流域重金屬遷移模型研究進(jìn)展

劉連華,張晴雯,王依滴,顧 翔

流域重金屬遷移模型研究進(jìn)展

劉連華1,張晴雯1,王依滴2*,顧 翔3

(1.中國(guó)農(nóng)業(yè)科學(xué)院農(nóng)業(yè)環(huán)境與可持續(xù)發(fā)展研究所農(nóng)業(yè)清潔流域團(tuán)隊(duì),北京 100081；2.北京大學(xué)環(huán)境科學(xué)與工程學(xué)院,水沙科學(xué)教育部重點(diǎn)實(shí)驗(yàn)室,北京 100871；3.北京師范大學(xué)環(huán)境學(xué)院,北京 100875)

論述了流域重金屬的主要來(lái)源和遷移機(jī)理,梳理了目前常用的經(jīng)驗(yàn)?zāi)Ｐ秃蜋C(jī)理模型的特點(diǎn),比較了兩類模型在流域重金屬遷移模擬中的優(yōu)缺點(diǎn).結(jié)果表明,從簡(jiǎn)單線性或非線性的經(jīng)驗(yàn)?zāi)Ｐ偷娇紤]隨著水文和土壤侵蝕等遷移轉(zhuǎn)化過(guò)程的機(jī)理模型,流域重金屬遷移模型的適用范圍逐漸擴(kuò)大、模擬精度不斷提高,在重金屬污染負(fù)荷估算和水質(zhì)預(yù)測(cè)等方面發(fā)揮了重要作用.經(jīng)驗(yàn)?zāi)Ｐ蛯?duì)基礎(chǔ)數(shù)據(jù)要求較低,計(jì)算過(guò)程相對(duì)簡(jiǎn)單,適用于數(shù)據(jù)缺乏流域的重金屬污染負(fù)荷宏觀評(píng)估.機(jī)理模型對(duì)數(shù)據(jù)量和數(shù)據(jù)精度要求較高,結(jié)構(gòu)復(fù)雜,可實(shí)現(xiàn)對(duì)重金屬遷移過(guò)程較為細(xì)致的模擬.同時(shí),提出了多模型耦合開發(fā)和應(yīng)用、不同遷移路徑的機(jī)理研究和重金屬污染溯源解析模擬是未來(lái)流域重金屬遷移模型研究的重點(diǎn),為流域重金屬模型應(yīng)用、模型改進(jìn)和重金屬污染溯源提供科學(xué)依據(jù).

重金屬；模型模擬；遷移轉(zhuǎn)化；過(guò)程機(jī)理；研究趨勢(shì)

隨著工業(yè)化、城市化和農(nóng)業(yè)集約化進(jìn)程的不斷加快,大量重金屬通過(guò)自然活動(dòng)和礦產(chǎn)資源開采利用等人類活動(dòng)進(jìn)入環(huán)境,在生物、物理及化學(xué)作用下累積到土壤中,并隨降雨/融雪徑流和土壤侵蝕等水文過(guò)程進(jìn)入周邊水體,導(dǎo)致嚴(yán)重的環(huán)境污染[1-2].重金屬種類較多,在環(huán)境污染研究中特別關(guān)注的重金屬主要包括生物毒性顯著的汞(Hg)、鎘(Cd)、鉛(Pb)、鉻(Cr)和類金屬(As),以及兼具營(yíng)養(yǎng)元素和生物毒性的銅(Cu)、鋅(Zn)、鎳(Ni)等.重金屬毒性強(qiáng),在環(huán)境中不可生物降解,但易被農(nóng)作物、植物和水生生物吸收,通過(guò)食物鏈對(duì)人體造成危害,對(duì)糧食和食品安全以及人類健康產(chǎn)生嚴(yán)重影響[3-4].國(guó)務(wù)院和生態(tài)環(huán)境部等國(guó)家部門發(fā)布的相關(guān)土壤污染防治行動(dòng)計(jì)劃及重金屬行業(yè)污染防控的意見中強(qiáng)調(diào)深入開展重點(diǎn)行業(yè)重金屬污染綜合治理,有效管控重點(diǎn)區(qū)域重金屬污染,體現(xiàn)了我國(guó)對(duì)于重金屬污染防治的決心.及時(shí)掌握流域重金屬污染時(shí)空分布和入河入江流失情況,有助于更好地把握重金屬對(duì)生態(tài)環(huán)境和人類健康的潛在不利影響,是重金屬污染高效精準(zhǔn)防控的前提.

流域重金屬遷移過(guò)程復(fù)雜,影響因素眾多,包括重金屬本身特性和土地利用類型等[5-6].同時(shí),重金屬遷移過(guò)程與降雨/融雪徑流和土壤侵蝕等過(guò)程密切相關(guān),重金屬污染具有較大的時(shí)空變異性和不確定性[7].由于室內(nèi)模擬、田間試驗(yàn)及區(qū)域監(jiān)測(cè)只是特定觀測(cè)尺度的結(jié)果,難以反映長(zhǎng)時(shí)間流域重金屬遷移轉(zhuǎn)化特征,因此模型被廣泛應(yīng)用于重金屬流失負(fù)荷的模擬[8-9].近年來(lái),學(xué)者們陸續(xù)開發(fā)了統(tǒng)計(jì)性經(jīng)驗(yàn)?zāi)Ｐ秃蜋C(jī)理性過(guò)程模型,可以在田塊、較小河流支流流域和較大干流如長(zhǎng)江黃河流域等多種尺度開展突發(fā)污染事件和長(zhǎng)期積累污染不同情景下的重金屬污染負(fù)荷模擬[10-15].目前,已有針對(duì)土壤重金屬污染空間分布[16]、土壤中重金屬累積預(yù)測(cè)模型[17]、水環(huán)境中重金屬的存在形態(tài)和遷移轉(zhuǎn)化規(guī)律[18]以及河流重金屬遷移轉(zhuǎn)化數(shù)學(xué)模型研究[19]等某一個(gè)方面的發(fā)展和應(yīng)用的系統(tǒng)研究.然而,對(duì)流域重金屬遷移轉(zhuǎn)化行為預(yù)測(cè)模型的發(fā)展現(xiàn)狀和未來(lái)研究重點(diǎn),缺乏系統(tǒng)性和綜合性的認(rèn)知.在系統(tǒng)梳理流域重金屬來(lái)源的基礎(chǔ)上,基于重金屬遷移轉(zhuǎn)化機(jī)理構(gòu)建適用于流域重金屬遷移模擬的模型工具,仍是目前重金屬污染研究關(guān)注的重點(diǎn)和難點(diǎn).

基于上述背景,本文系統(tǒng)闡述流域重金屬來(lái)源和遷移機(jī)理,梳理國(guó)內(nèi)外重金屬污染流失模型的主要特點(diǎn)、應(yīng)用情況和優(yōu)缺點(diǎn),歸納現(xiàn)有模型在污染來(lái)源、參數(shù)輸入等方面的關(guān)鍵問(wèn)題.在此基礎(chǔ)上提出流域重金屬遷移模型未來(lái)研究展望,為模型的改進(jìn)和應(yīng)用提供科學(xué)依據(jù).

1 流域重金屬的主要來(lái)源及遷移途徑

重金屬主要來(lái)源為自然和人為來(lái)源.自然來(lái)源以成土母質(zhì)為主,人為來(lái)源按人類活動(dòng)類型分為農(nóng)業(yè)源、工業(yè)源和生活源等[20].隨著社會(huì)經(jīng)濟(jì)的發(fā)展,頻繁的人類活動(dòng)成為影響重金屬污染最主要的因素.不同來(lái)源重金屬通過(guò)大氣沉降、雨雪徑流、土壤侵蝕、土壤淋溶等途徑進(jìn)入周邊水土環(huán)境(圖1).

