应用红外方法探讨耐镉菌株高积累Cd2+的机理

从安徽某冶炼厂污染土壤中分离出一株能耐高浓度镉的菌株(J5),经初步鉴定为假单胞菌属(Pseudomonas sp.).该菌株在液体培养基中耐受40 mmol·L-1 CdSO4,在固体培养基上耐受75mmol·L-1 CdSO4.培养基中Cd2+、Zn2+、Pb2+、Cu2+浓度分别为100 mg·L-1和Mn2+浓度为275mg·L-1时,菌株生长正常.在重金属Cu2+、Pb2+、Zn2+、Mn2+存在时,采用红外光谱与原子吸收光谱分析菌株对Cd2+的积累,结果表明,在低浓度Cd2+溶液中菌株细胞对Cd2+的积累,主要靠细胞壁上-NH2与Cd2+配位结合;在高浓度Cd2+溶液中,细胞壁上-NH2、-OH、-COOH、-PO43-、-M-O(O-M-O)基团吸附Cd2+的能力显著.Mn2+可以增加细胞壁上有效官能团活性,提高Cd2+积累率;但当有Zn2+、Pb2+、Cu2+重金属离子共存时,即使有Mn2+存在,菌体对Cd2+吸附积累能力未见提高.     

博斯腾湖有色可溶性有机物来源及季节变化特征

博斯腾湖是中国西北地区最大的外流湖,近年来随着湖区周边废水排入量的增加,严重威胁到湖泊周边地区居民的饮用水安全.对博斯腾湖开展有色可溶性有机物（CDOM）的来源及季节变化研究对该湖水质保护具有非常重要的意义.通过平行因子分析法解析博斯腾湖CDOM三维荧光光谱,得到类腐殖酸组分C1（255 nm/420 nm）,类酪氨酸组分C2（270 nm/324 nm）和类色氨酸组分C3（230 nm/340 nm）.2018年夏季盐度与C1呈显著负相关（r=－0.64,p<0.01）,与C2呈显著正相关（r=0.65,p<0.01）,这表明河流等外界输入是夏季湖水中类蛋白质和类腐殖质荧光组分的主要来源,夏季强烈的蒸发作用使得微生物活性增强.而2019年秋季盐度与C3呈显著正相关（r=0.70,p<0.01）,与C2呈显著负相关（r=－0.51,p<0.05）,意味着淡水输入直接稀释河口区CDOM中的类蛋白组分.整体上,博斯腾湖CDOM浓度在黄水区附近最大,且夏季CDOM浓度较秋季更大（t-test,p<0.001）,意味着夏季水质更差.河口区各指标的变异程度较大,受淡水输入影响较其他湖区大,这在2018年夏季表现得尤为显著.博斯腾湖CDOM具有高度空间异质性,2018年夏季该湖西部入湖河口区C1组分的贡献较大且该组分贡献率向东部水体交换弱的湖区方向逐渐减小,相应C2组分的贡献率逐步增大.2019年秋季各荧光组分占比表现为由黄水沟河口区以C1为主向东部湖区快速转变为以C2为主.     

Contributions of root cell wall polysaccharides to Cu sequestration in castor (Ricinus communis L.) exposed to different Cu stresses

Cell wall polysaccharides play a vital role in binding with toxic metals such as copper(Cu)ions.However, it is still unclear whether the major binding site of Cu in the cell wall varies with different degrees of Cu stresses.Moreover, the contribution of each cell wall polysaccharide fraction to Cu sequestration with different degrees of Cu stresses also remains to be verified.The distribution of Cu in cell wall polysaccharide fractions of castor(Ricinus communis L.) root was investigated with various Cu concentrations in the hydroponic experiment.The results showed that the hemicellulose1(HC1) fraction fixed 44.9%–67.8% of the total cell wall Cu under Cu stress.In addition, the pectin fraction and hemicelluloses2(HC2) fraction also contributed to the Cu binding in root cell wall,accounting for 11.0%–25.9% and 14.1%–26.6% of the total cell wall Cu under Cu treatments, respectively.When the Cu levels were ≤ 25 μmol/L, pectin and HC2 contributed equally to Cu storage in root cell wall.However, when the Cu level was higher than 25 μmol/L, the ability of the pectin to bind Cu was easy to reach saturation.Much more Cu ions were bound on HC1 and HC2 fractions, and the HC2 played a much more important role in Cu binding than pectin.Combining fourier transform infrared(FT-IR) and twodimensional correlation analysis(2 D-COS) techniques, the hemicellulose components were showed not only to accumulate most of Cu in cell wall, but also respond fastest to Cu stress.     

