Phosphorus and nitrogen excretion during growth span of carp kept under two rearing systems

ABSTRACT:   Two feeding trials were performed on carp to investigate phosphorus (P) and nitrogen (N) excretion during their growth span. Trial I was conducted under laboratory conditions by feeding 3.9 g carp an experimental diet (crude protein 34.8%, total P 1.41% and available P 0.67%) for 280 days under controlled conditions. Trial II was performed with 72.8 g carp, feeding them a commercial diet (CP 35.8%, total P 1.62% and available P 0.75%) for 180 days on a practical scale. Fish grew throughout the experiment in trial I, whereas they stopped growing in trial II when the water temperature fell below 15°C. In both trials, P and N content in fish body increased with increasing weight until it plateaued when fish were between 500 and 600 g. The retention rates of the two elements also followed a similar pattern, but decreased beyond the size range mentioned above. In both trials, P and N loading increased with an increase in fish size, but such a pattern was less evident until a bodyweight of 600 g, the trend being more pronounced in trial II. The results of the present study indicate that excretion is higher during the slow-growing stage of carp and is, hence, influenced by fish size.     

室内给水排水管径的快速设计

为了加快设计速度,及时满足建设进度的要求,减少设计中繁琐工作量,介绍一种室内给水排水管道允负荷的快速计算方法。     

Rangeland Monitoring: Water Quality and Riparian Systems

Ecological concepts serve as a foundation for developing a monitoring program to evaluate water quality and associated riparian systems. Ecological concepts used for developing a monitoring plan must be supported by scientific literature and related to streamflow dynamics and channel interactions. These interactions help determine natural or background habitat quality within and along river longitudinal and environmental gradients from mountains through basins in the western United States. In addition stream size, position in the watershed, and flow are related to sediment sorting, channel bank strength, and channel configuration. These relationships determine channel substrate habitat for aquatic organisms and population diversity. These habitat features may be modified by a channel's ability to store and transport sediment and associated pollutants within a watershed's drainage pattern. Sediment supply, delivery, and timing are altered by differences in snowmelt along elevation gradients, runoff from convective storms, water development history, and stream channel succession. Potential impairment of reference or background aquatic habitat in the western United States is generally sediment related and should be greater in basin river segments and during base flow conditions. Impairment sources can be shown to originate in the steep and first order tributaries of foothill and basin watersheds, and not from valley slopes where supply must cross established riparian zones. Water column, substrate disturbance, and channel bank disturbances may alter amount of sediment and bacteria pollution measured in basins and during base flow conditions.     

变动水位泵型组合的优选

本文通过对抽水量和水位的变化分析，提出了泵型的组合优选方法，使变动水位泵站以较小的能耗完成抽水。     

黄土丘陵区植被恢复与流域养分环境演变研究进展

针对在陕北黄土丘陵沟壑区实施的植被恢复及不同土地利用类型调整的政策,在小区和流域尺度上,就植被恢复对流域水土流失、养分流失、养分循环平衡影响方面的国内外研究概况进行了综述。指出植被恢复可减少流域水土流失和养分流失,使流域养分循环平衡能力加强、向良性循环方向发展,同时指出了在这方面需进一步研究的问题。     

桑树坪井田地下水化学特征及矿井水的再生利用

简要介绍了桑树坪井田地质与水文地质概况,按地层的含水性将井田含水层划分为第四系砂砾石层孔隙潜水中等含水层组(H1)、二叠系砂岩裂隙承压弱含水层组(H2)、石炭系砂岩灰岩裂隙承压极弱含水层组(H3)和奥陶系石灰岩溶隙溶洞承压强含水层组(H4)等4种类型。在分析各含水层组水质特征及矿井水水化学特征的基础上,得出奥灰水是矿井水的主要补给来源;并针对该井田矿井水硬度大,矿化度、SO_4~(2-)含量高的水质特征,提出了以物理一物理化学方法为基础,以电渗析法为主的净化处理矿井水方法。     