1.1 農(nóng)業(yè)源

農(nóng)業(yè)源主要包括農(nóng)業(yè)生產(chǎn)活動(dòng)(如化肥施用、農(nóng)藥噴施、污水灌溉、地膜覆蓋等)產(chǎn)生的重金屬污染[21].一方面,肥料和農(nóng)藥施用可導(dǎo)致重金屬直接進(jìn)入土壤;另一方面,肥料和農(nóng)藥施用改善作物生長(zhǎng),有機(jī)肥施用可增加土壤有機(jī)質(zhì)與重金屬作用形成絡(luò)合物,提高重金屬的生物有效性,增加重金屬污染風(fēng)險(xiǎn)[22-23].某些地區(qū)引污灌溉,導(dǎo)致重金屬通過(guò)土壤-作物系統(tǒng)、土壤-水系統(tǒng)遷移,進(jìn)而隨食物鏈累積對(duì)人體構(gòu)成威脅[24-25].此外,在農(nóng)業(yè)生產(chǎn)過(guò)程中,添加有Pb、Cd、Zn、錫、鋇等重金屬元素的農(nóng)用地膜老化破碎遺留在土壤中,增加了土壤中相關(guān)重金屬元素含量,改變重金屬生物有效性,對(duì)土壤環(huán)境安全和作物生長(zhǎng)構(gòu)成威脅[26-27].

1.2 工業(yè)源

工業(yè)生產(chǎn)活動(dòng)(如礦山開采、金屬冶煉、燃煤電廠等)是影響流域重金屬污染的重要來(lái)源.礦山開采中會(huì)產(chǎn)生廢石、尾礦以及高濃度重金屬酸性廢水,給周邊環(huán)境造成潛在的重金屬污染[28].例如,研究表明湖南錫礦山銻礦區(qū)周邊土壤銻(Sb)高達(dá)271～ 3640mg/kg、河流水體中Sb高達(dá)0.0053～309mg/L,遠(yuǎn)遠(yuǎn)高于WHO推薦的含量[29].由于礦產(chǎn)開采,廣西刁江沿岸土壤受到As、Pb、Cd、Zn等多種重金屬?gòu)?fù)合污染[30].工業(yè)生產(chǎn)過(guò)程中“三廢”排放導(dǎo)致周邊水、土和大氣均受到影響,從而導(dǎo)致重金屬污染[31].未凈化達(dá)標(biāo)的工業(yè)廢水漏排或污水灌溉到農(nóng)田,富集有大量重金屬元素的工業(yè)廢渣露天堆放于地上,以及煤燃燒產(chǎn)生攜帶重金屬的廢氣,經(jīng)過(guò)大氣沉降、雨雪徑流、土壤侵蝕等進(jìn)入土壤和周邊水體,造成不同程度的重金屬污染[32-33].

1.3 生活源

日常生活過(guò)程中生活垃圾的不恰當(dāng)處理,如隨意丟棄的電池等廢棄物會(huì)向周圍環(huán)境釋放大量重金屬污染物[34].在塑料生產(chǎn)加工過(guò)程中,重金屬通常被作為阻燃劑和增塑劑,當(dāng)遇到外界環(huán)境條件刺激時(shí),Pb、Cr、Cd等重金屬會(huì)從塑料中浸出,對(duì)周圍環(huán)境造成潛在威脅[35-36].此外,汽車尾氣和汽車輪胎磨損產(chǎn)生的大量有害氣體和粉塵,造成重金屬污染物在公路邊表層土壤累積[37].

圖1 流域重金屬主要來(lái)源及遷移途徑

2 流域重金屬的遷移機(jī)理

2.1 土壤中重金屬的遷移機(jī)理

重金屬與土壤活性組分發(fā)生物理、化學(xué)以及生物界面過(guò)程,使重金屬時(shí)空分布、形態(tài)和總量發(fā)生變化[17].物理過(guò)程中對(duì)流過(guò)程使重金屬?gòu)囊粋€(gè)地方遷移至另一個(gè)地方,彌散作用使其在空間范圍發(fā)生變化,被土壤膠體吸附或包裹在土壤顆粒的重金屬離子、土壤溶液中重金屬離子或可溶于水的螯合物可隨水體遷移[38-39].化學(xué)過(guò)程包括沉淀、溶解、離子交換等,可改變固相中重金屬的組成和結(jié)構(gòu)、液相中重金屬的組成和種類、固相結(jié)構(gòu)和液相流動(dòng)性[38].生物過(guò)程指重金屬被植物吸收后積累在植物體內(nèi),或植物殘?bào)w分解后重金屬重新回到土壤中,或植物收獲后被動(dòng)物人類食用遷移到其他地方[40-41].

2.2 土壤-水體中重金屬的遷移機(jī)理

土壤重金屬進(jìn)入水體主要通過(guò)土壤侵蝕、雨雪徑流和土壤淋溶三種方式.當(dāng)發(fā)生雨雪侵蝕時(shí),顆粒態(tài)重金屬隨著侵蝕泥沙遷移,其輸出量與降雨/降雪量及泥沙流失量有直接關(guān)系[42];當(dāng)發(fā)生降雨徑流時(shí),溶解態(tài)重金屬隨地表徑流遷移,其輸出量與土壤溶解態(tài)和顆粒態(tài)重金屬的比例有關(guān)[10];表層重金屬會(huì)隨著土壤流進(jìn)入深層土壤,可隨側(cè)向流(壤中流)進(jìn)入河流或地下水系統(tǒng)[43].土壤-水體系統(tǒng)中重金屬遷移受水文氣象、土壤性質(zhì)、坡長(zhǎng)坡度、土地利用等多因素影響[44-45].另外,重金屬性質(zhì)、氧化還原電位、初始土壤含水量、有機(jī)質(zhì)含量等是影響土壤-水體中重金屬的遷移轉(zhuǎn)化的重要因素[46-48].

2.3 流域水體中重金屬的遷移機(jī)理

進(jìn)入河流、湖泊等水體的重金屬遷移主要為溶解態(tài)、懸浮態(tài)以及底泥沉積態(tài)三者之間的相互轉(zhuǎn)化[11,49].物理過(guò)程包括擴(kuò)散、推移、再懸浮、對(duì)流、沉降吸附、解吸等,化學(xué)過(guò)程包括絡(luò)合、絮凝沉淀、氧化還原等,生物過(guò)程包括微生物轉(zhuǎn)化、生物攝取、生物富集等[13,18,50-51].溶解態(tài)重金屬可隨水遷移到下游,或吸附在懸浮物上轉(zhuǎn)化為懸浮態(tài)、或通過(guò)擴(kuò)散作用進(jìn)入到底泥孔隙水中[52];懸浮態(tài)可隨水和泥沙遷移到下游、或沉入底泥轉(zhuǎn)化為沉積態(tài)、或轉(zhuǎn)化為溶解態(tài);而底泥可作為“匯”吸附重金屬,又可成為重金屬的“源”,轉(zhuǎn)化為懸浮態(tài)或溶解態(tài),造成水體的二次污染[43,53].重金屬在三相中分配受鹽度、溫度、氧化還原電位、顆粒物組成等因素影響[47,54].

3 流域重金屬遷移模擬預(yù)測(cè)

用于重金屬遷移模擬的方法主要分為兩大類:經(jīng)驗(yàn)?zāi)Ｐ秃蜋C(jī)理模型[13,55-56].經(jīng)驗(yàn)?zāi)Ｐ褪墙⒅亟饘傥廴竞屯恋乩玫拳h(huán)境因子間的經(jīng)驗(yàn)關(guān)系,通過(guò)經(jīng)驗(yàn)系數(shù)核算污染負(fù)荷.機(jī)理模型是綜合考慮污染物產(chǎn)生、遷移轉(zhuǎn)化和匯集過(guò)程及其他影響因素對(duì)重金屬遷移進(jìn)行模擬.

