家兔肋胸膜淋巴孔的发现

为了研究成年家兔肋胸膜淋巴孔的超微结构与三维构形 ,作者应用扫描电镜和透射电镜对成年家兔肋胸膜淋巴孔进行观察 ,用计算机图像处理系统对胸膜淋巴孔作图像数据化处理 ;NaOH溶液消化间皮细胞 ,裸露间皮下结缔组织和筛斑 (maculacribriform)。发现肋胸膜立方形间皮细胞 (cuboidalmesothelialcell)之间有圆形或椭圆形的胸膜淋巴孔 (pleurallymphaticstomata) ,其平均面积和平均密度分别为 :7 2 0± 3 6 9μm2 和 1 2 1±0 72个 / 0 0 1mm2 。扁平形间皮细胞表面未见淋巴孔。胸膜淋巴孔籍胸膜下小管与毛细淋巴管相通。仅在立方形间皮下结缔组织中发现有筛斑。肋胸膜上还可见闭合淋巴孔 (closedlymphaticstomata)和由巨噬细胞组成的乳斑 (milkyspot)。覆盖在肋骨上的胸膜无淋巴孔分布。家兔胸膜淋巴孔通过胸膜下小管与淋巴管直接相连 ,形成从胸膜腔至脉管系的惟一直接通路。     

Treatment of acid mine drainage by sulphate-reducing bacteria using permeable reactive barriers: A review from laboratory to full-scale experiments

Acid mine drainage in-situbioremediation has in the last decades drawnthe attention in the field of environmentalbiotechnology. The most recent treatmenttechnique are the permeable reactive barriersusing sulphate-reducing bacteria. This viewdescribes the basis of many of the currentapproaches to use sulphate-reducing bacteria inacid mine drainage treatment, from laboratoryto full-scale realisations, and the limitationsencountered when applied to full scaleapplications.     

The neutralization of acidic coal mine lakes by additions of natural organic matter: a mesocosm test

Cylindrical polyethylene enclosures 3 m in length and 1 m in diameter reaching from the surface to the bottom were constructed in an acid (pH=3.1) lake on a coal surface mine in southern Illinois. Wheat straw was added to the enclosures to test the effects of dissimilatory sulfate reduction on water chemistry. Added straw increased sulfide concentrations, raised pH to 6.5, reduced O₂ and increased acid neutralizing capacity of the enclosed water columns when compared with a control enclosure and with the open lake. Generation of acid neutralizing capacity exceeded the standing stock of sulfide indicating that sulfide was removed either by precipitation of FeS or outgassing of H₂S. The pH and acid neutralizing capacity within the enclosures eventually returned to the level of the surrounding lake because of water exchange around the enclosure walls. Our results show that additions of organic matter to acid surface mine lakes result in the generation of acid neutralizing capacity.     

Fishes, their biology and fisheries management in Lake Peipsi

The management of aquatic weeds in an irrigation scheme is constrained by the agro-economic system in relation to scheme layout, the nature and ecology of the aquatic weeds, agricultural practice, irrigation and drainage requirements, and the available resources for maintenance. The way in which the ecology, engineering and economics of irrigation and drainage channels interact to produce a pattern of management is investigated for the Mwea Irrigation Settlement Scheme, Central Province, Kenya. This is used to develop a simple model which enables the economic implications of varying the aquatic weed management practice to be identified. The model brings the selection of a weed control programme within the principles of engineering economy.     

Wetlands of recent Dutch embankments

Wetlands of new embankments are characterized with respect to soil and hydrological regime and the processes of desalination and vegetation succession. Soil- and height gradients, the lack of local drainage and the generally low nutrient content provide conditions for dynamic mesoseries (groundwatertable low in summer, saturated in winter) and locally for stable mesoseries (relatively high in summer, saturated in winter). Relations between vegetation and herbivores (gees, ducks, cattle) are discussed.     

Drainage history and land use pattern of a Swedish river system — their importance for understanding nitrogen and phosphorus load

During the 19th and the first half of the 20th century, approximately 300 km² of lakes and wetlands, representing 29% of the River Kavlingean catchment in Southern Sweden, were drained to make land available for agriculture. Published accounts of nutrient loads from the catchment indicated that until the mid 20th century, factories and urban point sources were the major contributors of both nitrogen and phosphorus. By the middle of the 20th century, the construction of sewage treatment plants had effectively reduced phosphorus pollution. Concurrently, the land drained in the previous century underwent a more intense cultivation, with productivity being maintained by commercial fertilizers. Subsequently, net nutrient loads from agriculture continued to increase, reaching an annual load of 2652 tons total-nitrogen and 70 tons total-phosphorus for the River Kävlingeån. Whilst high nutrient leakage from agricultural watersheds may be a problem which is only recently recognized, it had its origins in nearly a hundred years of commonly accepted agricultural policy.To assess the importance of agriculture as the major source of nutrients to the River Kävlingeån system, three tributary catchment areas, differing in terms of their land use patterns (high, medium and low intensity of agricultural use), were studied and compared with literature figures. Results indicated that agricultural nutrient loss areal coefficients were substantially higher than the literature figures, demonstrating the role of agriculture as source of nutrients to the River Kävlingeån system. The agricultural land use policies of the last fifty years were revealed to be most important with regard to this role. Of such land use policies, the cultivation of the last 10–15% of land employed for agricultural use (primarily riparian ecotones) may be of most significance. The literature indicates that intense agricultural use of this final 10–15% may account for a ca. 50% increase in nitrogen loss. This suggests that one solution to the problem of agricultural diffuse pollution may lie in the restoration and sustainable management of riparian ecotones of agricultural streams.     

