謝倩雯，李一平，孔 文

(1.河海大學(xué)環(huán)境學(xué)院,江蘇南京 210098；2.深圳市規(guī)劃國(guó)土發(fā)展研究中心,廣東深圳 518040；3.南京智慧新城工程管理有限公司,江蘇南京 210012)

沉積物再懸浮測(cè)量方法綜述

謝倩雯1，2，李一平1，孔 文3

(1.河海大學(xué)環(huán)境學(xué)院,江蘇南京 210098；2.深圳市規(guī)劃國(guó)土發(fā)展研究中心,廣東深圳 518040；3.南京智慧新城工程管理有限公司,江蘇南京 210012)

為了研究沉積物侵蝕、再懸浮、運(yùn)輸?shù)纫幌盗行袨闄C(jī)制,從實(shí)驗(yàn)室裝置模擬法、室外原位裝置測(cè)量和野外直接測(cè)量3個(gè)方面總結(jié)了沉積物再懸浮測(cè)量方法。將沉積物再懸浮測(cè)量裝置分為循環(huán)水槽、直流水槽及其他儀器,描述了各類裝置的基本工作原理、優(yōu)缺點(diǎn)及適用環(huán)境,并對(duì)不同裝置的測(cè)量結(jié)果進(jìn)行對(duì)比。基于現(xiàn)有的技術(shù)和方法,主要是通過測(cè)量底床侵蝕剪切力和懸浮物濃度變化來定量分析沉積物再懸浮現(xiàn)象,剪切力施加方式、測(cè)試時(shí)間及儀器大小等因素的不同造成了各類裝置測(cè)量結(jié)果的差異性。

沉積物；再懸??；侵蝕閾值；剪切應(yīng)力；測(cè)量方法

沉積物再懸浮是湖泊、河口、近海等環(huán)境中普遍存在的一種現(xiàn)象[1]。沉積物再懸浮影響湖泊營(yíng)養(yǎng)物質(zhì)循環(huán),是大型淺水湖泊富營(yíng)養(yǎng)化的內(nèi)源[2],且黏性沉積物有吸附有機(jī)污染物和重金屬的能力[3],一旦遇到洪水和風(fēng)暴,將發(fā)生大規(guī)模再懸浮,從而影響水生生態(tài)系統(tǒng)健康,降低水體透明度,窒息底棲生物群落[4],懸浮物所吸附的污染物也將釋放到水體中去[3]。此外,沉積物侵蝕、再懸浮、輸移、沉降等一系列動(dòng)力學(xué)行為對(duì)水利工程應(yīng)用來說也是十分重要的,其影響航道和岸線的穩(wěn)定性[5]。黏性沉積物包括細(xì)顆粒粉砂和直徑小于0.075mm的黏土碎屑,非黏性沉積物主要由直徑介于0.075～0.5mm之間的細(xì)砂組成[6]。湖泊、河岸、河口潮間帶等環(huán)境中的沉積物大都是細(xì)砂、淤泥和黏土的混合物。Lam等[7]指出水流速度達(dá)到2～3 cm/s就足以使土黏和粉砂顆粒再懸浮,而要使沙再懸浮,水流速度需達(dá)到20 cm/s。由此可見,黏性沉積物是很容易發(fā)生再懸浮的,并以懸移質(zhì)形式進(jìn)行輸移,而粗砂和礫石(直徑大于0.5mm)通常情況下是呈推移質(zhì)形式運(yùn)動(dòng)的。

非黏性沉積物的侵蝕阻力主要是重力沉降,而黏性底床的侵蝕阻力是由粒子間吸引力、聚合物摩擦力和電化學(xué)阻力共同決定的,而這些又隨黏性沉積物性質(zhì)和水流條件等變化[8]。決定黏性沉積物再懸浮的兩個(gè)因素是:①黏性顆粒之間的凝結(jié)強(qiáng)度；①水流所施加的剪切力。當(dāng)水流產(chǎn)生的剪切力超過沉積底床凝結(jié)強(qiáng)度時(shí),沉積物開始脫離底床,水流變得渾濁,這標(biāo)志著侵蝕的開始[9]。黏性底床的侵蝕過程通常被劃分成兩種侵蝕類型[10]。類型Ⅰ是深度受限侵蝕,由于底床剪切強(qiáng)度在垂向上存在一個(gè)很大的梯度,當(dāng)達(dá)到某個(gè)侵蝕深度時(shí),底床剪切強(qiáng)度與水流剪切力相平衡,則侵蝕停止。類型Ⅱ是恒定侵蝕,其特點(diǎn)是勻質(zhì)底床剪切強(qiáng)度不隨沉積物深度的變化而改變,這種情況下的侵蝕速率是恒定的[10]。相對(duì)于非黏性沉積物而言,黏性沉積物侵蝕、懸浮、運(yùn)輸?shù)纫幌盗行袨闄C(jī)制要復(fù)雜得多,相關(guān)的物理、化學(xué)、生物進(jìn)程都還尚未完全了解。目前,研究者們主要通過實(shí)驗(yàn)室研究和現(xiàn)場(chǎng)原位測(cè)量來了解沉積物再懸浮機(jī)制,研究者們根據(jù)不同的研究目的以及水動(dòng)力情況,設(shè)計(jì)出了許多形狀各異、大小不一的再懸浮測(cè)量裝置,它們有著各自的適用環(huán)境、優(yōu)勢(shì)與弊端,如今正缺少對(duì)這些測(cè)量裝置及方法的歸納與總結(jié)。筆者回顧了沉積物再懸浮測(cè)量技術(shù)的發(fā)展,描述了各種裝置的基本工作原理、優(yōu)缺點(diǎn)及適用范圍,為研究沉積物再懸浮實(shí)驗(yàn)裝置和方法的選擇提供借鑒和參考。

1 實(shí)驗(yàn)室裝置模擬法

對(duì)沉積物侵蝕性能及再懸浮機(jī)制的了解主要是基于實(shí)驗(yàn)室研究,實(shí)驗(yàn)室研究可以控制水動(dòng)力條件及沉積物性質(zhì)相關(guān)參數(shù),比如沉積物顆粒大小、容積密度、水含量等。然而,自然黏性沉積物組成復(fù)雜,經(jīng)人工處理的沉積物樣品無法反映出自然環(huán)境中沉積物的物理、化學(xué)和生物特性[5,10]。即使是從現(xiàn)場(chǎng)采集原狀泥樣,在采樣和運(yùn)輸過程中也可能遭受擾動(dòng)而使樣品性能發(fā)生顯著改變[11]。

