腐殖酸对铊污染土壤中铊形态和分布的影响

选用云浮含铊硫铁矿周围冲积土壤为供试样品,在土样中投加不同比例腐殖酸,采用连续浸提法对比研究了外源腐殖酸对受铊污染土中的铊不同形态及活性的影响.结果表明:随腐殖酸投入比的加大,酸可交换态含量明显下降,Fe/Mn氧化物结合态反之,有机质结合态与Fe/Mn氧化物结合态雷同,残余态几乎无变化;腐殖酸对酸可交换态铊分配比率最高为13.6%～30.5%,分别是有机态铊和Fe/Mn氧化态铊的2.8～15.1倍和2.8～3.7倍.结果说明腐殖酸有降低冲积土壤上有害活动态铊的功能,其作用机制在于腐殖酸具备的络合(螯合)能力和胶体特性.研究确认,腐殖酸可作为土壤重金属污染修复的优质材料.     

粤东凤凰山茶区土壤锰、锌赋存形态特征及对茶叶的有效性

采用连续化学提取法对粤东凤凰山茶区12个茶园土壤Mn和Zn的5种赋存形态特征及对茶叶的有效性进行了研究。结果发现,茶区土壤Mn平均含量为337 mg.kg-1,Zn平均含量为166.0 mg.kg-1,Mn和Zn的形态分布规律均表现为残渣态>铁锰氧化物结合态>有机束缚态>可交换态>碳酸盐结合态。土壤铁锰氧化物结合态和碳酸盐结合态Mn含量以及碳酸盐结合态、有机束缚态和铁锰氧化物结合态Zn含量分别与土壤pH值呈显著正相关,可交换态Mn含量与土壤pH值呈显著负相关;有机束缚态Mn、Zn含量以及铁锰氧化物结合态Zn含量分别与土壤有机质含量呈显著正相关,而铁锰氧化物结合态Mn含量与土壤有机质含量呈显著负相关。茶区茶叶Mn平均含量为1 046.3 mg.kg-1,Zn平均含量为42.0 mg.kg-1。茶叶Zn含量分别与土壤可交换态、有机束缚态、碳酸盐结合态Zn含量以及有机质含量呈显著正相关;茶叶Mn含量分别与土壤可交换态、碳酸盐结合态、有机束缚态Mn含量呈显著正相关,而与土壤pH值呈显著负相关。土壤pH值和有机质含量对茶区土壤Mn和Zn的化学形态分布及茶叶中Mn和Zn的累积有重要影响。     

北方常见农作物根际土壤中铅、锌的形态转化及其植物有效性

采用盆栽试验结合形态分析技术研究了北方地区常见农作物对污染土壤中铅(Pb)、锌(Zn)的形态转化及其植物有效性的影响。土壤Pb、Zn形态分析结果显示,与非根际土壤相比,多数作物根际可交换态、碳酸盐结合态、有机质结合态Pb比例降低,而铁锰氧化物结合态、残渣态Pb则显著增加;Zn则表现为可交换态比例略呈降低趋势,碳酸盐结合态、铁锰氧化物结合态与有机质结合态升高,残渣态Zn则大幅下降。这提示,作物根际土壤Pb存在由松结合态向紧结合态转化的现象,从而植物有效性降低;而根际土壤Zn的形态变化则与Pb相反,即由紧结合态向松结合态转化,相应地提高了Zn的植物有效性。     

小麦根际土壤汞的分布和形态变化

采用根际箱试验和连续化学萃取法,结合氢化物原子吸收光谱法,研究了非根际和根际土壤汞形态分布特征及小麦(Triticum aestivum)生长期土壤汞形态变化.结果表明.非根际汞形态分布顺序为:残渣态>强有机质结合态>碳酸盐铁锰氧化物结合态>腐殖酸络合态>水溶态>交换态,根际汞形态分布为:残渣态>碳酸盐铁锰氧化态>强有机质结合态>交换态>腐殖酸络合态>水溶态.当外源汞进入土壤后,在小麦生长60 d内,植物吸收使残渣态汞和水溶态汞含量明显降低,交换态汞和碳酸盐铁锰氧化态汞含量增加.土壤汞污染程度越大,在小麦中积累的汞就越多.其生物毒性增强,环境危害加大.     

