稻田镉污染原位钝化修复及磷积累与迁移特征

选择苏南某镉（Cd）污染稻田,研究钙镁磷肥和钙铝水滑石2种钝化修复材料对Cd污染土壤原位钝化修复的效果,并且探讨含磷钝化剂的使用对水土环境磷累积与迁移特征的影响.结果表明：施用2种钝化剂后均能有效降低土壤中有效态Cd的含量,且随着钝化时间的推移,有效态Cd含量均呈现稳定缓慢降低的趋势,在施加钝化剂16周后达到最低,不同处理的钝化效果依次为：1500kg/hm²钙镁磷肥>6000kg/hm²钙铝水滑石>750kg/hm²钙镁磷肥,各处理有效态Cd比施加前分别降低了54.5%、50.3%以及46.9%.各处理在不同阶段的土壤pH值与有效态Cd含量呈显著负相关.施用钙镁磷肥作为钝化剂会加快土壤中磷的累积,且随着施用量的增加60~90cm深度渗漏水中总磷和溶解性磷酸盐含量有明显升高趋势.     

可生物降解螯合剂GLDA强化三叶草修复镉污染土壤

螯合剂可增加重金属的生物可利用性,强化植物的富集作用.以三叶草为研究对象,通过盆栽试验考察不同浓度可生物降解螯合剂谷氨酸N,N-二乙酸(GLDA)对三叶草修复重金属Cd污染土壤的影响机制.结果表明,低剂量GLDA能显著促进三叶草的生长,其中以2. 5 mmol·kg~(-1)的处理浓度三叶草生物量最高,达到对照组的1. 30倍;不同浓度GLDA均能提高三叶草各部分的Cd含量,总体而言,5 mmol·kg~(-1)GLDA的处理效果最为理想,根部、地上部分和整株Cd含量分别为对照组的3. 57、4. 69和4. 67倍; GLDA能显著增加土壤有效态Cd含量,促进三叶草根部对其直接吸收,并较好地转运至地上部分;通过拟合土壤理化性质、GLDA与三叶草Cd含量的线性关系得出的预测模型,可为今后土壤-三叶草富集效果的研究提供参考.研究表明,在强化植物修复重金属Cd污染土壤方面,生物可降解螯合剂GLDA具有潜在应用前景.     

Nano-selenium controlled cadmium accumulation and improved photosynthesis in indica rice cultivated in lead and cadmium combined paddy soils

Selenium nanoparticles (Se NPs) are less toxic and more biocompatible than selenite or selenate. However, studies involving spraying with Se NPs for reducing accumulation of cadmium (Cd) and lead (Pb) in rice grains have been rarely reported as yet. Herein, indica rice seedlings cultivated in Cd+Pb-spiked paddy soils (denoted as positive control) were sprayed with Se NPs sols for four times from tillering to booting stage. Compared to positive control, 50–100 μmol/L Se NPs downregulated Cd transporters-related genes such as OsLCT1, OsHMA2 and OsCCX2 in leaves and OsLCT1, OsPCR1 and OsCCX2 genes in node I at filling stage. Meanwhile, Se-binding protein 1 was distinctly elevated, involving the repression of Cd and Pb transportation to rice grains. Se NPs also differentially improved RuBP carboxylase and chlorophylls especially some key genes and proteins involving photosynthetic system. Besides, 25–50 μmol/L Se NPs diminished reactive oxygen species overproduction from NADPH oxidases whereas boosted glutathione peroxidase, reducing protein carbonylation in rice seedlings. However, the antioxidant isozymes and oxidatively modified proteins were slightly rebounded at 100 μmol/L. Se contents were noticeably elevated and confirmed to exist as selenomethionine in the rice grains following all the treatments by Se NPs. Thus, the optimal dosage of Se NPs for foliar application is 50 μmol/L, which significantly decreased Cd accumulation, improved photosynthesis and Se enrichment whereas caused no distinct reduction of Pb in the grains. Thus, an appropriate dosage of Se NPs can be conducted to decrease Cd accumulation, improve photosynthesis, and organic Se contents in rice grains.     

