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水體中主要的污染物有哪些?1、病(bing)原體污染(ran)物 生(sheng)活污(wu)水(shui)、畜禽(qin)飼養場污(wu)水(shui)以及制革、洗毛(mao)、屠宰(zai)業(ye)和(he)醫院等排出的(de)(de)(de)廢水(shui),常含有(you)各種(zhong)病原(yuan)體,如病毒、病菌、寄生(sheng)蟲(chong)。水(shui)體受(shou)到病原(yuan)體的(de)(de)(de)污(wu)染會(hui)傳(chuan)播疾病,如血(xue)吸蟲(chong)病、霍亂(luan)、傷(shang)寒(han)、痢疾、病毒性肝(gan)炎等。歷史上流(liu)(liu)行(xing)(xing)的(de)(de)(de)瘟疫,有(you)的(de)(de)(de)就(jiu)是水(shui)媒型傳(chuan)染病。如1848年和(he)1854年英國兩次霍亂(luan)流(liu)(liu)行(xing)(xing),死亡萬(wan)余(yu)人;1892年德國漢堡(bao)霍亂(luan)流(liu)(liu)行(xing)(xing),死亡750余(yu)人,均是水(shui)污(wu)染引起的(de)(de)(de)。 受(shou)病(bing)原(yuan)(yuan)體(ti)(ti)污(wu)染(ran)后的(de)水體(ti)(ti),微生(sheng)物(wu)激(ji)增,其(qi)中許多是致病(bing)菌(jun)、病(bing)蟲卵和病(bing)毒(du)(du),它們往往與其(qi)他(ta)細菌(jun)和大腸(chang)桿菌(jun)共存(cun),所以通常(chang)規定用細菌(jun)總數(shu)和大腸(chang)桿菌(jun)指(zhi)數(shu)及(ji)(ji)菌(jun)值數(shu)為病(bing)原(yuan)(yuan)體(ti)(ti)污(wu)染(ran)的(de)直接指(zhi)標。病(bing)原(yuan)(yuan)體(ti)(ti)污(wu)染(ran)的(de)特點是:(1)數(shu)量大;(2)分(fen)布廣;(3)存(cun)活時(shi)(shi)間較長(chang);(4)繁殖速度(du)快(kuai);(5)易產生(sheng)抗藥性,很難(nan)絕滅;(6)傳統的(de)二(er)級生(sheng)化污(wu)水處理及(ji)(ji)加氯消毒(du)(du)后,某些病(bing)原(yuan)(yuan)微生(sheng)物(wu)、病(bing)毒(du)(du)仍(reng)能(neng)(neng)大量存(cun)活。常(chang)見的(de)混凝、沉淀、過(guo)濾、消毒(du)(du)處理能(neng)(neng)夠去除水中99%以上(shang)病(bing)毒(du)(du),如(ru)出水濁(zhuo)度(du)大于0.5度(du)時(shi)(shi),仍(reng)會伴隨(sui)病(bing)毒(du)(du)的(de)穿透(tou)。病(bing)原(yuan)(yuan)體(ti)(ti)污(wu)染(ran)物(wu)可(ke)通過(guo)多種途徑進入(ru)水體(ti)(ti),一旦條件適合,就(jiu)會引起(qi)人(ren)體(ti)(ti)疾病(bing)。 2、耗氧污染物(wu) 在(zai)生(sheng)(sheng)活(huo)污水(shui)、食品加(jia)工和造(zao)紙(zhi)等(deng)工業廢水(shui)中(zhong)(zhong),含有(you)碳水(shui)化合(he)物(wu)(wu)、蛋白(bai)質、油脂、木質素等(deng)有(you)機(ji)物(wu)(wu)質。這些物(wu)(wu)質以懸浮或溶(rong)解(jie)(jie)(jie)(jie)狀(zhuang)態存在(zai)于污水(shui)中(zhong)(zhong),可(ke)通過微生(sheng)(sheng)物(wu)(wu)的生(sheng)(sheng)物(wu)(wu)化學作(zuo)用而(er)分(fen)解(jie)(jie)(jie)(jie)。