雷宏軍,劉 歡,張振華,Bhattarai Surya,Balsys Ron
NaCl及生物降解活性劑對曝氣灌溉水氧傳輸特性的影響
雷宏軍1,劉 歡1,張振華2,Bhattarai Surya※3,Balsys Ron4
(1. 華北水利水電大學水利學院,鄭州450045;2. 魯東大學地理與規(guī)劃學院,煙臺 264025;3. 澳大利亞中央昆士蘭大學醫(yī)學與應用科學學院,昆士蘭羅克漢普頓 4702;4. 澳大利亞中央昆士蘭大學工程與技術學院,昆士蘭羅克漢普頓 4702)
曝氣灌溉可有效調(diào)節(jié)植物根區(qū)環(huán)境、改善土壤通氣性。微咸水中NaCl的存在及活性劑添加對提高曝氣灌溉的氧傳質(zhì)效率,實現(xiàn)節(jié)能高效的灌溉有重要作用。為研究NaCl介質(zhì)及生物降解活性劑對純氧曝氣灌溉水氧傳輸特性的影響,該文采用變壓分離制氧技術-氧氣擴散系統(tǒng)-空氣注射技術耦合系統(tǒng),分析NaCl介質(zhì)(未添加和添加)及生物降解活性劑BS1000(醇烷氧基化物質(zhì)量濃度0、1、2、4 mg/L)2個因素對氧總傳質(zhì)系數(shù)、溶氧飽和度、流量均勻系數(shù)和溶氧均勻系數(shù)的影響。結(jié)果表明:BS1000的添加促進氧傳質(zhì)過程的發(fā)生,提高了曝氣水中的溶氧飽和度;隨著BS1000濃度增加,氧總傳質(zhì)系數(shù)逐漸增加,而溶氧飽和度呈現(xiàn)下降的趨勢;BS1000質(zhì)量濃度在2 mg/L及以上時,NaCl介質(zhì)對氧總傳質(zhì)系數(shù)的增幅顯著;NaCl介質(zhì)對曝氣水中的溶氧飽和度起到抑制作用。各組合條件下,曝氣滴灌中流量均勻系數(shù)均在95%以上,溶氧均勻系數(shù)均在97%以上。添加活性劑BS1000可使氧總傳質(zhì)系數(shù)平均提高18.85%以上(P<0.05)。無論添加NaCl與否,添加1 mg/L BS1000的溶氧飽和度均最大,故1 mg/L BS1000是適宜的活性劑添加濃度。
咸水;溶解氧;灌溉;純氧曝氣;BS1000;氧總傳質(zhì)系數(shù);飽和度;均勻性
灌溉過程中土壤水分入滲將土壤空氣驅(qū)逐開來,導致土壤出現(xiàn)周期性的滯水[1-2],造成土壤通氣性下降[3]。作物根系對土壤缺氧特別敏感,根際缺氧可直接抑制植物對水分和養(yǎng)分的吸收[4],影響作物的正常生長。曝氣灌溉可通過文丘里空氣射流器將氣加入灌溉水中,形成的水氣耦合物通過地下滴灌系統(tǒng)輸送到植物的根區(qū)[5-7],有效緩解植物根區(qū)的缺氧狀況。目前,加氣灌溉主要有直接通氣和曝氣2種方式。盧澤華等[8]利用空氣壓縮機將空氣通入作物根系,研究了該種加氣方式對溫室番茄生長和果實產(chǎn)量的影響。這種灌水和通氣分離的灌溉方法可促進番茄的生長和產(chǎn)量的增加。利用循環(huán)曝氣系統(tǒng)產(chǎn)生的水氣耦合物進行灌溉,亦可促進番茄的生長,增加果實的產(chǎn)量,改善果實的品質(zhì)[9]。曝氣灌溉過程中水氣傳輸不均勻會導致大量氣泡從滴頭附近向大氣散失[10],如何將氧氣以超微氣泡的形式均勻輸送到作物根區(qū),是決定曝氣灌溉能否大范圍推廣的關鍵。微納米氣泡水技術是一項最新引入中國、世界領先的農(nóng)業(yè)技術[11-12],實現(xiàn)了灌溉水氧氣的超飽和,為曝氣灌溉水氣均勻傳輸提供了新的機遇[13]。微氧氣泡易與水均勻混摻而大幅提高水中溶解氧。然而,灌溉水中摻氧濃度并不是越高越好。Zheng等[14]研究表明灌溉水中氧濃度介于飽和溶解氧(8.5 mg/L)和30 mg/L之間促進番茄的生長,而高于30 mg/L時抑制番茄的生長。微咸水的合理開發(fā)利用已成為緩解水資源緊缺的重要途徑之一[15]。馬文軍等[16]研究表明,微咸水灌溉下夏玉米和冬小麥產(chǎn)量有所降低,但是可節(jié)約淡水資源60%~70%。微咸水灌溉可緩解糧食產(chǎn)量和農(nóng)業(yè)用水之間的矛盾,在農(nóng)業(yè)可持續(xù)發(fā)展方面有廣闊的前景。然而,采用微咸水灌溉的過程中亦會造成根系缺氧的狀況。曝氣灌溉可顯著提高鹽漬土種植條件下作物根系活力,改善作物生長、提高氣體交換能力及其耐鹽性[7]。因此,曝氣灌溉技術為微咸水的農(nóng)業(yè)利用提供了機遇。
