水動力條件對淺水湖泊沉積物氮磷釋放的影響

余景芝,王 烜*,蔡劍英,廖珍梅,李春暉,劉 強

水動力條件對淺水湖泊沉積物氮磷釋放的影響

余景芝1,2,王 烜1,2*,蔡劍英1,2,廖珍梅1,2,李春暉2,劉 強2

(1.北京師范大學環境學院水環境模擬國家重點實驗室,北京 100875；2.北京師范大學環境學院水沙科學教育部重點實驗室,北京 100875)

水動力條件是影響淺水湖泊沉積物氮磷釋放過程的主要自然因素.研究水動力條件對沉積物氮磷釋放的影響對于掌握淺水湖泊營養鹽遷移轉化規律?預測與防控內源污染具有十分重要的意義.水動力因子中,流速通過影響沉積物-水界面剪切應力改變界面氮磷的交換通量;水位和水體擾動均會影響表層沉積物理化特征?沉積物-水界面氧化還原反應過程,通過多種效應耦合共同對氮磷釋放產生影響.本文綜述了流速?水位?水體擾動等主要水動力因子對淺水湖泊沉積物中氮磷釋放的影響機制研究并提出展望:多種水動力因子耦合作用對氮磷釋放的影響機理?基于多時空尺度構建原位監測-耦合模擬研究體系?內源氮磷釋放之后對生態系統的影響研究還有待加強.

水動力條件；淺水湖泊；沉積物；氮磷釋放；內源污染防治

湖泊在供給水源?調節徑流、降解污染物?保持生物多樣性等方面有極其重要的生態服務價值,在流域水循環與流域生態過程中起關鍵作用[1-2].我國淺水湖泊眾多,它們具有優越的自然生態系統服務功能和社會經濟價值.然而,這些湖泊流速較低,污染物輸移擴散緩慢,環境容量小.水文水動力條件的微小改變會驅動湖泊沉積物懸浮和內源營養鹽釋放,進而引起湖泊生態系統的結構與功能發生改變[3].當前白洋淀等淺水湖泊的外源污染已得到有效治理,日益突顯的沉積物懸浮與內源營養鹽釋放問題逐漸成為制約全局水質改善成敗?保障湖泊生態系統可持續發展的熱點問題.

由于長期以來淺水湖泊中氮磷元素的不斷累積,沉積物成為營養鹽的蓄積庫[4-5],在湖泊富營養化的過程中成為“匯”;當環境條件改變時,沉積物中的氮、磷等營養物質可通過生物分解、解吸附、礦化等作用釋放出來,成為影響上覆水體水質的“源”.沉積物-水界面的這種源、匯轉化是決定湖泊水質狀況的關鍵[6],而水體的pH值、溶解氧等理化特征和沉積物粒徑、孔隙度、組成分布、氮磷元素形態等理化特征決定了源、匯轉化的進程[7-8].在河湖水體中,流速、水位、水體擾動等水動力條件的改變對水相和沉積相特征產生的影響是氮磷釋放的重要驅動力[9-10].因此,摸清水動力因子作用下沉積物-水界面的氮磷釋放機制及遷移轉化規律已成為近20a來淺水湖泊水動力過程及其環境效應研究的重點[11-12],相關研究對于水體污染的模擬、預測和科學防控具有重要意義.

本文將分別綜述不同水動力因子對淺水湖泊沉積物中氮磷釋放的影響機制,并提出未來值得深入研究的方向,以期為淺水湖泊內源污染控制和水資源管理提供科學依據.

1 水動力因子對淺水湖泊沉積物氮磷釋放的影響機制

淺水湖泊沉積物中氮磷釋放主要通過兩種途徑.第一,由于沉積物-水濃度梯度或外力擾動下,附著在沉積物顆粒上的氮磷釋放到間隙水中,進一步擴散到上覆水中,這個過程簡稱為自由擴散過程.第二,吸附氮磷的沉積物顆粒由于外力作用再懸浮至上覆水中,增大氮磷含量,即再懸浮過程[13-14].水動力因子作用下,沉積物-水界面的剪切作用發生變化,直接改變水環境理化特征、沉積物理化特征[15-16],或改變水中生物生態特征、微生物活性等,進而對沉積物-水系統的理化特征產生影響,從而間接導致上覆沉積物-水界面氮磷交換過程的改變[14].水動力因子對淺水湖泊沉積物氮磷釋放的影響機制如圖1所示.不同水動力條件變化作用于沉積物氮磷釋放的機制不同,但都可以歸因為上覆水體與沉積物之間的氮磷濃度差的改變.

2 不同水動力因子對淺水湖泊氮磷釋放的影響

2.1 流速

流速是表征水動力條件最基本的因子,流速變化引起懸浮物運動狀態和沉積物營養鹽釋放速率改變,加速水質變化的過程[17-18].目前大多數研究采用室內水槽模擬方法(如波浪槽、生態水槽?環形水槽等)探究水體流速對沉積物氮磷釋放的影響機制.21世紀早期的研究較多關注不同流速對水相和沉積相中污染物濃度的影響.Barlow等[19]利用室內循環水槽結合Elovich方程模擬探究流速與水深對水體TP吸附效應的影響.Zhu等[20]、Tong等[21]也分別利用室內波浪槽和雙向環形水槽模擬實驗探究變化流速下沉積物的氮釋放特征.隨著環境監測技術的迅速發展,水體流速對沉積物氮磷的質量濃度、釋放通量、釋放速率等的影響規律逐漸成為內源釋放研究的熱點問題.Peng等[22]針對淺水、不分層的混合型湖泊,通過構建不同流速下的可溶性磷的濃度曲線,提出SRP(溶解態磷)的質量濃度與流速滿足正相關關系:= 0.0003+0.0404,其中為流速.隨后Li等[23]、Pang等[24]和Ding等[25]在此基礎上建立了一定范圍內沉積物中TN、TP釋放通量與流速的定量關系分別為=137.88e0.06x和=36.78e0.05x,其中為流速,并將此定量關系式應用于ECOMSED模型.考慮到沉積物-水界面氮磷的釋放由水相和沉積相理化特征等共同決定,在實際研究過程中需要綜合考慮水相與沉積相的特征及相互作用,不能將二者分開孤立地進行研究.因此一些研究建立了沉積物-水耦合模型,如Huang等[26]通過分析沉積物動力學建立水動力-沉積物-氮磷輸移的數學模型,并將其應用于三峽大壩水庫,較好地揭示了沉積物中磷的運移規律.當前針對流速對沉積物氮磷釋放影響的研究以室內水槽實驗、數學模型、試驗與模型相結合的方法為主,研究條件相對簡化,尚難以精確表征實際情況,因此后續的探究應綜合室內外的物理試驗方法和模型技術,以提高研究結果的合理性和可靠性.