3.1 經(jīng)驗(yàn)?zāi)Ｐ?/h3>

經(jīng)驗(yàn)?zāi)Ｐ椭饕峭ㄟ^(guò)對(duì)典型區(qū)域監(jiān)測(cè)和實(shí)驗(yàn)提取相關(guān)的數(shù)據(jù),研究水文參數(shù)、景觀參數(shù)、土壤類型、土地利用與重金屬污染負(fù)荷產(chǎn)生量之間的關(guān)系,建立經(jīng)驗(yàn)關(guān)系式,進(jìn)行負(fù)荷定量評(píng)估[13,57-58].常用的經(jīng)驗(yàn)?zāi)Ｐ?見表1.經(jīng)典輸出系數(shù)模型是Johnes在1996年提出,考慮了土地利用方式、社會(huì)經(jīng)濟(jì)、人口數(shù)量等對(duì)污染負(fù)荷的影響[59].在后續(xù)發(fā)展中,學(xué)者們建立了一系列的改進(jìn)輸出系數(shù)法模型,包括考慮流域重金屬離子有效性和溶于水的物質(zhì)有所不同,引入了土壤侵蝕模數(shù)和重金屬的水溶出率因子[55];考慮降雨和地形影響因素,在模型中引入降雨影響因子和地形影響因子[56].亦有學(xué)者結(jié)合不同土地利用類型采樣分析,利用空間信息技術(shù)和通用土壤流失方程與降雨徑流模型,計(jì)算不同土地利用類型的土壤侵蝕量與地表徑流量,估算流域重金屬在不同土地利用方式下的污染負(fù)荷[60-61].重金屬在河流、湖泊或水庫(kù)中的遷移也可以通過(guò)沖刷系數(shù)和沉積系數(shù)來(lái)解釋水體和底泥之間的物質(zhì)交換關(guān)系,一般通過(guò)大量室內(nèi)模擬試驗(yàn)獲得吸附解析過(guò)程中的關(guān)鍵參數(shù)值,建立簡(jiǎn)單的水體中重金屬遷移模型[62-63].總之,輸出系數(shù)模型對(duì)基礎(chǔ)數(shù)據(jù)要求較低,所需的資料較容易得到,計(jì)算過(guò)程較為簡(jiǎn)單,可利用少量數(shù)據(jù)簡(jiǎn)便快速地估算出流域重金屬污染負(fù)荷量,對(duì)于數(shù)據(jù)缺乏地區(qū)具有較強(qiáng)的實(shí)用性.但由于輸出系數(shù)模型缺乏對(duì)重金屬遷移過(guò)程中內(nèi)部機(jī)理的詳細(xì)描述,模擬的時(shí)空精度不足,僅適用于宏觀評(píng)估流域重金屬污染負(fù)荷的研究需要.

此外,美國(guó)國(guó)家環(huán)境保護(hù)局開發(fā)的WASP(水質(zhì)分析模擬程序)模型,可模擬河流、湖、河、水庫(kù)、河岸的水質(zhì).其中的TOXI(有毒化學(xué)物質(zhì))子模塊可以作為一個(gè)簡(jiǎn)單的概念模型對(duì)重金屬遷移進(jìn)行模擬[13].已有學(xué)者應(yīng)用了WASP模型對(duì)Hg、Cd、Pb等重金屬在河流水體中的遷移進(jìn)行模擬[64-65].WASP模型具有自定義模擬條件的功能,靈活性強(qiáng),通用性高,對(duì)自然和人類活動(dòng)造成的水質(zhì)狀況具有較好的模擬效果,特別是突發(fā)性水污染事故.但該模型在水動(dòng)力學(xué)模擬方面較薄弱,對(duì)于流速低的徑流模擬不夠精確.建議該模型與其他水動(dòng)力模型同時(shí)使用,形成水動(dòng)力水質(zhì)耦合模型,提高對(duì)流域重金屬遷移過(guò)程的準(zhǔn)確模擬.

表1 常用的流域重金屬流失模擬經(jīng)驗(yàn)?zāi)Ｐ?/p>

3.2 機(jī)理模型

機(jī)理模型較經(jīng)驗(yàn)?zāi)Ｐ偷臉?gòu)建和模擬過(guò)程復(fù)雜許多,是以水文過(guò)程為載體,綜合考慮污染物的來(lái)源、遷移轉(zhuǎn)化過(guò)程和其他的影響因素,具有計(jì)算時(shí)間序列性強(qiáng)、空間分布特征清晰等優(yōu)點(diǎn)[47].由于重金屬在陸面和水體的各種行為過(guò)程(釋放、擴(kuò)散、固液分配、沉積、再懸浮等物理過(guò)程以及重金屬各形態(tài)間相互轉(zhuǎn)化的化學(xué)變化過(guò)程等)以及污染流失過(guò)程(雨雪徑流、土壤侵蝕和土壤淋溶等)都承載于水文過(guò)程之上,因此機(jī)理模型構(gòu)成復(fù)雜,參數(shù)較多,考慮的影響因素也較多,可以更為準(zhǔn)確地模擬不同水文氣象條件、土地利用變化及管理措施下,流域重金屬流失負(fù)荷的時(shí)空動(dòng)態(tài)變化[10,66].目前國(guó)內(nèi)外流域重金屬遷移模擬常用的機(jī)理模型,見表2.

TREX(二維徑流侵蝕輸出)模型是美國(guó)科羅拉多州立大學(xué)開發(fā)的流域污染物流失模型[8,67],屬于短期模型,主要關(guān)注小時(shí)、日、周尺度的降雨洪水過(guò)程中重金屬的吸附、擴(kuò)散侵蝕和入滲等過(guò)程,有學(xué)者在TREX的基礎(chǔ)上,開發(fā)了考慮137Cs與植被的相互作用的修正模型,可以模擬森林流域中銫的流失過(guò)程[68].該模型對(duì)流域重金屬遷移過(guò)程的模擬時(shí)間較短,適用于突發(fā)性污染事件的模擬,對(duì)于不同重金屬形態(tài)之間復(fù)雜轉(zhuǎn)化的模擬有待改進(jìn).

表2 常用的流域重金屬流失模擬機(jī)理模型

SWAT(土壤和水分評(píng)價(jià)工具)模型是由美國(guó)農(nóng)業(yè)部農(nóng)業(yè)研究中心開發(fā),可以預(yù)測(cè)模擬不同土壤類型、土地利用方式和管理措施等條件下,流域產(chǎn)水、產(chǎn)沙和化學(xué)物質(zhì)流失的時(shí)空分布及入河流失負(fù)荷[69-70].由于SWAT模型目前沒(méi)有自帶的重金屬模擬模塊,學(xué)者們通過(guò)改進(jìn)SWAT模塊的方法,建立了流域重金屬面源污染流失模型.例如,在考慮重金屬固液兩相不同形態(tài)分布的轉(zhuǎn)化和其水文過(guò)程的耦合作用基礎(chǔ)上,建立了考慮重金屬陸面和水體中化學(xué)反應(yīng)(如吸附和老化反應(yīng))的流域重金屬流失模型,可以評(píng)估距離因子、稀釋因素等復(fù)雜水文過(guò)程對(duì)重金屬流失的影響[9-10,14,44].通過(guò)改進(jìn)SWAT模型,學(xué)者模擬了金屬沉積態(tài)、懸浮態(tài)和溶解態(tài)三相在沉積物、土壤和水體中分配過(guò)程,以及陸面和水體中重金屬不同路徑的遷移流失[66,73].有學(xué)者在SWAT優(yōu)化模型中,采用實(shí)測(cè)的大氣重金屬年沉降量作為模型輸入?yún)?shù),并使用植物吸收系數(shù)法考慮了植物對(duì)重金屬的吸收,這均在一定程度上提高了流域重金屬流失模擬的精度[6].在考慮了土壤pH值、土壤粒徑、徑流量、泥沙量、徑流中溶解的水溶性重金屬濃度和土壤顆粒吸附的不溶性重金屬等多種因素,利用改進(jìn)后的SWAT模型模擬證明了泥沙中重金屬流失量占研究流域總流失量的97%以上[1].也有學(xué)者在溫帶森林流域,綜合考慮了陸地和水生生物地球化學(xué)過(guò)程以及大氣沉降和凋落物分解對(duì)汞的地球化學(xué)過(guò)程的影響,開發(fā)了SWAT-Hg模型并評(píng)估了不同路徑中Hg的流失量[74].此外,SWAT模型與其他模型的耦合可以使模擬結(jié)果更加符合研究需求.例如,學(xué)者通過(guò)耦合SWAT模型和簡(jiǎn)化的經(jīng)驗(yàn)輸出系數(shù)法,對(duì)流域Cd面源污染流失進(jìn)行了動(dòng)態(tài)模擬[71-72];將改進(jìn)的一維輸運(yùn)模型嵌入SWAT的泥沙輸運(yùn)源模塊中,可以預(yù)測(cè)土壤-水界面錳的污染負(fù)荷[75];通過(guò)SWAT模型與WASP模型的耦合,可以模擬河流中Cu的濃度,并評(píng)估氣候變化和不同修復(fù)措施對(duì)Cu流失的影響[76].通過(guò)改進(jìn)SWAT模型或與其他模型耦合,可較為準(zhǔn)確的預(yù)測(cè)流域管理措施對(duì)重金屬遷移的影響.但是模型所需基礎(chǔ)資料量較大,建模和率定驗(yàn)證過(guò)程相對(duì)復(fù)雜.此外,模擬單元(水文響應(yīng)單元)的劃分是土壤屬性、土地利用和坡度三者簡(jiǎn)單疊合,無(wú)空間位置關(guān)系.若能通過(guò)模塊改進(jìn)增加對(duì)水文響應(yīng)單元間的徑流、泥沙運(yùn)移關(guān)系的考慮,或與其他模型耦合運(yùn)用,是增加SWAT模型適用范圍,提高模型模擬精度的重要途徑.

