1978年以来湖北省粮食生产波动状况分析

摘要 以1978～2001年湖北省粮食生产统计数据为依据,分析了24年来湖北省粮食生产所经历的阶段,总结出湖北省粮食总产波动属于古典型波动的基本特征和稳定粮食生产的几点结论。     

Loss of carbon from the deep sea since the Last Glacial Maximum

Deep-ocean carbonate ion concentrations ([CO(3)(2-)]) and carbon isotopic ratios (δ(13)C) place important constraints on past redistributions of carbon in the ocean-land-atmosphere system and hence provide clues to the causes of atmospheric CO(2) concentration changes. However, existing deep-sea [CO(3)(2-)] reconstructions conflict with one another, complicating paleoceanographic interpretations. Here, we present deep-sea [CO(3)(2-)] for five cores from the three major oceans quantified using benthic foraminiferal boron/calcium ratios since the last glacial period. Combined benthic δ(13)C and [CO(3)(2-)] results indicate that deep-sea-released CO(2) during the early deglacial period (17.5 to 14.5 thousand years ago) was preferentially stored in the atmosphere, whereas during the late deglacial period (14 to 10 thousand years ago), besides contributing to the contemporary atmospheric CO(2) rise, a substantial portion of CO(2) released from oceans was absorbed by the terrestrial biosphere.     

Ice core evidence for Antarctic sea ice decline since the 1950s

The instrumental record of Antarctic sea ice in recent decades does not reveal a clear signature of warming despite observational evidence from coastal Antarctica. Here we report a significant correlation (P < 0.002) between methanesulphonic acid (MSA) concentrations from a Law Dome ice core and 22 years of satellite-derived sea ice extent (SIE) for the 80 degrees E to 140 degrees E sector. Applying this instrumental calibration to longer term MSA data (1841 to 1995 A.D.) suggests that there has been a 20% decline in SIE since about 1950. The decline is not uniform, showing large cyclical variations, with periods of about 11 years, that confuse trend detection over the relatively short satellite era.     

Absolute Chronology of the Last Glaciation

It appears that there is evidence for two main types of climatic fluctuations that have occurred during the Last Glaciation on two different time scales, one of the order of 40,000 years and another of the order of 3500 years. The Last Glaciation embraces at least two of the long periods (Fig. 1) upon which are superimposed oscillations of the short period (Table 1). Apparent contradictions in radiocarbon dates (19) are at least in part the result of miscorrelations between events on these two different time scales (20).     

The timing of high sea levels over the past 200,000 years

The (230)Th ages and (234)U/(238)U ratios were determined for Barbados corals that grew during periods of high sea level within the last 200,000 years. The similarity of the initial (234)U/(238)U ratios of some of the corals to the modern marine value suggests that these samples are pristine and that the marine (234)U/(238)U ratio 83,000 and 200,000 years ago was within 2 per mil of the modern value. The accuracies of the (230)Th ages are evaluated on the basis of the (234)U/(238)U values and a model of the behavior of uranium and thorium isotopes during diagenesis. For the last three interglacial and two intervening interstadial periods, sea level peaked at or after peaks in summer insolation in the Northern Hemisphere. This overall pattern supports the idea that glacial-interglacial cycles are caused by changes in Earth's orbital geometry. The sea-level drop at the end of the penultimate interglacial, the last interglacial, and a subsequent interstadial period lagged behind the decrease in insolation by 5,000 to 10,000 years.     

Pleistocene sea levels from raised coral reefs of haiti

The elevations and ages of a sequence of three uplifted Pleistocene coral reefs on the Northwest Peninsula of Haiti have been determined. With the assignment of a sea level of +6 meters (relative to the present day) at 130,000 years before present and constant uplift of the reefs, the data indicate that sea level stood -10 and -13 meters at 108,000 and 81,000 years before present, respectively. These results are in substantial agreement with those reported for Barbados and New Guinea and support the hypothesis of constant uplift for each area. Sea level data from raised reefs indicate that the interglacial marine oxygen isotope oscillations during oxygen isotope stage 5 are a result of 30 percent ice volume effects and 70 percent temperature effects.     

Chronology of hawaiian glaciations

Both potassium/argon and carbon-14 ages of lava flows and tephra layers interstratified with glacial deposits on Mauna Kea, Hawaii, indicate that four episodes of ice cap glaciation culminated about 20,000, 55,000, 135,000, and 250,000 years ago. These episodes are correlated with marine isotope stages 2, 4, 6, and 8, marking times of high global ice volume.     

Interglacial high sea levels and the control of greenland ice by the precession of the equinoxes

The precession of the equinoxes appears to control the occurrence of high sea levels by partial or even total melting of the Greenland ice cap during interglacial ages.     

虾夷马粪海胆及其饵料中无机元素和蛋白质的初步研究

报道了对虾夷马粪海胆(Strongylocentrotus intermedius )生殖腺、壳及饵料中无机元素(Ca,Mg,Fe,Zn,Mn,Cu)和蛋白质含量的测定结果.结果表明:生殖腺中常量元素镁的质量分数高于钙,微量元素质量分数依次为w(Zn)>w(Fe)>w(Cu)>w(Mn);壳中钙的质量分数约为镁的20倍,微量元素的质量分数依此为w(Fe)>w(Zn)>w(Mn)>w(Cu).生殖腺和壳中无机元素的质量分数与饵料中相应元素的质量分数之间无明显相关性.此外,发现配合饵料在促进生殖腺发育方面明显优于海带,海带则在促进壳生长方面优于配合饵料.     