圖1 水動力條件對淺水湖泊沉積物氮磷釋放的影響

總體而言,在某一范圍內,流速的增大能夠促進沉積物中氮磷的釋放,當流速達到臨界流速之后,氮磷釋放驅動機制更加復雜,此時流速將不再成為主要的影響因素.當前研究對臨界流速的界定尚未提出較為統一的計算范式,需要深入探究流速對沉積物氮磷釋放產生影響的動力學過程,明確不同水體臨界流速的界定方法.

2.2 水位

水位是表征水文水動力條件的關鍵因子,淺水湖泊水位的變化與湖泊生態系統功能密切相關,直接作用于沉積物的理化特性,并影響營養鹽的遷移和循環過程[35].

通常水位調節會引起上覆水環境及表層沉積物理化特征的改變,大多數研究集中于氧化還原條件[36-37]、沉積物顆粒特征[38]、微生物生長[39-40]等因素,通過這些因素的變化進而間接研究水位對沉積物氮磷釋放的影響.水位調節也會直接影響氮磷的形態轉化過程.Yu等[41]提出水位調節過程中沉積物-水界面的氮循環模式發生了明顯的轉變,NH4+向NO3-的轉化明顯增強,削弱了水體中氮的去除.水位變化的范圍、變化頻度、持續時間等對沉積物中氮磷的釋放具有重要影響[35].Tong等[42]模擬不同水位和流速下沉積物磷的釋放特性,發現磷釋放速率與水位符合第二拋物線方程,當流速保持0.3m/s時,上覆水總磷濃度在25cm的水位處達到最大值,磷釋放速率隨水位升高而增加.Tang等[38]對水位調節速度與周期進行動態模擬,提出6cm/d的快速水位調節促進了氮的釋放,3cm/d的緩慢水位調節有利于磷的淋溶.此外,水位亦為水生植物群落分布和生長發育的重要限制因子,而水生植物根系的吸收作用會間接影響沉積物與間隙水中TN(總氮)?TP(總磷)交換過程[43].Bai等[44]的研究發現,狐尾藻的株高和生物量隨著水深的增加而呈現下降趨勢,相對較淺的水深條件促進狐尾藻對氮磷的根系吸收,一定程度上減少了沉積物與上覆水之間的氮磷交換.

圖2 流速對沉積物氮磷釋放過程的作用機制

水位的變化會導致不同的水文景觀格局和水文連通性的變化[45],這也是近年來湖泊濕地水文研究的熱點問題[46-47].水文連通性變化對淺水湖泊生態環境的影響極為復雜,不僅會影響水體的水文節律、水動力特征及沉積物的組成、結構,同時還會聯動影響污染物質的遷移、水生物遷移擴散等過程,進而對湖泊水質和水生態系統產生直接或間接的影響[48].因而在水文連通性變化背景下,湖泊的諸多特征如水量的交換、流速、水齡等都會受到影響,進而影響沉積物-水界面氮磷的釋放.

近10a來我國通過實施水文連通工程增加了近50個湖泊的湖水流動性[49],其水文水動力特征也隨之發生改變.如太湖水體經過引江濟太工程后調水周期從原來的300d縮短至250d[50],現階段太湖沉積物對TP的吸附和沉積作用要遠大于釋放[51].對于形狀復雜?面積較大的湖泊而言,不同湖區和湖區的不同位置水文連通性不同,造成的氮磷滯留與釋放效果差異大,Sun等[52]通過二維水動力模型分析后發現湯遜湖主要區域的NH3-N、TN、TP濃度下降,而邊界區域則無明顯改善情況.同時,水文連通性的變化也會改變淺水湖泊的風生流場,Zheng等[53]在利用Delft3D軟件構建大東湖水動力學模型過程中發現,連通之后水系流速大于0.01m/s的水面面積比連通前擴大了一倍以上,而通過水動力-水質耦合數學模型模擬分析發現主流線附近水域流速增加,其TN?TP濃度降低,在偏離主線較遠水域,流速變化與TN、TP濃度變化均不明顯[54].綜合來看,增強水文連通性能夠通過影響水文水動力特征,增強湖泊內部污染物的稀釋降解過程,促進沉積物從營養物質的“源”向“匯”的轉化.同時,水文連通性增強還可能造成污染物的輸入和水體擾動,容易發生沉積物再懸浮和增加氮磷內源釋放的風險.

以往研究表明一定范圍內淺水湖泊水位的增加促進氮磷的釋放,而水位變化的范圍、頻度、持續時間及引起水文連通性的改變,均可導致水位-沉積物氮磷釋放這一響應過程受到影響,而目前針對這一過程的機制研究尚為單一.未來研究中尤其需要關注水位-水文連通性-氮磷釋放風險這一影響路徑,定量評估水位變化下的沉積物水界面氮磷釋放風險.同時,綜合考慮湖泊形狀?地形地貌特征等其他因素,使研究結果更加準確可靠.

2.3 水體擾動

水體擾動是水動力條件的重要因子,擾動發生時,大量沉積物再懸浮至上覆水中,導致間隙水中的溶解態氮磷也隨之向上遷移擴散.需要注意的是,水體擾動與流速關系密切,二者相互聯系和影響.水流的流速直接決定流態的變化,進而改變水流剪切應力,使得氮磷的釋放受到影響;而擾動會引起淺水湖泊的流場和動能變化,進而引起上覆水體和沉積物顆粒的狀態變化.為便于描述,本文水體擾動特指水體外部的作用力(如風浪等)引起的流場變化,與“2.1流速”中水體內部的流速變化相區別,以更加針對性地研究淺水湖泊氮磷釋放的關鍵因子.