腐殖酸对土壤铅赋存形态的影响

通过室内培养试验,深入探讨了不同用量腐殖酸,对铅污染土壤中铅各形态的影响.结果表明,腐殖酸各处理均能显著降低土壤中铅的交换态(EX-),碳酸盐结合态(Cob-)和铁锰氧化物结合态(FeMn-)的含量,而有机结合态(Ob-)铅和残渣态(Res-)铅的含量则显著提高.施用腐殖酸有效地降低了铅的活性,且影响程度随腐殖酸用量的增加而显著增加.腐殖酸对土壤中铅离子的各形态含量随时间的变化的影响表现为,在培养040 d期间,随培养时间的延长交换态铅含量无明显变化,残渣态铅含量显著降低,其它三种形态均呈增加趋势;培养40 d后,随培养时间的延长各形态的含量均无显著变化.综合考虑认为施入10%质量比的腐殖酸即可显著降低铅的活性,从而可达到较好的修复效果.     

胡敏酸对沉积物中重金属形态分布的影响

采用连续提取法分析沉积物添加胡敏酸后,其中重金属(Cd, Cu, Zn, Pb和Ni)的形态分布状况.结果显示:随着胡敏酸的加入,重金属的可交换态含量都不同程度的降低,铁锰氧化物结合态含量不同程度的增加,有机结合态和残渣态含量有所提高.Pb和Ni有机质结合态的增加与胡敏酸的浓度有较好的相关关系.五种重金属中对Zn的影响最为显著,对Cd的影响最小.表明胡敏酸能促进重金属由非稳定态向稳定态转化,即能钝化沉积物重金属,降低其生物有效性.     

大气降尘与土壤中重金属铬的形态分布规律

主要对成都理工大学校园内大气降尘和土壤中重金属铬的形态分布进行了分析比较,得出以下结论:重金属铬在大气降伞和土壤中的含量存在差别,大气降尘中铬的最明显大于土壤中的量,且基本上是土壤的两倍左右.且形态分布规律不同,大气降尘中铬含量的形态分布由大到小的次序是:残渣晶格态,铁锰氧化物结合态,有机结合态,碳酸盐结合态,可交换态;土壤中南大到小的次序是:残渣品格态,有机结合态,铁锰氧化物结合态,碳酸盐结合态,可交换态;铬在大气降尘中多存在于残渣晶格态(35.35%～59.82%)和铁锰氧化物结合态(25.97%～40.23%),且两者相差不大.而在土壤中多存在于残渣晶格态(37.22%～75.06%)和有机结合态(4.30%～12.98%),且主要以残渣品格态为主.形态分离方法采用Tessier五步连续提取法,重金属铬的测定方法采用国标方法(GB/T 5009.123-2003)示波极谱法.     

外加锌在土壤中形态的研究

本文采用化学逐级提取法对吸附锌后的土壤分别提取了交换态、CaCO_3结合态、氧化物结合态和有机质结合态的锌量,并讨论pH、温度和溶液中锌离子浓度对不同形态锌分布的影响。实验结果表明:外加锌被石灰性土壤吸附后,高pH值(7.5)时形态分布为:CaCO_3结合态≥交换态>氧化物结合态>有机质结合态;低pH值(5.5)时则为:交换态>CaCO_3结合态>氧化物结合态>有机质结合态。各形态锌的分配系数还受到吸附时的温度和溶液中锌离子浓度的影响。     

