CaCl2对细颗粒泥沙静水絮凝沉积的影响

细颗粒泥沙的絮凝或分散对土壤渗透性,土壤、可蚀性有重要作用,是水土保持研究的重要内容。在ＣａＣｌ２浓度为０－１．０ｍｍｏｌ／Ｌ,泥沙浓度为１０ｇ／Ｌ时,用吸管法研究了ＣａＣｌ２对细颗粒泥沙絮凝沉降的影响,结果表明：泥沙沉降分２个阶段,分选沉降段和絮凝沉降段;在絮凝沉降段,ＣａＣｌ２浓度越大,絮凝沉降越快。但较高浓度时,细颗粒泥沙平均沉速反而随ＣａＣｌ２Ｉ浓度增大而农渐减小;泥沙浓度随时间呈指数衰减     

NaCl对细颗粒泥沙静水絮凝沉降影响初探

泥沙问题是黄河治理的关键，而黄河泥沙主要来源于中游黄土高原强烈的水土流失。在黄土高原，耕地水土流失面积占耕地总面积的71.3%［1］，其中坡耕地土壤流失量可占流域土壤总流失量的60%～70%［2］。水土流失时，土壤中的养分会随径流及侵蚀泥沙迁入水体［3］，使细颗粒泥沙发生絮凝或分散，而流失泥沙中细颗粒泥沙含量又往往高于耕层。细颗粒泥沙的絮凝或分散，对泥沙输移和沉积过程有重要作用，是造成水库、灌溉渠系以及港湾河口淤积的重要原因，也是研究高含沙水流、浑水淤灌，以及设计冲沙模型的基础［4］。同时，侵蚀径流中细颗粒泥沙的絮凝或分散也会影响表土的导水率，从而影响水土流失量［5，6］。显然，研究细颗粒泥沙的絮凝或分散对揭示土壤侵蚀机理，以及研究泥沙输移、沉积规律具有重要的意义。但以往研究多侧重于咸淡水交界地区的水质和沙样，较少考虑盐度变化对细颗粒泥沙运动的影响［7］。本文拟以天然级配的细颗粒泥沙作为研究对象，探讨不同浓度NaCl对细颗粒泥沙静水絮凝及沉降的影响，以期为有关问题的深入研究提供科学依据。     

细颗粒泥沙的絮凝沉降特性

电解质对细颗粒泥沙的絮凝或分散有重要作用 ,而细颗粒泥沙的絮凝沉降特性对土壤表层沉积性结皮的入渗性能有重要影响。在NaCl浓度为 0～ 10mmol/L ,泥沙初始浓度为 5、10、2 0 g/L时 ,本文利用吸管法研究了NaCl对细颗粒泥沙静水絮凝沉降特性的影响。结果表明 :泥沙沉降可分为两个阶段 ,分选沉降段和絮凝沉降段 ;在液面下同一深度 ,泥沙相对浓度随时间呈指数衰减 ;细颗粒泥沙絮凝的临界粒径为 0 .0 2 7mm ;泥沙平均沉速 ω随NaCl浓度以及泥沙初始浓度的增大而增大。在研究浑水入渗时 ,应该考虑水中电解质的作用     

表面电位对三峡库区细颗粒泥沙絮凝沉降的影响

测定了三峡库区紫色土细颗粒的表面电荷性质,用吸管法研究了K+和Mg2+体系对细颗粒泥沙静水沉降的影响。结果表明:(1)酸性紫色土、中性紫色土和石灰性紫色土细颗粒在Mg2+体系中的表面电位分别为-0.156,-0.171,-0.192V,在K+体系中约为其2倍;(2)当离子浓度为0.10molm-3时,三种紫色土细颗粒在Mg2+和K+体系中的泥沙平均沉降速度ω珚分别为1.56、1.47、1.35cmmin-1和1.05、1.01、0.99cmmin-1,表现为细颗粒泥沙表面电位值越大,其泥沙平均沉降速度越小;(3)在Mg2+离子体系和Na+离子体系中,三种紫色土细颗粒泥沙平均沉降速度ω珚随着电解质浓度的增大而加快。并且,细颗粒泥沙絮凝沉降在Mg2+和K+体系中均存在一个浓度临界点,在Mg2+体系中约为0.1molm-3,在K+体系中约为0.25molm-3。     

