自然水体生物膜对Pb^2＋Zn^2＋的吸附特性

以合肥董铺水库为水源、天然纯棉绳为人工基质培养自然水体生物膜,研究了该生物膜对Pb^2＋和Zn^2＋的吸附特性及其影响因素。结果表明,单一重金属离子体系中,生物膜对两种重金属离子的吸附均符合Freundlich吸附等温式（RP2b=0.9900,RZ2n=0.9989）和Langmuir吸附等温式（RP2b=0.9823,RZ2n=0.9792）;吸附过程符合Langmuir二级动力学方程（RP2b=0.9992,RZ2n=0.9999）;在pH6-7、温度25-30℃的条件下,Pb^2＋和Zn^2＋有较高的去除率;在Pb^2＋-Zn^2＋两元混合体系中,生物膜对Pb^2＋的吸附选择性明显比Zn^2＋强。     

Lipid-based Fe- and Zn- nanoformulation is more effective in alleviating Fe- and Zn- deficiency in maize

Improving uptake, translocation, and utilization of foliar applied Fe and Zn is essential for increasing biomass and grain yield under deficient conditions. We compared the effect of foliar applied lipid-based Pheroid Fe- or Zn- nanoformulation, chelate and sulfate forms on biomass, nutrient uptake and mobilization in maize grown under Fe and Zn deficiency scenarios in hydroponic systems and field trials. Foliar spray of Fe-Pheroid nanoformulation resulted in complete re-greening. Partial and no re-greening of mature and young leaves, respectively, were observed under FeSO₄ and Fe-HEDTA treatments. Foliar spray of Zn-Pheroid nanoformulation increased the Zn concentration of young leaves. In field trials, foliar spray of Fe- or Zn- chelate did not improve leaf Fe and Zn concentration or grain yield. Fe- and Zn-Pheroid nanoformulation improved the mobility of Fe and Zn within the plant. Field trials indicated that non-lipid-based formulation was not effective in amelioration of Fe- and Zn deficiency.     

An examination of zinc uptake patterns by cultivars of sorghum and maize : Differences amongst hybrids and their parents

Zinc absorption and transport patterns were examined in sorghum and maize hybrids and their parent cultivars with a view to observe, if any, and relate the differences amongst them meaningfully to traits like hybrid vigor. Short term uptake by excised roots or intact seedlings, from different concentrations of ZnCl₂ or ZnEDDHA and also, time course from 50 μM ZnCl₂, were measured. The results showed significant differences in the Zn absorption patterns by excised roots of sorghum cultivars. The rate of Zn transport to shoot in CSH‐8 was found to be higher than in others. The amount of Zn transported from ZnEDDHA was also more than that from ZnCl₂ in all sorghum cultivars. Furthermore, significant hybrid vigor was observed in Zn transport from ZnEDDHA for the two hybrids CSH‐7 and CSH‐8. The resemblance of absorption and transport patterns of Zn in CSH‐8 to those of 36‐A strongly suggests that the trait is inherited from the female parent.

No heterosis was observed in the absorption and transport of Zn in maize hybrids. However, a linear and an exponential isotherms for Zn transport in Ganga‐5 and Ganga‐2 hybrids indicates some hybrid vigor.     

Microbiological rates and enzyme activities as indicators of functionality in soils affected by the Aznalcóllar toxic spill

This study focused on the potential of using soil enzyme activities and general microbiological rates (respiration, N-mineralisation, nitrification) to evaluate the quality of soils affected by a pyrite mud spill which contained high concentrations of heavy metals. The quality of soils after restoration was estimated by comparing enzyme activities and general microbiological rates in three different types of experimental field plots: (i) non-polluted, (ii) polluted but restored, and (iii) polluted but un-restored soils. Non-polluted soils showed the highest levels of enzyme activity. Significant differences were detected for acid phosphatase, β-glucosidase and urease activities between all types of plots. However, arylsulfatase and alkaline phosphatase activities showed no significant differences between the restored plots and polluted but un-restored plots. Geometric mean statistics were used as an index of soil quality in terms of overall: (i) bioavailable heavy metal concentrations, (ii) assayed enzyme activities, and (iii) general microbiological rates, in order to compare plots differing in the degree of pyritic mud pollution. The results indicate that it is important to consider these three criteria in to estimate the soil quality of heavy-metal contaminated soils. Typically, enzyme activities were negatively correlated with bioavailable Cd, Cu and Zn concentrations, but positively with soil pH values. In contrast, pH values were negatively correlated with bioavailable concentrations of Cd, Cu and Zn. It is unclear if the generalised lower enzyme activities found in restored soils, compared to non-polluted soils, is promoted by pH or bioavailable heavy metals concentrations, or a combination of both.     