對水體擾動的研究常采用室外監測和室內模擬的方式進行,其中室外監測主要包括野外觀測和原位圍隔實驗法等,如Qin等[55]、Zhu等[56]通過野外觀測太湖大風浪過程和靜風期間水體TP、TDP等含量的變化,以探究風浪擾動對于水體內源磷釋放的影響.這類方法可以直接利用原位監測或實驗分析得到流速對沉積物氮磷釋放的影響規律和機制.然而,由于受地理環境、氣象水文等多種因素的綜合影響,野外觀測實驗受到一定限制,因此目前對水體擾動的研究大多采用室內模擬方式進行,且多關注于擾動引起的沉積物再懸浮行為.以往研究所采用的室內模擬擾動的方式各異,對擾動引起的沉積物再懸浮及營養鹽釋放的研究視角也有所不同.如Wang等[57]和Jiang等[58]采用六聯攪拌儀模擬巢湖、東平湖中不同擾動強度.隨后的研究開始逐漸采用水槽試驗對擾動進行模擬,如Hu等[59]、Sun等[60]采用矩形波浪水槽進行水動力試驗,在水槽中模擬不同波浪擾動對沉積物再懸浮及營養鹽釋放速率的影響;在此基礎之上也有研究提出采用改良的自制U型水槽,以不同水頭差來模擬波浪的循環載荷作用, Zhang等[61]提出沉積物液化狀態下的沉積物釋放速率的擬合方程,從沉積物自身狀態模擬的角度對以往研究進行了補充.

隨著室內模擬試驗的日益成熟,專家學者開始嘗試將其與數值模擬進行耦合.Huang等[26-62]提出了綜合水動力、風浪和泥沙輸運的磷動態模型,并結合水槽試驗定量估計風浪和湖流對磷釋放和分布的影響,精確化、定量化地模擬了風浪湖流作用下的磷釋放過程.水體擾動對沉積物氮磷釋放影響的室內模擬試驗可總結為表1.

表1 水體擾動對氮磷釋放影響的室內模擬實驗

一般說來,持續的擾動會直接改變沉積物的組成和結構特征從而影響沉積物氮磷的釋放.如Li等[68]、孫小靜等[69-70]提出指出持續的風浪擾動下懸浮物細顆粒組分的百分含量明顯增加,溶解態磷更易被吸附沉降從而抑制磷的釋放.同時擾動過程中大量的溶解性磷從水中釋放出來,導致溶解氧含量升高,在一定程度上制約磷的釋放[71].研究表明好氧條件下沉積物氮和磷的釋放量減小,厭氧條件更有利于沉積物釋放氮磷[72-73].同時,溶解氧含量的增加還將使得沉積物中大量的鐵錳硫化物被氧化,生成鐵錳氫氧化物,強烈吸附水中的溶解態磷,因而使得擾動后期磷釋放減弱[74-77].

此外,擾動還可以促進微生物對磷的分解以及水體中顆粒態磷的酶解,這也是內源磷釋放的重要途徑.Huang等[66]和Chao等[78]提出低至中度的擾動會使得DAPA(溶解性堿性磷酸酶)活性隨時間增加,有利于各類有機磷化合物從沉積物中水解.Fan等[79]定量估算了風浪擾動下太湖懸浮顆粒物中磷的生物轉化量,因生物分解導致的上覆水磷負荷的增量約為425.8t/a,并認為在水動力作用的促進下,附著于懸浮顆粒上的磷的生物分解對上覆水SRP負荷量的增加做出了重要貢獻.

研究表明擾動使得底泥氮磷釋放速率增大,Huang等[67]提出低至中度的擾動促使沉積物中氮磷及其他養分的釋放.Jiang等[58]的研究指出,擾動強度為25,50,100r/min時,TP、TN的釋放速率比靜態條件下分別增加了36.2%?41.7%?127.6%,呈現顯著增加的趨勢.同時,擾動帶來的沉積物-水界面的壓力差也會促進氮的釋放,Wu等[80]提出強風浪作用導致孔隙水運動大大增加了氮的擴散速率,在4和10cm高的風浪作用下,上覆水體NH4+濃度增加了0.016mg/L,是沉積物間隙水中NH4+降幅的近1倍.

在此基礎上,學者們深入探究了引起底泥懸浮的臨界擾動強度.Wang等[81]認為臨界風速可用于表征沉積物所受擾動大小,并提出引起太湖梅良灣沉積物再懸浮的臨界風速約為7m/s,此條件下的平均再懸浮率為1000g/(m2d).Li等[82]以湍流強度表述水體擾動的大小,提出在湍流強度較小時(3.6×10-3m2/ s3),水體中磷酸鹽的釋放較初始水平增加了36.36%;而當湍流強度增大至7.4×10-2m2/s3時,沉積物大量懸浮,從而使得磷被懸浮物吸附固定,抑制其釋放.值得注意的是,擾動作用過程常表現為最初釋放劇烈,隨后逐漸減緩并最終達到平衡.Yu等[83]通過水槽實驗模擬太湖沉積物釋放特性發現,TDP和TDN的釋放在最初30min內最劇烈, 30～60min輕度釋放,最后達到平衡,TDP和TDN的總釋放量及其平衡濃度的增長速率在達到一定值后減慢,Zhang等[84]的研究也得出類似的結論.

目前大多研究采用湖面風速、湍流強度、紊動強度來表征水體擾動強度,尚未形成統一的表征因子.同時,各研究以不同形態的氮磷為研究對象,如水體總磷總氮濃度、膠體氮(CN)?膠體磷(CP)濃度以及真溶解態氮(UDN)、真溶解態磷(UDP)等,結果之間缺乏可比性.因此,未來對水體擾動的研究中有必要提出通用的擾動強度表征因子和代表性氮磷元素標的,以便各研究之間的相互借鑒.此外,水體擾動的強度與持續時間等特征參數對氮磷釋放進程的定量化影響機制、再懸浮過程沉積物釋放氮磷的動力學過程及生態效應尚缺乏系統性的研究成果,如擾動之后沉積物氮磷再分配行為的響應機制,以及有多少氮磷重新吸附沉淀回到沉積物中,有多少被生物利用等問題需深入探究.

2.4 其他因子

水動力條件不僅體現在流速?水位?水體擾動這幾種因子上,國內外的很多學者從不同的角度對其他水動力表征因子進行了研究.

