科技日報訊(xun) 作(zuo)為一(yi)(yi)種對人體有害的重金屬，地(di)球(qiu)(qiu)上的汞(gong)(gong)是如何循環分布(bu)的？日前，天津大(da)(da)學(xue)地(di)科院孫(sun)若愚副(fu)教授(shou)與哈佛大(da)(da)學(xue)、法國科學(xue)院圖盧茲地(di)球(qiu)(qiu)環境研究所、南(nan)京(jing)大(da)(da)學(xue)等團隊(dui)合(he)作(zuo)，歷時5年，建成(cheng)了全球(qiu)(qiu)第一(yi)(yi)個動態、全耦合(he)、可拓(tuo)展的全球(qiu)(qiu)汞(gong)(gong)同(tong)位素(su)箱體模型，該模型首(shou)次(ci)加入了穩定汞(gong)(gong)同(tong)位素(su)多(duo)維分餾(liu)模塊，有助于更加精(jing)確地(di)觀測記錄(lu)全球(qiu)(qiu)汞(gong)(gong)排放和循環數據，從(cong)而幫(bang)助實(shi)現(xian)降低汞(gong)(gong)排放。該成(cheng)果發表(biao)于12月出版(ban)的地(di)學(xue)雜志《地(di)球(qiu)(qiu)化(hua)學(xue)與宇宙化(hua)學(xue)學(xue)報》上。
據介紹(shao)，當(dang)今世界汞(gong)排(pai)放約為工業革命前的3至5倍。地表環境中的汞(gong)負荷顯著增加，并進一步加劇(ju)(ju)了劇(ju)(ju)毒甲基(ji)汞(gong)在生物體(ti)特(te)別是(shi)食用魚類(lei)體(ti)內的累積，危害人類(lei)健(jian)康(kang)。
全(quan)球汞(gong)(gong)(gong)(gong)循環(huan)模(mo)(mo)(mo)型(xing)綜合研(yan)究(jiu)汞(gong)(gong)(gong)(gong)排放(fang)、遷移(yi)、轉化(hua)與沉(chen)降，能(neng)夠(gou)從(cong)理論上(shang)快速(su)反演環(huan)境(jing)(jing)體中汞(gong)(gong)(gong)(gong)的(de)歷(li)史變化(hua)趨(qu)勢(shi)，并預(yu)測未來汞(gong)(gong)(gong)(gong)排放(fang)所產生的(de)環(huan)境(jing)(jing)影(ying)響。但(dan)是，以往的(de)模(mo)(mo)(mo)型(xing)參(can)數都是建立在(zai)汞(gong)(gong)(gong)(gong)形(xing)態及其含量(liang)的(de)基礎上(shang)，不(bu)(bu)確(que)定度(du)較大(da)，存(cun)在(zai)很(hen)大(da)的(de)時間和空(kong)間上(shang)的(de)變異。穩定汞(gong)(gong)(gong)(gong)同(tong)(tong)位(wei)素是近十幾(ji)年發(fa)展起來的(de)用(yong)(yong)于研(yan)究(jiu)汞(gong)(gong)(gong)(gong)循環(huan)的(de)有效(xiao)技術手段，不(bu)(bu)但(dan)能(neng)夠(gou)有效(xiao)地示(shi)蹤(zong)源區，而(er)(er)且(qie)還能(neng)夠(gou)準確(que)地揭示(shi)造成汞(gong)(gong)(gong)(gong)同(tong)(tong)位(wei)素分(fen)餾的(de)地球化(hua)學過程(cheng)。孫(sun)若愚團隊(dui)在(zai)跟(gen)蹤(zong)研(yan)究(jiu)汞(gong)(gong)(gong)(gong)排放(fang)過程(cheng)中，創造性地開發(fa)出了(le)全(quan)球汞(gong)(gong)(gong)(gong)同(tong)(tong)位(wei)素箱體模(mo)(mo)(mo)型(xing)，該(gai)模(mo)(mo)(mo)型(xing)可利用(yong)(yong)汞(gong)(gong)(gong)(gong)同(tong)(tong)位(wei)素的(de)多(duo)維分(fen)餾信號，多(duo)個(ge)角度(du)去交叉模(mo)(mo)(mo)擬(ni)并驗證全(quan)球汞(gong)(gong)(gong)(gong)循環(huan)過程(cheng)，該(gai)模(mo)(mo)(mo)型(xing)能(neng)夠(gou)模(mo)(mo)(mo)擬(ni)各個(ge)環(huan)境(jing)(jing)儲(chu)庫(ku)的(de)歷(li)史汞(gong)(gong)(gong)(gong)同(tong)(tong)位(wei)素組成，從(cong)而(er)(er)為具有時間分(fen)辨(bian)率的(de)環(huan)境(jing)(jing)記錄體汞(gong)(gong)(gong)(gong)同(tong)(tong)位(wei)素觀察提供新標尺。該(gai)模(mo)(mo)(mo)型(xing)研(yan)究(jiu)結(jie)果(guo)顯示(shi)，當今廣泛采用(yong)(yong)的(de)全(quan)球汞(gong)(gong)(gong)(gong)循環(huan)速(su)率常數如土壤汞(gong)(gong)(gong)(gong)再釋放(fang)、大(da)氣汞(gong)(gong)(gong)(gong)干(gan)沉(chen)降和大(da)氣氧化(hua)汞(gong)(gong)(gong)(gong)光還原可能(neng)被嚴重低估(gu)，削減汞(gong)(gong)(gong)(gong)排放(fang)依然面(mian)臨嚴峻挑戰。