氮锌配施对不同冬小麦品种产量及锌营养的影响

为比较石灰性土壤氮锌配施对不同小麦品种生长及锌营养的影响,选10种本地主要种植小麦品种,进行连续两年的田间试验,测定小麦产量及锌含量。结果表明,在石灰性土壤上单施锌肥和氮锌配施对小麦产量、籽粒锌含量的影响因品种而异。单施锌肥及氮锌配施处理可显著增加土壤有效锌含量,但单施锌肥处理仅增加"西杂1号"、"武农148"、"郑麦9023"籽粒锌含量;氮锌配施增加除"小偃22"外其余9种供试小麦品种籽粒锌含量,增幅为7.3%～54.7%。单施锌肥对小麦锌累积量增加的效果不明显;氮锌配施可显著增加小麦地上部锌累积量,两季分别增加6.5%、29.8%。单施氮肥可显著增加小麦锌吸收,但其主要累积在小麦茎叶部。在石灰性土壤上,单施锌肥虽显著增加了土壤有效锌含量,但对小麦产量及籽粒Zn含量增加有限,氮锌肥配施可取得较好效果。     

合肥地区土壤中Zn元素的缓变型地球化学灾害特征

为了给土壤重金属污染提供定量依据,该文在缓变型地球化学灾害基本模型的基础上,基于土壤中Zn元素含量实测数据,分别研究了合肥大兴镇地区和义城镇地区土壤中Zn元素的缓变型地球化学灾害特征并进行了对比,确定其数学模型。研究结果显示,大兴镇地区土壤中Zn元素有从可释放态向有效态（TRCPZn→ZnE＋C）释放转化的趋势,其缓变型地球化学灾害临界值为70.333 mg∕kg,约22.6%面积的土壤具有爆发Zn元素缓变型地球化学灾害的可能性。而义城镇地区土壤中Zn元素还不具有爆发缓变型地球化学灾害的可能性。     

Effects of zinc activity in nutrient solution on uptake,translocation, and root export of cadmium and zinc in three wheat genotypes with different zinc efficiencies

The interactions of zinc (Zn) and cadmium (Cd) in uptake and translocation are common but not consistent. We hypothesized that Cd²⁺ and Zn²⁺ activity in the apoplasmic solution bathing root-cells could affect Zn accumulation in plants dependent on the wheat genotype. This hypothesis was tested using seedlings of two bread wheat genotypes (Triticum aestivum L. cvs. Rushan and Cross) and one durum wheat genotype (Triticum durum L. cv. Arya) with different Zn efficiencies grown in chelate-buffered nutrient solutions with three Zn²⁺ (10^?11.11, 10^?9.11, and 10^?8.81?µM) and two Cd²⁺ (10^?11.21 and 10^?10.2?µM) activity levels. Increasing Zn²⁺ activity in the nutrient solution significantly increased Zn concentration in root and shoots of all three wheat genotypes, although the magnitude of this increase was dependent on the genotype. Cadmium decreased Zn concentration in roots of “Cross” while it had no significant effect on root Zn concentration in “Rushan.” At Zn^2+?=?10^?11.11?µM, Cd decreased shoot Zn concentration in “Arya” whereas it increased shoot Zn concentration at Zn^2+?=?10^?8.81?µM. Cadmium increased shoot Zn concentration of “Rushan” and “Cross” at Zn^2+?=?10^?8.81?µM but it had no significant effect on shoot Zn concentration of these genotypes at Zn^2+?=?10^?11.11?µM. The zinc-inefficient genotype “Arya” accumulated significantly more Cd in its root in comparison with “Cross” and “Rushan.” Cadmium concentration in roots of “Arya” was decreased significantly with increasing Zn activity. The effect of Zn on accumulation of Cd in roots of “Cross” and “Rushan” was dependent on the dose provided, and therefore, both synergistic (at Zn^2+?=?10^?9.11?µM) and antagonistic (at Zn^2+?=?10^?8.81?µM) interactive effects were found in these genotypes. Zinc supply increased the Zn concentration of xylem sap in “Cross” and “Rushan” whereas Zn content in xylem sap of “Arya” was decreased at Zn^2+?=?10^?9.11?µM and thereafter increased at Zn^2+?=?10^?8.81?µM. Cadmium treatment reduced Zn concentration in xylem sap of “Arya,” while it tended to increase Zn content in xylem sap of “Cross.” At Zn-deficient conditions, greater retention of Zn in root cell walls of Zn-inefficient “Arya” resulted in lower root-to-shoot transport of Zn in this genotype. Results revealed that the effect of Cd on the root-to-shoot translocation of Zn via the xylem is dependent on wheat genotype and Zn activity in the nutrient solution.     