湖泊水庫的換水周期直接影響水體中營養物的濃度與停留時間,以及水體中發生的生物和化學反應過程時間長短.Hatcher和Frith[85]的研究表明,水體內銨濃度的長期均值與湖泊換水周期具有很好的相關性,在湖泊水質惡劣的情況下,換水周期過長會導致水質在空間上存在較大的差異性,減弱湖泊水動力;而換水周期過短則不利于水生生物的生長.因而換水周期也存在閾值問題,Wang等[50]通過構建湖泊水動力?沉積物-水營養鹽轉化?生物生長代謝及種群競爭等過程耦合的EcoTaihu模型,模擬了各湖區營養鹽狀況,得到太湖最適宜換水周期為150～160d.還有的研究將換水周期與其他因子耦合分析其對于營養鹽釋放的影響,Gao和Zong[86]采用鹽度、水齡和營養鹽之間的雙變量回歸分析,提出在一定程度上水齡參數顯著決定了研究區內營養鹽濃度的變化,明顯改變了氮磷釋放通量.

水體流態發生變化時,新的形態特征會改變水體物質分布特征.Xu等[87]在研究黃河河口營養鹽通量時發現,河口水流形態由于水沙調節而從原來的單一羽流變為雙羽流.羽流形態的改變使得營養鹽的混合更加均勻,也導致水體鹽度更低,水齡更小,從而影響水體氮磷的遷移輸送過程.除此之外水動力條件的改變還會影響水體混合過程,可能會使下層水體出現躍溫層現象,增大下層水體水層間粘滯力,從而抑制氮磷的大量釋放過程[88].除此之外,近年來還有研究對沉積物液化狀態進行探究,提出液化狀態的沉積物比固結狀態時釋放出更多的磷進入上覆水體中,Xu等[89]通過對比研究發現液化階段的總磷、總溶解磷分別是固結階段的59倍和25倍;Zhang等[61]采用不同水頭差來模擬波浪擾動作用,提出液化狀態下總氮和總溶解態氮的釋放速率會隨著水動力的增強而增加,且顯著高于固結狀態情境.

在考慮其他因子對于氮磷釋放造成的影響時,部分研究從單一變量角度出發,而忽視了其他因素的耦合作用,從而使得研究結果存在較大偏差.因此,對氮磷釋放的影響需要進一步探究多因子的耦合效應,以更準確的為淺水湖泊的管理提供科學依據.

3 結論與展望

水動力條件對淺水湖泊沉積物氮磷釋放的影響機制復雜,流速、水位、水體擾動等是影響沉積物氮磷釋放的主要水動力因子.水動力因子通過改變水體理化環境特征與沉積物特征而影響沉積物氮磷的釋放過程,還能通過影響水生生物、微生物等生長代謝過程而間接影響沉積物對氮磷的釋放.流速、擾動等因子均存在臨界值,高于或低于臨界值會對氮磷釋放產生不同的效果.同時,各水動力條件對沉積物界面氮磷釋放的影響不是線性關系,而是多個因子相互耦合作用,互相影響和聯系,存在顯著的不確定性特征.

目前水動力條件對沉積物氮磷釋放影響的定量關系并不明確,并且多種效應耦合下產生的綜合影響還有待研究,在研究方法、技術手段方面仍有待完善.針對當前研究中存在的不足,提出以下幾點展望.

3.1 由于淺水湖泊生態系統是一個要素高度關聯和互饋的多過程非線性系統,變化環境下影響沉積物-水界面氮磷釋放過程的環境因子較多,因子的作用強度及互饋關系具有不確定性.因此未來的研究需要結合野外監測?室內氮磷靜態模擬和釋放動力學實驗,厘清多因子共同作用下的釋放機制,更全面的預測評估水動力學條件改變帶來的影響.

3.2 當前對沉積物釋放的水動力學過程的研究手段多集中室內模擬實驗,對其動力學過程及機制研究還不夠深入,未來研究需要擴展時空尺度,結合原位監測、原型觀測,耦合水動力學模型、生態模型、系統動力學理論等多種研究手段,建立原位監測-耦合模擬綜合研究體系,從優化研究手段出發精確模擬水動力條件對于沉積物氮磷釋放的影響.

3.3 當前研究主要針對沉積物氮磷的吸附-釋放過程,缺少釋放之后對生態系統所產生影響的系統性探究,因此需要闡明釋放后的氮磷歸趨、再分配行為,明確釋放出的氮磷被重新吸附回到沉淀物中的比例、被生物利用的比例以及對于生物產生的影響,以便進一步明晰內源氮磷釋放對生態系統產生的綜合影響.

[1] 劉靜玲,楊志峰,林 超,等.流域生態需水規律研究[J]. 中國水利, 2006,(13):18-21. Liu J L, Yang Z F, Lin C, et al. Research on the rule of river basin eco-system demand [J]. China Water Resources, 2006,(13):18-21.

[2] Singh M, Sinha R. Evaluating dynamic hydrological connectivity of a floodplain wetland in North Bihar, India using geostatistical methods [J]. Science of the Total Environment, 2019,651:2473-2488.

[3] 劉正文,蘇雅玲,楊 柳.湖沼學是研究內陸水體的多學科整合科學——兼論我國湖沼學發展面臨的挑戰與機遇[J]. 湖泊科學, 2020,32(5):1244-1253. Liu Z W, Su Y L, Yang L. Limnology is a multidisciplinary and integrative science for studying inland waters: With special reference to the challenges and opportunities for the development of limnology [J]. Journal of Lake Sciences, 2020,32(5):1244-1253.

[4] Noe G B, Hupp C R. Carbon, nitrogen, and phosphorus accumulation in floodplains of Atlantic Coastal Plain rivers, USA [J]. Ecological Applications, 2005,15(4):1178-1190.

[5] 楊 洋,劉其根,胡忠軍,等.太湖流域沉積物碳氮磷分布與污染評價[J]. 環境科學學報, 2014,34(12):3057-3064. Yang Y, Liu Q G, Hu Z J, et al. Spatial distribution of sediment carbon, nitrogen and phosphorus and pollution evaluation of sediment in Taihu Lake Basin [J]. Acta Scientiae Circumstantiae, 2014,34(12):3057- 3064.