1.1 小型水流擾動(dòng)模擬裝置

小型沉積物再懸浮模擬裝置通常是在燒杯、錐形瓶等容器內(nèi)裝入一定量的沉積物和水樣,通過攪拌或振蕩產(chǎn)生擾動(dòng),模擬沉積物侵蝕的發(fā)生。如顆粒起動(dòng)模擬器(PES)[12]是通過振蕩網(wǎng)格的來回運(yùn)動(dòng)生成湍流,對(duì)沉積物進(jìn)行擾動(dòng)。但PES不能直接得到侵蝕剪切力的大小,需要通過環(huán)形水槽校準(zhǔn)實(shí)驗(yàn)來建立振蕩頻率與剪切力之間的關(guān)系[13]。范成新等[14]用振蕩三角瓶法,結(jié)合太湖現(xiàn)場(chǎng)風(fēng)力觀測(cè)數(shù)據(jù),以振蕩頻率模擬了不同風(fēng)速對(duì)沉積物擾動(dòng)產(chǎn)生的懸浮物量。該方法操作方便,但體系過小導(dǎo)致懸浮物濃度增長(zhǎng)受限,與實(shí)際情況有差異。Y型旋槳式沉積物再懸浮發(fā)生裝置[15]從斜向和垂向同時(shí)對(duì)底泥表面和水柱產(chǎn)生擾動(dòng),能夠減低懸浮物與器壁碰撞幾率,裝置外壁不同高度處的取樣口可以測(cè)定懸浮物濃度垂向分布?？傮w來說,小型模擬裝置結(jié)構(gòu)簡(jiǎn)單,可用于定性描述沉積物再懸浮現(xiàn)象,但封閉系統(tǒng)中湍流產(chǎn)生的渦流與自然水流條件下觀察到的渦流大小沒有可比性。

1.2 循環(huán)水流擾動(dòng)模擬水槽

循環(huán)水槽是一個(gè)封閉系統(tǒng),當(dāng)沉積物開始發(fā)生侵蝕時(shí),水槽中的懸浮物濃度逐漸變大直至飽和。水槽上覆水的高度一般較小,這使得懸浮物濃度遠(yuǎn)遠(yuǎn)超過自然水體情況。水體中的高懸浮物濃度可能會(huì)改變水流特性,有研究表明懸浮物濃度在200～2400mg/L時(shí),環(huán)形水槽內(nèi)的湍流強(qiáng)度下降了將近30%[16],這將導(dǎo)致不良的絮凝和沉淀現(xiàn)象發(fā)生。循環(huán)水槽通常是由一組平行墻組成,有環(huán)形和跑道形兩種外部形態(tài)。環(huán)形水槽通常由兩個(gè)直徑不同的同心圓環(huán)組成,通過不同的機(jī)械方法在沉積物表面形成侵蝕水流,如由旋轉(zhuǎn)蓋來推動(dòng)水流產(chǎn)生剪切力[17],還有通過旋轉(zhuǎn)蓋和其下方連接的4個(gè)等距槳來推動(dòng)水流[18],或者直接由旋槳生成水流[19]。環(huán)形水槽的優(yōu)點(diǎn)在于其“無限”的水流長(zhǎng)度生成了充分發(fā)展的邊界層,因此底床剪切力可通過測(cè)量流速分布利用對(duì)數(shù)法則計(jì)算得到[20]。然而,剪切力在徑向上的分布是不一致的,水槽的橫截面上產(chǎn)生二次流[21],有研究表明可以通過反向旋轉(zhuǎn)水槽外墻來最小化二次流的影響[22]。比如由覆蓋水面的環(huán)形圈和環(huán)形水槽同時(shí)往相反的方向旋轉(zhuǎn)形成均勻的剪切湍流[23],還有河海大學(xué)的雙向環(huán)形水槽[24-25]通過上部環(huán)形盤片和下部基座底盤做相向運(yùn)動(dòng)產(chǎn)生水流,還能通過調(diào)節(jié)上盤高度來控制水深。與環(huán)形水槽不同的是,跑道形循環(huán)水槽有一個(gè)相對(duì)長(zhǎng)直的侵蝕測(cè)試區(qū)域,兩端由彎曲段連接而成,因此二次流的影響較小[26],通常要在彎曲段布置平行導(dǎo)流墻來減小二次流的影響。水流驅(qū)動(dòng)裝置布置在水槽長(zhǎng)直段,有通過泵產(chǎn)生動(dòng)力的[27],也有通過電機(jī)驅(qū)動(dòng)旋轉(zhuǎn)盤推動(dòng)水流的[26],因此,懸浮絮體可能會(huì)被水流驅(qū)動(dòng)裝置破壞。

1.3 直型水流擾動(dòng)模擬水槽

上述循環(huán)水槽主要限制是水流施加剪切力小于1Pa,只有沉積物表層幾毫米發(fā)生侵蝕[28]。這只能代表一般情況下的沉積物再懸浮,卻無法模擬由洪水和風(fēng)暴引起的大規(guī)模再懸浮現(xiàn)象。而SED水槽[28-29]能在高剪切力情況下測(cè)量隨沉積物深度變化的侵蝕過程,施加剪切力最高可達(dá)10Pa。SED水槽實(shí)質(zhì)為封閉的直流水槽,水槽底部可插入含有沉積物的取芯管,取芯管底部活塞推動(dòng)沉積物向上移動(dòng),保證沉積物——水界面與水槽底部水平。然而,水槽底部與沉積物取芯管之間邊界糙率的突變影響了計(jì)算的精確性[30]。SED水槽通過調(diào)節(jié)泵不斷增大水流速度,測(cè)得發(fā)生初始侵蝕時(shí)對(duì)應(yīng)的臨界剪切力,侵蝕速率則是剪切力和沉積物深度的函數(shù)[31]。目前大部分水槽都只測(cè)量懸移質(zhì),忽略推移質(zhì),而ASSET水槽[30,32],除了包含SED水槽的所有性能,還增添了一個(gè)推移質(zhì)捕獲器,即能夠測(cè)定侵蝕發(fā)生后推移質(zhì)組分的比例。SED水槽和ASSET水槽在實(shí)驗(yàn)開始時(shí)都存在不確定性,因?yàn)樗蹚目帐紶顟B(tài)到充滿水流的過程對(duì)沉積物表面1～2mm施加的侵蝕剪切力很難準(zhǔn)確獲得。此外,還有底部非水平的直流水槽,如傾斜直槽[33]的底坡變化范圍為0.002417～0.01,能夠更加真實(shí)地模擬河道水流情況。另外,Mark[34]除了利用傾斜金屬架來調(diào)節(jié)水槽坡度以外,還在水槽底部和側(cè)面分別插入一個(gè)沉積物取芯管來同時(shí)模擬河道底泥和河岸邊坡的侵蝕,相比SED水槽,能更加全面的模擬河道沉積物再懸浮現(xiàn)象。

