半干旱榆中地区最小有效降水量及降水转化率的研究

有效降水对于土壤水分的补充和农作物的生长来说是一个很重要的概念。通常认为大于5 mm的降水即为有效降水。但是有效降水的影响因素很多,在不同的地理环境和气候背景条件下,最小有效降水量也会有所不同。利用2006年6月—2011年3月兰州大学半干旱气候与环境观测站资料,从土壤湿度变化的角度出发,根据有效降水的定义,对甘肃榆中地区的最小有效降水量做了初步研究。通过分析该地区不同季节、温度和植被条件下不同土壤深度最小有效降水量,发现5、10、20 cm土壤层的最小有效降水量分别为4、5、8 mm。季节分布上,各层土壤最小有效降水量均为夏季最高,春季和秋季值较为接近。高温年的最小有效降水量高于低温年的值,生长季高于非生长季。在降水超过最小有效降水量并且量级较小时,随着降水量的增大,土壤湿度增量呈指数形式增大,这时降水的转化率也较高;而当降水达到一定量级时,超过了土壤的入渗率,水分以径流的形式损失,土壤湿度增量的变化率减小,降水的转化率也趋于一定值。0—20 cm土壤层降水转化率达到70%。     

青海省植被净初级生产力的模拟研究

遥感技术根据植被光谱特征可以有效地估算植被的净初级生产力(NPP).利用遥感数据估算植被NPP,是近10年来NPP的模型研究和估算方法最为突出的特点.文章借鉴了CASA,GLO-PEM,VPM等光能利用率NPP模型的优点,同时充分考虑了研究区域其植被光能利用率和环境因素的典型特点,建立了针对研究区域基于光能利用率原理的...     

磷酸盐不同补充方式对塔玛亚历山大藻生长和产毒影响

实验室条件下探讨经过磷酸盐限制后,2种不同补给方式对塔玛亚历山大藻生长和产毒的影响.结果表明,经磷限制后,在一次性添加和脉冲式添加2种磷酸盐补充方式下,塔玛亚力山大藻的最大比生长速率分别为0.71 d-1和0.63 d-1,明显高于在f/2培养液条件下的0.40d-1;同时,一次性添加组所达到的最大生物量明显高于脉冲式添加组(P＜0.05),表明在寡磷酸盐海区,一旦磷酸盐得到丰富补充后,浮游植物会暴发性增长,极易引发赤潮.但是,2组在光能转化效率Fv/Fm值和毒素变化方面都没有表现出显著差异(P＞0.05).前6d受到磷酸盐限制的塔玛亚历山大藻,其光能转换效率值Fv/Fm从0.62降至0.40,单位细胞毒素含量却是在f/2培养液条件下的6倍;而添加磷酸盐后,Fv/Fm值在3d内迅速升至0.60,细胞数量呈现快速增长态势,单位细胞毒素含量却开始降低.至培养结束时,Fv/Fm值缓慢降低至0.40左右,单位细胞毒素含量分别为0.73和0.78 pgSTXeq/个,与f/2培养液条件下的0.76 pgSTXeq/个相当.HPLC测定结果表明,塔玛亚历山大藻南海株毒素含量主要是由GTX1,GTX4,neoSTX和C2四类组分构成,其和占总毒素含量的98％以上.     

阿姆山自然保护区气候资源研究

依据红河县气象站及保护区附近4个气象哨的气象观测资料,结合野外实地考察和访谈所得非常规资料,采用理论推算方法对保护区气候资源的时空变化特征进行系统分析.结果表明：保护区光、热、水资源的时空分布变化显著.随着海拔升高年均温、年日照时数、年积温逐渐下降,年降水量和年太阳总辐射量逐渐增多.一年中,光、热、水资源夏季最多,冬季最少,山地南坡较北坡多.针对热量和水分资源垂直分异特征将保护区划分为4个垂直气候带,可为保护区及附近社区自然资源的合理开发利用、保护和管理气候资源提供理论依据.     

Effects of feeding and stocking density on digestion of cultured Atlantic salmon Salmo salar L.

The combined effects of feeding rate （0.8%, 1.0%, and 1.2% initial body weight/day）, feeding frequency （two, three, and four times/day） and stocking density （10, 15, and 20 kg/m3） in recirculating aquaculture systems （RAS） on growth performance, digestion and waste generation of Atlantic salmon （Salmo salar L.） were investigated in an 8-week orthogonal experiment （L9（3）3） with a constant daily water renewal at 7.50% of total volume. No mortality occurred during the experimental period. Feed conversion ratio （FCR） varied from 0.90 to 1.13 and specific growth rate （SGR） ranged from 0.48% to 0.69%/day. SGR, thermal growth coefficient （TGC） and FCR were not significantly （P〉0.05） affected by the three factors, while net protein utilization （NPU） was significantly （P〈0.05） affected. Apparent digestibility coefficients （ADC） of dry matter in the present study were in the range 66.12%-73.55%. ADC in protein, lipid and energy were statistically different among all treatments and in the range of 90.07%-93.67%, 81.54%-89.15%, and 67.55%-71.87%, respectively. The proportion of mean total ammonia nitrogen excreted ranged from 1.37% to 1.64% of feed nitrogen at steady state, and the concentration of nitrogenous and phosphorus compounds were differently correlated to the three factors. The results will provide valuable reference data for culture management decisions in the Atlantic salmon farming industry.     