在(zai)其(qi)分(fen)解(jie)(jie)(jie)(jie)過程中(zhong)(zhong)需(xu)要消耗(hao)(hao)氧(yang)氣(qi),因而(er)被稱為耗(hao)(hao)氧(yang)污染物(wu)(wu)。這種污染物(wu)(wu)可(ke)造(zao)成水(shui)中(zhong)(zhong)溶(rong)解(jie)(jie)(jie)(jie)氧(yang)減少,影響魚類和其(qi)他水(shui)生(sheng)(sheng)生(sheng)(sheng)物(wu)(wu)的生(sheng)(sheng)長。水(shui)中(zhong)(zhong)溶(rong)解(jie)(jie)(jie)(jie)氧(yang)耗(hao)(hao)盡后,有(you)機(ji)物(wu)(wu)進行厭氧(yang)分(fen)解(jie)(jie)(jie)(jie),產(chan)生(sheng)(sheng)硫化氫(qing)、氨和硫醇等(deng)難(nan)聞氣(qi)味,使(shi)水(shui)質進一步惡化。水(shui)體(ti)(ti)中(zhong)(zhong)有(you)機(ji)物(wu)(wu)成分(fen)非常復雜,耗(hao)(hao)氧(yang)有(you)機(ji)物(wu)(wu)濃度常用單位體(ti)(ti)積水(shui)中(zhong)(zhong)耗(hao)(hao)氧(yang)物(wu)(wu)質生(sheng)(sheng)化分(fen)解(jie)(jie)(jie)(jie)過程中(zhong)(zhong)所消耗(hao)(hao)的氧(yang)量表示,即(ji)以生(sheng)(sheng)化需(xu)氧(yang)量(BOD)表示。一般用20℃時,五天生(sheng)(sheng)化需(xu)氧(yang)量(BOD5)表示。 3、植物(wu)營養物(wu) 植物(wu)營養(yang)物(wu)主要指氮、磷等能刺(ci)激藻類(lei)及(ji)水(shui)草生長、干擾水(shui)質(zhi)凈(jing)化,使(shi)BOD5升高(gao)的(de)(de)物(wu)質(zhi)。水(shui)體中營養(yang)物(wu)質(zhi)過量(liang)所造成的(de)(de)"富營養(yang)化"對于湖泊(bo)及(ji)流動(dong)緩慢的(de)(de)水(shui)體所造成的(de)(de)危害已成為水(shui)源(yuan)保護的(de)(de)嚴重問(wen)題。 富(fu)(fu)營養(yang)化(hua)(eutrophication)是指在人類(lei)活(huo)動的(de)影(ying)響下,生物(wu)(wu)所(suo)需的(de)氮、磷等(deng)(deng)營養(yang)物(wu)(wu)質(zhi)大量(liang)進入湖泊、河口、海灣等(deng)(deng)緩流水(shui)(shui)體,引起藻類(lei)及其他(ta)浮游生物(wu)(wu)迅速(su)繁殖(zhi),水(shui)(shui)體溶解氧量(liang)下降,水(shui)(shui)質(zhi)惡化(hua),魚類(lei)及其他(ta)生物(wu)(wu)大量(liang)死亡的(de)現(xian)象(xiang)。在自然(ran)(ran)條(tiao)件下,湖泊也會從貧(pin)營養(yang)狀態過渡到富(fu)(fu)營養(yang)狀態,沉積(ji)物(wu)(wu)不斷增多,先變(bian)為沼澤(ze),后變(bian)為陸(lu)地。這(zhe)種自然(ran)(ran)過程非常緩慢,常需幾千年(nian)甚至上萬年(nian)。而人為排放(fang)含營養(yang)物(wu)(wu)質(zhi)的(de)工業廢水(shui)(shui)和生活(huo)污水(shui)(shui)所(suo)引起的(de)水(shui)(shui)體富(fu)(fu)營養(yang)化(hua)現(xian)象(xiang),可以(yi)在短期內出現(xian)。 植物(wu)(wu)營養(yang)物(wu)(wu)質的(de)來(lai)源(yuan)廣、數量大,有(you)生(sheng)(sheng)(sheng)活污(wu)水(shui)(shui)(shui)(shui)(有(you)機質、洗滌(di)劑)、農(nong)業(化肥(fei)、農(nong)家肥(fei))、工業廢水(shui)(shui)(shui)(shui)、垃(la)圾等(deng)。