Development of New Green Feed for Large Water Surface Ecological Fishery

In view of the fact that cages and bait are not allowed in large water surface aquiculture,1-2 kinds of new green feeds"plankton+microecologics"were developed to solve the problems of yield reduction,slow growth and difficulty in fishing of aquatic organisms caused by extensive mode.The new green feed is ecological,environmentally friendly and residue-free,which not only supplements nutrition but also meets the requirements of environmental protection.

A Simulation Study on Effect of Surface Film-Forming Material on Water Evaporation

A greenhouse experiment was conducted to investigate the effect of surface film-forming material(SFFM),a mixture of 16-18-octadecanols by emulsification,on water evaporation,Air-dired soil with distilled water was incubated firstly for 7days to reestablish soil biological activity and then for another 7 days atfer treated with SFFM at rates of 0,1,2,4,6,8 and 8 g m^-2，respectively,Everyday during the 7-day incubation after addition of SFFM,water losses due to evaporation were measured by an electronic balance.The rate of water evaporation with the addition of SFFM was reduced significantly compared with the control treatment and the effectiveness of SFFM on water evaporation reduced with time.According to the equation expressions of the effect of SFFM on water evaporation ,the half-life of effectiveness of SFFM on water evaporation was introduced and calculated to analyze quantitative relationship between the effectiveness of SFFM on water evaporation and the addition rate of SFFM.The calculaed half-life increased with the addition rate of SFFM and the confidence of the calculated values of the half-life was high,suggesting that the half-life of effectiveness of SFFM on water evaporation could be described quantitaively and may be helpful for ameliorating application method of SFFM and screening surface-film forming materials in order to improve nitrogen fetilizer use efficiency in floodey rice fields.

Evaporation of nanoscale water on solid surfaces

The evaporation of water is essential in the macroscopic world.Recent researches show that,on solid surfaces,the evaporation of nanoscale water is quite different from that on bulk water surfaces.In this review,we show the theoretical progress in the study of nanoscale water evaporation on various solid surfaces:the evaporation rate of nanoscale water does not show a monotonic decrease when the solid surface changes from hydrophobic to hydrophilic;the evaporation of nanoscale water on hydrophobic-hydrophilic patterned surfaces is unexpectedly faster than that on uniform surface;the evaporation of nanoscale water on patterned graphene oxide is faster than that on homogeneous one;how temperature affects the evaporation of nanoscale water on solid surface;how ions affect the evaporation of nanoscale water on graphene oxide.

Comparing phreatic evaporation at zero water table depth with water surface evaporation

Salt-affected soils are mostly found in irrigated areas within arid and semi-arid regions where the groundwater table is shallow.Soils of this type have become an increasingly severe problem because they threaten both the environment and the sustainable development of irrigated agriculture.A tool to estimate phreatic evaporation is therefore urgently required to minimize the salinization potential of salt-affected areas.In this context,phreatic evaporation at zero water table depth(E0)is a key parameter for establishing a model for calculating phreatic evaporation.The aim of this study was to explore the law of phreatic evaporation and to develop structurally rational empirical models for calculating phreatic evaporation,based on E0data of six types of soil(i.e.,gravel,fine sand,sandy loam,light loam,medium loam,and heavy loam)observed using the non-weighing lysimeter and water surface evaporation(E601)data observed using a E601 evaporator of same evaporation area with a lysimeter-tube at the groundwater balance station of the Weigan River Management Office in Xinjiang Uygur Autonomous Region,China,during the non-freezing period(April to October)between 1990 and 1994.The relationship between E0and E601was analyzed,the relationship between the ratio of E0to E601and the mechanical compositions of different soils was presented,and the factors influencing E0were discussed.The results of this study reveal that E0is not equal to E601.In fact,only values of the former for fine sand are close to those of the latter.Data also show that E0values are related to soil texture as well as to potential atmospheric evaporation,the ratio of E0to E601and the silt-clay particle content(grain diameter less than 0.02 mm)is negatively exponentially correlated,and that soil thermal capacity plays a key role in phreatic evaporation at E0.The results of this analysis therefore imply that the treatment of zero phreatic depth is an essential requirement when constructing groundwater balance stations to study the law of phreatic evaporation.