目前關于曝氣產(chǎn)生的水氣耦合物在管道中的傳輸特性方面也有一定的研究。Torabi等[17]研究了增氧地下滴灌氣泡傳輸有效性的影響因素,探究了連接器的類型、管道的直徑以及滴頭出流速率對氣泡傳輸有效性的影響。為了直觀反映曝氣水中氣泡在滴灌帶沿程中的變化情況,Bhattarai等[18-19]運用可視化氣泡解析手段系統(tǒng)研究了摻氣條件下氣泡的數(shù)量和尺寸,闡明了活性劑的添加和滴灌帶滴頭埋設方向?qū)馀輸?shù)量和形態(tài)的影響。Torabi等[20]研究了活性劑濃度、連通器類型及尺寸、灌溉系統(tǒng)末端開、閉條件下滴灌帶出流均勻性的影響。雷宏軍等[21]利用承壓循環(huán)曝氣裝置研究了壓力和十二烷基磺酸鈉對短距離輸水過程中流量、摻氣比例和均勻性的影響,結(jié)果表明曝氣水中摻氣比例大幅度提高(高達36%),灌溉水均勻性在95%以上,摻氣傳輸均勻性在70%以上。然而,因微氣泡聚合作用的發(fā)生,灌溉水攜氧均勻性仍有待提高。
目前曝氣水中溶解氧在長距離輸水管道中傳輸特性的研究較少。本研究采用變壓分離制氧技術(AirSep)、氧氣擴散系統(tǒng)(Seair)和空氣注射技術(Mazzei air injector)相耦合的AirSep-Seair-Mazzei 系統(tǒng)進行曝氣,制備微納米氣泡水,擬實現(xiàn)微咸水及曝氣水超高溶解氧在輸水管道的均勻傳輸,為曝氣灌溉技術的大范圍推廣提供支持。試驗中于曝氣水中添加NaCl介質(zhì),模擬微咸水灌溉,為微咸水曝氣灌溉提供新的思路和理論依據(jù)。
1.1 試驗原理
利用AirSep-Seair-Mazzei系統(tǒng)進行曝氣,將文丘里空氣射流器置于水流的干路上,當水流通過文丘里喉部時,液體速度隨著涌流橫截面積急劇減小而上升,壓力迅速減小,產(chǎn)生壓力差,進而將氣體吸入水流。將變壓吸附制氧機和文丘里空氣射流器相連,以保證持續(xù)穩(wěn)定的向文丘里管提供純氧氣源。曝氣水與吸入的氧氣分別作為液相和氣相進入擴散器(氧氣擴散系統(tǒng))進行二次曝氣。通過水泵持續(xù)將儲水罐中的水抽出,以實現(xiàn)循環(huán)曝氣。
1.2 試驗簡介
試驗裝置示意圖如圖1所示。
圖1 灌溉裝置示意圖Fig.1 Schematic diagram of irrigation device
試驗中曝氣儲水罐的體積為200 L。循環(huán)水泵為Davey Powermaster 200,型號為PM200-0。AirSep-Seair-Mazzei 系統(tǒng)中的變壓吸附制氧機,利用變壓吸附專用分子篩選擇性吸附空氣中的雜質(zhì)氣體,在真空狀態(tài)下對已吸附的雜質(zhì)氣體進行解吸并排至大氣,即可持續(xù)制得高純度的氧氣;氧氣擴散器中采用多孔板或多孔管將氣泡分裂為直徑較小的氣泡,氣泡的直徑可達到100 nm~3.00 mm。通過對回路閘閥開度和變壓吸附制氧機純氧釋放閘門的調(diào)控可有效控制曝氣水的溶解氧濃度。試驗中將各處理的滴頭溶氧值控制在30 mg/L以內(nèi)。該系統(tǒng)曝氣產(chǎn)生的微氧氣泡與水均勻混摻,大幅提高水中溶解氧,有利于長管道輸水,并可根據(jù)作物氧氣需求調(diào)控曝氣水中溶解氧。同時,設備可實現(xiàn)現(xiàn)場制備純氧,零氧氣運輸成本,有利于實際生產(chǎn)的應用。氧氣擴散器和文丘里相結(jié)合曝氣過程中,減小氣泡的體積,增加氧氣與水的接觸面積,加之水氧混合物在曝氣過程中持續(xù)劇烈擾動,加快微氧氣泡溶于水。部分微氧氣泡溶于水而造成微氧氣泡湮滅的行為促進了水中溶解氧的增加。
試驗中采用非壓力補償式滴灌帶,型號為NETAFIM,長度為150 m,滴頭間距為0.5 m,內(nèi)徑為25 mm,壁厚為0.38 mm,滴頭的額定流量為1.05 L/h。從曝氣裝置出水口接入,于距地面10 cm處水平鋪設。試驗中采用的活性劑BS1000(醇烷氧基化物,Crop Care Australia Pty,Murarrie,Queensland,Australia)為非離子型活性劑,質(zhì)量濃度為1 000 g/L,可生物降解,不會對環(huán)境產(chǎn)生負面影響。試驗中設置不添加和添加0.1 mol/L NaCl介質(zhì)2種處理,分別記為M0、M1,設置4個活性劑質(zhì)量濃度水平,分別為0、1、2和4 mg/L,記為C0、C1、C2和C3,共計8個試驗組合方案。每個試驗組合3個重復。試驗中采用非等距取樣來選取樣本點,采樣點分布列于表1。