1.4 波浪擾動(dòng)模擬水槽

上述循環(huán)水槽和直流水槽只是測(cè)量單向流引起的沉積物再懸浮,而在河口、近海環(huán)境,振蕩波才是侵蝕主動(dòng)力[35]。因此,在SED水槽的基礎(chǔ)上發(fā)展了單向流與振蕩波共同作用的SEAWOLF水槽[35-36]。其中單向流由兩個(gè)儲(chǔ)水池的水頭差控制,能產(chǎn)生0.1～3 Pa剪切力,振蕩波由水槽一端的活塞運(yùn)動(dòng)產(chǎn)生,剪切力范圍為0.1～10 Pa,疊加后最高可產(chǎn)生12 Pa剪切力。SEAWOLF水槽能夠模擬振蕩波主導(dǎo)的侵蝕過程,實(shí)驗(yàn)證明在瞬時(shí)流速相同的情況下,振蕩波產(chǎn)生的剪切力遠(yuǎn)遠(yuǎn)大于單向流產(chǎn)生的剪切力。像太湖這種大型淺水湖泊,沉積物再懸浮的主要?jiǎng)恿碜杂诓ɡ撕秃鞯墓餐饔?尤其是在風(fēng)速比較大的情況下,波浪對(duì)沉積物的擾動(dòng)作用占主導(dǎo)地位[37]。孫小靜等[38]利用波浪水槽模擬了不同波高情況下太湖底泥的懸浮情況,并計(jì)算了波高與表層底泥切應(yīng)力以及風(fēng)速之間的對(duì)應(yīng)關(guān)系,水槽實(shí)驗(yàn)結(jié)果與野外觀測(cè)結(jié)果一致,說明能夠反映太湖的實(shí)際情況。Zheng等[39]指出波浪作用包括水平周期性剪切力和垂向壓力,研究發(fā)現(xiàn)臨界剪切力隨波浪周期數(shù)增大而減小,周期數(shù)大的波流更具破壞性。

2 室外原位裝置測(cè)量法

自然黏性沉積物組成復(fù)雜且容易破碎[40]。Tolhurst等[41]研究表明,在實(shí)驗(yàn)室和原位測(cè)得侵蝕閾值存在數(shù)量級(jí)上的差異,因?yàn)樵瓲畛练e物在采樣和運(yùn)輸過程中會(huì)受到擾動(dòng),這使得實(shí)驗(yàn)室數(shù)據(jù)的可靠性受到限制,因此更好的方法便是在未經(jīng)擾動(dòng)的沉積物底床上進(jìn)行原位測(cè)量。研究者們根據(jù)具體需求研制了各種各樣的便攜原位測(cè)量裝置,這包括剪切板、持續(xù)垂直射流裝置、攪拌裝置和不同形態(tài)的水槽,部分原位裝置總結(jié)如表1所示。

2.1 循環(huán)原位水槽

室外原位環(huán)形水槽是對(duì)實(shí)驗(yàn)室環(huán)形水槽進(jìn)行修正得到的,因此結(jié)構(gòu)類似,通常由兩個(gè)不同直徑的同心圓環(huán)組成,區(qū)別在于原位環(huán)形水槽的底部開放,可直接插入沉積物中。原位環(huán)形水槽可通過攪拌盤推動(dòng)水流[64],或者利用旋槳驅(qū)動(dòng)水流[51],還有旋轉(zhuǎn)蓋連接旋槳共同作用產(chǎn)生剪切力[42-43],通常利用ADV測(cè)得流速分布,OBS獲得懸浮物濃度,從而計(jì)算得出侵蝕剪切力和侵蝕速率。Tolhurst等[65]在不同裝置的對(duì)比研究中發(fā)現(xiàn)隨著儀器覆蓋底床面積的減小,侵蝕閾值增大。因?yàn)樗鄹采w面積的不同使得水槽包含的沉積物范圍不同,而沉積物性質(zhì)在空間上存在差異性,大型儀器將包含更多的性質(zhì)不同的沉積物,從而造成不同尺寸的儀器在侵蝕閾值大小上存在差異。然而,Widdows等[66]在對(duì)不同尺寸的環(huán)形水槽比較中發(fā)現(xiàn)侵蝕閾值有較好一致性,而侵蝕速率則變化較大,這可能跟測(cè)試時(shí)間有關(guān),大型水槽如Sea Carousel[42-43]平均測(cè)試時(shí)間為0.5～1 h,而微型便攜式環(huán)形水槽[50]只要幾分鐘。Widdows等[66]并沒有發(fā)現(xiàn)水槽大小和侵蝕閾值之間存在明顯的相關(guān)關(guān)系,其中PML’s AF[49]水槽外徑64 cm,與沉積物底床接觸面積0.17m2,是PML’s MAF微型水槽[50]的6.5倍。Tolhurst等[40]指出只有當(dāng)儀器占地面積小于沉積物空間異質(zhì)性范圍時(shí)才能檢測(cè)到沉積物空間異質(zhì)性。

2.2 直流原位水槽

直流原位水槽通常設(shè)計(jì)成一個(gè)底部開放的順直通道,是一個(gè)開放的系統(tǒng),懸浮物可以隨水流夾帶出水槽。因此,懸浮物濃度的分布通常是在施加剪切力之后立刻變大,再隨著時(shí)間減小。大部分直槽由收縮進(jìn)口段、直線侵蝕段和固定床部分組成,用于水下操作時(shí)上蓋封閉。典型直槽如NIWA水槽[4,57],其進(jìn)口段和侵蝕段底部開放,固定床部分有固定底部以防止螺旋槳對(duì)底泥侵蝕,最小操作水深大約為0.4m,適用于各種河流和海洋環(huán)境,可在水下操作。NIWAⅡ水槽[58]增加了超聲波測(cè)距系統(tǒng),該系統(tǒng)包含7個(gè)獨(dú)立的聲學(xué)傳感器,可直接測(cè)量水槽內(nèi)床底高程。此外,NIWAⅡ水槽還考慮了侵蝕發(fā)生后的推移質(zhì)組分,通過直接測(cè)量床面高程獲得侵蝕速率,再由OBS測(cè)得懸浮物濃度獲得再懸浮速率,利用質(zhì)量守恒方程得出推移質(zhì)所占比例。一般認(rèn)為二次流的影響在直槽中最小,但同時(shí)直槽的缺點(diǎn)在于侵蝕區(qū)域水流邊界層沒有得到充分發(fā)展,導(dǎo)致用對(duì)數(shù)法則評(píng)估底床剪切力時(shí)存在不確定性[57]。Ravens水槽[56]為解決侵蝕區(qū)水流邊界沒有充分發(fā)展的問題,將進(jìn)口前段底部封閉并增加橫欄以確保水流在到達(dá)侵蝕區(qū)之前充分發(fā)展。Ravens水槽由泵推動(dòng)水流,應(yīng)用剪切力范圍為0～3Pa,適用于淺灣環(huán)境,可水下操作,但是侵蝕深度受限,只能精確測(cè)量到3～4 cm。

