Sediment flow behavior in agro-watersheds of the purple soil region in China under different storm types and spatial scales

Conservation tillage has proved to be an effective option to reduce erosion and particulate phosphorus (PP) losses from fields to watercourses. However, it usually leads to the higher losses of P in dissolved reactive (DRP) form if P accumulates into the uppermost soil layer.In this study we investigated the influence of CaCO₃-rich boardmill sludge (BMS, applied 7 years ago) on soil properties and percolate quality with soil samples as well as undisturbed soil columns taken from a long-term conservation-tilled clay field experiment. A short-term laboratory experiment was undertaken to evaluate whether newly added BMS (FS) can be used to improve the quality of percolate waters by reducing turbidity, PP and DRP.The hypothesis was that BMS reduces the risk of dissolved reactive phosphorus (DRP) leaching from conservation-tilled soil. BMS served as a liming agent and counteracted the no-till-induced acidification and accumulation of DRP in the surface soil layer. Surface soil pH was on average 0.3 units higher and soil Ca 500 mg kg⁻¹ higher in the BMS-treated plots than in the plots without BMS. The ability of BMS to enhance the availability of P for plants may prevent the surface accumulation of P in NT cultivation. At the same time, BMS-induced increase in Ca and EC of the surface soil suppress the diffuse double layer by reducing P desorption and leaching risk.In the laboratory experiment, FS reduced percolate turbidity by 80% and PP and DRP concentrations by 62% and 50%, respectively. FS probably improved stability of soil aggregates in the laboratory experiment, obviously through enhanced microbial activity. The covering effect and infiltration of water through the 0–5 cm soil layer seemed to be crucial factors in reducing P losses.BMS proved to be a promising material for the applications to the conservation-tilled fields. The effect of BMS on microbes and immobilization of nutrients, should, however, be studied further in fields under a wider diversity of conditions.     

Factors controlling suspended sediment yield during runoff events in small headwater catchments of the Basque Country

For the first time in the Basque Country, turbidity (NTU), discharge (l/s) and precipitation (mm) have been continuously monitored in the gauging stations located at the outlet of three catchments (Aixola, Barrendiola and Añarbe) since October 2003. In this study, several data sets derived from flood events were used to develop turbidity and suspended sediment relationships for the three catchments separately, and so to estimate continuous suspended sediment concentration (SSC). Linear relationships are found in Barrendiola and Añarbe, and two curvilinear relationships for Aixola owing to changing sediment sources in the catchment. Several event (discharge, precipitation and suspended sediment concentration) and pre-event (discharge and precipitation) factors are calculated for all the events registered. With them correlation matrixes were developed for each catchment. Although some differences are found between catchments good correlation between precipitation (P), discharge (Q) and suspended sediment (SS) variables is found in general. Pre-event conditions are also well correlated with Q and SS variables in Barrendiola (higher regulation capacity) and Añarbe (larger area) but not in Aixola (“flash floods”). SSC-discharge evolutions through the events were also analysed. For Aixola four different types of hysteretic loops were observed: single lined, clockwise, counter-clockwise and eight-shaped; while for Barrendiola and Añarbe just clockwise loops were observed.     

响应面法优化混凝处理微污染源水研究

[目的]研究采用响应面法优化混凝处理微污染源水过程。[方法]以商业聚合硫酸铁絮凝剂为研究对象,研究了快速搅拌速度、快速搅拌时间、慢速搅拌速度对混凝处理效率的影响。采用响应面法优化混凝条件。[结果]实测残余浊度与模拟残余浊度相关系数达0.96,表明预测值与实际值相关性强,模型预测浊度去除率具有较高的可行性。采用5 mg/L混凝剂投加量,处理40.50 NTU与9 mg/L的TOC源水,获得响应面优化的混凝条件,残余浊度达到1.70 NTU。响应面优化获得最优条件:当在快速搅拌速度为347 r/min、快速搅拌时间为3 min、慢速搅拌速度为79 r/min、慢速搅拌时间为15 min的条件下,原水残余浊度为30.10 NTU,实测残余浊度为0.64 NTU,TOC去除率达到50.74%。[结论]基于响应面法优化混凝处理微污染源水具有较高的可应用性。     