非点源污染物细颗粒泥沙的絮凝—分散研究

细颗粒泥沙的絮凝－分散对土壤结构的稳定性,土壤中农用化合物的迁移以及侵蚀泥沙的输称、沉积有重要作用。文章概述了影响细颗粒泥沙絮凝－分散的几种主要因素－电解质种类及其深度,矿物组成,有机质含量,ｐＨ值以及水流紊动等;指出了当前研究中存在的不足之处。     

加气对灌溉水黏性泥沙絮凝沉降的影响

为研究黄河水水肥气一体化灌溉时加气对灌溉水中黏性泥沙沉降能力的影响,配置5种浓度的高岭土悬浊液（1、3、5、7和10 g/L）和4种肥料质量分数（0、0.2%、0.5%、1.0%）的硫酸钾肥、复合肥及尿素浑水,分析了加气前后的相对含沙量、泥沙中值沉速和沉降泥沙中值粒径。结果表明：加气显著促进浓度为3～10 g/L黏性泥沙的絮凝沉降（P<0.05）,且促进作用随泥沙浓度的增加而增强。与未加气处理相比,冬、夏季加气处理后泥沙中值沉速分别提高48.67%～70.98%和33.04%～57.52%,沉降泥沙中值粒径增大7.62%～13.95%和6.83%～13.24%。加气促进黏性泥沙絮凝沉降的作用与浑水中施加的肥料类型及浓度有关,促进作用随肥料浓度的增加而减小。对于肥料质量分数为0.2%～1.0%的硫酸钾肥、复合肥及尿素浑水,加气处理后泥沙中值沉速分别提高20.00%～32.12%、18.71%～130.40%和91.19%～170.21%。施加硫酸钾肥加气后泥沙中值沉速最大,为0.399～0.450 mm/s,施加复合肥加气后泥沙中值沉速最小,为0.288～0.330 mm/s。加气、肥料类型、肥料浓度分别单独或交互均极显著影响泥沙沉降（P<0.01）。研究结果对于明确水肥气一体化灌溉管网系统泥沙淤积规律具有重要意义。     

硫酸钾肥对静止黄河水泥沙絮凝沉降的影响

为探索硫酸钾肥对黄河水泥沙在静止状态下沉降的影响,以硫酸钾浓度和泥沙粒径为参数,用移液管法研究了5种硫酸钾浓度和4种粒径范围段(<100,50~100,34~50,<34μm)黄河泥沙的沉降过程,探讨不同硫酸钾浓度对细颗粒泥沙沉降絮凝的影响。结果表明:硫酸钾浓度越大,含沙量下降越快,泥沙沉降速度越大,初始粒径<100μm,当硫酸钾浓度分别为0,2.86,7,14mmol/L时,沉降30min后相对含沙量分别为35.35%,30.75%,27.02%,14.00%,中值沉速ω50分别为1.55,3.00,3.91,4.93cm/min;泥沙初始粒径越小,硫酸钾促进絮凝沉降的作用越明显,<34μm的泥沙受硫酸钾影响最大,当硫酸钾浓度从0增大到60mmol/L时,初始粒径为<34μm的泥沙絮凝后的中值沉降速度从1.38cm/min增加到8.53cm/min,增加518.12%,初始粒径为34~50μm的泥沙絮凝后的中值沉降速度从6.29cm/min增加到8.43cm/min,增加34.02%,初始粒径为50~100μm的泥沙中值沉降速度从7.12cm/min增加到7.59cm/min,增加6.60%;泥沙粒径越小,硫酸钾浓度越大,对絮凝后中值粒径的影响越大,当硫酸钾浓度从0增大到60mmol/L时,初始粒径为50~100μm的泥沙絮凝后中值粒径与硫酸钾浓度之间无明显规律,不同处理间无显著差异,硫酸钾基本对该粒径段泥沙絮凝沉降没有影响,初始粒径为34~50μm的泥沙絮凝后的中值粒径从38.8μm增加到41.0μm,增大5.76%,初始粒径<34μm的泥沙絮凝后中值粒径从15.7μm增加到21.6μm,增大37.82%;絮凝后沉降泥沙中小粒径颗粒相对含量减少,大粒径颗粒相对含量增加,最大粒径变大,泥沙初始粒径为<34μm、硫酸钾浓度为60mmol/L处理絮凝后最大粒径为200μm。研究成果为解决水肥一体化过程中的滴灌堵塞问题提供了参考。     