[6] Xia X, Zhang S, Li S, et al. The cycle of nitrogen in river systems: sources, transformation, and flux [J]. Environmental Science- Processes & Impacts, 2018,20(6):863-891.

[7] Zhou A M, Tang H X, Wang D S. Phosphorus adsorption on natural sediments: Modeling and effects of pH and sediment composition [J]. Water Research, 2005,39(7):1245-1254.

[8] 梁培瑜,王 烜,馬芳冰.水動力條件對水體富營養化的影響[J]. 湖泊科學, 2013,25(4):455-462. Liang P Y, Wang X, Ma F B. Effect of hydrodynamic conditions on water eutrophication:A review [J]. Journal of Lake Sciences, 2013, 25(4):455-462.

[9] Paerl H W, Scott J T, McCarthy M J, et al. It Takes Two to Tango: When and Where Dual Nutrient (N & P) Reductions Are Needed to Protect Lakes and Downstream Ecosystems [J]. Environmental Science & Technology, 2016,50(20):10805-10813.

[10] Xiao Y, Cheng H K, Yu W W, et al. Effects of water flow on the uptake of phosphorus by sediments: An experimental investigation [J]. Journal of Hydrodynamics, 2016,28(2):329-332.

[11] 范成新,劉 敏,王圣瑞,等.近20年來我國沉積物環境與污染控制研究進展與展望[J]. 地球科學進展, 2021,36(4):346-374. Fan C X, Liu M, Wang S R, et al. Research progress and prospect of sediment environment and pollution control in China in recent 20years [J]. Advances in Earth Science, 2021,36(4):346-374.

[12] 李乾崗,田 穎,劉 玲,等.水體中沉積物氮和磷的釋放機制及其影響因素研究進展[J]. 濕地科學, 2022,20(1):94-103. Li Q G, Tian Y, Liu L, et al. Research progress on release mechanisms of nitrogen and phosphorus of sediments in water bodies and their Influencing factors [J]. Wetland Science, 2022,20(1):94-103.

[13] 高 麗,楊 浩,周健民.湖泊沉積物中磷釋放的研究進展[J]. 土壤, 2004,(1):12-15,36. Gao L, Yang H, Zhou J M. Research progress on phosphorus release from lake sediments [J]. Soils, 2004,(1):12-15,36.

[14] Withers P J A, Jarvie H P. Delivery and cycling of phosphorus in rivers: A review [J]. Science of the Total Environment, 2008,400(1-3):379- 395.

[15] Kang M, Peng S, Tian Y, et al. Effects of dissolved oxygen and nutrient loading on phosphorus fluxes at the sediment-water interface in the Hai River Estuary, China [J]. Marine Pollution Bulletin, 2018, 130:132-139.

[16] Zhao K, Fu H, Zhu Y, et al. Environmental Impacts of Nitrogen and Phosphorus Nutrient Diffusion Fluxes at a Sediment-Water Interface: The Case of the Yitong River, China [J]. Sustainability, 2023,15(2): 1210.

[17] Qian J, Zheng S S, Wang P F, et al. Experimental study on sediment resuspension in Taihu Lake under different hydrodynamic disturbances [J]. Journal of Hydrodynamics, 2011,23(6):826-833.

[18] 鐘小燕,王船海,庾從蓉,等.流速對太湖河道底泥泥沙、營養鹽釋放規律影響實驗研究[J]. 環境科學學報, 2017,37(8):2862-2869. Zhong X Y, Wang C H, Yu C R, et al. Characteristics of sediments and nutrient release under different flow velocity [J]. Acta Scientiae Circumstantiae, 2017,37(8):2862-2869.

[19] Barlow K, Nash D, Grayson R. Investigating phosphorus interactions with bed sediments in a fluvial environment using a recirculating flume and intact soil cores [J]. Water Research, 2004,38(14/15):3420- 3430.

[20] 朱廣偉,秦伯強,張 路,等.太湖底泥懸浮中營養鹽釋放的波浪水槽試驗[J]. 湖泊科學, 2005,(1):61-68. Zhu G W, Qin B Q, Zhang L, et al. Wave effects on nutrient release of sediments from Lake Taihu by flume experiments [J]. Journal of Lake Sciences, 2005,(1):61-68.

[21] 童亞莉,梁 濤,王凌青,等.雙向環形水槽模擬變化水位和流速下洞庭湖沉積物氮釋放特征[J]. 湖泊科學, 2016,28(1):59-67. Tong Y L, Liang T, Wang L Q, et al. Characteristics of nitrogen release from Lake Dongting sediments under variable water level and velocity in the two-way annular flume [J]. Journal of Lake Sciences, 2016,28 (1):59-67.

[22] 彭進平,逄 勇,李一平,等.水動力條件對湖泊水體磷素質量濃度的影響[J]. 生態環境, 2003,(4):388-392. Peng J P, Pang Y, Li Y P, et al. The effect of water dynamical condition on phosphorus in lake [J]. Ecology and Environmental Sciences, 2003, (4):388-392.

[23] Li Y, Pang Y, Lu J, et al. On the Relation Between the Release Rate of TN, TP from Sediment and Water Velocity [J]. Scientia Limnologica Sinica, 2004,16(4):318-324.

[24] Pang Y, Han T, Li Y-p, et al. Simulation and model computation on dynamic release of nutrition factors of bottom mud in Taihu Lake [J]. Chinese Journal of Environmental Science, 2007,28(9):1960-1964.

[25] Ding L, Wu J Q, Pang Y, et al. Simulation study on algal dynamics based on ecological flume experiment in Taihu Lake, China [J]. Ecological Engineering, 2007,31(3):200-206.

[26] Huang L, Fang H, Reible D. Mathematical model for interactions and transport of phosphorus and sediment in the Three Gorges Reservoir [J]. Water Research, 2015,85:393-403.

[27] House W A, Denison F H, Armitage P D. Comparison of the uptake of inorganic phosphorus to a suspended and stream bed sediment [J]. Water Research, 1995,29(3):767-779.

[28] House W A, Denison F H, Smith J T, et al. An investigation of the effects of water velocity on inorganic phosphorus influx to a sediment [J]. Environmental Pollution, 1995,89(3):263-271.

[29] 王興奎.河流動力學基礎[M]. 北京:中國水利水電出版社, 2002: 195-210. Wang X K. Fundamental River Mechanics [M]. Beijing: China Water & Power Press, 2002:195-210.