Variations in evaporation from water surfaces along the margins of the Badain Jaran Desert over nearly 60 years and influencing factors

Based on meteorological data collected over nearly 60 years(1960-2017)from four national meteorological stations along the margins of the Badain Jaran Desert,this study analyzed the spatiotemporal variations in evaporation from water surfaces and identified the dominant controlling factors.Methods used included linear trend analysis,linear tendency estimation,the departure method,the rank correlation coefficient-based method,and Multiple Linear Regression(MLR).Results indicate notable spatiotemporal differences in evaporation distribution and evolution.Spatially,average annual evaporation exhibited a pronounced altitude effect,decreasing at a rate of about 8.23 mm/m from east to west with increasing altitude.Temporally,annual evaporation showed significant upward trends after 1996 at the northeastern(Guaizi Lake)and western(Dingxin)margins,with rates of 132 mm/10a and 105 mm/10a,respectively.Conversely,along the northwestern(Ejina Banner)and southern(Alxa Right Banner)margins of the desert,an evaporation paradox was observed,with annual evaporation trending downward at rates of 162 mm/10a and 187 mm/10a,respectively,especially after 1987.The dominant factors controlling evaporation varied spatially:Average annual temperature and relative humidity influended the western margin(Dingxin),average annual temperature was the key factor for the northeastern margin(Guaizi Lake),and average wind speed was crucial for the northern(Ejina Banner)and southern(Alxa Right Banner)margins.

Salt-Water Dynamics in Soils: II. Effect of Precipitation on Salt-Water Dynamics

Through a simulation test carried out with soil columns (61.8cm in diameter),the effect of precipitation on salt-water dynamics in soils was studied by in-situ monitoring of salt-water dynamics using soil salinity sensors and tensioneters.The results show that in the profile of whole silty loam soil,the surface runoff volume due to precipitation and the salt-leaching role of infiltrated precipitation increased with the depth of ground water;and in the profile with an intercalated bed of clay or with a thick upper layer of clay,the amount of surface runoff was greater but the salt-leaching role of precipitation was smaller than those in the profile of whole silty loam soil.In case of soil water being supplemented by precipitation,the evaporation of groundwater in the soil columns reduced,resulting in a great decline of salt accumulation from soil profile to surface soil.The effect of precipitation on the water regime of soil profile was performed via both water infiltration and water pressure transfer.The direct infiltration depth of precipitation was less than 1m in general,but water pressure transfer could go up to groundwater surface directly.

Composite laminar membranes for electricity generation from water evaporation

Harvesting clean energy from water evaporation has been extensively investigated due to its sustainability.To achieve high efficiency,energy conversion materials should contain multiple features which are difficult to be simultaneously obtained from single-component materials.Here we use composite laminar membranes assembled by nanosheets of graphene oxide and mica,and find a sustained power density induced by water evaporation that is two orders of magnitude larger than that from membranes made by either of the components.The power output is attributed to selective proton transport driven by water evaporation through the interlayer nanochannels in the membranes.This process relies on the synergistic effects from negatively charged and hydrophilic mica surfaces that are important for proton selectivity and water transport,and the tunable electrical conductivity of graphene oxide that provides optimized internal resistance.The demonstrated composite membranes offer a strategy of enhancing power generation by combining the advantages from each of their components.

Development of a new method for efficiently calculating of evaporation from the phreatic aquifer in variably saturated flow modeling

In this paper, we proposed a new method that has been developed based on the surface soil moisture content(SSMC) to more efficiently calculate the groundwater evaporation in variably saturated flow modeling. In this method, the empirical formula to calculate evaporation was modified and the value of the formula varies from zero to one as a closed interval. In addition, the simulation code for calculating the groundwater evaporation based on the SSMC method was incorporated into the EOS9 module of Tough2, a variably saturated flow modeling code. Finally, two numerical tests and a case simulation were conducted to verify the feasibility and accuracy of the SSMC method. Simulation results indicate that the SSMC method is capable of appropriately simulating the characteristics of water flow in vadose zone and the amount of evaporation with the variable water table. And such results are in coincidence with the value calculated by the logistic function method, and fit well with the measured data globally rather than locally.