基于UV-vis和EEMs解析白洋淀冬季冰封期间隙水DOM的光谱特征及来源

基于三维荧光光谱（EEMs）技术结合平行因子分析法（PARAFAC）以及紫外-可见光谱技术（UV-vis）,对雄安新区-白洋淀冬季冰封期不同特征区域间隙水溶解性有机物（DOM）的光谱特征以及来源进行解析.结果表明：冬季冰封期白洋淀不同特征淀区间隙水DOM的相对浓度差异显著,养殖区的最高、旅游区的最低;冰封期白洋淀大部分区域间隙水DOM的E₃/E₄均大于3.5,说明DOM以低腐殖质成分为主;三维荧光通过PARAFAC解析出3种组分,分别为类酪氨酸（C1）、类色氨酸（C2）和陆源腐殖质（C3）;对3个组分进行相关性分析,结果显示C1与C2之间的相关系数达到0.99（p<0.001）;白洋淀各个特征区域间的DOM总荧光强度和各荧光组分相对丰度呈现显著的差异（p<0.05）;DOM的总荧光强度以及各组分的荧光强度均呈现出唐河入淀口高的特征,C1+C2是DOM的主要成分呈现养殖区多、自然区少的特点,养殖区达到79.30%~92.04%,自然区达到26.60%~38.55%;冰封期白洋淀间隙水水体的DOM荧光指数FI为（2.58±0.23）>1.8,生物源指数（BIX）为1.20±0.25,表明白洋淀DOM来源于生物活动并且以自生源为主,与腐殖程度指标（HIX）的结果相吻合;a₂₅₄与硝氮、溶解性总磷和A₂₅₄/A₂₀₄,a₃₅₅与S_350~400;a₄₄₀与S_275~295、S_350~400、E₂/E₄、E₂/E₆和E₄/E₆,C1以及C2与Fn₂₈₀,C3与硝氮和Fn₃₅₅相关性很好（p<0.05）.综上,通过对冬季冰封期白洋淀各个典型淀区间隙水水体DOM光谱特征进行研究,可以为分析白洋淀水体有机物污染特征和白洋淀的水质管理提供技术支持.     

作物重金属铜污染的HHT边际谱特征与污染预测模型

为了解读作物受重金属污染的光谱响应与光谱特征,以不同浓度梯度硫酸铜（CuSO₄·5H₂O）胁迫土壤的盆栽玉米培养胁迫实验为研究对象,依据不同胁迫梯度下玉米叶片反射光谱以及叶片中Cu²⁺含量的测定数据,采用希尔伯特-黄变换（HHT）方法,研究了玉米叶片在不同Cu²⁺胁迫梯度下光谱的Hilbert边际谱变化特征与污染程度预测方法.通过构建玉米叶片光谱的边际谱熵（MSE）,边际谱幅值（MSA）、边际谱陡坡斜率（MSSS）和边际谱包围面积（MSEA）等特征参量,分析叶片在不同Cu²⁺污染程度下的边际谱变化;同时基于边际谱特征参量值与叶片中Cu²⁺含量的相关性分析和逐步回归统计,提出了玉米叶片重金属污染的Cu²⁺含量预测指数模型.实验结果表明,不同Cu²⁺胁迫梯度下,玉米叶片光谱的边际谱为分布在100Hz频率以内的连续谱;MSE值表现出与叶片中Cu²⁺含量呈负相关的变化趋势,而MSA、MSSS和MSEA值都表现出与叶片中Cu²⁺含量呈正相关的变化趋势;由于MSEA值与叶片中Cu²⁺含量的相关性最好,可把MSEA作为监测作物重金属污染衡量或预测的最优指标;根据MSE、MSA、MSSS和MSEA值构建的Cu²⁺含量预计指数模型应用结果比较,证明MSEA指数模型具有最优的预测能力.     

西北内陆河城区段入河水体CDOM三维荧光光谱特征

于2017年8月现场采集并测定了西北某内陆河城区段16个入河排放口水体的有色溶解性有机物（CDOM）三维荧光光谱（EEMs）,深入探讨和分析了其CDOM荧光光谱特征、组成成分、类型和可能来源,探讨了荧光组分对研究河段溶解性有机物的示踪特征.结果表明,污染物产生途径不同,入河水体CDOM的EEMs特征差异显著,除了工业、城镇生活等受人为处理影响的水体外,同类排放源的EEMs具有类似性,大多数入河水体中都包含有类腐殖质荧光A峰.平行因子分析方法（PARAFAC）解析出入河水体CDOM由3个荧光组分组成,即类腐殖质组分C₁（272,437/545nm）和C₃（281,368/437nm）,类蛋白组分C₂（<2150,281/366nm）,其中C₁和C₃具有同源性,且其A峰、C峰的位置发生老化红移现象,C₂组分的类蛋白荧光T峰则较为稳定,可以作为研究河段溶解性有机物来源的指示参数.入河排放水体CDOM的荧光指数（FI、HIX、BIX）在反映人类活动对水质的干扰方面较为敏感,工业企业、城镇生活废水排放源的荧光指数、生源指数与其他排放源有所差异,可以敏感指示人为污染的存在.入河水体CODM的光学参数（a（280）、a（350）、a（355））及荧光峰强度均与TOC、CODcr有一定的线性关系,可用于指示有机污染程度.三个荧光组分与TOC、TN的线性拟合关系相对较好,表明可以用荧光组分值对各入河排放源的TOC、TN等指标进行有效示踪.     