除了TREX和SWAT模型外,MIKE(水動(dòng)力數(shù)值模擬模型)、EFDC(環(huán)境流體動(dòng)力學(xué)模型)和QUAL(河流水質(zhì)模型)也常被用于重金屬流失模擬.MIKE模型是集流域、水文、水質(zhì)于一體的綜合模型,包括一維模型(MIKE11),二維模型(MIKE21),三維模型(MIKE3)以及流域綜合模型(MIKE-SHE)、河網(wǎng)模型(MIKE-BASIN)等,可以預(yù)測(cè)河流、湖泊、河口、海灣、海岸及海洋等區(qū)域的重金屬濃度.MIKE模型中重金屬模塊可以輸入大氣濕沉降相關(guān)參數(shù),可以考慮降雨中重金屬溶解態(tài)、吸附態(tài)和顆粒物的含量.有學(xué)者利用MIKE模型模擬了閩江支流彭村水庫(kù)庫(kù)區(qū)Zn、Cd、Pb污染分布規(guī)律[77],對(duì)遼寧省三灣水庫(kù)蓄水期As污染遷移特征進(jìn)行了預(yù)測(cè)[78]. MIKE模型功能較全,可根據(jù)地質(zhì)特征、氣候、水文等觀測(cè)資料的獲取情況,選擇最合適算法開展建模,計(jì)算精度較高.但該模型忽視水質(zhì)成分之間的相互作用,導(dǎo)致模擬結(jié)果與實(shí)際存在一定的誤差,可以通過(guò)與其他水質(zhì)模型的耦合,針對(duì)特定水質(zhì)問(wèn)題的實(shí)際情況發(fā)揮不同模型的特點(diǎn),提高預(yù)測(cè)預(yù)警的準(zhǔn)確度.

EFDC模型可以對(duì)河流、湖泊、河口、水庫(kù)、濕地、近岸海域等區(qū)域重金屬遷移轉(zhuǎn)化過(guò)程進(jìn)行模擬.例如,有學(xué)者基于EFDC模型模擬了湘江長(zhǎng)株潭河段突發(fā)重金屬污染事故下,污染物的時(shí)空變化規(guī)律[79].EFDC模型可以同時(shí)考慮風(fēng)、浪、潮、徑流等因子的影響,數(shù)值計(jì)算能力強(qiáng)[80],但模型對(duì)輸入數(shù)據(jù)的要求較高,數(shù)據(jù)量不夠或精度不高對(duì)水質(zhì)模擬效果的影響較大.該模型輸出的水文文件可供其他水質(zhì)模擬使用,從而實(shí)現(xiàn)與其他水質(zhì)模型的耦合. QUAL模型主要用于單一河道和樹枝狀河系點(diǎn)源污染和非點(diǎn)源污染對(duì)受納水體水質(zhì)的影響,有學(xué)者利用改進(jìn)后的QUAL2Kw模型模擬了刁江流域水體中Zn、Pb和Cd含量[81].該模型考慮了平流擴(kuò)散、稀釋等內(nèi)部作用及組分外部源匯對(duì)濃度的影響,將水體沿橫向變化視為均勻的,在相對(duì)狹長(zhǎng)的水體研究中更為適合,但對(duì)河段、源頭數(shù)量和全流域的計(jì)算單元總數(shù)有數(shù)量限制,只適用于中小型的河流的模擬.

綜上所述,相比經(jīng)驗(yàn)?zāi)Ｐ?機(jī)理模型對(duì)數(shù)據(jù)量和數(shù)據(jù)精度要求較高,且模型涉及的參數(shù)多,率定過(guò)程較為復(fù)雜,但模型對(duì)重金屬遷移過(guò)程的刻畫更詳細(xì),模型施用范圍廣,模擬精度較高,可推廣性強(qiáng),適合監(jiān)測(cè)資料比較完善的地區(qū).通過(guò)對(duì)常用機(jī)理模型的系統(tǒng)總結(jié)發(fā)現(xiàn),在流域重金屬來(lái)源考慮的方面,大氣沉降中干沉降是重金屬輸入流域的途徑之一,但干沉降占比較少且觀測(cè)難度大,因此大部分機(jī)理模型應(yīng)用過(guò)程中未充分考慮此參數(shù)輸入.在流域重金屬流失路徑模擬方面,雖然常用的機(jī)理模型可以模擬流域重金屬的流失負(fù)荷,但缺乏地下水中重金屬的遷移過(guò)程模擬,不能評(píng)估土壤重金屬經(jīng)過(guò)垂向遷移進(jìn)入地下水后向下游河流水體的遷移過(guò)程和流失負(fù)荷[82].如何對(duì)流域的地表徑流、壤中流、地下水和土壤侵蝕不同流失路徑中重金屬流失負(fù)荷進(jìn)行模擬,是流域尺度重金屬遷移過(guò)程的精準(zhǔn)模擬的未來(lái)研究重點(diǎn),可為重金屬污染精準(zhǔn)防控提供重要的工具和理論支撐.此外,由于各種模型具有不同適用條件和優(yōu)缺點(diǎn),多種模型的耦合應(yīng)用可以最大限度地發(fā)揮各模型優(yōu)勢(shì),實(shí)現(xiàn)流域重金屬?gòu)?fù)雜遷移過(guò)程較為準(zhǔn)確的模擬,以便滿足研究需要.

4 結(jié)論與展望

綜合已有研究可知,從簡(jiǎn)單線性或非線性相關(guān)關(guān)系的經(jīng)驗(yàn)?zāi)Ｐ偷娇紤]隨著水文和土壤侵蝕等過(guò)程遷移轉(zhuǎn)化的機(jī)理模型,從單一模型優(yōu)化到多種模型耦合應(yīng)用,流域重金屬遷移模型在研究過(guò)程中得到了逐步完善,為重金屬流失通量估算和水質(zhì)預(yù)測(cè)做出了重大貢獻(xiàn).在開展流域重金屬遷移模擬工作中,應(yīng)該結(jié)合研究區(qū)實(shí)際狀況、研究對(duì)象及模擬目的合理地選擇模型,對(duì)于資料條件較差或無(wú)資料研究區(qū)可選擇輸出系數(shù)模型進(jìn)行研究;對(duì)于模擬精度要求較高的地區(qū),可選擇機(jī)理模型進(jìn)行模擬,建議加強(qiáng)污染源實(shí)地監(jiān)測(cè)和河流水質(zhì)監(jiān)測(cè),保證模型參數(shù)輸入的準(zhǔn)確性,加強(qiáng)模型耦合應(yīng)用和推廣.雖然流域重金屬遷移模型研究已經(jīng)取得了顯著成果,多模型耦合開發(fā)和應(yīng)用、遷移過(guò)程機(jī)理研究和模擬、以及重金屬污染溯源模擬等方面是未來(lái)研究需要重點(diǎn)關(guān)注的發(fā)展方向.