不同面积蒸发池水温特征及Penman模型改进

分析蒸发池水温特征可深入认识蒸发池能量平衡特性,研究Penman模型计算误差来源并改进,对农业计划、水源评估和水文预报具有重要意义。基于太谷均衡实验站3个不同面积蒸发池的水温、蒸发量及气象数据,分析各蒸发池的垂向水温分布和蒸发量的变化特征,基于Penman模型探究适合3个蒸发池的模型参数。结果表明:1 m^(2)和5 m^(2)蒸发池4—8月水温随水深增加而显著降低,20 m^(2)蒸发池各月水温分布均比较均匀,且水温更高;1 m^(2)和5 m^(2)蒸发池各月蒸发量相近,与净辐射变化趋势一致,20 m^(2)蒸发池蒸发峰值滞后于净辐射峰值3个月;Penman模型中加入反映除净辐射外能量的综合影响参数可提高模型计算精度,夏季尤为明显,1、5、20 m^(2)蒸发池夏季的参数值分别为3.5、3.3和2.1。

氢氧同位素组成对丰沛平原区水循环的指示意义

丰沛平原区包括丰县、沛县与铜山区北部,近年来该地区出现地下水超采、地下水氟污染等严重的问题。为调查该地区水循环情况,采集了地表水与地下水样品共28个,分析了氢氧同位素组成的分布规律及其影响因素,并讨论了丰沛平原区浅层地下水与地表水转化关系以及各自的蒸发损失情况。研究结果表明:大气降水的云下二次蒸发程度较小,地下水的蒸发比附近地区更强烈。地下水同位素含量呈现总体沿地下径流方向逐渐富集的趋势,且地下水^(18)O与CO_(2)存在微弱的交换作用导致^(18)O贫化。结合水文地质调查与氢氧同位素特征,推断出河流中上游更倾向于地下水补给地表水,河流下游地表水对地下水大量渗漏。利用两端元法计算得出,总体上地表水受到地下水补给的比例为20%~40%左右,部分地区补给比例达60%以上。河流下游河水对地下水的补给比例大多介于25%~50%不等,部分点位可达90%。采用非平衡分馏条件下的Rayleigh模型计算蒸发比例,河水的蒸发损失约为23%~28%,地下水蒸发损失约为15%~20%。结果可为丰沛平原区及周边相似地区的水资源管理提供科学参考。

南大港湿地湖水蒸发及地表水地下水转化研究

南大港湿地是我国重要湿地之一,近年来湿地生态环境及其健康状况不容乐观。为揭示南大港湿地不同水体氢氧同位素特征及湖水蒸发与区域地表水—地下水转化关系,探究南大港地区水循环过程,本研究于2023年5月开展河水、湖水、海水和地下水样品的采集与分析。根据同位素分馏和氘盈余估算了湖水的蒸发损失,通过质量平衡混合模型研究了地表水与地下水之间的转化。结果表明:南大港地区浅层地下水大多沿当地大气降水线分布,降水为地下水的主要来源;受蒸发因素的影响,地表水体氢氧同位素值普遍高于地下水体。由湖水氢氧同位素回归分析得到湖水蒸发线方程:δ^(2)H=6.1498δ^(18)O-14.774 (n=12, R^(2)=0.9814),通过氘盈余(d值)估算的湖水蒸发损失为27%~37%。自内陆向沿海,地下水埋深逐渐变浅,氢氧同位素值逐渐增大。湖水运移受人类活动影响较大,湿地东南部是活水来源,湿地西部和北部水体滞留时间较长,氢氧同位素值较高,且d值较小。受北部盐场影响,湖水西部和北部的Cl-浓度普遍高于东部和南部。根据Cl-浓度和氧同位素值建立的混合端元模型得到, 50%的浅层地下水样品位于地下水海水混合线上。湖水在东侧存在渗漏,但其对浅层地下水的影响范围不超过1 km。分析表明:南大港湿地湖水从天然降水、南排河和廖家洼渠调水得到补给,而后通过蒸散发和渗漏等方式排泄。