每人每天(tian)帶進污(wu)水(shui)(shui)(shui)(shui)中(zhong)(zhong)的(de)氮約50g。生(sheng)(sheng)(sheng)活污(wu)水(shui)(shui)(shui)(shui)中(zhong)(zhong)的(de)磷(lin)(lin)(lin)主(zhu)要來(lai)源(yuan)于洗滌(di)廢水(shui)(shui)(shui)(shui),而(er)施入農(nong)田的(de)化肥(fei)有(you)50%~80%流入江河、湖海(hai)(hai)和地(di)下水(shui)(shui)(shui)(shui)體(ti)中(zhong)(zhong)。天(tian)然水(shui)(shui)(shui)(shui)體(ti)中(zhong)(zhong)磷(lin)(lin)(lin)和氮(特別是磷(lin)(lin)(lin))的(de)含量在一定(ding)程度上是浮游(you)生(sheng)(sheng)(sheng)物(wu)(wu)生(sheng)(sheng)(sheng)長的(de)控(kong)制(zhi)因素(su)。當(dang)大量氮、磷(lin)(lin)(lin)植物(wu)(wu)營養(yang)物(wu)(wu)質排入水(shui)(shui)(shui)(shui)體(ti)后(hou)(hou),促使(shi)某些生(sheng)(sheng)(sheng)物(wu)(wu)(如藻(zao)(zao)類)急劇繁(fan)殖生(sheng)(sheng)(sheng)長,生(sheng)(sheng)(sheng)長周期變短。藻(zao)(zao)類及其他(ta)浮游(you)生(sheng)(sheng)(sheng)物(wu)(wu)死(si)亡(wang)后(hou)(hou)被需(xu)氧(yang)生(sheng)(sheng)(sheng)物(wu)(wu)分解(jie),不斷(duan)消(xiao)耗(hao)水(shui)(shui)(shui)(shui)中(zhong)(zhong)的(de)溶解(jie)氧(yang),或被厭氧(yang)微(wei)生(sheng)(sheng)(sheng)物(wu)(wu)所(suo)分解(jie),不斷(duan)產(chan)生(sheng)(sheng)(sheng)硫化氫等(deng)氣(qi)體(ti),使(shi)水(shui)(shui)(shui)(shui)質惡(e)化,造成魚類和其他(ta)水(shui)(shui)(shui)(shui)生(sheng)(sheng)(sheng)生(sheng)(sheng)(sheng)物(wu)(wu)的(de)大量死(si)亡(wang)。藻(zao)(zao)類及其他(ta)浮游(you)生(sheng)(sheng)(sheng)物(wu)(wu)殘(can)體(ti)在腐爛過程中(zhong)(zhong),又把生(sheng)(sheng)(sheng)物(wu)(wu)所(suo)需(xu)的(de)氮、磷(lin)(lin)(lin)等(deng)營養(yang)物(wu)(wu)質釋放到(dao)水(shui)(shui)(shui)(shui)中(zhong)(zhong),供新的(de)一代藻(zao)(zao)類等(deng)生(sheng)(sheng)(sheng)物(wu)(wu)利用。因此,水(shui)(shui)(shui)(shui)體(ti)富營養(yang)化后(hou)(hou),即(ji)使(shi)切斷(duan)外界(jie)營養(yang)物(wu)(wu)質的(de)來(lai)源(yuan),也很難自凈和恢復(fu)到(dao)正常水(shui)(shui)(shui)(shui)平。水(shui)(shui)(shui)(shui)體(ti)富養(yang)化嚴重時,湖泊可被某些繁(fan)生(sheng)(sheng)(sheng)植物(wu)(wu)及其殘(can)骸(hai)淤塞,成為沼(zhao)澤甚至干地(di)。