本文關(guān)鍵詞： 生物炭 水稻 鎘 有效性 賦存形態(tài) 根際 根箱　出處：《沈陽農(nóng)業(yè)大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：鎘是一種對人體毒性極強(qiáng)的重金屬。我國近年官方土壤污染狀況調(diào)查公報顯示,全國耕地土壤近兩成存在污染物超標(biāo)的問題,其中絕大多數(shù)為無機(jī)污染,而無機(jī)污染物中以鎘污染超標(biāo)點位所占比例最高,且遠(yuǎn)高于其他元素。水稻是受土壤鎘污染危害非常嚴(yán)重的大宗作物,近年來關(guān)于稻米鎘超標(biāo)的食品安全問題已成為社會關(guān)注的熱點。生物炭具備改良土壤、作物增產(chǎn)、增匯減排等多種環(huán)境功能效應(yīng),因其較高的孔隙度、比表面積和酸堿度等理化特性,在消除和固定各類土壤污染物的環(huán)境解毒領(lǐng)域廣受關(guān)注。本研究以如何降低土壤鎘生物有效性、減少水稻鎘吸收積累兩個現(xiàn)實問題為出發(fā)點,以明確生物炭對"土壤-水稻"體系內(nèi)鎘行為的影響為目的,向土壤添加生物炭作為土壤重金屬污染改良劑,采取原位化學(xué)鈍化修復(fù)的方式,利用多類型土壤培養(yǎng)試驗、多年大田試驗和近根際模擬試驗三種研究方法,著重研究了生物炭對土壤中鎘的生物有效性和賦存形態(tài)、水稻各器官鎘含量與鎘積累量的影響,最終探討生物炭應(yīng)用于鎘污染土壤修復(fù)的潛力、機(jī)制和方式。培養(yǎng)試驗中,以6種不同類型土壤試材模擬鎘污染土壤,在不同生物炭添加比例(0、1%、5%)處理條件下、不同培養(yǎng)條件下(不同培養(yǎng)時間、是否培植稻苗)研究了生物炭對各類型土壤的生物有效性鎘含量、苗期水稻鎘含量的影響,試驗中分別用5種提取方法(HC1法、Mehlich3法、DTPA法、CaC12法和TCLP法)測定了土壤有效性鎘含量的變化情況,進(jìn)而評價了提取方法的適用性。大田試驗中,選擇沈陽市郊一塊由于污灌而形成鎘污染的稻田為試驗點,以不同生物炭添加量為處理(0、7.5、15.0、30.0t/hm2,3.0t/hm2/年),連續(xù)三年關(guān)注生物炭對污染水稻土壤鎘賦存形態(tài)及主要理化性質(zhì)、水稻各器官鎘含量和積累量的變化情況。根際模擬試驗中,采取三室多土層根箱法培植水稻,取得模擬水稻近根際1-5mm范圍內(nèi)各個層次的土壤樣品,研究了添加生物炭對水稻近根際土壤有效性鎘含量和水稻鎘吸收積累的影響。取得的結(jié)果顯示:培養(yǎng)條件下,1%和5%的生物炭添加能夠顯著降低多類型土壤條件下有效性鎘含量及苗期水稻地上部分鎘含量;不同有效性鎘提取法提取率不同,TCLP法最低,CaC12次低,Mehlich3法與DTPA法提取效率相對較高,HC1法總體最高;DTPA法、CaCl2法和TCLP法提取結(jié)果與稻苗鎘積累量相關(guān)性較好,推薦DTPA法應(yīng)用于分析添加生物炭條件下土壤有效性鎘含量變化。大田條件下,不同生物炭用量處理在三年中均未對水稻各器官干物質(zhì)積累量產(chǎn)生顯著影響;較高用量生物炭處理顯著降低了水稻糙米、莖鞘、根系的鎘含量,而對水稻葉片和稻殼鎘含量影響微弱;生物炭在試驗第二年顯著降低了水稻多個器官的鎘積累量;生物炭處理對水稻體內(nèi)鎘轉(zhuǎn)移和積累的比例無顯著影響,但能夠顯著降低水稻整體自土壤富集鎘的比例;中高量生物炭處理能夠顯著降低土壤可交換態(tài)鎘含量、提高鐵錳氧化物結(jié)合態(tài)鎘含量,對碳酸鹽結(jié)合態(tài)和殘渣態(tài)鎘含量未有顯著影響,有機(jī)結(jié)合態(tài)鎘含量在試驗最后一年有所提高;三年中,生物炭處理均能有效提高土壤pH和SOC。根際模擬實驗中,生物炭對水稻各器官干物質(zhì)積累量無顯著影響,對水稻莖、鞘、糙米鎘含量有顯著降低作用;生物炭顯著降低了水稻地上部分總鎘含量、積累量,增加了水稻干物質(zhì)積累量。生物炭能夠降低水稻近根際土壤有效性鎘含量,表現(xiàn)為添加生物炭縮小了水稻根系在土壤中吸收鎘的有效范圍。
[Abstract]:Cadmium is a heavy metal with strong toxicity to the human body. In recent years in China's official survey of Soil Pollution Bulletin shows that the cultivated soil nearly 20% existing pollutants exceed the standard problem, and most of them are inorganic pollution, and inorganic pollutants to cadmium pollution exceed the standard point accounted for the highest proportion, and far higher than other elements in rice. Is the harm of cadmium in soil bulk crops are very serious, in recent years, food safety problems on rice cadmium exceed the standard has become the focus of the society. With biochar soil, crop yield, increasing sequestration and other environmental functional effects, because of its high porosity, specific surface area and pH of physicochemical properties. Wide attention in the elimination and fixed all kinds of pollutants in the soil. The detoxification research in order to reduce the availability of soil cadmium bio, reduce rice cadmium accumulation of two practical problems as a starting Point to clear the biological carbon effect on the soil rice system of cadmium behavior for the purpose of adding biochar to soil as a soil heavy metal pollution improver, taken in situ chemical immobilization, culture test by different types of soil, years of field experiments and near rhizosphere simulation test of three kinds of research methods, focusing on the biochar on soil cadmium bioavailability and speciation of cadmium, cadmium content and accumulation in the organs of rice, finally discusses biochar application in remediation of soil contaminated with cadmium. The potential mechanism and culture test, with 6 different types of soil samples in Cd contaminated soil in different