Stimulated activity of the soil nitrifying community accelerates community adaptation to Zn stress

Field data have shown that soil nitrifying communities gradually adapt to zinc (Zn) after a single contamination event with reported adaptation times exceeding 1 year. It was hypothesized that this relatively slow adaptation relates to the restricted microbial diversity and low growth rate of the soil nitrifying community. This hypothesis was tested experimentally by recording adaptation rates under varying nitrification activities (assumed to affect growth rates) and by monitoring shifts in community composition. Soils were spiked at various Zn concentrations (0-4000 mg Zn kg⁻¹) and two NH₄⁺-N doses (N1, N2) were applied to stimulate growth. A control series receiving no extra NH₄⁺-N was also included. Soils were incubated in pots under field conditions with free drainage. The pore water Zn concentration at which nitrification was halved (EC50, mg Zn l⁻¹) did not change significantly during 12 months in the control series (without NH₄⁺-N applications), although nitrification recovered after 12 months at the highest Zn dose only. The EC50 after 12 months incubation increased by more than a factor 10 with increasing NH₄⁺-N dose (p < 0.05) illustrating that increased activity accelerates adaptation to Zn. Zinc tolerance tests confirmed the role of Zn exposure, time and NH₄⁺-N dose on adaptation. Zinc tolerance development was ascribed to the AOB community since the AOB/AOA ratio (AOB = ammonia oxidizing bacteria; AOA = ammonia oxidizing archaea) increased from 0.4 in the control to 1.4 in the most tolerant community. Moreover, the AOB amoA DGGE profile changed during Zn adaptation whereas the AOA amoA DGGE profile remained unaffected. These data confirm the slow but pronounced adaptation of nitrifiers to Zn contamination. We showed that adaptation to Zn was accelerated at higher activity and was associated with a shift in soil AOB community that gradually dominated the nitrifying community.     

水稻锌污染胁迫的光谱奇异性分析

通过研究锌污染胁迫下水稻的光谱奇异性特征来诊断水稻锌污染水平。根据试验区水稻各个生长期的ASD实测高光谱数据和同步获取的作物与农田土壤重金属含量2 a田间试验数据,利用Daubechies小波系中的“Db5”小波函数对锌污染胁迫水稻的350～1 300 nm光谱波段进行5层小波分解,并利用奇异范围、奇异幅度和奇异指数等参数对水稻光谱奇异性进行定量计算与分析。结果表明,“Db5”小波函数分解的第5层小波系数能精准探测水稻光谱的奇异性,其奇异范围集中在480～850 nm波段范围;奇异幅度从出苗期到分蘖期迅速增加,并达到最大值,在随后的分蘖期→拔节期→开花期→成熟期逐渐减少;奇异指数从出苗期→分蘖期→拔节期→开花期→成熟期逐渐增加;水稻叶片锌含量与奇异幅度及奇异指数之间存在较强的相关关系,其决定系数（R2）为0.8445,均方根误差 （RMSE）为5.60。光谱奇异性能有效地诊断并定量分析水稻锌污染胁迫状况,从而为作物重金属污染胁迫监测提供重要参考。     

Rotifers enriched with iodine,copper and manganese had no effect on larval cod (Gadus morhua) growth,mineral status or redox system gene mRNA levels

It currently remains unclear if rotifers contain sufficient mineral levels to meet larval fish requirements. In this study, rotifers were enriched with a commercial enrichment (control), or with additional iodine, iodine and copper, or iodine, copper and manganese, and the effects of feeding these rotifers to Atlantic cod (Gadus morhua) larvae from 3 to 18 days post hatch were investigated. Rotifer enrichment with minerals was successful, but Mn enrichment also increased rotifer zinc levels. No differences were observed between treatments in larval growth or survival, or in the mRNA levels in the majority of the redox system genes analysed. Only Zn levels increased in cod larvae in response to mineral enrichment of rotifers. Apart from Zn, little evidence was found to suggest that cod larvae require increased concentrations above the control rotifer levels of the essential elements studied here.     

锌肥不同用量对旱地油用亚麻生长及种子产量的影响

以油用亚麻为试验材料,采用随机区组试验设计,研究锌肥对宁南山区旱地油用亚麻生长发育及种子产量的影响,结果表明：锌肥有利于促进油用亚麻苗期的生长发育,改善油用亚麻植株高度、单株鲜重、单株干重及农艺性状指标,增加油用亚麻产量,以施锌肥30.0kg/hm ²处理产量最高,为1 111.65kg/hm ²。     

Evaluation of selected metal nanoparticles on hatching and survival of larvae and fry of Indian major carp,rohu (Labeo rohita)

Different laboratory synthesized metal nanoparticles viz. Copper oxide (CuO), Zinc oxide (ZnO) and silver doped titanium dioxide (Ag‐TiO₂) were studied for their effect on hatching and survival of larvae and fry of Indian major carp, rohu, Labeo rohita both in direct application in tank water & coated onto tanks. Among these nanoparticles, CuO and ZnO nanoparticles exhibited highest percentage of hatching in both direct addition (78.0 ± 3.1% and 78.05 ± 4.2%, respectively) and coating onto tanks (58.6 ± 2.1% and 61.2 ± 2.7%, respectively) at 1 mg mL^?1 while least percentage of hatching was recorded in Ag‐TiO₂ nanoparticles irrespective of its concentration & mode of supplementation. Highest survival of L. rohita fry (50.13 ± 2.2%) was observed after 15 days post hatching in CuO coated tanks followed by ZnO coated tanks (38.6 ± 2.8%) while least was recorded in Ag‐TiO₂ coated tanks (22.53 ± 3.0%). However in control tanks coated with Poly‐Urethane base with hardener and uncoated control tanks, the survival was 42.4 ± 1.2% and 41.36 ± 1.8% respectively. Further, significantly lower microbial load of water was recorded in CuO nanoparticles coated tanks (1.5 × 10¹⁰ CFU L^?1) as compared to uncoated control tanks (1.1 × 10¹⁶ CFU L^?1) without affecting water quality parameters. On the other hand, in Ag‐TiO₂ coated tanks, significantly lower microbial load (1.0 × 10⁶ CFU L^?1) as compared to uncoated control tanks at 15 days post hatching was recorded. However, Ag‐TiO₂ was toxic to L. rohita larvae & fry both in direct application and coating onto tanks. Considering the beneficial effects of CuO nanoparticle application, it has the scope of being used in a more eco‐friendly way in hatchery operations.     