Rapid development and infilling of a buried gully under cropland, central Belgium

Analysis of contemporary and past gully erosion and infilling processes allowed to reconstruct the long-term evolution of a permanent gully system under cropland. An active and a buried gully under cropland were investigated. The recent sediment deposits within the active gully, adjacent to the buried gully, showed that the recent gully was filling in at a mean rate of 6.4 cm a^{− 1}. In the buried gully, several erosion and deposition phases could be identified and the type of deposited sediments revealed a complex infilling history. Charcoal, pottery and brick fragments of different sizes were found at all depths of the gully infilling. Their age indicates that the first gully incised after the midst of the 17th century, most probably in the second half of the 18th century or the early 19th century. Gully morphology and analogy with the processes in the recent gully indicate that the buried gully filled in rapidly. Overall, five cycles of cut and fill occurred in 350 years or less and four cycles even within little less than a few decades, indicating that gully development and infilling under cropland can be very rapid processes.     

Nasolacrimal obstruction caused by root abscess of the upper canine in a cat

A 10‐year‐old, castrated male domestic short hair cat was presented to the Small Animal Clinic at the Western College of Veterinary Medicine with a presenting complaint of chronic, ocular discharge from the left eye. Ocular examination confirmed epiphora and mucopurulent discharge but there were no apparent reasons for the ocular discharge, and nasolacrimal obstruction was suspected. The cat had swelling of the left side of the face, severe periodontal disease and a fractured upper left canine tooth with pulpal exposure. Dacryocystorhinography revealed narrowing of the nasolacrimal duct above the root of the fractured upper left canine and dental radiographs showed a severe periapical lucency at the apex of the upper left canine tooth. The fractured canine tooth was removed. Subsequently, the ocular discharge and facial swelling resolved. After 2 years, the epiphora has never reoccurred. This is a noteworthy case because a suspected root abscess resulted in extralumenal compression of the nasolacrimal duct, which shows the importance of a thorough oral examination when nasolacrimal obstruction is evident.     

River flooding and reproduction of migratory fish species in the Magdalena River basin,Colombia

Jiménez‐Segura LF, Palacio J, Leite R. River flooding and reproduction of migratory fish species in the Magdalena River basin, Colombia.
Ecology of Freshwater Fish 2010: 19: 178–186. © 2010 John Wiley & Sons A/S Abstract – In most tropical rivers subject to a single‐yearly flooding, migratory fish usually spawn in the onset of the flooding and larvae drift to their nursery habitats. To define when the migratory fish species reproduce, its relationship with the water level and when nursery areas in floodplain lakes are supplied with ichthyoplankton in the Magdalena River, a two‐yearly peak flooding river, we sampled the ichthyoplankton weekly throughout 2 years. The fish species Pseudoplatystoma magdaleniatum, Prochilodus magdalenae, Leporinus muyscorum, Sorubim cuspicaudus and Curimata mivartii spawn twice a year in the main channel and its larvae input into the floodplain lakes are not always associated with flooding. Spawning in the main channel and larvae inputs into the floodplain lakes suggest that the habitat used by the migratory fishes may be consistent with some hypotheses on habitats used by these fishes.     

滇池沉积物总氮的时空变化特征研究

采用GPS定位,对滇池海埂、斗南、罗家村、新街、昆阳等5个代表性样点沉积物总N含量进行为期1年的动态监测,分析了不同区域、不同层次、不同时期滇池沉积物总N的变化.结果表明全湖全年沉积物总N的平均含量为4.91g/kg,年变化范围是4.13～5.41 g/kg,呈现明显的季节性变化,总体趋势夏季高、冬季低,但不同区域变化高峰和趋势不同.沉积物总N层次变化差异显著,表现为表层＞中层＞底层,各层次年变化范围分别为表层3.54～9.10g/kg、中层2.72～8.04 g/kg、底层1.23～5.37g/kg.各区域沉积物总N平均含量以海埂和罗家村最高,斗南和新街较低.