organisms, carbon proportion (0,1%, 5%) under different culture conditions (different culture time, whether to cultivate seedlings) of biochar on various types of soil bioavailable contents of cadmium, cadmium content in rice seedling. Ring, 5 extraction methods were used in the test (HC1 method, Mehlich3 method, DTPA method, CaC12 method and TCLP method) changes the effectiveness of soil cadmium content was determined, and then evaluate the applicability of the extraction method. The field test, choose a Shenyang suburb because of sewage irrigation and the formation of cadmium pollution in paddy field as the test point, to add a different amount of biochar treatment (0,7.5,15.0,30.0t/hm2,3.0t/hm2/), and the physicochemical properties of chemical speciation of cadmium contaminated paddy soil for three consecutive years to focus on biological carbon, cadmium content and accumulation in the organs of rice rhizosphere changes. In the simulation test, take three more root box method of rice cultivation. To simulate the soil samples at different levels in rice rhizosphere in the range of 1-5mm, the addition of biochar accumulation effect on rice near rhizosphere effective cadmium content in soil and rice. The results showed that cadmium culture conditions, 1% Biochar and 5% additive can significantly reduce soil conditions under multiple types of effective cadmium content in rice seedling and aboveground cadmium content; different cadmium availability extraction rate, TCLP was the lowest, CaC12 low, Mehlich3 method and DTPA extraction efficiency is relatively high, the highest total body HC1 method; DTPA method the extraction results of CaCl2 method and TCLP method and rice Cd accumulation correlated well, recommended DTPA method is applied to analyzing the effectiveness of adding cadmium content in soil biochar conditions. Under field conditions, different amount of biochar treatment in three years were not on the dry matter accumulation was significantly influenced by various organs of rice; the higher amount of biochar treatment significantly reduced the rice, stem and sheath, the CD content in root and leaves of rice husk, and cadmium content influence the weak; in the second year of biochar significantly reduced rice multiple organ cadmium accumulation; biological activated carbon treatment No significant effect on the transfer and accumulation of cadmium in rice ratio, but can significantly reduce the overall proportion of rice from soil Cd enrichment; high biomass carbon treatment can significantly reduce the soil exchangeable cadmium content, improve the bound cadmium content of iron and manganese oxides, bound and residual cadmium content had no significant influence on carbonate. The organic combination of cadmium content increased in the test last year; three years, biochar treatments could effectively improve soil pH and SOC. in rhizosphere experiment, biochar had no significant effect on the organs of rice dry matter accumulation of rice, stem, sheath, Cd content in brown rice decreased significantly; biological activated carbon significantly reduced the rice on the part of the total cadmium content, accumulation, increased dry matter accumulation of rice. The biological carbon can reduce rice near rhizosphere soil effective cadmium content, performance of biochar reduced rice roots The effective range of cadmium absorption in the soil.

【學(xué)位授予單位】：沈陽農(nóng)業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：X53;S511

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