pH对宁夏引黄灌区盐碱化土壤重金属吸附-解吸过程的影响

高pH值是宁夏引黄灌区盐碱化土壤的显著特征,研究盐碱化土壤的高pH值对不同重金属元素的富集和释放规律,可为宁夏引黄灌区盐碱化土壤重金属污染的控制及治理提供科学依据。通过调节pH值,采用土柱淋溶的方法,模拟盐碱化土壤的Cd和Pb的吸附-解吸过程,研究pH对盐碱化土壤重金属Cd、Pb吸附-解吸特征、形态和生物活性的影响。结果表明:在试验设定的pH范围内,盐碱化土壤对Cd的吸附量随着pH值的升高而呈升高趋势,在pH值为8时达到峰值,对Pb的吸附量随pH的升高呈波动状变化状态,在pH值为10时达到峰值;同时,Cd的解吸量随吸附量增加而线性增大,解吸量随pH升高而增加,但解吸量随吸附量变化而变化的幅度随pH值的升高而减小,Pb的解吸量随吸附量增加而呈选择性增加。随着pH的升高,Cd可交换态和碳酸盐结合态的含量变化趋势相反,生物活性基本不变,其Fe/Mn氧化物结合态、有机结合态和残渣态的含量不变;Pb可交换态和碳酸盐结合态的含量随着pH的升高而升高,生物活性增强,有机结合态的含量减少,Fe/Mn氧化物结合态和残渣态的含量不变。宁夏引黄灌区盐碱化土壤的高pH值可以降低土壤对重金属Cd、Pb的吸附,缓解重金属污染引起的生态、粮食及其食品安全压力。     

准好氧填埋场垃圾中重金属化学形态分布特征

通过模拟准好氧填埋场中试试验,对垃圾原样和经准好氧填埋消化8个月后不同空间位置固体样中重金属含量、化学形态分布和迁移性进行研究.结果表明,垃圾原样中Pb,Ni,Cr,Cu和Fe的含量分别为88 mg·kg-1,52 mg·kg-1,304.667 mg·kg-1,29 mg·kg-1 和1632.67 mg·kg-1.垃圾原样中Ni和Cu以残渣态所占比例最高,分别为60.26%和60.92%,Pb以有机物结合态所占比例最高,为54.92%,Cr以铁锰氧化物结合态所占比例最高,为57.44%,而Fe以铁锰氧化物结合态、有机物结合态、残渣态为主,所占比例相近,为31%-34%左右.垃圾经准好氧填埋消化8个月后,Pb,Ni的有机物结合态所占比例降低,可交换态、碳酸盐结合态或铁锰氧化物结合态所占比例增加;Cu,Fe残渣态所占比例降低,可交换态、碳酸盐结合态或有机物结合态所占比例增加;Cr铁锰氧化物结合态所占比例降低,碳酸盐态或残渣态所占比例增加,金属活性增大.垃圾中Fe,Ni,Pb的迁移能力较强,迁移能力依次为Fe＞Ni＞Pb＞Cr＞Cu.     

腐殖酸存在下镉和铅对土壤脱氢酶活性的影响

采用室内培养试验研究Cd和Pb污染红壤添加不同组分腐殖酸后,其脱氢酶活性的变化,结果表明,红壤遭受镉和铅污染后,脱氢酶活性显著降低,然而腐殖酸特别是胡敏酸的存在能够使脱氢酶活性得到显著回升,说明腐殖酸与重金属的相互作用对重金属污染土壤微生物活性的改善和修复功能,对土壤有一定的去污降毒作用.不同腐殖酸组分的效应大小为:灰色胡敏酸(GHA)>棕色胡敏酸(BHA)>富里酸(FA),表明分子量愈大、芳构化程度愈高的腐殖酸组分,其对重金属的钝化愈强,从而解除土壤重金属对生物毒害的能力愈强.     