气象因子对农田设计排涝模数的影响

设计排涝模数的计算对农田安全和有效降低涝灾损失意义重大.本文选取天津市宁河区封闭农田小区为研究对象,分析了主要气象因子对农田设计排涝模数的影响.为解决观测样本有限的问题,在现场观测试验的基础上,以总径流深为目标,使用互信息、偏秩相关方法分析了参数敏感性,结合土壤含水量、地下水位相对变化量得到了合理的模型参数,建立了三水源超渗-蓄满耦合产流模型,进行了产流量和设计排涝模数估算,并分析了降雨和蒸发等气象因子对设计排涝模数的影响.结果表明:1960—2015年,研究区夏季降水量显著减少,蒸发量变化不明显.排涝模数随降水量减少而减少,且随着设计重现期的增大,降水和设计排涝模数的减少量均有所增大,但总体来讲,气象因子对设计排涝模数的影响并不大,现行设计排涝模数可不进行修订.     

Rock glaciers in crystalline catchments: Hidden permafrost‐related threats to alpine headwater lakes

A global warming‐induced transition from glacial to periglacial processes has been identified in mountainous regions around the world. Degrading permafrost in pristine periglacial environments can produce acid rock drainage (ARD) and cause severe ecological damage in areas underlain by sulfide‐bearing bedrock. Limnological and paleolimnological approaches were used to assess and compare ARDs generated by rock glaciers, a typical landform of the mountain permafrost domain, and their effects on alpine headwater lakes with similar morphometric features and underlying bedrock geology, but characterized by different intensities of frost action in their catchments during the year. We argue that ARD and its effects on lakes are more severe in the alpine periglacial belt with mean annual air temperatures (MAAT) between ?2°C and +3°C, where groundwater persists in the liquid phase for most of the year, in contrast to ARD in the periglacial belt where frost action dominates (MAAT < ?2°C). The findings clearly suggest that the ambient air temperature is an important factor affecting the ARD production in alpine periglacial environments. Applying the paleoecological analysis of morphological abnormalities in chironomids through the past millennium, we tested and rejected the hypothesis that unfavorable conditions for aquatic life in the ARD‐stressed lakes are largely related to the temperature increase over recent decades, responsible for the enhanced release of ARD contaminants. Our results indicate that the ARDs generated in the catchments are of a long‐lasting nature and the frequency of chironomid morphological deformities was significantly higher during the Little Ice Age (LIA) than during pre‐ or post‐LIA periods, suggesting that lower water temperatures may increase the adverse impacts of ARD on aquatic invertebrates. This highlights that temperature‐mediated modulations of the metabolism and life cycle of aquatic organisms should be considered when reconstructing long‐term trends in the ecotoxicological state of lakes.     

低位胆道恶性梗阻性黄疸术前胆红素异常的处理策略探讨(附134例报告)

目的:探讨低位胆道恶性梗阻性黄疸患者术前胆红素异常的处理策略,以提高该类患者的临床疗效。方法:回顾性分析西京医院肝胆外科2008年1月1日-2017年12月31日收治的符合研究条件的134例低位胆道恶性梗阻性黄疸(术前总胆红素≥171μmol/L)患者,按胆红素水平分为中、重度黄疸组,分析和比较两组术前黄疸的处理方法、术后肝功能、并发症情况等。结果:两组患者胆道引流后总胆红素水平均明显低于引流前,而肝功能Child-Pugh分级比较差异均无统计学意义(P0.05);两组行术前胆道引流患者与未行胆道引流患者的围手术期情况比较均无统计学差异(P0.05);两组行术前胆道引流患者与未行胆道引流患者的手术并发症的发生情况比较均无统计学差异(P0.05)。结论:对于低位胆道恶性梗阻性黄疸患者,无论中度黄疸还是重度黄疸,原则上术前不必行胆道引流。对于伴有脏器功能不全、急性炎症或其他暂不宜手术的患者,可先行胆道引流处理,限期手术。若行术前胆道引流,采用PTCD方式,更为简单安全有效。