The evaluation of potential purification of a horizontal subsurface flow constructed wetland treating greywater in semi-arid environment

The potential purification of an horizontal subsurface flow constructed wetlands (HSSFCW) treating greywater in a Moroccan primary school was investigated according to the monitoring of water quality parameters over a period of 100 days through two simultaneous stages: first, an internal three dimensional grid of sampling ports; secondly, an entry and exit. The calibration of the relaxed TIS concentration model based on tank in series hydraulic assumption with experimental data gave the frequency distribution profiles of K-rate constant values for the three parameters: BOD₅, COD and TN, whose maximum values are respectively 50 m/yr, 70 m/yr, and 42 m/yr. The HSSFCW system has higher K-rate coefficient for all the three parameters at the bottom layer compared with the surface layer, with increasing K-rates over length. The analysis of bacteriological and chemical results has shown that the HSSFCW could not completely remove all pollutants (especially TN and TP), but it could be used successfully to upgrade the quality of greywater to an acceptable level. However, we predict that there will be an increase in removal efficiencies with time bearing in mind that the system is newly implemented.     

MANAGING ROTATIONAL CANAL WATER SUPPLIES ON THE FARM1

ABSTRACT: A procedure to determine optimal irrigation scheduling strategies under rotational water delivery systems is presented. The methodology involves integration of water delivery amount and frequency, irrigation management strategies, evapotranspiration sequences and crop-evapotranspiration-production functions to arrive at an optimal irrigation strategy. Application of the methodology to a farm in the service area of Western Yamuna Canal (India) where a two-stage system of rotation, one among the irrigation channels and the other among the farmers, is in vogue, reveals that maximum production is obtained with water application in a rotational manner (RI) rather than with irrigation in every or alternate supply periods. Increase in mean water supply which can be effected through improvement in on-farm conveyance and application systems, has a greater effect on yield than decrease in variance of the supply. Benefit cost analyses indicates that precision land leveling is more cost effective in increasing water supply as compared to water-course lining.     

Use of man-made impoundment in mitigating acid mine drainage in the North Branch Potomac River

The US Department of the Army, Baltimore District Corps of Engineers, oversees a long-term monitoring study to assess and evaluate effects of the Jennings-Randolph reservoir on biota in the North Branch Potomac River. The reservoir was intended, in part, to mitigate effects of acid mine drainage originating in upstream and headwater areas. The present study assessed recovery of benthos and fish in this system, six years after completion of the reservoir. Higher pH and lower iron and sulfate concentrations were observed upstream of the reservoir compared to preimpoundment conditions, suggesting better overall water quality in the upper North Branch. Water quality improved slightly directly downstream of the reservoir. However, the reservoir itself was poorly colonized by macrophytes and benthic organisms, and plankton composition suggested either metal toxicity and/or nutrient limitation. One large tributary to the North Branch and the reservoir (Stony River) was shown to have high (and possibly toxic) levels of manganese, iron, zinc, and aluminum due to subsurface coal mine drainage. Macroinvertebrate diversity and number of taxa were higher in sites downstream of the reservoir in the present study. Compared with previous years, the present study suggested relatively rapid recovery in the lower North Branch due to colonization from two major unimpacted tributaries in this system: Savage River and South Branch Potomac. Abundance of certain mayfly species across sites provided the most clear evidence of longitudinal gradients in water quality parameters and geomorphology. Fish data were consistent with macroinvertebrate results, but site-to-site variation in species composition was greater. Data collected between 1982 and 1987 suggested that certain fish species have unsuccessfully attempted to colonize sites directly downstream of the reservoir despite the more neutral pH water there. Our results show that recovery of biota in the North Branch Potomac was attributed to decreased acid inputs from mining operations and dilution from the Savage River, which contributed better water quality. Continued improvement of North Branch Potomac biota may not be expected unless additional mitigation attempts, either within the reservoir or upstream, are undertaken.     

THE WATER BALANCE IN NEWFOUNDLAND1

ABSTRACT: Due to the lack of instrumentally obtained data on evaporation in Newfoundland, and the underrepresentation of precipitation values an accurate assessment of the water balance of the Province is not possible at this time. The various existent assessments of PE and AE are reviewed and water surplus of the Island is calculated.     

重庆主城区污水排放截流处理方案的比较

重庆市主城排水系统的污水处理方案从以自然汇水区为主的排水和处理方案转为集中截流处理。本文利用MIKE模型，对重庆市主城排水系统项目的各方案进行了比较，结合模型的解析结果，提出应结合三峡成库时间，采用分阶段逐步提高的最优方案。     

煤矿酸性水治理方案的评价

通过煤矿酸性水处理方案的评价提出最终选用的工艺。首先提出酸性水的问题及要求达到的目标，提出三个供选方案，然后，分别对这三个方案进行系统的结构分析，确定评价因子及模糊评价模型。通过分析计算，得出综合评价值，最后以该值作为选用方案的依据，这样避免了方案选择的盲目性。     

淄博煤矿区矿井水的化学形成及其模拟

研究矿井水形成过程，对于防治采矿活动引起水环境污染具有重要意义，以淄博煤矿区矿井水为例，分析其形成过程并利用化学平衡热力学法对其进行模拟。结果表明，矿井水的形成分为产酸过程与中和过程；矿井水的化学性状是由两过程相对作用程度确定；该矿区矿井水的硫酸根源于黄铁矿氧化，钙、镁离子不是来自通常认为的方解石与白云石，而是方解石和绿泥石。     

矿井水中微量乳化油处理试验研究

矿井水中存在的生量乳化油污染制约了其资源化程度，对它的处理已日益受到人们的重视。通过对多种吸附剂进行实验室试验。结果表明：状状活性炭有较好的吸附处理效果，并且对影响其吸附效果的有关因素进行了研究，在优化吸附条件下，通过投加混凝剂可使乳化油去除率达８５％以上。     

Feto-amniotic shunting—report of the experience of four european centres

Few reports concerning intrauterine shunting are available. We investigated the impact of this method. In order to evaluate intrauterine shunting and the complication rate for different indications, we sent a questionnaire to all German-speaking level 3 centres. In four level 3 centres, 52 intrauterine catheters were inserted in 34 fetuses. The indications were uni- or bilateral hydrothorax in nine cases, cystic adenomatoid malformation of the lung in four cases, infravesical stenosis in 13 cases, and fetal ascites in eight cases. In three cases (6 per cent), difficulties occurred when the drain was inserted. In 15 cases (29 per cent), the function of the drain was reduced by dislocation or occlusion. The mortality rate caused by shunting was as high as eight per cent (four cases). The application of an intrauterine shunt currently represents a rarely performed ultrasound-guided therapeutic intervention in the fetus. In all cases, the indication for shunting is to avoid compression of normal tissue by cystic structures. A high complication rate restricts the application of drainage to selected cases.     

淋洗模拟研究有机盐膜抑制黄铁矿的生物氧化效果

经有机难溶盐包膜后的黄铁矿矿石接菌下间歇循环淋洗一年后其循环收集液中SO4^2-含量点供试样品中总SO4^2量的0.16%，较对照的下降了97％，pH从初始6.82下降至5.48，但对照pH却从初始的7.57下降至2.35，矿石样品经扫描电子显微镜显示：包膜的矿石样品表面仍呈光洁状，而对照的表面布满细小洞穴，清楚指出：笔者首次提出的有机盐膜能有效地抑制T．F菌对黄铁矿的氧化作用。