4.1 加強(qiáng)多模型耦合開發(fā)和應(yīng)用,擴(kuò)大模型的適用性.流域重金屬遷移過(guò)程是多因素共同影響的結(jié)果,包括了復(fù)雜的水文過(guò)程和化學(xué)生物過(guò)程的相互作用.鑒于各種模型的適用條件、模擬側(cè)重點(diǎn)和優(yōu)缺點(diǎn)不同,僅單一模型的應(yīng)用不能滿足流域重金屬遷移過(guò)程的細(xì)致模擬.通過(guò)開發(fā)多模型的耦合,構(gòu)建模型耦合框架,可以最大限度地發(fā)揮各模型優(yōu)勢(shì),提高模型模擬的精度.

4.2 加強(qiáng)不同遷移路徑的機(jī)理研究,夯實(shí)模型研發(fā)理論基礎(chǔ).流域重金屬遷移過(guò)程機(jī)理復(fù)雜,模型構(gòu)建需要的參數(shù)多,導(dǎo)致模擬的不確定性大.多數(shù)重金屬遷移模型未能充分考慮所有污染來(lái)源和遷移途徑,特別對(duì)于大氣沉降過(guò)程中重金屬來(lái)源的參數(shù)輸入較缺乏;且大部分模型將重金屬垂向遷移和縱向遷移分開模擬[47,82].亟需通過(guò)室內(nèi)模擬、現(xiàn)場(chǎng)監(jiān)測(cè)試驗(yàn)與模型模擬耦合,進(jìn)一步加強(qiáng)重金屬遷移過(guò)程中各個(gè)環(huán)節(jié)的機(jī)理研究,進(jìn)而開發(fā)綜合考慮各種污染來(lái)源并耦合多路徑遷移過(guò)程的流域模型.

4.3 加強(qiáng)重金屬污染溯源識(shí)別和定量解析模擬,提高流域重金屬污染防控效率.流域內(nèi)重金屬來(lái)源復(fù)雜,定量辨識(shí)水體及泥沙中重金屬污染物的來(lái)源與負(fù)荷貢獻(xiàn),是有針對(duì)性的開展重金屬污染精準(zhǔn)防控的關(guān)鍵.目前大部分流域重金屬遷移模型主要應(yīng)用于總污染負(fù)荷估算、突發(fā)性污染事件的水質(zhì)評(píng)估和預(yù)測(cè)等方面.如何通過(guò)傳統(tǒng)地球化學(xué)或穩(wěn)定性同位素技術(shù)與流域模型的耦合應(yīng)用,定量解析流域重金屬污染來(lái)源,也是未來(lái)研究的重點(diǎn)和難點(diǎn),可為重金屬污染防治提供重要科學(xué)依據(jù).

[1] Qiao P W, Lei M, Yang S C, et al. Development of a model to simulate soil heavy metals lateral migration quantity based on SWAT in Huanjiang watershed, China [J]. Journal of Environment Sciences, 2019,77:115-129.

[2] 劉 楠,唐瑩影,陳 盟,等.基于APCS-MLR和PMF的鉛鋅礦流域土壤重金屬來(lái)源解析 [J]. 中國(guó)環(huán)境科學(xué), 2023,43(3):1267-1276. Liu N, Tang Y Y, Chen M, et al. Source apportionment of soil heavy metals in lead-zinc area based on APCS-MLR and PMF [J]. China Environmental Science, 2023,43(3):1267-1276.

[3] 雷 梅,王云濤,顧閏堯,等.基于知識(shí)圖譜的土壤重金屬快速監(jiān)測(cè)技術(shù)進(jìn)展 [J]. 中國(guó)環(huán)境科學(xué), 2018,38(1):244-253. Lei M, Wang Y T, Gu R R, et al. A review of the rapid monitoring of soil heavy metals based on mapping knowledge domains [J]. China Environmental Science, 2018,38(1):244-253.

[4] Wu Y, Li X, Yu L, et al. Review of soil heavy metal pollution in China: Spatial distribution, primary sources, and remediation alternatives [J]. Resources, Conservation & Recycling, 2022,181:106261.

[5] Meite F, Alvarez-Zaldívar P, Crochet A, et al. Impact of rainfall patterns and frequency on the export of pesticides and heavy-metals from agricultural soils [J]. Science of the Total Environment, 2018, 616-617:500-509.

[6] Zhou L, Meng Y, Vaghefi S A, et al. Uncertainty-based metal budget assessment at the watershed scale: Implications for environmental management practices [J]. Journal of Hydrology, 2020,584:124699

[7] Jiao W, Ouyang W, Hao F, et al. Combine the soil water assessment tool (SWAT) with sediment geochemistry to evaluate diffuse heavy metal loadings at watershed scale [J]. Journal of Hazardous Materials, 2014,280:251-259.

[8] Velleux M L, England J F, Julien P Y. TREX: spatially distributed model to assess watershed contaminant transport and fate [J]. Science of the Total Environment, 2008,404:113-128.

[9] Meng Y, Zhou L, He S, et al. A heavy metal module coupled with the SWAT model and its preliminary application in a mine-impacted watershed in China [J]. Science of the Total Environment, 2018,613- 614:1207-1219.

[10] 周凌峰,孟耀斌,逯 超,等.流域尺度重金屬行為模擬及其對(duì)不同氣象因子的響應(yīng)特征研究 [J]. 農(nóng)業(yè)環(huán)境科學(xué)學(xué)報(bào), 2019,38(5):1112- 1120. Zhou F L, Meng Y B, Lu C, et al. Modeling the fate and transport of heavy metals, and their response to climate change at the watershed scale [J]. Journal of Agro Environment Science, 2019,38(5):1112- 1120.

[11] 易 琦,王瑞芳,趙筱青,等.中小河流水體重金屬Zn、Pb、As 沿程遷移擴(kuò)散過(guò)程模擬—以沘江為例 [J]. 云南大學(xué)學(xué)報(bào)(自然科學(xué)版), 2022,44(1):98-106. Yi Q, Wang R F, Zhao X Q, et al. Simulation of migration and diffusion processes of heavy metals Zn, Pb and As in medium and small rivers: Taking Bijiang River as an example [J]. Journal of Yunnan University: Natural Sciences Edition, 2022,44(1):98-106.

[12] 任伯幟,劉科家,馬宏璞,等.基于SWAT模型的金屬礦區(qū)雨水徑流中錳污染負(fù)荷分析 [J]. 環(huán)境污染與防治, 2014,36(11),50-54. Ren B Z, Liu J K, Ma H P, et al. Analysis of manganese pollution load of rainfall runoff in manganese ore zone based on SWAT model [J]. Environmental Pollution & Control, 2014,36(11),50-54.

[13] 茆 峰.礦區(qū)特征污染物在河流中的遷移轉(zhuǎn)化數(shù)學(xué)模型研究 [D]. 合肥工業(yè)大學(xué), 2012. Mao F. Research on mathematical models of migration and transformation for features pollutants of mining area in rivers [D]. Hefei: Hefei University of Technology, 2012.

[14] 何壽亮,孟耀斌,逯 超.基于改進(jìn)SWAT模型的滹沱河上游流域重金屬模擬初步研究—以Zn為例 [J]. 中國(guó)科技論文, 2013,8(5): 458-464. He S L, Meng Y B, Lu C. Preliminary research on heavy metal behavior modeling in Hutuohe river upstream watershed based on SWAT model: taking Zinc as an example [J]. China Sciencepaper, 2013,8(5):458-464.