不同阳离子对紫色土细颗粒絮凝沉降的影响

以紫色土细颗粒泥沙作为研究对象,探讨不同阳离子对紫色土细颗粒絮凝沉降的影响.结果表明:(1)Na+浓度为0～10 mmol/L时,随着浓度升高悬液澄清的时间缩短,浓度为7 mmol/L时105 min后悬液澄清,当Na+浓度为10 mmol/L时,60～70 min达到澄清,临界絮凝浓度在5～7 mmol/L之间;(2)Ca2+浓度较高(0.8～1.0 mmol/L)时,其对细颗粒泥沙絮凝沉降的影响逐渐减小;(3)Al3+浓度在0～0.3mmol/L时对土壤颗粒沉降速度影响非常显著,＞0.3 mmol/L时,沉降速度略有增加,但幅度明显小于初始阶段;(4)3种电解质体系中土壤颗粒发生凝聚过程拐点的排斥压强均在1.3～1.4 atm之间.     

人工湿地对水体悬浮泥沙的影响

根据自然水体湿生植物(挺水植物)、浮叶植物以及沉水植物的空间分布规律,利用水生高等植物菖蒲(Acorus calamus)、菱(Trapa incisa)、黑藻(Hydrilla verticillata)、苦草(Vallisneria spiralis)和狐尾藻(Myriophyllum spicatum)构建的阶梯式人工湿地,定量化研究了植物群落对不同浓度悬浮泥沙水体在不同水力停留时间下的影响,并对输入悬浮泥沙浓度、输出悬浮泥沙浓度、水力停留时间等参数进行了比较分析。结果表明:(1)输入悬浮泥沙浓度依次为98.69,191.76,273.13 mg/L,平均为187.76 mg/L,流经人工湿地植物群落后,输出植物组的水体悬浮泥沙平均浓度为26.52 mg/L,为对照组平均浓度51.96 mg/L的51.04%;(2)输出人工湿地的悬浮泥沙浓度随输入悬浮物浓度的增加而增加,随水力停留时间的延长而降低,回归方程为Cplant out=1.231 0.170Cin-0.356H;(3)试验水体中滞留的悬浮泥沙浓度随输入悬浮物浓度的增加而增加,随水力停留时间的延长而减小,回归方程为Cplant water=1.158 0.261Cin-0.623H;(4)悬浮泥沙在人工湿地中的沉降量随输入悬浮物浓度的增加和水力停留时间的延长而增加,回归方程为Wplant=0.810Cin 0.886H-2.340;(5)要维持人工湿地沉水植物生长需要的透明度条件,输入悬浮泥沙浓度(Cin)与最小水力停留时间(Hmin)要满足如下关系:Hmin=0.419Cin-38.478(98.7相似文献   

泥沙粒径与含沙量对迷宫流道滴头堵塞的影响

为探明泥沙粒径与含沙量对内镶片式斜齿形迷宫流道滴头的堵塞过程和原因,采用筛分法,分选出6个小于0.1 mm的粒径段,配制成不同含沙量的浑水,在恒压条件下,采用周期性间歇灌水试验观测流量变化,通过电镜扫描法观测堵塞泥沙结构。试验结果表明:粒径为0.075≤D0.1 mm和0.03≤D0.038 mm的泥沙易引起滴头堵塞;粒径为0.038≤D0.05和D0.02 mm的泥沙较难引起堵塞,且含沙量变化对堵塞的影响较小;粒径0.02≤D0.03 mm和0.05≤D0.075 mm的堵塞情况介于上述两者之间。当含沙量为1.2~1.3 g/L时,是最易引起堵塞的临界含沙量。当0.038≤D0.1 mm时,泥沙在流道内不易形成团聚体,造成滴头堵塞的原因是泥沙沉降、堆积;当D0.038 mm时,泥沙易在流道中凝结成大的团聚体,是造成滴头堵塞的主要原因。     