间接蒸发冷却技术在数据中心节能改造中的应用

将间接蒸发冷却技术、大温差高温冷冻水技术及动态冰蓄冷技术运用于某老旧数据中心的节能改造,并实际运行测试,结果表明:经过节能改造后,该数据中心PUE由改造前2.00降至改造后的1.25,数据中心空调系统耗电量降低75%。

水洗条件对PAN水洗丝条结构和力学性能的影响

研究了水洗条件对聚丙烯腈(PAN)水洗丝条结构和力学性能的影响。用万能材料测试机、XRD、SEM、压汞仪测试纤维的力学性能、晶态结构、表面形态和孔结构,得到结构对力学性能的影响规律。结果表明:随着水洗温度升高,丝束的最大应力和最大载荷降低;水洗温度从55℃增大到90℃,结晶度从64.84%降低到57.73%,晶粒大小从4.034nm变为5.007nm;水洗温度升高,丝表面出现更加明显的纵向沟槽,表面缺陷增多,丝的直径也变得不均匀,孔隙率和孔径变小,微孔逐渐增多;随着结晶度降低、晶粒尺寸变大、表面缺陷增多,丝的力学性能随之下降;相同温度,超声波使纤维的孔径和孔隙率变小,同时使表面缺陷增多,所以超声波对丝的力学性能影响不大。

三峡库区水陆水面蒸发量差异特性及其原因探讨

三峡水库是中国最大的人工水资源调蓄中心,其库区蒸发深刻影响着地表生态水文过程,研究三峡库区漂浮水面蒸发和陆上水面蒸发变化差异及其原因,对于理解区域水文循环和气候变化具有重要意义。基于三峡库区巴东水面漂浮站和相邻陆面站的多年蒸发观测资料,分析库区水陆水面蒸发的季节差异;结合ERA5辐射资料,分析水陆水面蒸发能量平衡的各组分季节变化特征,探究水陆水面蒸发差异的主控因子。结果表明:(1)水陆水面蒸发存在显著的季节变化差异,其中陆面站水面蒸发峰值通常出现在8月,而漂浮站水面蒸发峰值通常出现在12月;(2)能量平衡分析表明,三峡库区水体在夏半年蓄热,在冬半年则释放热量显著增加表层水体可利用能量,进而增加潜热效能,导致漂浮站蒸发峰值出现的时间较陆面站平均滞后约4个月;(3)主控因素分析表明,水陆水面蒸发及热力性质差异受多种微气象因素非线性综合影响,其中在水体蓄热阶段(3—9月),主控因素为气温和饱和水汽压,在水体放热阶段(10月至翌年2月),主控因素为水温和水气温差。

三峡水库水面蒸发年内滞后效应分析

水面蒸发在季节变化上相比净辐射等气象要素的相位延迟反映了水体储热对水面蒸发的影响,量化这一对气象要素波动的滞后响应对理解和估算深水水库(湖泊)蒸发非常重要。三峡水库等河道型深水水库的水位和面积具有显著周期性变动,使得其水面蒸发的响应模式更为复杂,而目前对其认识非常薄弱。本文利用2013年8月—2020年7月三峡水库巴东站水面蒸发场和陆面蒸发场的蒸发和气象观测数据,分析了水面蒸发的季节变化及其年内滞后效应。结果表明:水面蒸发场蒸发量在年内的8和12月呈现双峰变化,与只有8月单峰值的陆面蒸发场蒸发量显著不同。水面蒸发场蒸发量相对净辐射、平均气温和水面温度分别存在4、3和2个月的滞后,而陆面蒸发场蒸发量相对滞后时间均在1个月以内;水面与陆面蒸发场相比,水温、蒸发量和水面与大气饱和差之间的滞后时间分别为1、3和4个月,而平均气温和净辐射之间不存在滞后。本文揭示出三峡水库巴东段水面蒸发年内滞后效应主要受到水库水温引起的水面与大气饱和差在季节上滞后的影响,需通过深入分析水温的时空变化来明确整个三峡水库的水面蒸发特征。