表1 原位測(cè)量裝置

2.3 其他原位監(jiān)測(cè)設(shè)備

以上所述環(huán)形水槽和直流水槽都是利用水平流對(duì)沉積物表明產(chǎn)生侵蝕剪切力,還有一些設(shè)備是通過其他方式使沉積物發(fā)生再懸浮的,如垂直射流[1]、湍流[3,61]、剪切板[62,67]等。CSM[1,68]是利用垂直射流產(chǎn)生侵蝕剪切力,校準(zhǔn)后的等價(jià)水平應(yīng)力范圍為0.2～9.05 Pa,適用于不同類型的潮間帶泥灘和沼澤地,但不能水下操作。大型水槽因其較大的接觸面積和較長(zhǎng)的測(cè)試時(shí)間而無法反應(yīng)沉積物的空間異質(zhì)性,而CSM因其0.000 7m2的接觸面積和5min的測(cè)試時(shí)間,是目前唯一能夠小規(guī)模檢測(cè)沉積物時(shí)空異質(zhì)性的儀器。但CSM的侵蝕水流形態(tài)與自然水流結(jié)構(gòu)相比,缺乏相似性,通常會(huì)產(chǎn)生一個(gè)比自然流更大的剪切力,但這可以表示紊動(dòng)湍流的突然涌入所觸發(fā)的沉積物再懸浮。EROMES[61]是通過螺旋槳產(chǎn)生擾動(dòng),模擬自然紊流條件下的侵蝕裝置,裝置內(nèi)壁均勻分布的6塊導(dǎo)流板抑制渦流形成,主要產(chǎn)生垂直湍流。ISEF[59]是垂直站立的環(huán)形水槽,比傳統(tǒng)環(huán)形水槽輕巧,易于攜帶。ISEF水槽由上部的螺旋槳來驅(qū)動(dòng)水流,對(duì)下部的沉積物形成單向流侵蝕,同時(shí)測(cè)量流速和懸浮物濃度,當(dāng)懸浮物濃度保持穩(wěn)定后(即沉積物不再被侵蝕),此時(shí)剪切力大小等價(jià)于沉積物侵蝕阻力。ISIS[60]是將一個(gè)鐘形頭部放置在圓柱形容器內(nèi),水流通過擴(kuò)散器成放射狀流下,再由泵將水從漏斗中心抽走,如此形成循環(huán),可對(duì)整個(gè)沉積物表面產(chǎn)生0.02～5 Pa均勻的剪切力。但若泵汲水過于強(qiáng)烈,可能導(dǎo)致漏斗中心形成漩渦,從而使得沉積物表面剪切力分布不均。Widdows等[66]在不同裝置的對(duì)比研究中發(fā)現(xiàn)侵蝕閾值的差異性主要源于不同的剪切力施加方式,而這些不同方式的測(cè)量裝置都需要通過實(shí)驗(yàn)校準(zhǔn)才能獲得真正的侵蝕剪切力。

3 野外直接測(cè)量懸浮物濃度法

沉積物再懸浮濃度可以通過光學(xué)、聲學(xué)儀器直接測(cè)量,目前使用較多的有紅外傳感器、光學(xué)后向散射濁度計(jì)(OBS)和聲學(xué)多普勒流速儀(ADV)等。光學(xué)儀器的基本原理是測(cè)量光束在水中的吸收(衰減)或者散射[69],從而得到懸浮物濃度在時(shí)間和空間上的變化。水體上層夾帶的懸浮物顆粒要比接近底部的少,因此水體懸浮物濃度隨到底部的距離增大而減小的規(guī)律提供了一個(gè)很好的測(cè)量再懸浮強(qiáng)度的方法[69]。紅外傳感器通過測(cè)量底部相對(duì)高程,從而計(jì)算出沉積物再懸浮量,但是,由于紅外光在水中吸收非常迅速,因此紅外傳感器只能用于近岸或者幾米深的淺水區(qū)[70]。此外,光學(xué)儀器還會(huì)受到濁度的影響,比如光電檢測(cè)器在低濁度時(shí)顯示與懸浮物濃度呈線性關(guān)系,但一旦超過某值后就呈現(xiàn)非線性關(guān)系[57],這導(dǎo)致無法準(zhǔn)確估計(jì)懸浮物濃度的增長(zhǎng)。相比之下,OBS則具有更大的適用范圍,在懸浮物濃度5g/L范圍內(nèi)都能保持良好的線性關(guān)系。隨后,激光和電子全息影像也開始用于沉積物再懸浮測(cè)量,它提供了一個(gè)可視化工具來量化沉積物侵蝕過程,可以追蹤單獨(dú)的顆?；蛐躞w從底床被侵蝕到水體中去的全過程[71]。如SETEG系統(tǒng)[72]是在SED水槽的基礎(chǔ)上通過CCD攝像機(jī)連續(xù)的快照,依靠計(jì)算機(jī)分析某一時(shí)段內(nèi)沉積物體積損失量,從而得出侵蝕速率；Bertrand[73]在河岸布置光電探針測(cè)量河流侵蝕；Notebaert等[74]用激光雷達(dá)成像技術(shù)研究了河道形態(tài)變化并評(píng)估河岸總體侵蝕量。該技術(shù)可用于評(píng)估整個(gè)湖泊或河流的再懸浮過程,不再局限于某個(gè)具體位置,可是由于其較高的技術(shù)要求和相對(duì)高昂的費(fèi)用,并未得到廣泛應(yīng)用。

聲學(xué)儀器的基本原理是通過回聲探測(cè)和顆粒物反向散射獲取信息,從而以獲取底床剪切力[69]。目前應(yīng)用最廣泛的為ADV,能夠接近沉積物表面進(jìn)行三維流速測(cè)量,提供較高的時(shí)空分辨率[75]。基于恒定應(yīng)力層的假設(shè),利用ADV測(cè)量流速,通過以下4種計(jì)算方法可估計(jì)底床切應(yīng)力[76]:①協(xié)方差；①湍流動(dòng)能；③流速對(duì)數(shù)分布規(guī)律；④能量耗散。如Andersen等[77]基于流速剖面符合對(duì)數(shù)分布及粗糙紊流邊界層的假設(shè),利用ADV測(cè)量流速計(jì)算得出河口潮汐流作用下的泥灘侵蝕閾值。流速對(duì)數(shù)分布規(guī)律應(yīng)用廣泛,尤其在實(shí)驗(yàn)室水槽試驗(yàn),適用于光滑沉積物；然而,湍流動(dòng)能方法被認(rèn)為是最穩(wěn)定的,在不同高度處表現(xiàn)出最小的變異性,只需測(cè)量固定單點(diǎn)的流速就能夠記錄一系列紊流觸發(fā)現(xiàn)象[75]。還有ADCP(聲學(xué)多普勒流速剖面儀)廣泛用于不同河口地區(qū)來檢測(cè)靠近底床的水流結(jié)構(gòu)以及垂向貫穿整個(gè)水體的湍流結(jié)構(gòu)。如Rippeth等[78]利用ADCP觀測(cè)潮汐周期內(nèi)湍流結(jié)構(gòu),并用方差的方法估計(jì)雷諾應(yīng)力的大小、湍流動(dòng)能產(chǎn)生速率以及渦流黏度。