局部海(hai)(hai)區可變成"死(si)海(hai)(hai)",或出現"赤潮"現象。 常用氮、磷含(han)量,生產率(O2)及葉(xie)綠素-α作為水體富(fu)營(ying)養化程度的指(zhi)標。防治富(fu)營(ying)養化,必須控制進入水體的氮、磷含(han)量。 4、有毒污染物 有(you)毒(du)(du)(du)污(wu)(wu)染(ran)物(wu)(wu)(wu)指的(de)是進入生(sheng)(sheng)物(wu)(wu)(wu)體后(hou)累(lei)積到一定數量能(neng)(neng)(neng)使體液(ye)和(he)(he)組織發生(sheng)(sheng)生(sheng)(sheng)化和(he)(he)生(sheng)(sheng)理(li)功能(neng)(neng)(neng)的(de)變(bian)化,引起暫時或(huo)(huo)持久的(de)病理(li)狀(zhuang)態(tai),甚至危及生(sheng)(sheng)命的(de)物(wu)(wu)(wu)質(zhi)。如(ru)重(zhong)金屬和(he)(he)難分(fen)解(jie)的(de)有(you)機污(wu)(wu)染(ran)物(wu)(wu)(wu)等。污(wu)(wu)染(ran)物(wu)(wu)(wu)的(de)毒(du)(du)(du)性(xing)(xing)與攝入機體內(nei)的(de)數量有(you)密切(qie)關系(xi)。同一污(wu)(wu)染(ran)物(wu)(wu)(wu)的(de)毒(du)(du)(du)性(xing)(xing)也與它的(de)存(cun)在形(xing)態(tai)有(you)密切(qie)關系(xi)。價(jia)態(tai)或(huo)(huo)形(xing)態(tai)不同,其(qi)毒(du)(du)(du)性(xing)(xing)可以(yi)有(you)很大(da)的(de)差異。如(ru)Cr(Ⅵ)的(de)毒(du)(du)(du)性(xing)(xing)比Cr(Ⅲ)大(da);As(Ⅲ)的(de)毒(du)(du)(du)性(xing)(xing)比As(Ⅴ)大(da);甲(jia)基(ji)汞(gong)的(de)毒(du)(du)(du)性(xing)(xing)比無機汞(gong)大(da)得多。另外污(wu)(wu)染(ran)物(wu)(wu)(wu)的(de)毒(du)(du)(du)性(xing)(xing)還與若干綜(zong)(zong)合(he)(he)效(xiao)(xiao)應(ying)(ying)有(you)密切(qie)關系(xi)。從(cong)傳(chuan)統毒(du)(du)(du)理(li)學來看,有(you)毒(du)(du)(du)污(wu)(wu)染(ran)物(wu)(wu)(wu)對生(sheng)(sheng)物(wu)(wu)(wu)的(de)綜(zong)(zong)合(he)(he)效(xiao)(xiao)應(ying)(ying)有(you)三種:(1)相加作用(yong),即兩種以(yi)上(shang)毒(du)(du)(du)物(wu)(wu)(wu)共(gong)存(cun)時,其(qi)總效(xiao)(xiao)果大(da)致是各(ge)成分(fen)效(xiao)(xiao)果之(zhi)和(he)(he)。(2)協(xie)同作用(yong),即兩種以(yi)上(shang)毒(du)(du)(du)物(wu)(wu)(wu)共(gong)存(cun)時,一種成分(fen)能(neng)(neng)(neng)促進另一種成分(fen)毒(du)(du)(du)性(xing)(xing)急(ji)劇增加。如(ru)銅、鋅共(gong)存(cun)時,其(qi)毒(du)(du)(du)性(xing)(xing)為它們單獨存(cun)在時的(de)8倍。(3)拮抗作用(yong),兩種以(yi)上(shang)的(de)毒(du)(du)(du)物(wu)(wu)(wu)共(gong)存(cun)時,其(qi)毒(du)(du)(du)性(xing)(xing)可以(yi)抵消一部分(fen)或(huo)(huo)大(da)部分(fen)。