西湖沉积物有机质特征

分析了西湖沉积物腐殖质的组成及腐殖酸的红光谱特性,结果显示西湖沉积物腐殖质具有典型的湖泊沉积物腐质特征,腐殖化程度较高;结合形分析表明,腐殖质中：胡敏素〉胡敏酸〉富里酸〉脂类,钱塘江引水工程、水面种植荷花明显改变了沉积物有机质的构成,对西湖的碳和富营养化状况有显著影响。     

Effects of water quality on the coagulation performances of humic acids irradiated with UV light

The presence of humic acid in drinking water treatment has received significant attention in recent years because of its adverse effects on the removal of many pollutants in coagulation. In this paper, the effects of water quality including pH, turbidity, alkalinity, and hardness on the removal of humic acid were investigated in a UV light hybridized coagulation process. Our results suggested that UV light radiation could effectively improve the removal rate of humic acid in coagulation under both neutral and basic conditions, and the variations of the selected water quality parameters had little adverse effect on the function of UV light. After UV light radiation, the removal rate of the nitro-humic acid (NHA) increased from 20% to 60% in coagulation, and increased further to 75% and 85% for the raw waters with 10.0 NTU kaolin and 100 mg·L^-1 hardness, respectively. In addition to NHA, the removal rates of the humic acid extracted from peat coal (PHA) and the humic acid provided by Japan metals and chemicals company (JHA) in coagulation were also improved, both in the range of 80%–90% after undergoing UV light radiation. By changing the radiation location from prior to coagulation to the flocculation process, similar experimental results were obtained. The formation of positive charged sites after UV light radiation was considered to be the primary factor that led to an enhanced removal of the humic acid in coagulation.     

荧光猝灭法测定菲、苊、芘与腐殖酸的结合常数

用荧光猝灭法测定了胡敏酸（Fluka）与苊、菲和芘相互作用的结合常数（KDOC），其lgKDOC值分别为4．4，4．48和4．89．用同样方法测得长江水生FA以及黑龙江水生FA和HA的KDOC之间有显著差别．HA的KDODC一般高于FA．黑龙江水生FA的KDOC高于长江．对同一来源的腐殖酸，三种多环芳烃的KDOC与KOW呈线性相关．     

Strong adsorption of DNA molecules on humic acids

Analysing soil microbial communities is often hampered by DNA adsorption on soil organic compounds such as humic acids. However the role of humic acids in DNA adsorption and stability in soils remains controversial. To characterize DNA–humic acid interactions, we studied DNA adsorption on two commercially available humic acids and a soil humic acid extracted from an Andosol. Desorption of the adsorbed DNA using 4 different solutions—distilled water, 0.1 M NaCl, 0.1 M sodium phosphate buffer (pH 6.0), and 1% sodium dodecyl sulfate solution—was also studied to understand the mechanism of DNA adsorption on humic acids. Here, we show that humic acids play an important role in DNA adsorption to soils. DNA molecules were adsorbed on the humic acids, with adsorption increasing proportionally with the DNA concentrations in the solution. The adsorption on all humic acid samples was fitted with Freundlich equation, and the parameters obtained from the equation indicated a high affinity between the humic acids and DNA molecules. The total amount of DNA desorbed by the 4 solutions was less than 2% of the total DNA adsorbed on all the humic acids. The results demonstrate that DNA molecules are able to bind strongly to humic acids by ligand binding, hydrophobic interaction, aggregation, or precipitation.     

微生物降解褐煤产生的腐植酸化学特性研究

本文对微生物降解褐煤产生的腐植酸的化学特性进行了分析.结果表明,褐煤经微生物降解后其腐植酸与降解前相比,氢和氧百分含量增加,碳百分含量减少,分子量减小 ,而絮凝极限明显增大,红外吸收光谱也发生明显变化.     