相較于上述各種原位水槽,光學(xué)、聲學(xué)儀器提供了一種無損性的測(cè)量方法,儀器通常固定在移動(dòng)船或者實(shí)驗(yàn)平臺(tái)上,無須像原位水槽那樣插入沉積物從而造成入侵性損害,并且隨移動(dòng)船的水平移動(dòng)還能測(cè)得懸浮物濃度在水平方向上的分布。越來越多的研究者利用光學(xué)、聲學(xué)儀器在大規(guī)?，F(xiàn)場(chǎng)試驗(yàn)中直接測(cè)量自然水動(dòng)力情況下的再懸浮過程,如大規(guī)模波浪水槽CIEM[79]就利用波高儀、ADV和OBS測(cè)得近岸沖浪地帶水動(dòng)力特性與再懸浮物濃度之間的關(guān)系。Aagaard等[80]將ADV、OBS和壓力傳感器固定在H型不銹鋼架上,在海濱波浪破碎地帶測(cè)得不同波浪條件下的懸浮物濃度分布及懸浮物垂直混合運(yùn)動(dòng)過程。但是,這要求儀器布置在水中有足夠長(zhǎng)的時(shí)間,否則測(cè)量的只是瞬時(shí)的懸浮物濃度,而無法觀測(cè)到再懸浮發(fā)生的全過程。

此外,還有一個(gè)能夠獲得水體垂向上懸浮物濃度分布的方法就是多點(diǎn)采樣法[81-82]。通常在沉積物——水界面以上不同高度處設(shè)置多個(gè)采樣點(diǎn)來采集原狀水樣,利用真空設(shè)備將水樣吸進(jìn)采樣瓶。然而,采樣器的支撐結(jié)構(gòu)固定到沉積物底部的過程可能會(huì)人為地引起沉積物再懸浮,因此需靜待一段時(shí)間后再開始采樣。

另外一個(gè)測(cè)量沉積物再懸浮的方法就是在接近底部沉積物表面處垂直放置沉積物捕獲器來收集發(fā)生再懸浮的沉積物。Gasith[83]于1975年提出了一個(gè)公式來計(jì)算再懸浮量,即沉積物捕獲器收集量減去捕獲器上方及附近水體懸浮物量等于再懸浮通量。該公式通常假設(shè)沉積物中有機(jī)質(zhì)的含量小于水體懸浮物中有機(jī)質(zhì)含量[84]。李一平等[85]用沉積物捕獲器來測(cè)定太湖沉降通量,然后利用該公式來推算再懸浮通量,所用捕獲器高寬比為3:1。因?yàn)镕lower[86]曾比較了高縱橫比(高:直徑＞5)和低縱橫比的捕獲器,發(fā)現(xiàn)后者才能得出更準(zhǔn)確真實(shí)的沉降通量。然而,Floderus[87]指出在水體懸浮物快速沉降時(shí)(比如春天浮游植物爆發(fā)時(shí)常伴有生物碳酸鹽沉淀),這個(gè)方法將低估再懸浮量。因?yàn)槟切┮呀?jīng)沉降但還未固結(jié)成沉積物的顆粒,它們的有機(jī)質(zhì)含量與水體懸浮物相同,當(dāng)它們發(fā)生再懸浮時(shí)并未被算作沉積物顆粒[88]。

4 總結(jié)與展望

沉積物再懸浮現(xiàn)象(包括隨后的懸浮物傳輸和再沉積)普遍存在于河流、湖泊、海岸等環(huán)境。沉積物再懸浮影響營(yíng)養(yǎng)物質(zhì)循環(huán),并釋放有機(jī)物和重金屬等污染物到水體中,影響水生生態(tài)健康,而這一系列行為機(jī)理并沒有完全被弄清楚?；诂F(xiàn)有的技術(shù)和方法,可以通過測(cè)量底床侵蝕剪切力和懸浮物濃度變化來定量分析沉積物再懸浮現(xiàn)象。室內(nèi)水槽實(shí)驗(yàn)?zāi)茏畲蟪潭鹊乜刂瓢ㄋ?、流速、沉積物性質(zhì)在內(nèi)的一系列參數(shù),為沉積物再懸浮機(jī)制的研究奠定了堅(jiān)實(shí)的基礎(chǔ)。然而自然黏性沉積物性質(zhì)復(fù)雜易碎,因此無法保證帶回實(shí)驗(yàn)室的原狀泥樣未受擾動(dòng),

使得實(shí)驗(yàn)室所得數(shù)據(jù)的可靠性受限,進(jìn)而要求在未經(jīng)擾動(dòng)的沉積物表面進(jìn)行原位測(cè)量?，F(xiàn)有的原位測(cè)量裝置可大致分為循環(huán)水槽、直流水槽和其他儀器,

每一個(gè)裝置都是根據(jù)具體的需要和邊界條件所設(shè)計(jì)。因此,每一個(gè)裝置都有其自身的優(yōu)缺點(diǎn)及適用范圍,所以無法評(píng)判哪一個(gè)是最好的,但這些裝置都是在原有基礎(chǔ)上不斷改進(jìn)的,新的裝置將會(huì)更加輕便、易于操作,適用于更深的水域。目前大部分裝置都忽略了推移質(zhì)的存在,這將導(dǎo)致總侵蝕量和侵蝕速率測(cè)量的不準(zhǔn)確性。不同裝置之間的對(duì)比研究顯示,基于同一工作原理的儀器所測(cè)結(jié)果一致性較好,

而剪切力施加方式完全不同的儀器所得結(jié)果幾乎沒有可比性,此外測(cè)試時(shí)間、儀器大小等也會(huì)造成結(jié)果的差異性,而目前并沒有一個(gè)衡量標(biāo)準(zhǔn)。值得一提的是,目前還沒有將原位直槽與循環(huán)水槽或者其他裝置在原位現(xiàn)場(chǎng)進(jìn)行對(duì)比測(cè)試過。目前測(cè)量裝置都依賴于動(dòng)力系統(tǒng)引發(fā)沉積物再懸浮,而動(dòng)力系統(tǒng)都預(yù)先設(shè)定了流速變化的范圍,并不是在自然沉積物再懸浮事件中直接測(cè)量的。因此,開展大規(guī)模現(xiàn)場(chǎng)試驗(yàn),直接測(cè)量再懸浮現(xiàn)象發(fā)生時(shí)的水力參數(shù)和侵蝕性能是有必要的,這有利于更加深入了解再懸浮機(jī)制。目前研究大都在淺水區(qū)域,今后可以往深水區(qū)域發(fā)展,研究適用于深水湖泊、深海等的測(cè)量裝置,拓寬對(duì)不同沉積物類型的了解。

[1]TOLHURST T J,BLACK K S,SHAYLER S A,et al. Measuring the in situ erosion shear stress of intertidal sediments with the cohesive strength meter(CSM)[J]. Estuarine,Coastal and Shelf Science,1999,49(2):281-294.