表1 采樣點與水源距離Table1 Distance between sampling point and water source
試驗時先開啟變壓吸附制氧機,再打開水泵進行曝氣。采用Oriental Legend 溶解氧測定儀(鄭州達而克電子科技有限公司),動態(tài)監(jiān)測曝氣水中的溶解氧濃度(mg/L)。儲水罐中的溶解氧讀數(shù)穩(wěn)定時停止曝氣,打開首部閘閥向滴灌帶供水,待滴灌帶中水氧耦合物運行穩(wěn)定時(約5 min)開始試驗。試驗中定時測量各樣本點出水量,計算其流量。各處理3次重復樣本點平均流量的平均值即平均流量。儲水罐與滴灌帶中的溶氧值和水溫采用便攜式Fibox4光纖微氧傳感器測定(Presens,Germany)。試驗所需的活性劑濃度較小,在添加活性劑時,需配置500 mg/L的母液,以便精確加入相應濃度的活性劑。水量由天平稱質(zhì)量,精度為0.01 g。
1.3 指標測定及計算方法
1.3.1 氧總傳質(zhì)系數(shù)
氧總傳質(zhì)系數(shù)是反映氧氣轉(zhuǎn)移能力和衡量曝氣效率的重要指標。試驗中利用AirSep-Seair-Mazzei系統(tǒng)以純氧與水混摻進行循環(huán)曝氣。氧傳遞的基本方程[22-23]可由式(1)表示:
式中KLa為氧總傳質(zhì)系數(shù),min-1;C為t時刻水中溶解氧質(zhì)量濃度,mg/L;t為曝氣時間,min;Cm為曝氣過程中水中最大溶解氧質(zhì)量濃度,mg/L。
為了計算方便,對式(1)進行積分變換,繪制ln(Cm-C)~t的函數(shù)曲線,利用回歸法擬合線性方程[24],即可求得KLa。
KLa受溫度的影響很大,故需要進行校正[25]。氧總傳質(zhì)系數(shù)與溫度存在如下關系:
式中T為溫度,℃;KLa(T)表示溫度為T時的氧總傳質(zhì)系數(shù),min-1;KLa(20)表示溫度為20 ℃時的氧總傳質(zhì)系數(shù),min-1;θ為常數(shù),微氣泡中取1.029[25]。
1.3.2 溶氧飽和度
滴灌帶中溶解氧測量連接裝置如圖2所示。測量溶氧值時,將溶解氧測定儀探針插入相應樣本點的溶解氧測量連接裝置中,打開球閥即可。
圖2 溶解氧測量連接裝置示意圖Fig.2 Schematic diagram of connecting device for dissolved oxygen measurement
水中飽和溶解氧的含量主要與溫度和大氣壓有關。試驗中DOf可由張朝能[26]提出的式(3)求得。
式中DOf為飽和溶解氧(saturated dissolved oxygen),mg/L。
溶氧飽和度是指氣體的溶氧含量占所處條件下飽和含量的比例,即
式中WD為溶氧飽和度,%;Ct為某一溫度下滴灌帶中監(jiān)測的溶解氧,mg/L;CS為該溫度條件下的飽和溶解氧,mg/L。
1.3.3 灌溉均勻性
均勻性是衡量灌溉質(zhì)量最重要的指標之一。采用克里斯琴森公式[27]計算均勻系數(shù)(Christiansen uniformity coefficient,CUC),包括流量均勻系數(shù)和溶氧均勻系數(shù)。
式中M為樣本點平均流量,L/h;xi為第i個滴頭(共n個)的流量;L/h;D為各滴頭流量與平均流量之差絕對值的平均值,L/h;CUC為流量均勻系數(shù),%。
溶氧均勻系數(shù)的計算利用式(5)~(7),將滴頭流量換為樣本點溶氧值即可。應用Sigmaplot軟件進行數(shù)據(jù)分析。
2.1 NaCl和BS1000對氧總傳質(zhì)系數(shù)的影響