如(ru)鋅可以(yi)抑制鎘的(de)毒(du)(du)(du)性(xing)(xing);又如(ru)在一定條件下(xia)硒對汞(gong)能(neng)(neng)(neng)產生(sheng)(sheng)拮抗作用(yong)。總之(zhi),除考慮有(you)毒(du)(du)(du)污(wu)(wu)染(ran)物(wu)(wu)(wu)的(de)含(han)量外,還須考慮它的(de)存(cun)在形(xing)態(tai)和(he)(he)綜(zong)(zong)合(he)(he)效(xiao)(xiao)應(ying)(ying),這樣(yang)才能(neng)(neng)(neng)全面深入地了(le)解(jie)污(wu)(wu)染(ran)物(wu)(wu)(wu)對水質(zhi)及人體健康的(de)影(ying)響。 有(you)(you)(you)(you)毒污(wu)染(ran)物(wu)主(zhu)要(yao)有(you)(you)(you)(you)以下幾(ji)類:(1)重金屬(shu)(shu)。如汞、鎘、鉻、鉛(qian)、釩、鈷(gu)、鋇等(deng),其中汞、鎘、鉛(qian)危害較(jiao)大;砷(shen)、硒和鈹(pi)的(de)毒性(xing)(xing)(xing)也較(jiao)大。重金屬(shu)(shu)在自然界中一般(ban)不易(yi)消失,它們能通過食物(wu)鏈而(er)被富集;這類物(wu)質除直(zhi)接作用(yong)于人(ren)體(ti)(ti)引起疾病外,某些金屬(shu)(shu)還可能促(cu)進(jin)慢(man)性(xing)(xing)(xing)病的(de)發(fa)展。(2)無機(ji)陰離(li)子,主(zhu)要(yao)是(shi)NO2-、F-、CN-離(li)子。NO2-是(shi)致癌物(wu)質。劇(ju)毒物(wu)質氰化(hua)物(wu)主(zhu)要(yao)來自工業廢水排放。(3)有(you)(you)(you)(you)機(ji)農(nong)(nong)(nong)(nong)(nong)藥(yao)(yao)(yao)(yao)(yao)、多(duo)(duo)氯聯苯(ben)(ben)。目前世界上有(you)(you)(you)(you)機(ji)農(nong)(nong)(nong)(nong)(nong)藥(yao)(yao)(yao)(yao)(yao)大約(yue)6000種(zhong),常用(yong)的(de)大約(yue)有(you)(you)(you)(you)200多(duo)(duo)種(zhong)。農(nong)(nong)(nong)(nong)(nong)藥(yao)(yao)(yao)(yao)(yao)噴在農(nong)(nong)(nong)(nong)(nong)田中,經淋溶(rong)等(deng)作用(yong)進(jin)入(ru)水體(ti)(ti),產(chan)生(sheng)污(wu)染(ran)作用(yong)。有(you)(you)(you)(you)機(ji)農(nong)(nong)(nong)(nong)(nong)藥(yao)(yao)(yao)(yao)(yao)可分為有(you)(you)(you)(you)機(ji)磷(lin)農(nong)(nong)(nong)(nong)(nong)藥(yao)(yao)(yao)(yao)(yao)和有(you)(you)(you)(you)機(ji)氯農(nong)(nong)(nong)(nong)(nong)藥(yao)(yao)(yao)(yao)(yao)。有(you)(you)(you)(you)機(ji)磷(lin)農(nong)(nong)(nong)(nong)(nong)藥(yao)(yao)(yao)(yao)(yao)的(de)毒性(xing)(xing)(xing)雖大,但一般(ban)容易(yi)降解(jie),積(ji)累(lei)性(xing)(xing)(xing)不強,因(yin)而(er)對生(sheng)態系統的(de)影響(xiang)不明顯;而(er)絕大多(duo)(duo)數的(de)有(you)(you)(you)(you)機(ji)氯農(nong)(nong)(nong)(nong)(nong)藥(yao)(yao)(yao)(yao)(yao),毒性(xing)(xing)(xing)大,幾(ji)乎不降解(jie),積(ji)累(lei)性(xing)(xing)(xing)甚高(gao),對生(sheng)態系統有(you)(you)(you)(you)顯著影響(xiang)。