免耕与常规耕作下黑土腐殖酸含量与结构的差异

以东北农业科学院长期耕作定位实验为研究对象,结合元素分析和红外光谱来研究免耕与翻耕两种耕作方式对黑土腐殖酸含量与胡敏酸结构的影响。结果表明：免耕处理的腐殖酸含量高于常规耕作处理18.28%,两种耕作处理间HA/FA值差异很小;免耕处理的碳、氮和氢元素含量分别高于翻耕处理5.48%、36.49%和27.65%,N/C和H/C值也高于翻耕处理,而翻耕处理的O/C值高于免耕处理;不同耕作处理的红外光谱吸收带表现相似趋势,其中2920、2580、1620、1420和1220σ·cm-1处吸光度免耕信号高于翻耕,而1026、721σ·cm-1处吸光度相反。免耕增加了腐殖酸、胡敏酸及富里酸含量;免耕增加了黑土胡敏酸的芳香度、脂肪化程度和聚合程度,而翻耕作增加了黑土胡敏酸的氧化程度,这说明经过长达26年的免耕处理使黑土腐殖质结构趋于稳定,而翻耕处理使黑土腐殖质结构趋于简单。     

络合态金属铜在大型水蚤(Daphnia magna)体内的生物积累及生物毒性

以人工稀释水作为背景水样,通过实验室暴露和化学平衡软件的辅助分析,研究了4种有机络合剂(草酸、酒石酸、EDTA和腐殖酸)对大型水蚤(Daphniamagna)体内铜的生物积累(BBD)以及生物毒性的影响.结果表明,有机络合剂的存在降低了大型水蚤体内生物积累量和金属硫蛋白(MT)含量,明显降低了水体中金属Cu的毒性,4种不同有机络合剂所产生的效果大体相同;有机络合态的铜也能为大型水蚤所吸收和利用,在相同浓度条件下大型水蚤对腐殖酸络合态铜的利用大于EDTA络合态铜.     

Plant Bioavailability of “natural” and “model” Humic acid‐bound [14c] Atrazine residues

The release of bound [14C] atrazine residues and their uptake by maize plants was investigated.

“Natural”; humic acids, extracted from a brown soil, and “model”; humic acids, prepared from catechol, both containing bound [14C] atrazine residues were incubated with plants in soil. After 21 days, the maize plants contained 0.7% (plants grown in soil mixed with “natural”; humic acids) to 1.7% (plants grown in soil mixed with “model”; humic acids) of the radioactivity originally introduced.

The roots contained 55 to 70% of the [14C] residues whereas the remainder was present in the shoots. A significant amount of the total [14C] residues (29 to 53%) became again bound in plant tissues, whereas the, majority of extractable [14C] residues was present in the form of conjugates.

The behaviour of “model”; humic acid‐bound residues was comparable to that of “natural”; humic acid‐bound residues or soil‐bound residues.     

Effect of co-existing organic compounds on adsorption of perfluorinated compounds onto carbon nanotubes

Co-existing organic compounds may affect the adsorption of perfluorinated compounds (PFCs) and carbon nanotubes in aquatic environments. Adsorption of perfluorooctane sulfonate (PFOS), perfluorooctane acid (PFOA), perfluorobutane sulfonate (PFBS), and perfluorohexane sulfonate (PFH_xS) on the pristine multi-walled carbon nanotubes (MWCNTs-Pri), carboxyl functionalized MWCNTs (MWCTNs-COOH), and hydroxyl functionalized MWCNTs (MWCNTs-OH) in the presence of humic acid, 1-naphthol, phenol, and benzoic acid was studied. Adsorption kinetics of PFOS was described well by the pseudo-second-order model and the sorption equilibrium was almost reached within 24 h. The effect of co-existing organic compounds on PFOS adsorption followed the decreasing order of humic acid>1-naphthol>benzoic acid>phenol. Adsorbed amounts of PFOS decreased significantly in the presence of co-existing or preloaded humic acid, and both adsorption energy and effective adsorption sites on the three MWCNTs decreased, resulting in the decrease of PFOS adsorption. With increasing pH, PFOS removal by three MWCNTs decreased in the presence of humic acid and phenol. The adsorbed amounts of different PFCs on the MWCNTs increased in the order of PFBSxS相似文献