化学絮凝法对高质量浓度养猪废水预处理效果

以COD质量浓度超过30 000 mg/L有机养猪废水为研究对象,研究硫酸铁、硫酸铝、结晶氯化铝、聚合氯化铝钾、聚合氯化铝、壳聚糖6种絮凝剂对该废水浊度、COD、 NH₃-N、 TP、BOD₅的影响,并简要分析絮凝法预处理的经济成本。结果表明,6种絮凝剂对废水各项指标均有一定的处理能力,浊度的去除率为95.2%～99.7%;COD的去除率为36%～53%;NH₃-N的去除率为25%～72%;TP去除为82%～97%;经6种絮凝剂处理后,水质BOD₅/COD依次为0.415,0.504,0.424,0.505,0.379,0.135,除壳聚糖外,生物可降解性均比原废水提高。6种絮凝剂对养猪废水的预处理效果显著,为后续的生物处理提供了有利条件,综合考虑处理效果和经济因素,聚合氯化铝钾为最佳絮凝剂。     

胶对混浊苹果汁混浊稳定性的影响

为研究胶对混浊苹果汁混浊稳定性的影响。采用HCLP和SDS-PAGE等技术分析了果汁沉淀物的成份、沉淀物中酚类物质和蛋白质的性质，测定加了胶的果汁的黏度、Zeta电位和果汁在120d的储藏过程中浊度的变化。果汁沉淀物以蛋白质为主，还含有碳水化合物、酚类（表儿茶素、绿原酸、单宁等）、5-羟甲基糠醛（5-HMF）等VC降解产物，成分很复杂。沉淀物主要是由果汁中原有的颗粒聚集长大下沉产生。混浊苹果汁的混浊稳定性可进一步通过添加0.05%（W/V）的CMC得以改善。CMC主要是通过提高果汁的粘度和果汁中悬浮颗粒的zeta电位来改善混浊苹果汁的混浊稳定性。添加瓜尔胶主要是通过提高果汁的粘度来改善混浊苹果汁的混浊稳定性。     

胶对混浊苹果汁混浊稳定性的影响

为研究胶对混浊苹果汁混浊稳定性的影响。采用HCLP和SDS-PAGE等技术分析了果汁沉淀物的成份、沉淀物中酚类物质和蛋白质的性质,测定加了胶的果汁的黏度、Zeta电位和果汁在120d的储藏过程中浊度的变化。果汁沉淀物以蛋白质为主,还含有碳水化合物、酚类(表儿茶素、绿原酸、单宁等)、5-羟甲基糠醛(5-HMF)等VC降解产物,成分很复杂。沉淀物主要是由果汁中原有的颗粒聚集长大下沉产生。混浊苹果汁的混浊稳定性可进一步通过添加0.05%(W/V)的CMC得以改善。CMC主要是通过提高果汁的粘度和果汁中悬浮颗粒的zeta电位来改善混浊苹果汁的混浊稳定性。添加瓜尔胶主要是通过提高果汁的粘度来改善混浊苹果汁的混浊稳定性。     

The effect of microorganisms,salinity and turbidity on hydraulic conductivity of irrigation channel soil