多(duo)(duo)氯聯苯(ben)(ben)(PCB)是(shi)聯苯(ben)(ben)分子中一部(bu)分氫或(huo)全部(bu)氫被氯取代后所(suo)形成的(de)各種(zhong)異構體(ti)(ti)混合(he)物(wu)的(de)總稱。 多氯(lv)聯苯(ben)(ben)劇(ju)毒,脂溶性大,易(yi)被生物(wu)(wu)吸收,化學性質十分(fen)穩(wen)定,難以(yi)和(he)酸、堿、氧化劑等作用,有(you)高度耐熱(re)性,在1000~1400℃高溫下才能完全分(fen)解(jie),因而在水體(ti)和(he)生物(wu)(wu)中(zhong)很難降解(jie)。(4)致癌物(wu)(wu)質。致癌物(wu)(wu)質大體(ti)分(fen)三類(lei):稠環(huan)芳(fang)香烴(PAHs),如(ru)3,4-苯(ben)(ben)并芘等;雜環(huan)化合(he)物(wu)(wu),如(ru)黃(huang)曲霉素等;芳(fang)香胺(an)類(lei),如(ru)甲、乙苯(ben)(ben)胺(an),聯苯(ben)(ben)胺(an)等。(5)一般有(you)機物(wu)(wu)質。如(ru)酚(fen)(fen)類(lei)化合(he)物(wu)(wu)就(jiu)有(you)2000多種,最(zui)(zui)簡單的是(shi)苯(ben)(ben)酚(fen)(fen),均為(wei)高毒性物(wu)(wu)質;腈(jing)類(lei)化合(he)物(wu)(wu)也有(you)毒性,其(qi)中(zhong)丙烯(xi)腈(jing)的環(huan)境影響最(zui)(zui)為(wei)注目(mu)。 5、石油類污(wu)染物(wu) 石油(you)(you)(you)(you)(you)污(wu)染(ran)是(shi)水(shui)體污(wu)染(ran)的(de)重要(yao)類型之(zhi)一,特別在河口(kou)、近海水(shui)域(yu)更為突出。排入海洋的(de)石油(you)(you)(you)(you)(you)估計每年(nian)高達數百萬噸(dun)至上千萬噸(dun),約占世界石油(you)(you)(you)(you)(you)總產(chan)量的(de)千分之(zhi)五。石油(you)(you)(you)(you)(you)污(wu)染(ran)物主要(yao)來自(zi)工業排放,清洗(xi)石油(you)(you)(you)(you)(you)運輸船(chuan)只的(de)船(chuan)艙、機件及發(fa)生意外事(shi)故、海上采油(you)(you)(you)(you)(you)等均可造成(cheng)石油(you)(you)(you)(you)(you)污(wu)染(ran)。而(er)油(you)(you)(you)(you)(you)船(chuan)事(shi)故屬于爆炸(zha)性的(de)集中(zhong)污(wu)染(ran)源,危害是(shi)毀滅性的(de)。 石(shi)油是(shi)烷烴、烯烴和(he)芳香烴的混(hun)合物,進入水體(ti)后的危害(hai)是(shi)多方面(mian)的。如在(zai)水上形成油膜(mo),能(neng)阻礙(ai)水體(ti)復氧作用,油類粘附(fu)在(zai)魚鰓上,可(ke)使魚窒息;粘附(fu)在(zai)藻類、浮游生物上,可(ke)使它們死亡。油類會抑制水鳥(niao)產卵和(he)孵化(hua),嚴重(zhong)時使鳥(niao)類大量死亡。石(shi)油污(wu)染還(huan)能(neng)使水產品質量降低。 6、放射性污染物 放(fang)(fang)射(she)性(xing)(xing)污染是(shi)放(fang)(fang)射(she)性(xing)(xing)物質(zhi)進入水(shui)(shui)體(ti)后(hou)造(zao)(zao)成的。