[30] Geng X, Li D P, Xu C T, et al. Using sediment resuspension to immobilize sedimentary phosphorus [J]. Environmental Science and Pollution Research, 2021,28(2):1837-1849.

[31] Xie L Q, Xie P. Long-term (1956-1999) dynamics of phosphorus in a shallow, subtropical Chinese lake with the possible effects of cyanobacterial blooms [J]. Water Research, 2002,36(1):343-349.

[32] Wan J, Wang Z, Li Z, et al. Critical velocity in phosphorus exchange processes across the sediment-water interface [J]. Journal of Environmental Sciences, 2013,25(10):1966-1971.

[33] Huang L, Fang H, Fazeli M, et al. Mobility of phosphorus induced by sediment resuspension in the Three Gorges Reservoir by flume experiment [J]. Chemosphere, 2015,134:374-379.

[34] Sharma A, Huang L, Fang H, et al. Effects of hydrodynamic on the mobility of phosphorous induced by sediment resuspension in a seepage affected alluvial channel [J]. Chemosphere, 2020,260.

[35] Wu Q X, Han G L, Yang T. Effects of Water Level Fluctuations on Ecological Environment of Lake/Reservoir Riparian Zone: A Review [J]. Earth and Environment, 2009,37(4):446-453.

[36] Tang X Q, Wu M, Li Q Y, et al. Impacts of water level regulation on sediment physic-chemical properties and phosphorus adsorption- desorption behaviors [J]. Ecological Engineering, 2014,70:450-458.

[37] Sun H, Zhao S, Gang D, et al. Organic P transformations and release from riparian soils responding to water level fluctuation [J]. Environmental Monitoring and Assessment, 2021,193(12):781.

[38] Tang X, Wu M, Yang W, et al. Impact of Simulated Water Level Regulation on Sediment Nutrient Release [J]. Water Air and Soil Pollution, 2015,226(8):248.

[39] 白曉華,胡維平.太湖水深變化對氮磷濃度和葉綠素a濃度的影響[J]. 水科學進展, 2006,(5):727-732. Bai X H, Hu W P. Effect of water depth on concentration of TN, TP and Chla in Taihu Lake, China [J]. Advances in Water Science, 2006, (5):727-732.

[40] 王悅敏,倪兆奎,馮明雷,等.鄱陽湖枯水期沉積物磷釋放特征及對水位變化響應[J]. 環境科學學報, 2017,37(10):3804-3812. Wang Y M, Ni Z K, Feng M L, et al. Characteristics of phosphorus release in sediment and its response to the change of water level in Poyang Lake in dry season [J]. Acta Scientiae Circumstantiae, 2017,37 (10):3804-3812.

[41] Yu J, Zhang Y, Zhong J, et al. Water-level alterations modified nitrogen cycling across sediment-water interface in the Three Gorges Reservoir [J]. Environmental Science and Pollution Research, 2020, 27(21):25886-25898.

[42] Tong Y L, Liang T, Wang L Q, et al. Simulation on phosphorus release characteristics of Poyang Lake sediments under variable water levels and velocities [J]. Journal of Geographical Sciences, 2017,27(6): 697-710.

[43] Ye L, Tan L, Wu X H, et al. Nonlinear causal analysis reveals an effective water level regulation approach for phytoplankton blooms controlling in reservoirs [J]. Science of the Total Environment, 2022, 806.

[44] Bai X, Chen K N, Ren K X, et al. Influence of Myriophyllum spicatums growth on nitrogen and phosphorus in sediment in different water depth [J]. Ecology and Environmental Sciences, 2011,20(6/7): 1086-1091.

[45] Liu D, Wang X, Zhang Y L, et al. A Landscape Connectivity Approach for Determining Minimum Ecological Lake Level: Implications for Lake Restoration [J]. Water, 2019,11(11):2237.

[46] Xia J, Chen Y, Zhou Z, et al. Review of mechanism and quantifying methods of river system connectivity [J]. Advances in Water Science, 2017,28(5):780-787.

[47] Beck W J, Moore P L, Schilling K E, et al. Changes in lateral floodplain connectivity accompanying stream channel evolution: Implications for sediment and nutrient budgets [J]. Science of the Total Environment, 2019,660:1015-1028.

[48] 劉 丹,王 烜,李春暉,等.水文連通性對湖泊生態環境影響的研究進展[J]. 長江流域資源與環境, 2019,28(7):1702-1715. Liu D, Wang X, Li C H, et al. Eco-environmental effects of hydrological connectivity on lakes: a review [J]. Resources and Environment in the Yangtze Basin, 2019,28(7):1702-1715.

[49] 郭云騰.四湖流域水文連通度及其對洪水期水文過程的影響[D]. 華中師范大學, 2014. Guo Y T. Hydrological connectivity and the hydrological processes influence on flood season in Si hu Area [D]. Central China Normal University, 2014.

[50] 王冼民,翟淑華,張紅舉,等.基于水質改善目標的太湖適宜換水周期分析[J]. 湖泊科學, 2017,29(1):9-21. Wang X M, Zhai S H, Zhang H J, et al. Research on appropriate hydraulic retention time on basis of water quality improvement of Lake Taihu [J]. Journal of Lake Sciences, 2017,29(1):9-21.

[51] 吳浩云,賈更華,徐 彬,等.1980年以來太湖總磷變化特征及其驅動因子分析[J]. 湖泊科學, 2021,33(4):974-991. Wu H Y, Jia G H, Xu B, et al. Analysis of variation and driving factors of total phosphrus in Lake Taihu, 1980～2020 [J]. Journal of Lake Sciences, 2021,33(4):974-991.

[52] Sun J, Xiao Y, Zhang L, et al. Study of effect of connection engineering between Liangzi Lake and Tangxun Lake in Wuhan City [J]. Engineering Journal of Wuhan University, 2018,51(2):125-131.

[53] 鄭 清,李 建,段功豪,等.水網連通工程對大東湖水動力影響的研究[J]. 水電能源科學, 2016,34(2):90-93,68. Zheng Q, Li J, Duan G H, et al. Influences of water-network connection project on hydrodynamic conditions in East Lake [J]. Water Resources and Power, 2016,34(2):90-93,68.