不同組合條件下的氧總傳質(zhì)系數(shù)如表2所示。表2表明,活性劑的添加促進氧傳質(zhì)過程的發(fā)生,C1、C2和C3下的KLa(20)顯著高于C0下的KLa(20)(P<0.05)。M0C1、M0C2和M0C3組合的KLa(20)分別為0.145、0.178和0.213 min-1,較M0C0分別提高了18.85%、45.90%和74.59%(P<0.05);組合M1C1、M1C2和M1C3的KLa(20)分別為0.157、0.216和0.248 min-1,較M1C0分別提高了21.71%、67.44%和92.25%(P<0.05)。添加活性劑條件下,KLa(20)隨著活性劑濃度增大而增大,未添加NaCl介質(zhì)下,濃度C2和C3的KLa(20)較濃度C1分別提高了22.76%和46.90%(P<0.05);添加NaCl介質(zhì)下,濃度C2和C3的KLa(20)較濃度C1分別提高37.58%和57.96%(P<0.05)。當活性劑濃度為C0和C1時,M0和M1的KLa(20)差異不顯著(P>0.05)。當濃度為C2和C3時,M0和M1的KLa(20)差異顯著(P<0.05),C2和C3在添加NaCl介質(zhì)條件下的KLa(20)較未添加NaCl介質(zhì)條件分別增加21.35%和16.43%(P<0.05),故添加2 mg/L及以上濃度的BS1000,NaCl介質(zhì)的添加對KLa(20)的增加顯著??傮w而言,添加活性劑BS1000可使氧總傳質(zhì)系數(shù)平均提高18.85%以上(P<0.05)。
表2 不同組合條件下的氧總傳質(zhì)系數(shù)Table2 Oxygen transfer coefficient under different conditions
2.2 NaCl和BS1000對滴灌帶水中溶解氧的影響
不同條件下滴灌帶溶氧值監(jiān)測結(jié)果列于表3。結(jié)果顯示,純氧曝氣條件下,與飽和溶解氧相比,滴灌帶中灌溉水的溶氧值大幅提高,DO飽和度平均值達到299.87%?;钚詣┑奶砑语@著提高了曝氣水中的WD,C1、C2和C3的WD顯著高于C0(P<0.05)。未添加NaCl介質(zhì)下,C1、C2和C3的WD較C0分別提高了21.11%、17.85%和14.24%;添加NaCl介質(zhì)下,C1、C2和C3的WD較C0分別提高了25.95%、18.63%和13.00%。未添加NaCl介質(zhì)下,C1與C2的WD差異不顯著(P>0.05),但與C3差異顯著(P<0.05),組合M0C3的WD較M0C1降低了5.67%;添加NaCl介質(zhì)下,C2與C3的WD較C1分別降低了5.81%和10.28%。總體而言,添加活性劑條件下各處理WD隨著活性劑濃度增加而呈現(xiàn)下降的趨勢。C1濃度下,M1和M0的WD差異不顯著(P>0.05)。C0、C2和C3在添加NaCl介質(zhì)條件下的WD較未添加NaCl介質(zhì)條件分別降低了5.55%、4.92%和6.57%,表明NaCl介質(zhì)的添加可對曝氣水中的WD起到抑制作用。總之,無論添加NaCl與否,添加1 mg/L BS1000的DO飽和度均最大。
表3 不同條件下滴灌帶溶氧值結(jié)果Table3 DO results in drip tape under different conditions
2.3 不同組合下流量均勻系數(shù)及溶氧均勻系數(shù)
灌溉均勻性是衡量灌溉質(zhì)量的重要指標之一。表4列出了不同組合條件下的均勻性。
表4 不同組合條件下的均勻性Table 4 Flow and DO uniformity coefficient under different conditions
各組合條件的流量均勻系數(shù)較高且無顯著性差異(P>0.05),均在95%以上。各組合條件下的溶氧均勻系數(shù)較高且無顯著性差異(P>0.05),均在97%以上。活性劑BS1000的臨界膠束質(zhì)量濃度可能在1~5 mg/L[18-20]。添加活性劑BS1000使氧總傳質(zhì)系數(shù)提高18.85%以上,縮短了曝氣時間,提高了曝氣效率,與雷宏軍等[21]研究結(jié)果一致。當土壤水中氧氣濃度低于植物需氧上限時,較高的溶解氧對作物生長起著積極的作用,試驗中1 mg/L BS1000的DO飽和度最大。利用AirSep-Seair-Mazzei 系統(tǒng)進行循環(huán)曝氣,各活性劑濃度的能耗成本均較低,且均勻性較高、差異不顯著。故不管采用微咸水灌溉與否,1 mg/L的BS1000是適宜的活性劑添加濃度,本研究結(jié)論與Torabi等[20]的研究保持一致。