放(fang)(fang)射(she)性(xing)(xing)污染物主要來(lai)源于核(he)(he)動力(li)工廠排(pai)出的冷(leng)卻水(shui)(shui),向海洋投棄的放(fang)(fang)射(she)性(xing)(xing)廢物,核(he)(he)爆炸(zha)降(jiang)落到水(shui)(shui)體(ti)的散落物,核(he)(he)動力(li)船舶事(shi)故泄漏的核(he)(he)燃料;開(kai)采、提煉(lian)和使用放(fang)(fang)射(she)性(xing)(xing)物質(zhi)時(shi),如果處(chu)理不當,也會造(zao)(zao)成放(fang)(fang)射(she)性(xing)(xing)污染。水(shui)(shui)體(ti)中(zhong)的放(fang)(fang)射(she)性(xing)(xing)污染物可(ke)以附著在生物體(ti)表(biao)面(mian),也可(ke)以進入生物體(ti)蓄積起來(lai),還可(ke)通過食物鏈對人產(chan)生內照射(she)。 水中主要(yao)的天然放射(she)性元素有40K、238U、286Ra、210Po、14C、氚等(deng)。目前,在世界(jie)任(ren)何海區幾乎都能測出90Sr、137Cs。 7、酸、堿(jian)、鹽無機污染物 各種酸、堿(jian)、鹽等無機(ji)物進入水(shui)(shui)(shui)(shui)體(酸、堿(jian)中(zhong)和生成(cheng)鹽,它們與水(shui)(shui)(shui)(shui)體中(zhong)某些(xie)礦(kuang)(kuang)物相互作用(yong)產生某些(xie)鹽類),使淡水(shui)(shui)(shui)(shui)資源的(de)礦(kuang)(kuang)化度提高,影響各種用(yong)水(shui)(shui)(shui)(shui)水(shui)(shui)(shui)(shui)質。鹽污染主要來自(zi)生活污水(shui)(shui)(shui)(shui)和工礦(kuang)(kuang)廢水(shui)(shui)(shui)(shui)以及(ji)某些(xie)工業廢渣。另(ling)外(wai),由于(yu)酸雨規(gui)模日益(yi)擴大(da),造成(cheng)土壤(rang)酸化、地下水(shui)(shui)(shui)(shui)礦(kuang)(kuang)化度增高。 水(shui)體中無機鹽(yan)增加能提高水(shui)的滲透壓,對淡水(shui)生(sheng)(sheng)(sheng)物(wu)、植物(wu)生(sheng)(sheng)(sheng)長產生(sheng)(sheng)(sheng)不(bu)良影響(xiang)。在鹽(yan)堿化(hua)地(di)區,地(di)面(mian)水(shui)、地(di)下(xia)水(shui)中的鹽(yan)將對土(tu)壤質量產生(sheng)(sheng)(sheng)更大(da)影響(xiang)。 8、熱污染 熱污(wu)染是一(yi)種能量(liang)污(wu)染,它是工(gong)礦企業向水體排(pai)放高(gao)溫廢水造成的。一(yi)些熱電廠(chang)及各種工(gong)業過程(cheng)中(zhong)的冷卻水,若(ruo)不采取措施,直接(jie)排(pai)放到(dao)水體中(zhong),均(jun)可使(shi)水溫升(sheng)高(gao),水中(zhong)化(hua)學反應、生化(hua)反應的速度隨之加(jia)快,使(shi)某(mou)些有毒物質(如氰化(hua)物、重金(jin)屬離(li)子等)的毒性提高(gao),溶解氧減少,影響魚類的生存和繁殖,加(jia)速某(mou)些細菌的繁殖,助長水草(cao)叢生,厭氣發酵,惡臭。 魚(yu)(yu)(yu)類(lei)(lei)生(sheng)長都有一(yi)個最佳的水(shui)溫(wen)區間。水(shui)溫(wen)過高或過低都不(bu)適(shi)合魚(yu)(yu)(yu)類(lei)(lei)生(sheng)長,甚至(zhi)會導致死亡。不(bu)同魚(yu)(yu)(yu)類(lei)(lei)對水(shui)溫(wen)的適(shi)應性也(ye)是不(bu)同的。如熱帶(dai)魚(yu)(yu)(yu)適(shi)于(yu)15~32℃,溫(wen)帶(dai)魚(yu)(yu)(yu)適(shi)于(yu)10~22℃,寒帶(dai)魚(yu)(yu)(yu)適(shi)于(yu)2~10℃的范圍。