利用基于周期的小波能量谱评价有机涂层防护性能

目的验证离散小波分解在军用车里有机涂层防护性能评价中的有效性。方法通过设计并完成多因子综合环境下的循环加速腐蚀试验,测得军绿有机涂层在每个试验周期之后的电化学噪声数据,并应用改进的小波能量分布图谱(EDP)计算方法,联合d1—d8小波细节系数对涂层性能进行评价。结果 d1晶胞标准差从初始状态的2×10~(-11) A/cm~2增长到第6周期的7.98×10~(-11) A/cm~2,最后又下降到2.51×10~(-11) A/cm~2。由EDP分析结果可知,前3周期为军绿有机涂层腐蚀前期,相对能量主要分布在d7、d8晶胞,涂层可以为基底金属提供有效防护;4—7周期为腐蚀中期,噪声电流振动幅度和频率有较大波动,相对能量分布转移至d1、d2晶胞;8、9周期为腐蚀后期,相对能量在d1—d4之间分散开来。结论基于周期的小波能量谱方法可以明显描述军绿有机涂层腐蚀过程中的变化情况,是一种有效的涂层性能评价方法。     

Two-dimensional correlation spectroscopic analysis on the interaction between humic acids and aluminum coagulant

In this study, two-dimensional correlation spectroscopy integrated with synchronous fluorescence and infrared absorption spectroscopy was employed to investigate the interaction between humic acids and aluminum coagulant at slightly acidic and neutral p H. Higher fluorescence quenching was produced for fulvic-like and humic-like fractions at p H 5. At p H 5, the humic-like fractions originating from the carboxylic acid, carboxyl and polysaccharide compounds were bound to aluminum first, followed by the fulvic-like fractions originating from the carboxyl and polysaccharide compounds. This finding also demonstrated that the activated functional groups of HA were involved in forming the Al-HA complex, which was accompanied by the removal of other groups by co-precipitation.Meanwhile, at p H 7, almost no fluorescence quenching occurred, and surface complexation was observed to occur, in which the activated functional groups were absorbed on the amorphous Al(OH)3. Two-dimensional FT-IR correlation spectroscopy indicated the sequence of HA structural change during coagulation with aluminum, with IR bands affected in the order of COOH COO-NH deformation of amide Ⅱ aliphatic hydroxyl C\OH at p H 5, and COO-aliphatic hydroxyl C\OH at p H 7. This study provides a promising pathway for analysis and insight into the priority of functional groups in the interaction between organic matters and metal coagulants.     

Effect of bioflocculants on the coagulation activity of alum for removal of trihalomethane precursors from low turbid water

Reactivity of chlorine towards hydrophobic groups present in natural organic matter(NOM)provokes the formation of carcinogenic disinfection byproducts such as trihalomethanes in chlorinated water. The present study aimed to investigate the variations in coagulant activity of alum using two different bioflocculants(coagulant aid) namely, Moringa oleifera and Cyamopsis tetragonoloba for the removal of hydrophobic fractions of NOM and subsequent chlorine consumption by treated water. Effect of dual coagulants on trihalomethane surrogate parameters such as total organic carbon, dissolved organic carbon, UV absorbing materials and prominent hydrophobic species such as phenolic groups along with aromatic chromophores, polyhydroxy aromatic moiety have also been studied. The concept of differential spectroscopy and absorbance slope index has been employed to understand the combined effects of alum-bioflocculants on the reactivity of NOM with chlorine. Our result shows that the combination of alum and C. tetragonoloba is more efficient for reducing trihalomethane surrogates from chlorinated water as compared to M. oleifera. C. tetragonoloba elicited synchronized effects of sweep coagulation and particle bridging-adsorption which eventually facilitated efficient removal of hydrophobic fractions of NOM. The variation in the mechanistic approach of bioflocculants was due to the presence of cationic charge on M. oleifera and adhesive property of C. tetragonoloba.     

两种紫铜在3.5％NaCl溶液中的腐蚀性能比较

采用极化曲线和交流阻抗技术,研究了2种紫铜在3.5％(质量分数)NaC1溶液中的腐蚀行为,比较了其耐腐蚀性能.结果表明,随着浸泡时间的延长,2种紫铜的自腐蚀电位先降低再升高,腐蚀速率先增大后减小.金相观察发现紫铜T2的第二相夹杂颗粒大小不均匀、晶粒粗大,经扫描电镜和能谱分析后发现其夹杂的成分不同,这是导致其耐蚀性能出现...