試驗中以AirSep-Seair-Mazzei系統(tǒng)曝氣為依據(jù),研究了曝氣水中的溶解氧變化特性。在添加少量活性劑時,活性劑分子匯聚于氣液接觸面上,減緩了氧氣向水中擴散,阻礙氧傳質(zhì)過程的發(fā)生[27-28]。氧傳質(zhì)系數(shù)受水體擾動程度、溫度和曝氣等因素的影響[23]。試驗中通過水泵使得水流快速通過文丘里進行曝氣,增加了水流的湍流程度;利用變壓吸附制氧機提供純氧曝氣氣源,提高了氧分壓;另外,相連擴散器減小氧氣氣泡直徑,增加了氧氣與水的接觸面積,故添加活性劑時,KLa(20)依然增加?;钚詣┑氖褂每梢詼p小生成氣泡的直徑,增加氣泡的數(shù)量,加大氣液的接觸面積[29]。活性劑濃度的增加對起泡性能起到促進作用[30]。另外,隨著活性劑濃度的增加,氣液接觸面的剪切力逐漸增加,將接觸面聚集的活性劑分子驅(qū)逐開[31],促進氧傳質(zhì)過程的發(fā)生。這與本試驗得到的KLa(20)值變化趨勢相一致。NaCl介質(zhì)的添加,降低氣液接觸面的電勢,阻止氣泡的合并,增加氣泡的停留時間,加強氧傳質(zhì)的過程[32],故NaCl介質(zhì)的添加對KLa(20)起到促進作用。
表面活性劑具有一定的分散性[33],可使微氧氣泡均勻分散于液體中,維持氣泡的穩(wěn)定性。隨著BS1000濃度的增加,微氧氣泡的數(shù)量不斷增加,罐體水源在擾動的過程中加大了微氧氣泡凝聚的幾率。添加活性劑條件下,水中溶氧值隨著BS1000濃度增加呈現(xiàn)降低的趨勢可能是微氧氣泡的部分凝聚減少了氧氣與水的接觸面積導致的。水中溶解氧的含量受水質(zhì)及鹽度等因素的影響[34]。試驗中加入NaCl介質(zhì),使得水中含鹽度增加,導致溶解氧的含量減小,故添加NaCl條件下WD有所下降。試驗中沒有涉及滴灌帶的不同連接方式和不同曝氣氣源的水氧傳輸特性,這將是今后研究的重要方向;另外,純氧循環(huán)曝氣的溶解氧在土壤中的保持特性以及不同摻氧濃度對根區(qū)環(huán)境的影響有待進一步研究。
1)活性劑的添加對氧傳質(zhì)過程起到促進作用;添加活性劑條件下,各組合條件的氧總傳質(zhì)系數(shù)隨著活性劑濃度增加而顯著增加;BS1000質(zhì)量濃度在2 mg/L及以上時,NaCl介質(zhì)添加對氧總傳質(zhì)系數(shù)的增幅顯著。
2)活性劑BS1000添加可提高曝氣水中的溶氧飽和度;添加活性劑條件下,隨著活性劑BS1000濃度增加,曝氣水中溶氧飽和度呈下降趨勢;NaCl介質(zhì)添加對曝氣水中的溶氧飽和度起到抑制作用。
3)各組合條件對滴灌帶輸水和供氧均勻性無影響。試驗中流量均勻系數(shù)在95%以上,溶氧均勻系數(shù)在97%以上;1 mg/L的BS1000是適宜的活性劑添加濃度。研究成果為長距離曝氣灌溉提供了技術手段和理論支持。
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Impact of NaCl and biodegradable surfactant on water and oxygen transmission under aerated irrigation
Lei Hongjun1, Liu Huan1, Zhang Zhenhua2, Bhattarai Surya3※, Balsys Ron4
(1. School of Water Conservancy, North China University of Water Conservancy and Electric Power, Zhengzhou 450045, China; 2. College of Geography and Planning of Ludong University, Yantai 264025, China; 3. School of Medical and Applied Science, CQUniversity, Rockhampton, QLD 4702, Australia;4. School of Engineering and Technology, CQUniversity, Rockhampton, QLD 4702, Australia)