[2]秦伯強(qiáng),柳燕,陳非洲,等.湖泊富營(yíng)養(yǎng)化發(fā)生機(jī)制與控制技術(shù)及其應(yīng)用[J].科學(xué)通報(bào),2006,51(16):1857-1866.(QING Boqiang,LIU Yan,CHEN Feizhou,et al. Lake eutrophication mechanism and control technology and its app lication[J].Chinese Science Bulletin,2006, 51(16):1857-1866.(in Chinese))

[3]KALNEJAIS L H,MARTIN W R,BOTHNER M H.The release of dissolved nutrients and metals from coastal sediments due to resuspension[J].Marine Chemistry, 2010,121(1):224-235.

[4]ABERLE J,NIKORA V,WALTERSR.Data interpretation for in situ measurements of cohesive sediment erosion [J].Journal of Hydraulic Engineering,2006,132(6): 581-588.

[5]BLACK K S,TOLHURST T J,PATERSON D M,et al. Working with natural cohesive sediments[J].Journal of Hydraulic Engineering,2002,128(1):2-8.

[6]王海龍,李國(guó)勝.黃河入海泥沙在渤海中懸浮輸送季節(jié)變化的數(shù)值研究[J].海洋與湖沼,2009,40(2):129-137.(WANG Hailong,LI Guosheng.Floating in the sediment of the Yellow River into the sea in the Bohai Sea transportation numerical studies of seasonal change [J].Oceanologia et Limnologia Sinica,2009,40(2): 129-137.(in Chinese))

[7]LAM D C L,JAQUET J M.Computations of physical transport and regeneration of phosphorus in Lake Erie,fall 1970[J].Journal of the Fisheries Board of Canada, 1976,33(3):550-563.

[8]ANSARISA,KOTHYARIU C,RAJU K GR.Influence of cohesion on scour under submerged circular vertical jets [J].Journal of Hydraulic Engineering,2003,129(12): 1014-1019.

[9]KOTHYARIU C,JAIN R K.Influence of cohesion on the incipient motion condition of sediment mixtures[J]. Water Resources Research,2008,44(4):1-15.

[10]PATERSON D M,BLACK K S.Water flow sediment dynamics and benthic biology[J].Advances in Ecological Research,1999,29:155-194.

[11]BLACK K S,PATERSON D M.Measurement of the erosion potential of cohesivemarine sediments:a review of current in situ technology[J].Journal of Marine Environmental Engineering,1997,4(1):43-83.

[12]TSAI C H,LICK W.A portable device for measuring sediment resuspension[J].Journal of Great Lakes Research,1986,12(4):314-321.

[13]JEPSEN R A.Uncertainty in experimental techniques for measuring sediment erodability[J].Integrated Environmental Assessment and Management,2006,2 (1):39-43.

[14]范成新,張路,秦伯強(qiáng),等.風(fēng)浪作用下太湖懸浮態(tài)顆粒物中磷的動(dòng)態(tài)釋放估算[J].中國(guó)科學(xué):D輯,2003,33 (8):760-768.(FAN Chengxin,ZHANG Lu,QIN Boqiang,et al.Under the action of wind and waves in Taihu Lake state suspended particulate matter in thedynamic release of phosphorus estimates[J].Science in China:Series D,2003,33(8):760-768.(in Chinese))

[15]尤本勝,王同成,范成新,等.太湖沉積物再懸浮模擬方法[J].湖泊科學(xué),2007,19(5):611-617.(YOU Bensheng,WANG Tongcheng,FAN Chengxin,et al. Quantitative simulative method of sediment resuspension in Taihu Lake[J].Journal of Lake Sciences,2007,19 (5):611-617.(in Chinese))

[16]CLOUTIER D,LECOUTURIER M N,AMOS C L,et al. The effects of suspended sediment concentration on turbulence in an annular flume[J].Aquatic Ecology, 2006,40(4):555-565.

[17]FUKUDA M K,LICK W.The entrainment of cohesive sediments in freshwater[J].Journal of Geophysical Research:Oceans,1980,85(C5):2813-2824.

[18]MANNING A J,FRIEND P L,PROWSE N,et al. Estuarinemud flocculation properties determined using an annular mini-flume and the LabSFLOC system[J]. Continental Shelf Research,2007,27(8):1080-1095.

[19]SATO T,TANIGUCH K,TAKAGAWA T,etal.Generation of tidal bedding in a circular flume experiment:formation process and preservation potential of mud drapes[J]. Geo-Marine Letters,2011,31(2):101-108.

[20]STONE M,KRISHNAPPAN B G.Floc morphology and size distributions of cohesive sediment in steady-state flow [J].Water Research,2003,37(11):2739-2747.

[21]GRAHAM D I,JAMES P W,JONES T E R,et al. Measurement and prediction of surface shear stress in annular flume[J].Journal of Hydraulic Engineering, 1992,118(9):1270-1286.

[22]KRISHNAPPAN BG.Rotating circular flume[J].Journal of Hydraulic Engineering,1993,119(6):758-767.

[23]PARCHURE T M,MEHTA A J.Erosion of soft cohesive sediment deposits[J].Journal of Hydraulic Engineering, 1985,111(10):1308-1326.

[24]李一平,逄勇,陳克森,等.水動(dòng)力作用下太湖底泥起動(dòng)規(guī)律研究[J].水科學(xué)進(jìn)展,2004,15(6):770-774.(LI Yiping,PANG Yong,CHNE Keseng,et al.Study on the starting principles of sediment by water force in Taihu Lake[J].Advances in Water Science,2004,15(6): 770-774.(in Chinese))

[25]WANG Y,YU Q,GAO S.Relationship between bed shear stress and suspended sediment concentration:annular flume experiments[J].International Journal of Sediment Research,2011,26(4):513-523.

[26]ANTA J,PENA E,PUERTAS J,et al.A bedload transport equation for the Cerastoderma edule cockle[J].Journal of Marine Systems,2013,111:189-195.

[27]PIEDRA-CUEVA I,MORY M,TEMPERYILLE A.A racetrack recirculating flume for cohesive sediment research [J].Journal of Hydraulic Research,1997,35(3):377-396.

[28]MCNEIL J,TAYLOR C,LICKW.Measurements of erosion of undisturbed bottom sediments with depth[J].Journal of Hydraulic Engineering,1996,122(6):316-324.

[29]LICK W,MCNEIL J.Effects of sediment bulk properties on erosion rates[J].Science of the Total Environment, 2001,266(1):41-48.

[30]ROBERTS JD,JEPSEN R A,JAMES SC.Measurements of sediment erosion and transport with the adjustable shear stress erosion and transport flume[J].Journal of Hydraulic Engineering,2003,129(11):862-871.

[31]ROBERTS J,JEPSEN R,GOTTHARD D,et al.Effects of particle size and bulk density on erosion of quartz particles[J].Journal of Hydraulic Engineering,1998,124 (12):1261-1267.

[32]JEPSEN R,ROBERTS J,GAILANI J.Effects of bed load and suspended load on separation of sands and fines in mixed sediment[J].Journal of Waterway,Port,Coastal, and Ocean Engineering,2010,136(6):319-326.