[15] 蔡 明,李懷恩,莊詠濤,等.改進(jìn)的輸出系數(shù)法在流域非點(diǎn)源污染負(fù)荷估算中的應(yīng)用 [J]. 水利學(xué)報(bào), 2004,35(7):40-45. Cai M, Li H N, Zhuang Y T, et al. Application of modified export coefficient method in polluting load estimation of non-point source pollution [J]. Journal of Hydraulic Engineering, 2004,35(7):40-45.

[16] 費(fèi) 坤,汪甜甜,鄒文嵩,等.土壤重金屬污染空間插值及其驗(yàn)證方法研究綜述 [J]. 環(huán)境監(jiān)測(cè)管理與技術(shù), 2022,34(2):1-6. Fei K, Wang T T, Zou W H, et al. Review on spatial interpolation and its verification method of heavy metal pollution in soil [J]. The Administration and Technique of Environmental Monitoring, 2022, 34(2):1-6.

[17] 侯靜濤,劉 娟,向永金,等.土壤中重金屬累積預(yù)測(cè)模型研究進(jìn)展 [J]. 環(huán)境污染與防治, 2022,44(1):72-78. Hou J T, Liu J, Xiang Y J, et al. Application of heavy metal accumulation prediction model in soil: a review [J]. Environmental Pollution & Control, 2022, 44(1):72-78.

[18] 王 霞,仇啟善.水環(huán)境中重金屬的存在形態(tài)和遷移轉(zhuǎn)化規(guī)律綜述 [J]. 內(nèi)蒙古環(huán)境保護(hù), 1998,10(2):22-24. Wang X, Chou Q S. Review on the existing forms, migration and transformation of heavy metals in water environment [J]. Inner Mongolian Environmental Protection, 1998,10(2):22-24.

[19] 黃歲樑,萬(wàn)兆惠.河流重金屬遷移轉(zhuǎn)化數(shù)學(xué)模型研究綜述[J].泥沙研究, 1995,4:42-49. Huang S L, Wan Z H. Reviews on present research situation of mathematical modeling transport and transformation of heavy metals in fluvial rivers [J]. Journal of Sediment Research, 1995,4:42-49.

[20] 陳雅麗,翁莉萍,馬 杰,等.近十年中國(guó)土壤重金屬污染源解析研究進(jìn)展 [J]. 農(nóng)業(yè)環(huán)境科學(xué)學(xué)報(bào), 2019,38(10):2219-2238. Chen Y L, Weng L P, Ma J, et al. Review on the last ten years of research on source identification of heavy metal pollution in soils [J]. Journal of Agro Environment Science, 2019,38(10):2219-2238.

[21] 吳 迪,董 彬,尉海東.土壤重金屬污染來(lái)源研究綜述 [J]. 安徽農(nóng)學(xué)通報(bào), 2017,23(23):58-60. Wu D, Dong B, Wei H D. Review of soil heavy metal pollution sources [J]. Anhui Agricultural Science Bulletin, 2017,23(23):58-60.

[22] 盧維宏,劉 娟,張乃明,等.設(shè)施菜地土壤重金屬累積及影響因素研究 [J]. 中國(guó)環(huán)境科學(xué), 2022,42(6):2744-2753. Lu W, Liu Y, Zhang N, et al. Study on the accumulation of heavy metals and influencing factors in the soil of facility vegetable fields [J]. China Environmental Science, 2022,42(6):2744-2753.

[23] 黃國(guó)秦,王興祥,錢海燕,等.施用化學(xué)肥料對(duì)農(nóng)業(yè)生態(tài)環(huán)境的負(fù)面影響與對(duì)策 [J]. 生態(tài)環(huán)境, 2004,13(4):656-660. Huang G Q, Wang X X, Qian H Y, et al. Negative impact of inorganic fertilizes application on agricultural environment and its countermeasures [J]. Ecology and Environment, 2004,13(4):656-660.

[24] 辛術(shù)貞,李花粉,蘇德純,等.我國(guó)污灌污水中重金屬含量特征及年代變化規(guī)律 [J]. 農(nóng)業(yè)環(huán)境科學(xué)學(xué)報(bào), 2011,30(11):2271-2278. Xin S Z, Li H F, Su D C, et al. Concentration characteristics and historical changes of heavy metals in irrigation sewage in China [J]. Journal of Agro-Environment Science, 2011,30(11):2271-2278.

[25] Meng W, Wang Z, Hu B, et al. Heavy metals in soil and plants after long-term sewage irrigation at Tianjin China: A case study assessment [J]. Agricultural Water Management, 2016,171:153-161.

[26] 于立紅,王 鵬,于立河,等.地膜中重金屬對(duì)土壤大豆系統(tǒng)污染的試驗(yàn)研究 [J]. 水土保持通報(bào), 2013,33(3):1-4. Yu L H, Wang P, Yu L H, et al. Experimental study of pollution by heavy metals of plastic film in soil—Soybean system [J]. Bulletin of Soil and Water Conservation, 2013,33(3):1-4.

[27] Luo H W, Liu C Y, He D Q, et al. Effects of aging on environmental behavior of plastic additives: Migration, leaching, and ecotoxicity [J]. Science of the Total Environment, 2022,849:157951.

[28] He M C, Wang X Q, Wu F C, et al. Antimony pollution in China [J]. Science of the Total Environment, 2012,421-422:41-50.

[29] Guo W J, Zhang Z Y, Wang H, et al. Exposure characteristics of antimony and coexisting arsenic from multi-path exposure in typical antimony mine area [J]. Journal of Environmental Management, 2021,289:112493.

[30] 宋書巧,梁利芳,周永章,等.廣西刁江沿岸農(nóng)田受礦山重金屬污染現(xiàn)狀與治理對(duì)策 [J]. 礦物巖石地球化學(xué)通報(bào), 2003,22(2):152-155. Song S Q, Liang L F, Zhou Y Z, et al. The situation and remedial measures of the cropland polluted by heavy metals from mining along the Diaojian River [J]. Bulletin of Mineralogy, Petrology and Geochemistry, 2003,22(2):152-155.

[31] 趙紀(jì)新,尹鵬程,岳 榮,等.我國(guó)農(nóng)田土壤重金屬污染現(xiàn)狀·來(lái)源及修復(fù)技術(shù)研究綜述 [J]. 安徽農(nóng)業(yè)科學(xué), 2018,46(4):19-21,26. Zhao J X, Yin P C, Yue R, et al. Research progress of status, source, restoration technique of heavy metals pollution in cropland of China [J]. Journal of Anhui Agricultural Sciences, 2018,46(4):19-21,26.

[32] Herath I, Vithanage M, Bundschuh J, et al. Antimony as a global dilemma: Geochemistry, mobility, fate and transport [J]. Environmental Pollution, 2017,223:545-559.

[33] 劉 雯,盧新衛(wèi),陳燦燦,等.電廠周圍土壤磁化率對(duì)重金屬污染的指示意義 [J]. 土壤通報(bào), 2013,44(4):994-996. Liu W, Lu X W, Chen C C, et al. The indicating significance of magnetic susceptibility of soil around coal-fired power plant for heavy metal pollution [J]. Chinese Journal of Soil Science, 2013,44(4):994- 996.

[34] 謝博文,王 藝,趙晟雯,等.土壤重金屬污染研究綜述 [J]. 廣州化工, 2016,44(1):21-23. Xie B W, Wang Y, Zhao S W, et al. Review of soil heavy metal pollution [J]. Guangzhou Chemical Industry, 2016,44(1):21-23.

[35] Alam O, Billah M, Ding Y J. Characteristics of plastic bags and their potential environmental hazards [J]. Resources, Conservation and Recycling, 2018,132:121-129.

[36] 向靜雅,王 倩,邵明帥,等.深圳海灘塑料垃圾及其重金屬污染分析[J]. 中國(guó)環(huán)境科學(xué), 2020,40(7):3097-3105. Xiang J Y, Wang Q, Shao M S, et al. Assessment of beach plastic waste and its heavy metal pollution in Shenzhen [J]. China Environmental Science, 2020,40(7):3097-3105.