氯化钙添加量对地衣芽孢杆菌凝乳酶凝乳性能的影响

凝乳酶是生产干酪中极为关键的酶制剂。在凝乳酶作用过程中,添加适量的氯化钙可缩短凝乳时间,增加凝块硬度,减少生产成本,对干酪品质的影响至关重要。本研究利用从甘肃省天祝藏族自治县牦牛牧区土壤中筛选得到的一株高效产凝乳酶的地衣芽孢杆菌菌株D3.11,优化培养后得到凝乳酶,通过分析凝乳过程中相关指标的变化规律、观察比较凝块的微观结构,研究氯化钙添加量对该酶凝乳性能的影响。结果表明,当氯化钙添加量为0.014%~0.022%时,地衣芽孢杆菌D3.11凝乳酶体系的黏度值随凝乳时间的延长先增大后保持稳定;地衣芽孢杆菌D3.11凝乳酶体系和商品酶体系的浊度值均随Ca²⁺浓度的增大而显著增大(P<0.05);地衣芽孢杆菌D3.11凝乳酶体系的粒径主峰分布在136.9~246.7 μm范围内,且粒径值在氯化钙添加量为0.020%时最大;流变学特性分析结果表明,地衣芽孢杆菌D3.11凝乳酶体系达到储能模量G'峰值的时间随氯化钙添加量的增加而缩短;两种酶体系的持水力在氯化钙添加量为0.014%~0.022%范围内显著增大(P<0.05),乳清OD值在氯化钙添加量为0.016%~0.022%范围内变化均不显著(P>0.05);通过激光扫描共聚焦显微镜观察凝块微观结构发现,随着氯化钙添加量的增加,两种酶体系中蛋白微粒均凝结得更紧密。本研究结果为细菌凝乳酶在干酪生产中的应用提供了理论依据。     

Nitrogen compounds extracted by electroultrafiltration (EUF) or CaCl2 solution and their relationships to nitrogen mineralization in soils

The objective of the investigation was to identify the most important organic N-containing fractions extracted from soils by electroultrafiltration (EUF) or a CaCl₂ solution, respectively, and their importance for nitrogen mineralization. The investigation comprised 19 agricultural and one forest top soil. Net N mineralization was tested in Mitscherlich pot experiments with three treatments: (1) fallow soil without N fertilizer, (2) soil cultivated with rye grass without N fertilizer, (3) soil cultivated with rye grass with N fertilizer. The highest proportion of N in the extracts was the amino N fraction (amino acids + peptides) amounting to approximately 60% of the total N extracted by CaCl₂ and to about 40% of the total N extracted by EUF. The proportion of amino sugars from total N extracted was in average 10% for the CaCl₂ and 5.2% for the EUF extracts. The proportion of heterocyclic N bases derived from nucleic acids amounted in average to 4.8% and 3.6% for the CaCl₂ and EUF extract, respectively. Amino N (amino acids + peptides) were correlated best with net N mineralization (EUF, r = 0.81***, CaCl₂, r = 0.86***). The correlation between amino sugars and net N mineralization was r = 0.55* for the EUF extract and r = 0.49* for the CaCl₂ extract. The heterocyclic N bases did not correlate with net N mineralization. Correlations between Norg extracted by CaCl₂ versus net N mineralization were higher than those obtained by the EUF extract. Net N mineralization was about four times higher in the fallow soils than in the treatment with grass and no N fertilizer. In the treatment with grass + N fertilizer on average no net N mineralization occurred, moreover there was a tendency of N immobilization. It is assumend that in the treatments with grass cultivation, organic C released by roots stimulated the assimilation of mineral N and amino acids by soil microorganisms resulting in a low net N mineralization. Net N mineralization led to a highly significant depletion in the Norg pools and particularly in the amino N and amino sugar pools in the treatment with grass and without N fertilizer. This depletion was particularly evident in the CaCl₂ extracts. The results justify the conclusion that the Norg obtained with both extraction methods originates from a dynamic N pool into which N flows in and out. The amino N extractable with EUF or CaCl₂ is a reliable indicator for the net N mineralization potential of soils.     

肉桂精油及其复配物对砀山酥梨保鲜效果（简报）

采用涂膜处理和低温冷藏(0～2℃)相结合的方法,测试了肉桂精油及其与壳聚糖和CaCl2复配对砀山酥梨的保鲜效果.结果表明,肉桂精油及其与壳聚糖和CaCl2复配对砀山酥梨采后贮藏具有明显的保鲜作用,其中以60 μL/L肉桂精油 1%壳聚糖 1?Cl2配比的复合物保鲜效果最好,可显著延缓砀山酥梨采后口感和风味的变化,可使呼吸高峰较对照推迟10d出现,并能显著抑制丙二醛(MDA)含量的增加及相对电导率和多酚氧化酶(PPO)活性的上升;贮藏后第40 d,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性分别较对照增加238.54%、146.06%,而过氧化物酶(POD)活性较对照降低了55.56%.     