黔北地区红黏土大气影响急剧层深度探讨

贵州黔北地区红黏土广泛分布。红黏土具有失水收缩、裂隙发育、上硬下软的特点。对于荷载不大的低层建筑,为充分利用红黏土上硬下软的特性、充分发挥浅部硬层的承载能力,采用天然地基时基础宜浅埋,充分利用上部坚硬、硬塑土层作持力层,但为避免地面不利因素的影响,红黏土地基基础埋深又必须大于大气影响急剧层的深度,该深度目前无相关规范数据可查。本文收集黔北地区仁怀、桐梓、湄潭、汇川等4个气象站最近较长一段时间内的气象资料,依据《膨胀土地区建筑技术规范》(GB 50112—2013)相关规定,对黔北地区红黏土大气影响急剧层深度进行计算,确定红黏土地基基础最小埋置深度,以供参考使用。

富水卵漂石地层盾构近距离下穿运营地铁隧道施工技术研究

[目的]富水卵漂石地层盾构下穿既有地铁线路施工过程中,易导致既有地铁线路上方土体不规则沉降超出控制范围,进而可能引发地下水喷涌和地面塌陷问题。为此,需要对富水卵漂石地层盾构近距离下穿运营地铁隧道的施工技术进行研究。[方法]以新建成都地铁17号线凤溪大道站盾构下穿既有地铁4号线为案例,在阐述工程概况的基础上,选取了4个地面沉降测点和4个深层土体沉降测点,分析了盾构掘进过程中地层的沉降变化规律。采用MIDAS GTS软件建立了三维有限元模型,对采用38 m超长管棚与斜向注浆相结合的加固施工进行模拟,对4号线隧道预加固效果进行了分析。基于此,明确了地面跟踪注浆的时机,进一步分析了地面跟踪注浆的效果。[结果及结论]该加固措施有效提高了4号线结构底部土体的整体性,改善了4号线结构的受力状况,有效控制了4号线的结构沉降。

基于数值模拟和试验研究的大仓面水环式真空渣分离机理分析

以大仓面水环式真空渣处理工艺为基础,对该工艺中的主要设备进行了设计计算。利用FLUENT软件建立三维模型并进行数值模拟,通过与实验数据对比验证了模型的可靠性;在此基础上,分别从气相流场分布、颗粒运动轨迹以及温度场变化等方面对渣室结构参数及操作参数进行优化,得到最佳运行工况点。最后针对影响脱水效果的因素:转鼓转速、进口风速、真空度、入料浓度四个变量进行单因素试验,考察各因素对脱水率的影响规律。

1980-2020年疏勒河流域水面蒸发量变化趋势及预测

[目的]揭示疏勒河流域水面蒸发量的变化特征及未来演变趋势,以期更深入了解流域内水资源的动态变化,为该地区规划和管理水资源的利用提供决策支撑。[方法]基于1980—2020年昌马堡、双塔堡水库、党城湾、党河水库4个水文站逐月、逐年水面蒸发资料,采用线性倾向率、滑动t检验、R/S分析法、BP神经网络等分析方法对流域近40年水面蒸发变化特征进行了研究,并预测了未来水面蒸发量及其变化趋势。[结果](1)1980—2020年疏勒河流域各站点水面蒸发量年际变化整体均呈减少趋势,各站倾向率排序为:双塔堡水库站(-187.10 mm/10 a)>党河水库站(-178.20 mm/10 a)>昌马堡站(-33.00 mm/10 a)>党城湾站(-30.00 mm/10 a),其中双塔堡水库和党河水库站减少趋势十分显著。(2)昌马堡、双塔堡水库和党河水库站四季水面蒸发量均表现为减少趋势,党城湾站春季呈不显著增加趋势,其他季节呈下降趋势。(3)昌马堡、党城湾、双塔堡水库和党河水库4站突变年份分别为2004年、2015年、2007年和2007年。(4)流域水面蒸发量不均匀系数和集中度整体表现为减少趋势。(5)预测2021—2026年水面蒸发量将继续呈下降变化趋势。[结论]整体上,疏勒河流域全年和四季水面蒸发量呈减少变化趋势,且未来也表现为下降演变趋势。