铜、锰诱导吉富罗非鱼血细胞凋亡及铁、锌的干预作用

为了研究重金属铜与锰对吉富罗非鱼血细胞凋亡的影响以及铁、锌的拮抗作用,采用原子吸收分光光度法检测血液及饲料中重金属的含量,采用流式细胞术检测实验鱼血细胞凋亡情况。360 尾吉富罗非鱼幼鱼随机分为12 组,每组30 尾,分别以硫酸铜(0、2000 mg/kg)、硫酸锰(0、120 mg/kg)为攻毒组重金属源,以硫酸锌(20、320 mg/kg)、硫酸铁(150、350 mg/kg)为拮抗组金属源,通过饲料投喂的方式进行血细胞凋亡的研究,养殖周期为20 周。细胞凋亡分析结果表明,染铜组、染锰组实验鱼血细胞凋亡率显著高于对照组;补充铁和锌后,随着饲料添加铁、锌水平的增加,实验鱼血细胞凋亡率明显下降,但铁、锌干预组血细胞凋亡率显著高于对照组。实验表明,过量铜、锰可诱发实验罗非鱼血细胞凋亡;较高水平的铁、锌对铜、锰的毒性作用具有拮抗作用。     

弹簧垫圈断裂原因分析

通过宏观检验观察、化学成分分析、硬度测试、金相检验和断口分析等方法对弹簧垫圈的断裂原因进行分析。结果表明:该弹簧垫圈热处理时产生淬火裂纹,镀锌时氢原子在裂纹尖端偏聚,这两种因素的共同作用导致弹簧垫圈在装配预紧过程中发生脆性断裂。     

锌对黄瓜幼苗根系生长及保护酶活性的影响

为促进科学合理施用微量元素肥料、培育黄瓜壮苗,进一步提高黄瓜产量和品质,以‘新津春4号’黄瓜为材料,缺锌的1/2 Hoagland营养液为基础,设置4个不同浓度的ZnSO4?7H2O处理(0、0.1、0.2、0.4 mg/L)。通过营养液水培的方法,研究不同锌浓度对黄瓜幼苗根系生长及保护酶活性的影响。结果表明：（1）随着锌浓度的增加,黄瓜幼苗根系的总长度、平均直径、总面积、总体积、根尖数逐渐提高,Zn3(0.4 mg/L)时达到最大。（2）在Zn0(0 mg/L)到Zn2(0.2 mg/L)范围内,随着锌浓度的提高,POD、CAT活性升高,当锌浓度大于Zn2时,POD、CAT活性降低;SOD活性随着锌浓度的增加显著提高;丙二醛(MDA)含量随着锌浓度的增加显著降低。（3）综合考虑的黄瓜生长生理指标,黄瓜幼苗根系生长的最佳ZnSO4?7H2O浓度为0.2 mg/L的1/2 Hoagland营养液。     

施磷量及磷锌配施对夏玉米生长发育及籽粒产量的影响

为更好探索小麦/玉米一年两熟种植制度下,夏玉米施肥制度,实现夏玉米抗逆高产丰产。于2010年采用裂区设计,对施磷量及磷锌配施对夏玉米生长发育及籽粒产量的影响进行研究。结果表明：单施磷肥或磷锌配施促进夏玉米生长发育,增加干物质积累和次生根数,降低秃尖、改善穗部性状、提高抗病能,且配施效果优于单施磷肥。单施磷较对照增产幅度为7.70%~31.21%,配施增产15.99%~40.34%,磷锌配施较单施磷肥增产幅度达4.03%~8.73%。其中以施P2O5量在180 kg/hm2时配施15 kg/hm2硫酸锌,产量最高达9581.2 kg/hm2。经回归拟合,单施磷肥和磷锌配施的最佳施P2O5量分别为178.65 kg/hm2和203.49 kg/hm2,籽粒产量可达8823.0 kg/hm2和9499.61 kg/hm2。因此,在施氮基础上,配施磷或磷锌可促进夏玉米生长发育,实现高产抗逆高效栽培。     

锌胁迫对虞美人种子萌发的影响

[目的]研究水培条件下重金属锌胁迫对虞美人种子萌发的影响。[方法]用浓度为05、01、00、1502、002、50、3003、50、400 mg/L的硫酸锌溶液对虞美人种子进行胁迫处理,测定锌胁迫对虞美人种子的发芽势、发芽率、发芽指数等发芽指标的影响。[结果]在锌胁迫条件下,虞美人种子的发芽指标随着锌浓度的增加均表现出先升高后降低的变化趋势。发芽势、发芽率、发芽指数均在锌浓度为200 mg/L时达到最大;种子活力指数在锌浓度为150 mg/L时达到最大。[结论]浓度为200 mg/L的锌可以更好地促进虞美人种子的萌发。