[54] 曹慧群,李曉萌,羅慧萍.大東湖水網連通的水動力與水環境變化響應[J]. 人民長江, 2020,51(5):54-59. Cao H Q, Li X M, Luo H P. Hydrodynamic and water environmental response to Great Donghu Lake Water Network Connection Project [J]. Yangtze River, 2020,51(5):54-59.

[55] Qin B Q, Zhu G W, Luo L C, et al. Estimation of internal nutrient release in large shallow Lake Taihu, China [J]. Science in China Series D-Earth Sciences, 2006,49:38-50.

[56] 朱廣偉,秦伯強,高 光.風浪擾動引起大型淺水湖泊內源磷暴發性釋放的直接證據[J]. 科學通報, 2005,(1):66-71. Zhu G W, Qin B Q, Gao G. Direct evidence of sudden release of endogenous phosphorus from large shallow lakes caused by wind and wave disturbance [J]. Chinese Science Bulletin, 2005,(1):66-71.

[57] 汪家權,孫亞敏,錢家忠,等.巢湖底泥磷的釋放模擬實驗研究[J]. 環境科學學報, 2002,(6):738-742. Wang J Q, Sun Y M, Qian J Z, et al. Simulated study on phosphorus release of Chao Lake sediment [J]. Acta Scientiae Circumstantiae, 2002,(6):738-742.

[58] 姜永生,李曉晨,邢友華,等.擾動對東平湖表層沉積物中氮磷釋放的影響[J]. 環境科學與技術, 2010,33(8):41-44. Jiang Y S, Li X C, Xing Y H, et al. Impacts of disturbance on release of total nitrogen and total phosphorus from surficial sediments of Dongping Lake [J]. Environmental Science & Technology, 2010, 33(8):41-44.

[59] Hu K M, Pang Y, Wang H, et al. Simulation study on water quality based on sediment release flume experiment in Lake Taihu, China [J]. Ecological Engineering, 2011,37(4):607-615.

[60] Sun X J, Zhu G W, Luo L C, et al. Experimental study on phosphorus release from sediments of shallow lake in wave flume [J]. Science in China Series D-Earth Sciences, 2006,49:92-101.

[61] 張嚴嚴,房文艷,許國輝,等.波浪作用下沉積物中氮、磷釋放速率的試驗研究[J]. 中國海洋大學學報(自然科學版), 2020,50(4): 102-110. Zhang Y Y, Fang W Y, Xu G H, et al. Release rate of nitrogen and phosphorus from sediments under wave action [J]. Periodical of Ocean University of China, 2020,50(4):102-110.

[62] Huang L, Fang H W, He G J, et al. Effects of internal loading on phosphorus distribution in the Taihu Lake driven by wind waves and lake currents [J]. Environmental Pollution, 2016,219:760-773.

[63] 夏 波,張慶河,蔣昌波,等.水體紊動作用下湖泊泥沙解吸釋放磷的實驗研究[J]. 泥沙研究, 2014,(1):74-80. Xia B, Zhang Q H, Jiang C B, et al. Experimental investigation of effect of flow turbulence on phosphorus release from lake sediment [J]. Journal of Sediment Research, 2014,(1):74-80.

[64] Sun X, Zhu G, Luo L, et al. Experimental study on phosphorus release from sediments of shallow lake in wave flume [J]. Science in China Series D-Earth Sciences, 2006,49:92-101.

[65] Hu K, Pang Y, Wang H, et al. Simulation study on water quality based on sediment release flume experiment in Lake Taihu, China [J]. Ecological Engineering, 2011,37(4):607-615.

[66] Huang J, Xu Q, Xi B, et al. Impacts of hydrodynamic disturbance on sediment resuspension, phosphorus and phosphatase release, and cyanobacterial growth in Lake Tai [J]. Environmental Earth Sciences, 2015,74(5):3945-3954.

[67] Huang J, Xi B D, Xu Q J, et al. Experiment study of the effects of hydrodynamic disturbance on the interaction between the cyanobacterial growth and the nutrients [J]. Journal of Hydrodynamics, 2016,28(3):411-422.

[68] Li T, Wang D, Zhang B, et al. Characterization of the phosphate adsorption and morphology of sediment particles under simulative disturbing conditions [J]. Journal of Hazardous Materials, 2006,137 (3):1624-1630.

[69] 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研究[J]. 中國科學(D輯:地球科學), 2005,(S2):81-89. Sun X J, Zhu G W, Luo L C, et al. Experimental study of phosphorus release from shallow lake sediments by wave flume [J]. Scientia Sinica (Terrae), 2005,(S2):81-89.

[70] 孫小靜,秦伯強,朱廣偉,等.持續水動力作用下湖泊底泥膠體態氮、磷的釋放[J]. 環境科學, 2007,(6):1223-1229. Sun X J, Qin B Q, Zhu G W, et al. Release of colloidal N and P from sediment of lake caused by continuing hydrodynamic disturbance [J]. Environmental Science, 2007,(6):1223-1229.

[71] 華祖林,王 苑.水動力作用下河湖沉積物污染物釋放研究進展[J]. 河海大學學報(自然科學版), 2018,46(2):95-105. Hua Z L, Wang Y. Advance on the release of pollutants in river and lake sediments under hydrodynamic conditions [J]. Journal of Hohai University (Natural Sciences), 2018,46(2):95-105.

[72] Jiang X, Jin X, Yao Y, et al. Effects of biological activity, light, temperature and oxygen on phosphorus release processes at the sediment and water interface of Taihu Lake, China [J]. Water Research, 2008,42(8/9):2251-2259.

[73] Ni Z, Wang S. Historical accumulation and environmental risk of nitrogen and phosphorus in sediments of Erhai Lake, Southwest China [J]. Ecological Engineering, 2015,79:42-53.

[74] Peng J F, Wang B Z, Song Y H, et al. Adsorption and release of phosphorus in the surface sediment of a wastewater stabilization pond [J]. Ecological Engineering, 2007,31(2):92-97.

[75] Wang Y, Shen Z, Niu J, et al. Adsorption of phosphorus on sediments from the Three-Gorges Reservoir (China) and the relation with sediment compositions [J]. Journal of Hazardous Materials, 2009,162 (1):92-98.