[37] Men C, Liu R M, Wang Q R. et al. Spatial-temporal characteristics, source-specific variation and uncertainty analysis of health risks associated with heavy metals in road dust in Beijing, China [J]. Environmental Pollution, 2021,278:116866.

[38] 王 建,夏 天,羅 政,等.基于GIS 的土壤重金屬污染模擬擴(kuò)散研究及應(yīng)用 [J]. 測(cè)繪與空間地理信息, 2022,45(1):74-78. Wang J, Xia T, Luo Z, et al. Research and application on soil heavy metal pollution simulated diffusion based on GIS [J]. Geomatics & Spatial Information Technology, 2022,45(1):74-78.

[39] 王劉煒,侯德義.農(nóng)田重金屬污染長(zhǎng)期演變LIVE 模型構(gòu)建 [J].土壤通報(bào), 2021,53(6):1471-1480. Wang L W, Hou D Y. Modeling the Long-term evolving features of heavy metal concentration in agricultural soil [J]. Chinese Journal of Soil Science, 2021,53(6):1471-1480.

[40] Zhu Y M, Yang J G, Wang L Z, et al. Factors influencing the uptake and speciation transformation of antimony in the soil-plant system, and the redistribution and toxicity of antimony in plants [J]. Science of the Total Environment, 2020,738:140232.

[41] Feng R W, Wei C Y, Tu S X, et al. The uptake and detoxification of antimony by plants: A review [J]. Environmental and Experimental Botany, 2013,96:28-34.

[42] Kerr J G, Cooke C A. Erosion of the Alberta badlands produces highly variable and elevated heavy metal concentrations in the Red Deer River, Alberta [J]. Science of the Total Environment, 2017,596-597: 427-436.

[43] Li Z Y, Pan F, Xiao K, et al. An integrated study of the spatiotemporal character, pollution assessment, and migration mechanism of heavy metals in the groundwater of a subtropical mangrove wetland [J]. Journal of Hydrology, 2022,612:128251.

[44] Zhou H Y, Rao K, Yao M J, et al. Effects of land use, meteorology, and hydrology on nutrients, biochemical indexes, and heavy metals in Qingjiang River Basin, China [J]. Journal of Cleaner Production, 2022, 370:1334116.

[45] Zhang Y, Zhang X, Bi Y L, et al. The impact of land use changes and erosion process on heavy metal distribution in the hilly area of the Loess Plateau, China [J]. Science of the Total Environment, 2020, 718:137305.

[46] 羅小青.基于GIS的湘江水環(huán)境重金屬污染分布式物理過(guò)程及模擬 [D]. 長(zhǎng)沙:中南大學(xué), 2013. Luo X Q. The distributed physical processes and modeling of heavy metal pollution on Xiangjiang River based on GIS [D]. Changsha, Central South University, 2013.

[47] Qiao P, Wang S, Li J, et al. Process, influencing factors, and simulation of the lateral transport of heavy metals in surface runoff in a mining area driven by rainfall: a review [J]. Science of the Total Environment, 2023,857:159119.

[48] Cao L Y, Li W, Deng H, et al. Effect of land use pattern on the bioavailability of heavy metals: A case study with a multi-surface model [J]. Chemosphere, 2022,307:135842.

[49] Gu X, Ouyang W, Xu L, et al. Occurrence, migration, and allocation of arsenic in multiple media of a typical semi-enclosed bay [J]. Journal of Hazardous Materials, 2020,384:121313.

[50] Fan J Y, Fan D, Wu Y J. Spatiotemporal variations of heavy metal historical accumulation records and their influencing mechanisms in the Yangtze River Estuary [J]. Science of the Total Environment, 2023,854:158733.

[51] 祁 彧.汾河干流重金屬遷移規(guī)律研究 [D]. 太原:太原理工大學(xué), 2017. Qi Y. Study on the heavy metal migration rule in the mainstream of Fenhe river [D]. Taiyuan: Taiyuan University of Technology, 2017.

[52] Deng M H, Yang X E, Dai X, et al. Heavy metal pollution risk assessments and their transportation in sediment and overlay water for the typical Chinese reservoirs [J]. Ecological Indicators, 2020,112: 106166.

[53] Dan S F, Udoh E C, Wang Q Q. Contamination and ecological risk assessment of heavy metals, and relationship with organic matter sources in surface sediments of the Cross River Estuary and nearshore areas [J]. Journal of Hazardous Materials, 2022,438:129531.

[54] Hu X P, Shi X Y, Su R G, et al. Spatiotemporal patterns and influencing factors of dissolved heavy metals off the Yangtze River Estuary, East China Sea [J]. Marine Pollution Bulletin, 2022,182: 113975.

[55] 王 苗.流域重金屬分布式運(yùn)移模型研究 [D]. 蘭州:西北師范大學(xué), 2019. Wang M. Research on distributed migration model of heavy metals in watershed [D]. Lanzhou: Northwest Normal University, 2019.

[56] 吳云龍.基于改進(jìn)輸出系數(shù)模型的鉛鎘砷非點(diǎn)源污染負(fù)荷研究 [D]. 湘潭:湘潭大學(xué), 2017. Wu Y L. Study on non-point source load of Pb, Cd, As based on improved export coefficient model [D]. Xiangtan: Xiangtan University, 2017.

[57] 隋紅建,吳 璇,崔巖山.土壤重金屬遷移模擬研究的現(xiàn)狀與展望 [J].農(nóng)業(yè)工程學(xué)報(bào), 2006,22(6):197-200. Sui H J, Wu X, Cui Y S. Modeling heavy metal movement in soil: review and further study directions [J]. Transactions of the Chinese Society of Agricultural Engineering, 2006,22(6):197-200.

[58] Brezonik P L, Stadelmann T H. Analysis and predictive models of stormwater runoff volumes, loads, and pollutant concentrations from watersheds in the Twin Cities metropolitan area, Minnesota, USA [J]. Water Research, 2002,36:1743-1757.

[59] Johnes P J. Evaluation and management of the impact of land use change on the nitrogen and phosphorus load delivered to surface waters: the export coefficient modelling approach [J]. Journal of Hydrology, 1996,183(3/4):323-349.

[60] 張?zhí)祢?劉 剛,王圣偉.基于GIS/RS的不同土地利用類型重金屬面源污染比較 [J]. 農(nóng)業(yè)機(jī)械學(xué)報(bào), 2014,45:124-132. Zhang T J, Liu G, Wang S W. Estimation of heavy metal pollution loads from non-point sources based on GIS/RS [J]. Transactions of the Chinese Society of Agricultural Machinery, 2014,45:124-132.

[61] 高 磊,陳建耀,朱愛萍,等.基于SCS模型的跨界小流域物質(zhì)通量估算—以東莞石馬河流域?yàn)槔?[J]. 中國(guó)環(huán)境科學(xué), 2015,35(3):925- 933. Gao L, Chen J Y, Zhu A P, et al. Calculation of masses flux in a transboundary catchment based on SCS model: A case study in Shima River catchment, Dongguan City [J]. China Environmental Science, 2015,35(3):925-933.

[62] Yi Y, Ken H. A preliminary model for prediction heavy metal contaminant loading from an urban catchment [J]. Science of the Total Environment, 2001,266(1):299-307.

[63] Donald J. Model of sorptive toxic substance in freshwater systems I: basic equation [J]. Journal of Environmental Engineering, 1988,3:507- 532.

[64] Lin Y, Larssen T, Vogt R D, et al. Modelling transport and transformation of mercury fractions in heavily contaminated mountain streams by coupling a GIS-based hydrological model with a mercury chemistry model [J]. Science of The Total Environment, 2011,409(21): 4596-4605.

[65] 胡 晞.基于WASP模型的湘江湘潭段水質(zhì)目標(biāo)管理研究 [D]. 湘潭:湘潭大學(xué), 2013. Hu X. The water quality target management research on Xiangtan section of Xiangjiang river based on WASP model [D]. Xiangtan: Xiangtan University, 2013.