Effect of Dietary Potassium on Growth,Nitrogen Metabolism,Osmoregulation and Immunity of Pacific White Shrimp （Litopenaeus vannamel） Reared in Low Salinity Seawater

An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physio-logical acclimation of Pacific white shrimp （Litopenaeus vannamei） reared in diluted seawater （salinity 4）. Six semi-purified practical diets containing 0.59, 0.96, 1.26, 1.48, 1.74, and 2.17 g potassium K＋ per 100 g diet were formulated, respectively. The survival and feed conversion rate did not show significant difference among groups of shrimps given these diets （P〉0.05）. The shrimps fed the diets containing 0.96-1.48 g K＋ per 100g diet gained the highest weight, specific growth rate, and protein efficiency ratio. Their ammonium-N excretion rate as well as hemolymph concentration of Na＋ and C1- were significantly lower than those of the control （P〈0.05）, but a reverse trend was observed for their gill Na＋/K＋-ATPase. Moreover, the shrimps fed with 1.48 g K＋ per 100 g diet were the highest in hemolymph urea level, and the phenoloxidase and lysozyme activities were significantly higher than those of the control （P〈0.05）. The growth and physiological response of the test shrimps suggested that diet containing 1.48 g K＋ per 100 g diet improved the growth of L. vannamei in low-salinity seawater, and enhanced the physiological acclimation of the organism.     

论煤岩组分的液化性能

通过高压釜在溶剂和催化剂条件下对煤的加氢液化试验,探讨了低煤级煤中煤岩组分的液化性能。结果表明,在不同宏观煤岩成分的液化试验中,转化率和油产率表现出镜煤>亮煤>暗煤>丝炭;对于显微组分的液化,不仅镜质组和壳质组具有反应活性,半镜质组也有一定活性,且活性组分(镜质组+半镜质组+壳质组)含量与液化转化率、油产率表现出良好的正比关系。低煤级煤中,R_max<1.50%的半丝质组分在液化时有反应活性,其活性低于同一煤中的半镜质组,而R_max>1.50%的惰质组分已不具反应活性。      

The Effect of Three Culture Methods on Intensive Culture System of Pacific White Shrimp （Litopenaeus vannama）

Different culture methods may affect the intensive culture system of Pacific white shrimp （Litopenaeus vannamei） re- garding water quality and growth and economic performance. This study evaluated the potential effects of three culture methods through cultivation of juvenile shrimps under consistent tank management conditions for 84 d. The three methods involved shrimp cultivation in different tanks, i.e., outdoor tanks with cement bottom （mode-C）, greenhouse tanks with cement bottom （mode-G） and outdoor tanks with mud-substrate （mode-M）. Results showed that water temperature was significantly higher in mode-G than that in mode-C （P 〈 0.05）. In contrast to the other two treatments, mode-M had stable pH after 50 d cultivation of shrimps. In the mid-late period, the average concentrations of TAN, NO2-N, DIP and COD were significantly lower in mode-M and mode-G compared with those in mode-C （P 〈0.05）. Despite lack of differences in the final shrimp weight among different treatments （P 〉0.05）, mode-M had significantly higher shrimp yield, survival rate and feed conversion rate （P 〈 0.05） than other modes. There were significant dif- ferences in revenue and net return among different treatments （P 〈 0.05）. These demonstrated that the treatments of mode-G and mode-M were conductive to the intensive culture system ofL. vannamei.     

不同投喂率对细鳞鲑(Brachymystax lenok)幼鱼生长及体成分的影响

选取同一种进口鳟鱼标准饲料,设1.0%、2.0%、3.0%、4.0%和5.0%共5个投喂率水平,在溶解氧为8.0—8.5mg/L、水温为(16±0.5)℃的流水条件下,对初始体重为5.32—6.43g的细鳞鲑幼鱼进行为期35d的生长实验。结果表明,随着投喂率的增加,相对增重率(WGR)和特定生长率(SGR)先升高后降低,4.0%处理组的这两项指标显著高于其它各处理组(P<0.05),分别为289.82和3.89;饲料转化率(FCE)则呈现逐渐降低趋势,2.0%组的FCE最低,5.0%组最高。随着投饲率的增加,细鳞鲑幼鱼鱼体水分含量呈下降趋势;灰分含量无规律性变化;粗蛋白含量保持在相近水平(除1.0%处理组);粗脂肪含量无规律性变化,但3.0%组显著高于其它各处理组,4.0%组鱼体粗脂肪含量最低。综合衡量WGR、SGR和FCE等指标,认为细鳞鲑幼鱼(5—25g体重)在密度为300尾/m3、水温为(16±0.5)℃流水条件下,最适宜的投饲率为3.0%—4.0%。     

天山及周边地区空中水资源的稳定性及可开发性研究

利用天山及周边地区大气含水量序列的方差值和降水转化率,分析了天山地区空中水资源的稳定性和可开发性,结果表明：天山山区大气含水量的稳定性与大气含水量多少有密切关系,大气含水量低的地区,水资源稳定,而大气含水量高的地区,水资源不稳定。夏季是四季中方差最大的季节,稳定性较差;冬季是大气含水量方差最低的季节,特别是山区大气含水量稳定,秋季略高于春季。天山东部和西部地区的大气含水量方差明显要小,而中部地区较大,这主要是由控制风带的强弱及水汽输送决定的。大气含水量的稳定性和海拔成反相关关系,这主要与水汽凝结的高度有关。地形高度变化和降水转化率密切相关,随海拔高度上升,降水转化率增大,降水转化率在2000m左右形成一个高值,天山山区年降水转化率最大,伊犁河谷冬季降水转化率最大。