调理剂对磷镉富集土壤中两种元素交互作用的影响

以磷镉富集的农业土壤（总Cd：0.94mg·kg^-1和全P：0.86g·kg^-1）为研究对象,按照湖北地区中稻生育期及至下茬作物播种期的时长进行室内培养试验,探究生物质炭（BC）、钙镁磷肥（CMP）和粉煤灰（FA）影响下土壤磷与镉的生物有效性、二者形态变化及其耦合作用效应.结果表明：①培养至140d时,添加调理剂处理土壤有效磷含量与未添加调理剂的对照土壤相比均显著增加,有效磷水平可达22.47~37.81mg·kg^-1,在不额外施用磷肥条件下可满足水稻最适生长需求,且添加BC处理的效果最佳.②供试土壤中的磷主要为无机正磷酸盐,且不同形态无机磷含量在调理剂作用下均有所提高,并随着时间土壤中固定态的O-P和Ca₁₀-P逐渐向活性较高的Ca₂-P、Ca₈-P、Al-P和Fe-P形态转变.③添加调理剂处理土壤有效态Cd含量在对照处理基础上显著降低8.74%~17.48%,这与3种调理剂对土壤pH的提高作用相关联.与此同时,添加调理剂的处理与对照相比,可交换态Cd显著降低,碳酸盐结合态Cd和残渣态Cd均有所提高,这与土壤有机质在BC的促进效应下,其表面富含的活性基团能够与Cd²⁺吸附螯合有关.结果初步证明,3种调理剂均能实现供试磷镉富集土壤中磷活化和镉钝化的双重功能,并以生物质炭和钙镁磷肥效果为佳,其效果可覆盖整个水稻生长时段并可延续至其下茬作物播种期.     

贵阳市“两湖一库”周边蜘蛛体内镉含量及暴露风险

调查了高镉地质背景区蜘蛛(肖蛸科、园蛛科、蟹蛛科和络新妇科)及其生境水体、土壤和植物中的镉含量,探讨了蜘蛛体内镉的来源、影响因子及存在风险。结果表明,研究区蜘蛛体内的平均镉含量为1. 82±1. 37μg/g(n=130),表现为园蛛科肖蛸科络新妇科≈蟹蛛科。蜘蛛体重与体内镉含量表现出弱的负相关关系(r=-0. 17,p=0. 08),暗示了蜘蛛生长发育过程中的生物稀释效应。狩猎型蟹蛛科和结网型园蛛科蜘蛛体内镉含量与对应土壤镉含量呈显著正相关关系(r=0. 61,0. 97),并且它们对土壤的生物富集因子均大于1,表明这两类蜘蛛可以用来指示土壤镉污染。生物有毒物质残留指数显示,研究区蜘蛛受高镉地质背景影响,体内存在着一定的镉暴露风险。     

接种微生物对油菜吸收Cd效果的影响研究

采用盆栽土壤模拟试验方法,以油菜（Brassica campestris）为供试植物,通过向土壤中接种微生物,研究了四种菌株JA1,JA2,JA3,JA4对油菜吸收Cd的效果影响。结果表明：菌株JA1,JA2,JA4不仅可以促进植株的生长,分别使油菜的生物量提高17%,28%和32%,而且增强了植株对土壤Cd的吸收,使油菜地上部富集量较对照提高了26.8%,48.8%和65.9%,植物提取量较对照增加了48.9%,76.1%和119%,并且可有效促进土壤Cd的活化,分别使土壤Cd的有效态含量提高了25.9%,59.2%和41.9%;菌株JA3则使其植株地上部富集量、植物提取量和土壤Cd有效态含量降低,较对照降低了14.6%,11.8%和13.6%。各处理的叶绿素和可溶性蛋白含量均略高于对照。     

铜陵新桥矿区土壤中耐Cu微生物的筛选研究

选择安徽铜陵新桥矿区富Cu的污染土壤,充分利用微生物受自然环境重金属胁迫而产生耐性这一特点,进行土壤中耐Cu微生物的筛选研究。实验过程中分别配制三种不同的培养基,细菌、真菌和放线菌培养基。在水浴恒温振荡器中对土壤中耐受重金属的微生物进行驯化,将得到的对cu2＋耐受性最高的液体培养基作为菌源,在琼脂平板培养基上进行划线分离,并将得到的纯菌株在光学显微镜下进行形态观察,菌种经试管斜面富集培养后保存在4℃冰箱中以便后续使用。研究发现,土样中细菌和真菌对cu的耐受性低,最高耐受质量浓度分别只达到500mg·L-1和1100mg·L-1。而放线菌表现出cu高耐受性,分离得到的放线菌耐受Cu的质量浓度最高达到10000mg·L-1,初步鉴定该放线菌株为链霉菌属。该放线菌菌种可能同时对Cu有吸附降解特性,具有成为污染土壤生物治理的高效耐受吸附菌种的潜力巨大。     