[66] Du X Z, Shrestha N K, Wang J. Incorporating a non-reactive heavy metal simulation module into SWAT model and its application in the Athabasca oil sands region [J]. Environmental Science Pollution Research, 2019,26:20879-20892.

[67] Velleux M L, Julien P Y, Rojas-Sanchez R, et al. Simulation of metals transport and toxicity at a mine-impacted watershed:California Gulch, Colorado [J]. Environmental Science & Technology, 2006,40(22): 6996-7004.

[68] Wei L Z, Kinouchi T, Yoshimura K, et al. Modeling watershed-scale Cs-137transport in a forested catchment affected by the Fukushima Dai-ichi Nuclear Power Plant accident [J]. Journal of Environmental Radioactivity, 2017,171:21-33.

[69] Neitsch S L, Arnold J G, Kiniry J R, et al. Soil and Water Assessment Tool Theoretical Documentation: Version 2005 [M]. Texas:Texas Water Resources Institute, 2005.

[70] 郝芳華,程紅光,楊勝天.面源污染模型:理論方法與應(yīng)用 [M]. 北京:中國(guó)環(huán)境科學(xué)出版社, 2006. Hao F H, Cheng H G, Yang S T. Non-point source pollution model: Theoretical method and application [M]. Beijing: China Environmental Science Press, 2006.

[71] 林鐘榮,鄭 一,向仁軍,等.重金屬面源污染模擬及其不確定性分析:以湘江株洲段鎘污染為例 [J]. 長(zhǎng)江流域資源與環(huán)境, 2012,21(9): 1112-1118. Lin Z R, Zheng Y, Xiang R J, et al. Simulation of the nonpoint sources load of heavy metals and its uncertainty analysis: A case study of cadmium pollution at the Xiangjiang River in the Zhu zhou City [J]. Resources and Environment in the Yangtze Basin, 2012,21(9): 1112-1118.

[72] 張青梅,韓 峰,劉 湛,等.基于SWAT 模型的湘江株洲段汞面源污染負(fù)荷測(cè)算 [J]. 四川環(huán)境, 2018,37(2):32-37. Zhang Q M, Han F, Liu Z, et al. Calculation of mercury non-point source pollution of Xiangjiang river Zhuzhou section based on the SWAT model [J]. Sichuan Environment, 2018,37(2):32-37.

[73] 劉科家.改進(jìn)SWAT模型在銻礦區(qū)土水界面流銻污染負(fù)荷模擬中的應(yīng)用研究 [D]. 湘潭:湖南科技大學(xué), 2015. Liu K J. The applied research of antimony pollution load simulation by improved SWAT model in the soil-water interface of antimony mine [D]. Xiangtan: Hunan University of Science and Technology, 2015.

[74] Jeong J, Yang J, Han S, et al. Assessment of coupled hydrologic and biogeochemical Hg cycles in a temperate forestry watershed using SWAT-Hg [J]. Environmental Modelling and Software, 2020,126: 104644.

[75] Zhang Y, Ren B Z, Hursthouse A S, et al. An improved SWAT for predicting manganese pollution load at the soil-water interface in a manganese mine area [J]. Polish Journal of Environmental Studies, 2018,27:2357-2365.

[76] Chueh Y Y, Fan C, Huang Y Z. Copper concentration simulation in a river by SWAT-WASP integration and its application to assessing the impacts of climate change and various remediation strategies [J].Journal of Environmental Management, 2021,279:111613.

[77] 軒曉博,逄 勇,李一平,等.金屬礦區(qū)重金屬遷移對(duì)水體影響的數(shù)值模擬[J]. 水資源保護(hù), 2015,31(2):30-35. Xuan X B, Pang Y, Li Y P, et al. Numerical simulation of influence of heavy metal migration on water in metallic mining areas [J]. Water Resources Protection, 2015,31(2):30-35.

[78] 齊兆東.三灣水庫(kù)蓄水期重金屬遷移特性數(shù)值模擬研究[J]. 中國(guó)水能及電氣化, 2019,5:35-38. Qi Z D. Numerical simulation of heavy metal migration characteristic in Sanwan reservoir during impoundment period [J]. China Water Power & Electrification, 2019,5:35-38.

[79] 武萬(wàn)國(guó).湘江長(zhǎng)株潭河段突發(fā)重金屬水污染事故模擬研究[J]. 中國(guó)水運(yùn), 2018,18(10):63-67. Wu W G. Simulation study on sudden accidents of heavy metal water pollution in the Changzhutan Section of Xiangjiang River [J]. China Water Transport, 2018,18(10):63-67.

[80] 龔 然,何 躍,徐力剛,等.EFDC(Environmental Fluid Dynamics Code) 模型在湖庫(kù)水環(huán)境模擬中的應(yīng)用進(jìn)展[J]. 海洋湖沼通報(bào), 2016,6:12-19. Gong R, He Y, Xu L G, et al. The application progress of environmental fluid dynamics code (EFDC) in lake and reservoir environment [J]. Transactions of Oceanology and Limnology, 2016, 6:12-19.

[81] 劉 艷,李 川,曹碧波,等.基于改進(jìn)QUAL2Kw模型的水環(huán)境重金屬污染模擬[J]. 安全與環(huán)境學(xué), 2016,16(5):258-264. Liu Y, Li C, Cao B B, et al. Improved QUAL2Kw model for assessing the heavy metal pollution in the aquarium environment [J]. Journal of Safety and Environment, 2016,16(5):258-264.

[82] Sui C M, Fatichi S, Burlando P, et al. Modeling distributed metal pollution transport in a mine impacted catchment: Short and long-term effects [J]. Science of the Total Environment, 2022,812:151473.

Research progress on heavy metal migration model at watershed scale.

LIU Lian-hua1, ZHANG Qing-wen1, WANG Yi-di2*, GU Xiang3

(1.Agricultural Clean Watershed Research Group, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing 100081, China；2.Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China；3.School of Environment, Beijing Normal University, Beijing 100875, China)., 2023,43(8)：4229～4238

This paper elucidated the main sources, migration mechanisms of heavy metals in the watershed and reviewed the characteristics of commonly used empirical and mechanistic models. The advantages and disadvantages of common-used models were compared synthetically. Results showed that, heavy metal migration models have been improved from the empirical models with simple linear or nonlinear to the mechanism models with the migration and transformation with hydrological and soil erosion processes. The applicability of heavy metal migration models is gradually expanding, and the simulation accuracy is constantly improving, which play an important role in the simulation of heavy metal loadings and water quality prediction. Empirical models require fewer basic data and have relatively simple calculation processes, making them suitable for rough evaluation of heavy metal loadings in the watersheds with limited data. Mechanism models require many high-accuracy data, and have complex model structures, which can achieve the detailed simulation of heavy metal migration processes. The authors proposed outlook on the development of multiple model coupling, the mechanism research of different migration paths, and the identification analysis of heavy metal pollution tracing. Achieving these prospects will provide scientific support for the application, improvement, and source identification of heavy metal pollution at watershed scale.

heavy metal；model simulation；migration and transformation；process mechanism；research trends

X131

A

1000-6923(2023)08-4229-10

劉連華(1991-),女,山東臨沂人,助理研究員,博士,主要從事流域水環(huán)境過(guò)程與污染物遷移轉(zhuǎn)化研究.liulianhua@caas.cn.

劉連華,張晴雯,王依滴,等.流域重金屬遷移模型研究進(jìn)展 [J]. 中國(guó)環(huán)境科學(xué), 2023,43(8):4229-4238.

Liu L H, Zhang Q W, Wang Y D, et al. Research progress on heavy metal migration model at watershed scale [J]. China Environmental Science, 2023,43(8):4229-4238.

2023-01-05

國(guó)家自然科學(xué)基金資助項(xiàng)目(42107394、U21A2039);中國(guó)博士后科學(xué)基金資助項(xiàng)目(20237160019,2020M680432);中央級(jí)公益性科研院所基本科研業(yè)務(wù)費(fèi)專項(xiàng)(BSRF202309)

* 責(zé)任作者,講師, yidiwang@pku.edu.cn