Aerated irrigation can effectively alleviate the oxygen stress in the plant root zone and improve the environment of the plant root zone. This study investigated the effect of the addition of surfactant BS1000 in saline irrigation water on water and oxygen transmission under pure oxygen aerated irrigation. The oxygen transmission characteristic was investigated by using a Mazzei air injector, pressure swing adsorption oxygen generator and Seair diffuser coupled system (AirSep-Seair-Mazzei). Micro-bubbles produced by the AirSep-Seair-Mazzei system provide a good opportunity for its application in the long-distance aerated irrigation because of slow buoyancy characteristics and high dissolved oxygen concentration. The dissolved oxygen (DO) and temperature of water tank and drip tap were monitored by a dissolved oxygen meter. For simulating saline irrigation water, 0.1 mol/L NaCl solution was prepared. Four BS1000 concentrations were also prepared (0, 1, 2 and 4 mg/L). Therefore, a total of 8 combinations of NaCl and BS1000 were designed. During the experiment, oxygen transfer coefficient, DO saturation, flow uniformity coefficient and DO uniformity coefficient were determined. The results showed that the addition of BS1000 had a positive effect of oxygen transfer process, and resulted in an increase of the DO saturation. The DO saturation of the irrigation water averaged 299.87% under pure oxygen aeration. Under the addition of BS1000 in the aerated irrigation, an increase of the BS1000 concentration caused an increase of the oxygen transfer coefficient, while a decrease of the DO saturation. The oxygen transfer coefficient of 2 and 4 mg/L BS1000 was 22.76% and 46.90% higher than that of 1 mg/L BS1000, respectively, under the condition without NaCl addition. Under the addition of NaCl in the aerated irrigation water, the high surfactant concentration (not less than 2 mg/L) would result in a large oxygen transfer coefficient. The addition of NaCl could inhibit the DO saturation. The DO saturation in treatments of surfactant BS1000 of 0, 2 and4 mg/L with NaCl addition was decreased by 5.55%, 4.92% and 6.57%, respectively, compared