[33]JAIN R K,KOTHYARI U C.Cohesion influences on erosion and bed load transport[J].Water Resources Research,2009,45(6):1-17.

[34]MARK W.Bank Erosion in the Petitcodiac River Estuary [D].Kingston:Queen’s University,2011.

[35]JEPSEN R,ROBERTS J,GAILANI J.Erosion measurements in linear,oscillatory,and combined oscillatory and linear flow regimes[J].Journal of Coastal Research,2004,20(4):1096-1101.

[36]JEPSEN R,ROBERTS J,KEARNEY S,et al.Shear stress measurements and erosion implications for wave and combined wave-current generated flows[J].Jounral of Waterway,Port,Coastal and Ocean Engineering,2012, 138(4):323-329.

[37]秦伯強(qiáng),胡維平,高光,等.太湖沉積物懸浮的動(dòng)力機(jī)制及內(nèi)源釋放的概念性模式[J].科學(xué)通報(bào),2003,48 (17):1822-1831.(QIN Boqiang,HU Weiping,GAO Guang,et al.The dynamic mechanism of sediment suspension in Taihu Lake and endogenous release of conceptualmodel[J].Chinese Science Bulletin,2003,48 (17):1822-1831.(in Chinese))

[38]孫小靜,朱廣偉,羅瀲蔥,等.淺水湖泊沉積物磷釋放的波浪水槽試驗(yàn)研究[J].中國(guó)科學(xué):D輯,2005,35 (Ⅱ):81-89.(SUN Xiaojing,ZHU Guangwei,LUO Liancong,et al.Wave flume experiment research of the shallow water lake sediment phosphorus release[J]. Science in China:Series D,2005,35(Ⅱ):81-89.(in Chinese))

[39]ZHENG JW,JIA Y G,LIU X L,etal.Experimental study of the variation of sediment erodibility underwave-loading conditions[J].Ocean Engineering,2013,68:14-26.

[40]TOLHURST T J,BLACK K S,PATERSON D M.Muddysediment erosion:Insights from field studies[J].Journal of Hydraulic Engineering,2009,135(2):73-87.

[41]TOLHURSTT J,RIETHMULLER R,PATERSON DM.In situ versus laboratory analysis of sediment stability from intertidalmudflats[J].Continental Shelf Research,2000, 20(10):1317-1334.

[42]AMOS C L,CHRISTIAN H A,GRANT J,et al.A comparison of in situ and laboratory methods to measure mudflat erodibility[C].Hydraulic and Environmental Modelling:Coastal Waters,Proceedings of the Second International Conference on Hydraulic and Environmental Modelling of Coastal,Estuarine and River Waters, Brad ford:wiley,1993:325-336.

[43]AMOS C L,FEENEY T,SUTHERLAND T F,et al.The stability of fine-grained sediments from the Fraser River Delta[J].Estuarine,Coastal and Shelf Science,1997,45 (4):507-524.

[44]AMOSC L,BERGAMASCO A,UMGIESSER G,et al.The stability of tidal flats in Venice Lagoon:the results of insitumeasurements using two benthic,annular flumes[J]. Journal of Marine Systems,2004,51(1-4):211-241.

[45]MOREAU A L,LOCAT J,HILLP,et al.Resuspension potential of surficial sediments in Saguenay Fjord (Quebec,Canada)[J].Marine Geology,2006,225(1-4):85-101.

[46]AMOS C L,UMGIESSER G,FERRARIN C,et al.The erosion rates of cohesive sediments in Venice Lagoon, Italy[J].Continental Shelf Research,2010,30(8):859-870.

[47]MAA J P Y,SANFORD L P,HALKAJ P.Sediment resuspension characteristics in Baltimore Harbor, Maryland[J].Marine Geology,1998,146:137-145.

[48]MAA J P Y.Sediment erosion characteristics in the Anacostia River[J].Journal of Hydraulic Engineering, 2008,134(8):1102-1109.

[49]WIDDOWS J,BRINSLEY M D,BOWLEY N,et al.A benthic annular flume for in situ measurement of suspension feeding/biodeposition rates and erosion potential of intertidal cohesive sediments[J].Estuarine, Coastal and Shelf Science,1998,46(1):27-38.

[50]BALE A J,WIDDOWS J,HARRIS C B,et al. Measurements of the critical erosion threshold of surface sediments along the Tamar Estuary using a m ini-annular flume[J].Continental Shelf Research,2006,26(10): 1206-1216.

[51]THOMPSON C E L,COUCEIRO F,FONESG R,et al.In situ flumemeasurements of resuspension in the North Sea [J].Estuarine,Coastal and Shelf Science,2011,94(1): 77-88.

[52]BLACK K S,CRAMP A.A device to examine the in situ response of intertidal cohesive sediment deposits to fluid shear[J].Continental Shelf Research,1995,15(15): 1945-1954.

[53]YOUNG R A,SOUTHARD J B.Erosion of fine-grained marine sediments:seafloor and laboratory experiments [J].Geological Society of America Bulletin,1978,89 (11):663-667.

[54]GUSTG,MORRISM J.Erosion threshold and entrainment rates of undisturbed in situ sediments[J].Journal of Coastal Research,1989,5:87-100.

[55]HAWLEY N.Preliminary observations of sediment erosion from a bottom resting flume[J].Journal of Great Lakes Research,1991,17(3):361-367.

[56]RAVENS TM,GSCHWEND PM.Flumemeasurements of sediment erodibility in Boston Harbor[J].Journal of Hydraulic Engineering,1999,125(10):998-1005.

[57]ABERLE J,NIKORA V,MCLEAN S,et al.Straight benthic flow-through flume for in situ measurement of cohesive sediment dynamics[J].Journal of Hydraulic Engineering,2003,129(1):63-67.

[58]DEBNATH K,NIKORA V,ABERLE J,et al.Erosion of cohesive sediments:Resuspension,bed load,and erosion patterns from field experiments[J].Journal of Hydraulic Engineering,2007,133(5):508-520.

[59]HOUWING E J,VANRIJIN L C.In situ erosion flume (ISEF):determination of bed-shear stress and erosion of a kaolinite bed[J].Journal of Sea Research,1998,39 (3):243-253.

[60]WILLIAMSON H,OCKENDEN M.ISIS:An instrument for measuring erosion shear stress in situ[J].Estuarine, Coastal and Shelf Science,1996,42(1):1-18.

[61]KALNEJAIS L H,MARTINW R,BOTHNER M H.The release of dissolved nutrients and metals from coastal sediments due to resuspension[J].Marine Chemistry, 2010,121(1):224-235.

[62]BARNESM P,O＇DONOGHUE T,ALSINA JM,et al. Direct bed shear stress measurements in bore-driven swash[J].Coastal Engineering,2009,56(8):853-867.

[63]GRANT J,WALKER T R,HILL P S,et al.BEAST-A portable device for quantification of erosion in natural intact sediment cores[J].Methods in Oceanography, 2013,5:39-55.