又如鱒魚(yu)(yu)(yu)雖在24℃的水(shui)中生(sheng)活(huo),但其繁殖溫(wen)度(du)則要低于(yu)14℃。一(yi)般水(shui)生(sheng)生(sheng)物能夠生(sheng)活(huo)的水(shui)溫(wen)上限是33~35℃。 除了(le)上述八(ba)類污(wu)染物(wu)(wu)以外,洗滌劑等表(biao)面活性劑對水(shui)環境的主要(yao)危害在于使水(shui)產生(sheng)泡沫(mo),阻止(zhi)了(le)空(kong)氣與水(shui)接觸(chu)而降低(di)溶(rong)解(jie)氧,同時由于有機物(wu)(wu)的生(sheng)化降解(jie)耗(hao)用水(shui)中(zhong)溶(rong)解(jie)氧而導致水(shui)體缺氧。高濃(nong)度表(biao)面活性劑對微生(sheng)物(wu)(wu)有明顯毒性。 水(shui)體(ti)(ti)污染的例子很(hen)多(duo),如京(jing)杭(hang)大(da)(da)運河(he)(he)(杭(hang)州段)兩岸(an)有(you)許多(duo)工廠,每天均有(you)大(da)(da)量廢水(shui)排入運河(he)(he),使水(shui)體(ti)(ti)中(zhong)固體(ti)(ti)懸(xuan)浮(fu)物、有(you)機(ji)物、重金屬(Zn,Cd,Pb,Cu等(deng))及(ji)酚、氰化物等(deng)含量大(da)(da)大(da)(da)超過地面水(shui)標(biao)準,有(you)的超過幾十倍,使水(shui)體(ti)(ti)處(chu)于厭(yan)氧的還(huan)(huan)原狀態,烏(wu)黑(hei)發臭,魚蝦絕跡,不(bu)能(neng)用于生活、農(nong)業等(deng)用水(shui);水(shui)體(ti)(ti)自凈(jing)能(neng)力差(cha),若(ruo)不(bu)治理,并控制污染源,水(shui)體(ti)(ti)污染還(huan)(huan)會進(jin)一步擴大(da)(da)。 水(shui)(shui)環(huan)境(jing)(jing)中(zhong)的(de)污(wu)染(ran)物(wu)(wu)(wu),總體上可劃分(fen)為(wei)無機污(wu)染(ran)物(wu)(wu)(wu)和(he)(he)有(you)機污(wu)染(ran)物(wu)(wu)(wu)兩大類(lei)。在(zai)水(shui)(shui)環(huan)境(jing)(jing)化學中(zhong)較(jiao)為(wei)重(zhong)要的(de),研(yan)究得較(jiao)多的(de)污(wu)染(ran)物(wu)(wu)(wu)是(shi)重(zhong)金(jin)屬和(he)(he)有(you)機物(wu)(wu)(wu)。我國水(shui)(shui)污(wu)染(ran)化學研(yan)究始(shi)于70年代,從重(zhong)金(jin)屬、耗氧有(you)機物(wu)(wu)(wu)、DDT、六(liu)六(liu)六(liu)等農藥污(wu)染(ran)開(kai)始(shi),目前研(yan)究的(de)重(zhong)點已(yi)轉向有(you)機污(wu)染(ran)物(wu)(wu)(wu),特別是(shi)難降解有(you)機物(wu)(wu)(wu),因(yin)(yin)其在(zai)環(huan)境(jing)(jing)中(zhong)的(de)存(cun)留期長,容易沿(yan)食(shi)物(wu)(wu)(wu)鏈(lian)(網(wang))傳遞積(ji)累(富集),威脅(xie)生物(wu)(wu)(wu)生長和(he)(he)人(ren)體健康,因(yin)(yin)而(er)日益受(shou)到(dao)人(ren)們重(zhong)視。本章著重(zhong)介紹(shao)重(zhong)金(jin)屬和(he)(he)有(you)機污(wu)染(ran)物(wu)(wu)(wu)在(zai)水(shui)(shui)體中(zhong)遷移轉化的(de)環(huan)境(jing)(jing)化學行為(wei)。 |