成团泛菌(Pantoea agglomerans)对镉胁迫下蒌蒿耐受性的影响

为探讨功能微生物对镉(Cd)胁迫下蒌蒿耐受性的影响,以成团泛菌(Pantoea agglomerans)J2为对象,通过盆栽试验,研究不同Cd处理水平下J2菌对蒌蒿生长、生理、Cd富集转运与根际微生态的影响。结果表明:J2菌可显著促进蒌蒿株高、地上部干重、地下部干重、总生物量及根冠比的增加。在J2菌的作用下,蒌蒿叶绿素a、叶绿素b和总叶绿素含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均显著增加,丙二醛(MDA)含量明显减少。J2菌可显著促进蒌蒿对Cd的富集转运,蒌蒿地上部、地下部与总Cd含量均显著增加,地上部生物富集系数(BCF)明显大于地下部,转运系数(TF)相比于对照增加了7.5%~37.4%。J2菌可显著增加蒌蒿根际土壤细菌、放线菌数量及微生物总量,明显减少真菌数量。研究表明成团泛菌J2对蒌蒿生长、生理、Cd富集转运与根际微生态可产生积极影响,在一定程度上可提高蒌蒿植株对Cd的耐受性。     

镉胁迫下黑点青鳉(Oryzias melastigma)肝脏金属硫蛋白mRNA性别差异性表达研究

鱼类金属硫蛋白(metallothionein,MT)mRNA作为生物标志物已越来越多地应用到水环境重金属污染的监测中,然而重金属胁迫下鱼类MT mRNA表达是否具有性别差异性特征目前尚无相关报道。以海洋模式鱼类—黑点青鳉(Oryzias melastigma)为实验鱼类,首次克隆了其MT基因全长c DNA序列,分析了黑点青鳉MT基因和氨基酸序列特征,然后进一步研究了水体中镉暴露后雌、雄性黑点青鳉肝脏中MT mRNA表达的差异性。结果显示,黑点青鳉MT基因c DNA全长为385 bp,编码60个氨基酸,预测编码的多肽分子量为5 990 Da,含有脊椎动物MT基因特征性序列结构cys-x-cys、cys-x-x-cys和cys-x-cys-cys。镉胁迫下雌、雄性黑点青鳉肝脏MT mRNA表达结果显示,在0.8,4.0和8.0μg·L-1环境浓度的镉暴露1~7 d条件下,与对照组相比,雄性黑点青鳉在所有的不同暴露浓度和不同暴露时间的实验组中肝脏MT mRNA几乎均被显著性诱导表达;而雌性黑点青鳉只在较高暴露浓度和较长暴露时间的实验组中才被显著性诱导表达,并且MT mRNA的表达水平比雄性低得多。上述研究结果表明,在相同的镉胁迫条件下,雄性黑点青鳉肝脏MT mRNA的表达比雌性更敏感;以黑点青鳉MT mRNA作为生物标志物监测海洋环境重金属污染生物效应状况时,应选择更敏感的雄性黑点青鳉作为监测鱼类。利用生物标志物监测水环境污染物生物效应时,监测动物的性别差异是一个应当考虑的重要因素。     

Modelling cadmium bioaccumulation in Gammarus pulex by using experimental design approach

Recently, although dynamic approaches have been used increasingly to describe metal bioaccumulation in aquatic organisms, the validation of such laboratory-derived modelling is rarely assessed under environmental conditions. The present study aims to evaluate and verify statistical and mathematical models for the bioaccumulation of cadmium (Cd) and to evaluate the suitability of Gammarus pulex as a biomonitor for Cd. To optimise Cd²⁺ ion bioaccumulation conditions a Box–Behnken design was used and whether G. pulex can be used as an estimated tool to assess aquatic quality was investigated. A Box–Behnken experimental design combined with response surface modelling (RSM) was employed for Cd²⁺ bioaccumulation in G. pulex. Independent variables including temperature, contact time and Cd²⁺ ion concentration significance and their interactions were tested using analysis of variance. The selected variables’ optimum values were obtained by solving the quadratic regression model along with by analysing the response surface contour plots. Based on Box–Behnken design, the applied model is significant because model F-value and R² were obtained as 5121.49, 0.9998, respectively. Bioaccumulation of Cd amount was analysed using electrothermal atomic absorption spectrophotometer. The obtained data suggest that G. pulex can be evaluated as Cd biomonitor.