[76] 楊文斌,唐 皓,韓 超,等.太湖沉積物鐵形態分布特征及磷鐵相關性分析[J]. 中國環境科學, 2016,36(4):1145-1156. Yang W B, Tang H, Han C, et al. Distribution of iron forms and their correlations analysis with phosphorus forms in the sedimentary profiles of Taihu Lake [J]. China Environmental Science, 2016,36(4): 1145-1156.

[77] Zhao H, Zhang L, Wang S, et al. Features and influencing factors of nitrogen and phosphorus diffusive fluxes at the sediment-water interface of Erhai Lake [J]. Environmental Science and Pollution Research, 2018,25(2):1933-1942.

[78] 晁建穎,高 光,湯祥明,等.風浪擾動中太湖OA對水體磷循環影響的原位實驗研究[J]. 環境科學, 2011,32(10):2861-2867. Chao J Y, Gao G, Tang X M, et al. Effects of Wind-Induced Wave on Organic Aggregates Physical and Chemical Characteristics in a Shallow Eutrophic Lake (Lake Taihu) in China [J]. Environmental Science, 2011,32(10):2861-2867.

[79] 范成新,張 路,秦伯強,等.風浪作用下太湖懸浮態顆粒物中磷的動態釋放估算[J]. 中國科學(D輯:地球科學), 2003,(8):760-768. Fan C X, Zhang L, Qin B Q, et al. Estimation of dynamic phosphorus release from suspended particulate matter in Taihu Lake under wind and waves [J]. Scientia Sinica (Terrae), 2003,(8):760-768.

[80] Wu T F, Qin B Q, Zhu G W, et al. Flume simulation of wave-induced release of internal dissolved nitrogen in Taihu Lake, China [J]. Chinese Journal of Oceanology and Limnology, 2012,30(5):796-805.

[81] Wang J, Pang Y, Li Y, et al. The regularity of wind-induced sediment resuspension in Meiliang Bay of Lake Taihu [J]. Water Science and Technology, 2014,70(1):167-174.

[82] Li H, Yang G, Ma J, et al. The role of turbulence in internal phosphorus release: Turbulence intensity matters [J]. Environmental Pollution, 2019,252:84-93.

[83] Yu Z, Zhong X, Yu C, et al. Characteristics of nutrient release from sediments under different flow conditions [J]. Chemical Speciation and Bioavailability, 2017,29(1):70-77.

[84] Zhang K, Cheng P D, Zhong B C, et al. Total phosphorus release from bottom sediments in flowing water [J]. Journal of Hydrodynamics, 2012,24(4):589-594.

[85] Hatcher A I, Frith C A. The control of nitrate and ammounium concentrations in a coral-reef lagoon [J]. Coral Reefs, 1985,4(2): 101-110.

[86] Gao L, Zong H. Using water age to study the biogeochemistry of nutrients in a large-river estuary and the adjacent shelf area [J]. Journal of Marine Systems, 2021,214.

[87] Xu B, Yang D, Burnett W C, et al. Artificial water sediment regulation scheme influences morphology, hydrodynamics and nutrient behavior in the Yellow River estuary [J]. Journal of Hydrology, 2016,539:102- 112.

[88] 劉洪波,朱夢羚,王精志,等.水庫水動力對水體富營養化影響[J]. 水資源與水工程學報, 2013,24(2):19-21. Liu H B, Zhu M L, Wang J Z, et al. Influence of reservoir hydrodynamic on eutrophication of water body [J]. Journal of Water Resources and Water Engineering, 2013,24(2):19-21.

[89] Xu G, Sun Z, Fang W, et al. Release of phosphorus from sediments under wave-induced liquefaction [J]. Water Research, 2018,144:503- 511.

[90] Ishikawa M, Nishimura H. Mathematical-model of phosphate release rate from sediments considering the effect of dissolved-oxygen in overlying water [J]. Water Research, 1989,23(3):351-359.

[91] Nakamura Y. Effects of flow velocity on phosphate release from sediment [J]. Water Science and Technology, 1994,30(10):263-272.

Effects of hydrodynamic conditions on nitrogen and phosphorus release from sediments in shallow lakes.

YU Jing-zhi1,2, WANG Xuan1,2*, CAI Jian-ying1,2, LIAO Zhen-mei1,2, LI Chun-hui2, LIU Qiang2

(1.State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China；2.Key Laboratory for Water and Sediment Sciences of Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875, China)., 2023,43(8)：4219～4228

Hydrodynamic conditions are the main natural factors affecting the release of nitrogen and phosphorus from sediments in shallow lakes. It is meaningful to study the effects of hydrodynamic conditions on the release of nitrogen and phosphorus in sediments and to grasp the migration and transformation of water nutrients for preventing lake endogenous pollution in lakes. Among the hydrodynamic factors, the flow velocity can change the exchange flux of nitrogen and phosphorus of the sediment-water interface by affecting the shear stress. Both water level and water disturbance affect the physical and chemical characteristics of surface sediments and the REDOX reaction process of sediment-water interface, and thus jointly affect the release of nitrogen and phosphorus through multiple coupling effects. The mechanism of major hydrodynamic factors such as velocity, water level, water disturbance on nitrogen and phosphorus release in shallow lake sediments was reviewed and the prospect was put forward: The mechanism of coupling effects of various hydrodynamic factors on nitrogen and phosphorus release, the construction of in-situ monitoring and coupling simulation research system based on multi-temporal and spatial scales, and the impact of endogenous nitrogen and phosphorus release on the ecosystem need to be further strengthened.

hydrodynamic condition；shallow lake；sediment；nitrogen and phosphorus release；prevention and control of endogenous

X524

A

1000-6923(2023)08-4219-10

余景芝(2000-),女,江西九江人,北京師范大學碩士研究生,主要研究方向為流域水環境過程.yujz2000@mail.bnu.edu.cn.

余景芝,王 烜,蔡劍英,等.水動力條件對淺水湖泊沉積物氮磷釋放的影響 [J]. 中國環境科學, 2023,43(8):4219-4228.

Yu J Z, Wang X, Cai J Y, et al. Effects of hydrodynamic conditions on nitrogen and phosphorus release from sediments in shallow lakes [J]. China Environmental Science, 2023,43(8):4219-4228.

2023-01-17

國家自然科學基金資助項目(52270194,52070024)

* 責任作者, 教授, wangx@bnu.edu.cn