Critical Olsen P and CaCl2‐P levels as related to soil properties: results from micropot experiments

The usefulness of soil phosphorus (P) tests used in routine soil analyses is limited by the fact that a single measurement cannot encompass all P‐related factors potentially affecting plant performance. In this work, we performed micropot (15 mL) experiments to test the hypothesis that the predictive value of two common soil P tests (Olsen P and CaCl₂‐P) can be improved by considering properties commonly measured in laboratory analyses. Forty‐nine sets of soils ranging widely in properties were used for this purpose, each set consisting of samples with similar properties but differing in P status. Ryegrass and turnip were grown in a chamber for 30 days in two separate experiments and their yields at harvest recorded. The critical Olsen P and CaCl₂‐P levels, which were taken to be those corresponding to 95% asymptotic yield as calculated from data fitted to a Mitscherlich equation, were greater for turnip than for ryegrass, probably as a result of the difference in yield (49 and 160 mg dry matter/micropot on average for ryegrass and turnip, respectively) and hence in P requirements between the two species. Critical Olsen P spanned narrower ranges than critical CaCl₂‐P in both crops and is therefore seemingly the more robust of the two tests. Both critical P values exhibited moderate correlations with soil properties. Thus, critical Olsen P was (a) lower in soils with a medium pH – which is consistent with the fact that the bicarbonate solution method tends to overestimate plant‐available P in strongly acid and calcareous soils; (b) positively correlated with pH and carbonate content in calcareous soils; and (c) uncorrelated with soil properties in noncalcareous soils. On the other hand, critical CaCl₂‐P in some soil groups was negatively correlated with some properties increasing the P buffering capacity of soil (e.g. Fe oxide content). Taken together, our results suggest that routinely measured soil properties help to predict critical Olsen P better than critical CaCl₂‐P.     

CaCl2和6-BA溶液处理对枣果软化褐变及相关酶活性的影响

试验探讨了鲜枣贮藏过程中果肉软化褐变与PG活性、PPO活性的关系以及采前CaCl₂和6-BA溶液处理对采后枣果果肉软化褐变、PG活性、PPO活性的影响。结果表明,枣果采后硬度逐渐下降且与贮藏时间呈极显著负相关,PG活性在贮藏期间呈起伏变化,与枣果软化无显著相关性。 随贮藏时间延长果肉褐变指数逐渐增大,PPO活性逐渐升高,PPO活性与果肉软化褐变的发生相一致。采前用1% CaCl₂、15 mg/kg 6-BA以及1% CaCl₂+15 mg/kg 6-BA对枣果进行喷雾处理,能降低采后枣果的PG活性和PPO活性,抑制果肉硬度的下降和果肉的褐变进程。1% CaCl₂处理可使赞皇大枣贮藏末期的果肉硬度比对照增加1.2 kg/cm²;1% CaCl₂+15 mg/kg 6-BA处理可使赞皇大枣贮藏末期的果肉硬度增加1.5 kg/cm²。15 mg/kg 6-BA处理对枣果软化褐变及PG活性、PPO活性有一定影响,但效果不及CaCl₂处理。     

The Effect of Flocculation on the Size Distributions of Bottom Sediment in Coastal Inlets: Implications for Contaminant Transport

Grain size is the most basic of classification criteria for sediments. The size distribution of a given sediment records the physical transport processes involved in its formation. By using precise grain size analysis and the model of Kranck et al. (1996a,b), it is possible to break down a sediment into the three major components from which it was formed: material deposited as flocs, material deposited as single grains from suspension, and material carried under higher energy conditions. With this method, both the amount of material deposited in a flocculated state and the maximum size, or floc limit, of the particles composing the floc can be determined. Changes in floc limit indicate changes in the aggregation dynamics of the system. As most trace metals and many other contaminants associate closely with the fine particle fraction of sediments, it is important to determine both the areal distribution and reworking history of the floc settled portion of a sediment. This paper discusses the application of the method to coastal inlets in Atlantic Canada and examines the relationship between proportion of floc-settled material and trace metal concentrations. Disaggregated inorganic grain size distributions are also used to illustrate changes in the aggregation dynamics in areas of intense aquaculture.