[64]GUST G,MUKLLER V.Interfacial hydrodynamics and entrainment functions of currently used erosion devices [C]//Proceedings of the fourth Nearshore and Estuarine Cohesive Sediment Transport Conference.Chichester: Wiley,1997.

[65]TOLHURST T J,BLACK K S,PATERSON D M,et al.A comparison and measurement standardisation of four in situ devices for determining the erosion shear stress of intertidal sediments[J].Continental Shelf Research, 2000,20(10):1397-1418.

[66]WIDDOWS J,FRIEND P L,BALE A J,et al.Intercomparison between five devices for determ ining erodability of intertidal sediments[J].Continental Shelf Research,2007,27(8):1174-1189.

[67]HUO G,WANG Y,YIN B,et al.A new measure for direct measurement of the bed shear stress of wave boundary layer in wave flume[J].Journal of Hydrodynamics,Series B,2007,19(4):517-524.

[68]VARDY S,SAUNDERS J E,TOLHURST T J,et al. Calibration of the high-pressure cohesive strength meter (CSM)[J].Continental Shelf Research,2007,27(8): 1190-1199.

[69]BLORSCH J.A review of methods used to measure sediment resuspension[J].Hydrobiologia,1994,284(1): 13-18.

[70]ERLINGSSON U.A sensor for measuring erosion and deposition[J].Journal of Sedimentary Petrology,1991, 61:620-622.

[71]SUN H,PERKINS R G,Watson J,et al.Observations of coastal sediment erosion using in-line holography[J]. Journal of Optics A:Pure and Applied Optics,2004,6 (7):703-710.

[72]WITT O,WESTRICH B.Quantification of erosion rates for undisturbed contaminated cohesive sediment cores by image analysis[J].The Interactions between Sediments and Water Developments in Hydrobiology 2003,169: 271-276.

[73]BERTRAND F.Fluvial erosion measurements of streambank using Photo-Electronic Erosion Pins(PEEP) [D].Iowa:The University of Iowa,2010.

[74]NOTEBAERT B,VERSTRAETEN G,GOVERSG,et al. Qualitative and quantitative applications of LiDAR imagery in fluvial geomorphology[J].Earth Surface Processes and Landforms,2009,34(2):217-231.

[75]POPE N D,WIDDOWS J,BRINSLEY M D.Estimation of bed shear stress using the turbulent kinetic energy approach-a comparison of annular flume and field data [J].Continental Shelf Research,2006,26(8):959-970. [76]KIM SC,FRIEDRICHSC T,MAA JPY,etal.Estimating bottom stress in tidal boundary layer from acoustic Doppler velocimeter data[J].Journal of Hydraulic Engineering,2000,126(6):399-406.

[77]ANDERSEN T J,FREDSOE J,PEJRUP M.In situ estimation of erosion and deposition thresholds by Acoustic Doppler Velocimeter(ADV)[J].Estuarine, Coastal and Shelf Science,2007,75(3):327-336.

[78]RIPPETH T P,WILLIAMS E,SIMPSON J H.Reynolds stress and turbulent energy production in a tidal channel [J].Journal of Physical Oceanography,2002,32(4): 1243-1252.

[79]ALSINA JM,CACERES I.Sediment suspension events in the inner surf and swash zone:measurements in largescale and high-energy wave conditions[J].Coastal Engineering,2011,58(8):657-670.

[80]AAGAARD T,JENSEN SG.Sediment concentration and vertical mixing under breaking waves[J].Marine Geology,2013,336:146-159.

[81]ROSA F,NRIAGU JO,WONGH K,et al.Particulate flux at the bottom of Lake Ontario[J].Chemosphere,1983,12 (9):1345-1354.

[82]胡春華,胡維平,張發(fā)兵,等.太湖沉積物再懸浮觀測(cè)[J].科學(xué)通報(bào),2005,50(22):2541-2545.(HU Chunhua,HUWeiping,ZHANG Fabing,et al.Taihu Lake sediment resuspension observation[J].Chinese Science Bulletin,2005,50(22):2541-2545.(in Chinese))

[83]GASITH A.Tripton sedimentation in eutrophic lakessimp le correction for the resuspended matter[J].Verh. int.Ver.Limnol,1975,19:116-122.

[84]BLOMQVIST S,LARSSON U.Petrogenicmetals as tracers of resuspended and primary settling matter in a coastal area of the Baltic Sea[J].Blomqvist,1992(S):1-37.

[85]李一平,逄勇,李勇.水動(dòng)力作用下太湖底泥的再懸浮通量[J].水利學(xué)報(bào),2007,38(5):558-564.(LIYiping, PANG Yong,LI Yong.Resuspended flux of sediment in Taihu Lake under hydrodynamic action[J].Journal of Hydraulic Engineering,2007,38(5):558-564.(in Chinese))

[86]FLOWER R J.Field calibration and performance of sediment traps in a eutrophic holomictic lake[J].Journal of Paleolimnology,1991,5(2):175-188.

[87]FLODERUS S.The effect of sediment resuspension on nitrogen cycling in the Kattegat-variability in organic matter transport[D].Uppsala:Uppsala University,1981. [88]HICKSR E,OWEN C J,AASP.Deposition,resuspension, and decomposition of particulate organic matter in the sediments of Lake Itasca,Minnesota,USA[J]. Hydrobiologia,1994,284(1):79-91.

Review on methods ofmeasuring sediment re-suspension

XIE Qianwen1,2,LIYiping1,KONG W en3
(1.College ofEnvironment,Hohai University,Nanjing 210098,China；2.Shenzhen Urban Planning&Land Resource Research Center,Shenzhen 518040,China；3.Nanjing wisdom New Town ProjectManagement Co.,Ltd,Nanjing 210012,China)

In order to study the series of behavioral mechanisms including sediment erosion,re-suspension, transportation,this paper summarized the sediment re-suspension measurementmethod in three aspects:laboratory device simulation,in situ measurement and directly measurement in field.Sediment re-suspension measuring device can be divided into circulating water flume,straight flow-through flumes,and other devices.Hydraulic working principles,advantages and disadvantages,range of application environment of different devices were described.And the measuring results of different device were compared.Based on existing technologies and methods,the phenomenon of sediment re-suspension was quantified by measuring seabed erosion shear stress and suspended solids concentration changes.Different shearing force,testing time and equipment size and other factors cause the diversity of the result from all kinds of devices.

sediment；re-suspension；erosion threshold；shear stress；measurementmethod

X832

：A

：1004 6933(2015)06 0141 09

10.3880/j.issn.1004 6933.2015.06.023

2014 07 17 編輯:陳玉國(guó))

中央高校業(yè)務(wù)費(fèi)(2014B29114)；江蘇省自然科學(xué)基金(BK20131370)

謝倩雯(1991—),女,碩士研究生,研究方向?yàn)樗h(huán)境數(shù)學(xué)模型和河湖富營(yíng)養(yǎng)化機(jī)理研究。E-mail:673565543@qq.com

李一平,副教授,博士生導(dǎo)師。E-mail:yipinglihhu@gmail.com