Quaternary climates and sea levels of the u.s. Atlantic coastal plain

Uranium-series dating of corals from marine deposits of the U.S. Atlantic Coastal Plain coupled with paleoclimatic reconstructions based on ostracode (marine) and pollen (continent) data document at least five relatively warm intervals during the last 500,000 years. On the basis of multiple paleoenvironmental criteria, we determined relative sea level positions during the warm intervals, relative to present mean sea level, were 7 +/- 5 meters at 188,000 years ago, 7.5 +/- 1.5 meters at 120,000 years ago, 6.5 +/- 3.5 meters at 94,000 years ago, and 7 +/- 3 meters at 72,000 years ago. The composite sea level chronology for the Atlantic Coastal Plain is inconsistent with independent estimates of eustatic sea level positions during interglacial intervals of the last 200,000 years. Hydroisostatic adjustment from glacial-interglacial sea level fluctuations, lithospheric flexure, and isostatic uplift from sediment unloading due to erosion provide possible mechanisms to account for the discrepancies. Alternatively, current eustatic sea level estimates for the middle and late Quaternary may require revision.     

Chronology of guitarrero cave, peru

Dating by accelerator mass spectrometry of wooden artifacts, cord, and charcoal samples from Guitarrero Cave, Peru, supports the antiquity of South America's earliest textiles and other perishable remains. The new dates are consistent with those obtained from disintegration counters and leave little doubt about the integrity of the lower Preceramic layers and their early cultivars. Re-evaluation of the mode of deposition suggests that most of the remains resulted from short-term use of the cave in the eighth millennium B.C., with a possible brief human visit as early as 12,560 years ago.     

不同饲料蛋白水平对仿刺参生长的影响

在水温为(14±0.5)℃、盐度为31～31.5的条件下,研究了仿刺参幼参Apostichopus japonicus对蛋白水平为6%、13%、20%、27%、34%的5种饲料(以鱼粉、鼠尾藻粉、玉米面粉、复合维生素和复合矿物质为原料)的能量收支。结果表明:当饲料蛋白水平为19.48%时,幼参的特定生长率和饲料转化效率均达到最高水平,分别为1.27%/d和5.58%,此时饲料系数最低,为1.134;在该蛋白水平下,仿刺参生长能的比例最大,能量收支方程为100C=5.28G+27.24F+4.22U+3.46Rs+59.80R。     

不同饲料蛋白水平对仿刺参生长的影响

在水温为（14±0.5）℃、盐度为31～31.5的条件下,研究了仿刺参幼参Apostichopus japonicus对蛋白水平为6%、13%、20%、27%、34%的5种饲料（以鱼粉、鼠尾藻粉、玉米面粉、复合维生素和复合矿物质为原料）的能量收支。结果表明：当饲料蛋白水平为19.48%时,幼参的特定生长率和饲料转化效率均达到最高水平,分别为1.27%/d和5.58%,此时饲料系数最低,为1.134;在该蛋白水平下,仿刺参生长能的比例最大,能量收支方程为100C=5.28G＋27.24F＋4.22U＋3.46Rs＋59.80R。     

饲料中添加不同海藻对刺参幼参生长、免疫、消化及营养组成的影响

为缓解刺参Apostichopus japonicus饲料原料供给不足,降低养殖饲料成本,试验配制分别添加30%的马尾藻Sargassum、浒苔Enteromorpha、石莼Ulva及产于越南、印尼、菲律宾的大叶菜Sargassum fusiforme 6种配合饲料,每种饲料分别投喂3组初始体质量为(1.0±0.2)g的幼参,养殖周期为60 d,试验结束后比较不同藻类饲料对幼参生长、免疫、消化和营养组成的影响。结果表明:马尾藻组幼参终末体质量和增重率最高,其次是越南大叶菜组,两组幼参终末体质量和增重率均显著高于浒苔组(P<0.05);越南大叶菜组幼参脏壁比最高且显著高于石莼组和浒苔组(P<0.05);越南大叶菜组幼参体壁粗脂肪含量最高(9.59%)且显著高于其他组(P<0.05);幼参体壁中含量较多的氨基酸包括谷氨酸、甘氨酸、天冬氨酸和精氨酸,越南大叶菜组总氨基酸含量最高,菲律宾大叶菜组最低,两者有显著性差异(P<0.05),其余各组无显著性差异(P>0.05);总必需基酸和药效氨基酸在各组中无显著性差异(P>0.05),越南大叶菜组的呈味氨基酸最高(190.22 mg/g)且显著高于菲律宾大叶菜组(178.64 mg/g)、浒苔组(178.95 mg/g)(P<0.05)。研究表明,越南大叶菜可替代部分马尾藻,提高幼参增重率,增加幼参体壁粗脂肪、总必需氨基酸和呈味氨基酸含量,提升刺参体壁的营养价值,同时也为幼参的饲料配制提供更加广泛的原料资源。