,20℃好气培养时S0分别为17.82-24.88mg kg^-1和17.83-27.7mg kg^-1,S0分别为17.50-21.49mg kg^-1和19.19-22.50mg kg^-1,30℃淹水条件下S0分别为28.26-35.87mg kg^-1和26.59-34.25mg kg^-1。土壤有机硫矿化速率常数(K)和矿化量达50%矿化势(S0)所需的时间(K1)受不同土壤和培养温度的影响,都可用一级动力学方程和双倒数方程来评价。碳键硫对有机硫矿化的贡献较大,尤其在淹水条件下更明显。 相似文献
39.
Tillage changes soil environmental conditions and controls the distribution of residues in the soil, both actions that affect the production and emission of soil biogenic gases (CO2, N2O, and CH4). The objective of this study was to determine how tillage-induced environmental conditions and substrate quality affect the mineralization rate of easily metabolizable compounds and the subsequent production of these gases. Carbon compounds, with and without nitrogen, were applied to soil cropped to maize under tilled and no-till systems. Following substrate application in the spring and summer, biogenic gases were measured periodically at the soil surface (flux) and within the profile (concentration) at 10-, 20-, and 30-cm depths (i.e., within, at the bottom of, and below the plough layer). Strong CO2 and N2O responses to sucrose and glycine in both the field and the laboratory indicate that the soil was C- and N-limited. Surface fluxes of CO2 and N2O were greater in soils amended with glycine than with sucrose and were greater in tilled than no-till soils. Transient emission of CH4 following the addition of glycine was observed and could be attributed to inhibition of N mineralization and nitrification processes on CH4 oxidation. Laboratory and field measurements indicated that the larger substrate-induced CO2 emission from the tilled soils could not be attributed to differences in the total biomass or the basal respiratory activity of the soils. Thus, there appears to be no underlying difference in the functional capacity of the microbial communities under different tillage regimes. Comparison of gas profiles indicates relative accumulation of CO2 at depth in soils under no-till, as well as greater decline in profile CO2 content with time in the tilled compared to the no-till soil. These results support the conclusion that greater CO2 efflux from the tilled soils resulted from more rapid gas diffusion through the profile. Hence, the observed differences in gas fluxes between tilled and no-till soils can be attributed to differences in physical environment. 相似文献
40.