to the treatment without NaCl. The average value of flow uniformity coefficient under the aerated irrigation was greater than 95% and the DO uniformity coefficient of each combination remained above 97%. The high DO had a positive effect of the growth of crop when the oxygen concentration in soil water was lower than the upper limit demanded by crop. The oxygen transfer coefficient was greater than 18.85% (P<0.05) under the addition of surfactant BS1000. The DO saturation was the highest in the treatment with 1 mg/L BS1000 regardless of NaCl addition. And all the treatments had high uniformity. Therefore, the surfactant concentration of 1 mg/L was suggested. This research demonstrates the great importance of uniform transmission of super-oxygenated water in drip tap and provides a method support for a wide range of aerated irrigation application.
saline water; dissolved oxygen; irrigation; pure oxygen aeration; BS1000; oxygen transfer coefficient; saturation; uniformity
10.11975/j.issn.1002-6819.2017.05.014
S273.5; P342+.2
A
1002-6819(2017)-05-0096-06
雷宏軍,劉 歡,張振華,Bhattarai Surya,Balsys Ron. NaCl及生物降解活性劑對曝氣灌溉水氧傳輸特性的影響[J]. 農(nóng)業(yè)工程學報,2017,33(5):96-101.
10.11975/j.issn.1002-6819.2017.05.014 http://www.tcsae.org
Lei Hongjun,Liu Huan,Zhang Zhenhua,Bhattarai Surya,Balsys Ron. Impact of NaCl and biodegradable surfactant on water and oxygen transmission under aerated irrigation[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2017, 33(5): 96-101. (in Chinese with English abstract)
doi:10.11975/j.issn.1002-6819.2017.05.014 http://www.tcsae.org
2016-08-05
2016-12-10
國家自然科學基金(U1504512、41271236);河南省科技創(chuàng)新人才項目(174100510021)
雷宏軍,男,湖北大冶人,博士,副教授,2014年赴澳大利亞中央昆士蘭大學研修,主要從事節(jié)水灌溉理論與技術及水資源高效利用研究。鄭州 華北水利水電大學水利學院,450045。Email:hj_lei2002@163.com※通信作者:Bhattarai Surya,男,澳大利亞人,博士,高級教師,主要從事農(nóng)業(yè)水資源管理、加氧灌溉研究。澳大利亞昆士蘭羅克漢普頓中央昆士蘭大學醫(yī)學與應用科學學院,4702。Email:s.bhattarai@cqu.edu.au