The introduction of polysaccharide producing benthic algae and bacteria could provide a low cost technique for seepage control in irrigation channels. The ability of algae and bacteria to produce polysaccharides proved to be successful in reducing the hydraulic conductivity of irrigation channel soil. Hydraulic conductivity was reduced to less than 22% of its original value within a month of inoculating soil columns with algae. Chlorophyll and polysaccharide concentrations in irrigation channel soil were measured in order to assess the growth of algae and extent of polysaccharide production, and their correlation with hydraulic conductivity of channel soil. Increases in polysaccharide occurred in the top layer (0–5 mm) of the soil column. The reduction of hydraulic conductivity was highly correlated with the amount of polysaccharides produced (r ² = 0.92). Hydraulic conductivity decreased with increasing algal and bacterial numbers. The first few millimetres of the soil core where microbial activity was concentrated, seemed effective in controlling seepage. Incorporation of extra nitrate and phosphate into algal medium did not increase the production of polysaccharides by algae in channel soil. The effect of salinity and turbidity of irrigation channel water on channel seepage was studied by measuring the effects on hydraulic conductivity of channel soils. When the electrical conductivity (EC) of the water increased above a threshold value, the hydraulic conductivity increased because of the flocculating effects on clay particles in channel soils. A relationship between sodium adsorption ratio (SAR) and EC of the channel water was established which indicated 15% increase in channel seepage due to increases in salinity. Increasing the turbidity of irrigation water (by increasing the concentration of dispersed clay) resulted in lowering the hydraulic conductivity of the channel soil due to the sealing of soil pores by dispersed clay particles. When the turbidity of the water was 10 g clay l^–1, the hydraulic conductivity was reduced by 100%. An increase in clay concentration above 1 g l^–1 resulted in significant reduction in hydraulic conductivity. Soil bowl experiments indicated that clay sealing with a coating of hydrophobic polymer on the surface could also effectively prevent seepage of saline water.     

不同浊度水体下李氏禾（Leersiahexandra Swartz）叶绿素荧光特性研究

为探究不同浊度水体胁迫下李氏禾（Leersiahexandra Swartz）的叶绿素荧光特性,将李氏禾幼苗置于浊度分别为0、30、60和90NTU的水体中完全淹没。试验处理持续13天,于第1天开始间隔一天采用水下调制荧光仪（DIVING—PAM）测定叶片叶绿素荧光的实时光量子产量（Yield）、最大光量子产量（Fv／Fm）、暗适应最小荧光（F0）、相对光合电子传递速率（ETR）、光化学淬灭系数（q^p）、非光化学淬灭系数（NpQ）。结果显示：第7天时30NTu的水体中,Fv／Fm、ETR、q^p的值降到最低,李氏禾的光合作用受阻;此时30NTu的Fv／Fm、Yield、q^p值比0NTU分别高9．3％、8-4％、21．1％,表明李氏禾在一定时间内能适应30NTU的胁迫。该研究结果将有助于认识李氏禾在浊度下的生理变化。对李氏禾在浑浊水体的消涨带植被修复的应用具有指导意义。     

超滤膜与混凝对浊度去除的影响

[目的]探讨超滤膜与PAC混凝两种方法对低浊度的去除效果。[方法]试验原水均为自行配制,模拟低浊度微污染水源水浊度范围。设3种浊度（5、10、15NTU）的原水,选用超滤与聚合氯化铝混凝两种方法,分别对3种低浊度进行处理效果的试验。[结果]无论进水浊度多少,超滤膜出水浊度均在1NTU以下,出水浊度稳定;PAC去除高岭土浊度的最佳pH为8左右,即中性和弱碱性条件PAC混凝效果最好;处理浊度为5NTU的原水的最佳投药量为7.5 mg/L;原水浊度为10和15NTU时,原水的最佳投加量分别为10和15 mg/L,去除率分别达74.2%和超过80%。[结论]建议使用混凝—超滤组合工艺,既避免了高浊度对膜组件的污染,减少膜污染速率,又保证了出水水质。     

不同混凝剂处理低浊水效果对比试验研究

通过对某水厂水源水进行的混凝沉淀试验,研究优化不同混凝剂及与助凝剂联用对低浊水处理效果的影响,选择确定最佳混凝剂的种类和用量.试验表明,聚合氯化铝铁PAFC对低浊水具有较好的除浊效果,硫酸铝As与聚丙烯酰胺PAM联用也是一个经济可靠的方案.