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This paper deals with a new system of aquaculture, i.e., a closed recirculating system for shrimp-mollusk polyculture. The culture system consisted of several shrimp ponds, a mollusk water-purifying pond and a reservoir. During the production cycle, water circulated between the shrimp and mollusk ponds, and the reservoir compensated for water loss from seepage and evaporation. Constricted tagelus, Sinonovacula constricta, was selected as the cultured mollusk, and Pacific white shrimp, Litopenaeus vannamei, as the cultured shrimp. The main managing measures during the production cycle were： setting and using the aerators; introducing the probiotic products timely into the shrimp ponds; adopting a “pen-closing” method for controlling shrimp viral epidemics; setting the flow diversion barriers in the mollusk pond to keep the circulating water flowing through the pond along a sine-like curve and serve as substrate for biofilm; no direct feeding was necessary for the cultured mollusk until the co-cultured shrimp was harvested; natural foods in the water from the shrimp ponds was used for their foods. Two sets of the system were used in the experiment in 2002 and satisfactory results were achieved. The average yield of the shrimp was 11 943.5 kg/hm^2, and that of the mollusk was 16 965 kg/hm^2. After converting the mollusk yield into shrimp yield at their market price ratio, the food coefficient of the entire system averaged at as low as 0.81. The water quality in the ponds was maintained at a desirable level and no viral epidemics were discovered during the production cycle. 相似文献
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陕西双王金矿床地质特征 总被引：7，自引：0，他引：7
双王含金角砾岩带位于陕西省太白县南部王家楞—王家庄一带,系一九六五年我局第三综合普查队检查一比二十万区调重砂异常时所发现。近年来第三地质队的工作初步证实此角砾岩带规模大,类型较特殊,有进一步工作价值。为了促进秦巴地区金矿地质工作,兹将已获地质成果作一概略介绍。谬误之处,敬请指正。一、地质特征(一)矿区地质(图1)含金角砾岩带位于东秦岭印支褶皱区的泥盆纪地层中。太白地区的泥盆系只发育中、上统,为秦岭泥盆纪海槽中带浅海—陆棚区的一套粉砂泥岩沉积,总厚在5000米以上。按区调资料,划分为四个岩组,自上而下依次为九里坪组(D_3j)、星红铺组(D_2x)、古道岭组(D_2g)、王家楞组(D_2w)。含金角砾岩带即赋存于古道岭组下部的泥质板岩夹钠长板 相似文献
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贵州及滇东地区下古生界油气资源评价 总被引：3，自引：0，他引：3
评价在纵向上涉及上震旦统、寒武、奥陶及志留系四个层系计七个评价单元。分析了评价区的石油地质背景,指出在晚古生代晚期浅变质岩基底的基础上,经历了四个构造发育阶段,即加里东期、海西印支期、燕山期及喜山期,从各构造期表现的构造特征来看,在整个构造发育中,改造大于继承,似以改造为主。这一特征对下古生代油气在地史中的分配和再分配,将有着极为复杂的影响。 文章分析了油气富集和保存的四个因素,即(1)生油岩及油气在地史中的演化过程;(2)储层;(3)盖层及保存条件;(4)圈闭条件。指出:在以下古生界各层系为目的层的勘探中,找气的领域大于找油的领域。 文章运用恢复氯仿沥青“A”法,计算了生油量,并对远景资源作了推算。通过评价指出了有勘探前景的区块。 相似文献
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