Distribution of Zinc Fractions in Some Major Soils of India and the Impact on Nutrition of Rice

Abstract

Speciation study of microelements in soils is useful to assess their retention and release by the soil to the plant. Laboratory and greenhouse investigations were conducted for five soils of different agro‐ecological zones (viz., Bhuna, Delhi, Cooch‐Behar, Gurgaon, and Pabra) with diverse physicochemical properties to study the distribution of zinc (Zn) among the soil fractions with respect to the availability of Zn species for uptake by rice plant. A sequential extraction procedure was used that fractionated total soil Zn into water‐soluble (WS), exchangeable (EX), specifically adsorbed (SA), acid‐soluble (AS), manganese (Mn)‐oxide‐occluded (Mn‐OX), organic‐matter‐occluded (OM), amorphous iron (Fe)‐oxide‐bound (AFe‐OX), crystalline Fe‐oxide‐bound (CFe‐OX), and residual (RES) forms. There was a wide variation in the magnitude of these fractions among the soils. The studies revealed that more than 90% of the total Zn content occurred in the relatively inactive clay lattice and other mineral‐bound form (RES) and that only a small fraction occurred in the forms of WS, EX, OM, AFe‐OX, and CFe‐OX. Rice (Oryza sativa L.) cultivars differ widely in their sensitivity to Zn deficiency. Results suggested that Zn in water‐soluble, organic complexes, exchange positions, and amorphous sesquioxides were the fractions (pools) that played a key role in the uptake of Zn by the rice varieties (viz., Pusa‐933‐87‐1‐11‐88‐1‐2‐1, Pusa‐44, Pusa‐834, Jaya, and Pusa‐677). Isotopic ally exchangeable Zn (labile Zn) was recorded higher in Typic Ustrochrept of Pabra soil, and uptake of Zn by rice cultivars was also higher in this soil. The kinetic parameters such as maximum influx at high concentrations (I_max) and nutrient concentration in solution where influx is one half of I_max (K_m) behaved differentially with respect to varieties. The highest I_max value recorded was 9.2×10^?7 µmol cm^?2 s^?1 at the 5 mg kg^?1 Zn rate for Pusa‐933‐87‐1‐11‐88‐1‐2‐1, and the same was lowest for Pusa‐44, being 4.6×10^?7 µmol cm^?2 s^?1 at the 5 mg kg^?1 Zn rate. The K_m value was highest for Pusa‐44 (2.1×10^?4µmol cm^?2 s^?1) and lowest for Pusa‐933‐87‐1‐11‐88‐1‐2‐1 (1.20×10^?4µmol cm^?2 s^?1). The availability of Zn to rice cultivars in Typic Ustrochrepts of Bhuna and Delhi soils, which are characterized by higher activation energy and entropy factor, was accompanied by breakage of bonds or by significant structural changes.     

高量施锌肥对玉米Zn吸收和积累及产量的影响

在田间试验条件下,研究正常施锌(10kg/hm2,25kg/hm2 ZnSO4.7H2O)和超高量施锌处理(50kg/hm2,100kg/hm2,150kg/hm2 ZnSO4.7H2O),对玉米各个生育期植株锌吸收和积累以及产量的影响,以期为玉米增产、品质改善和合理施锌肥提供科学依据。结果表明:在施锌肥量10～150kg/hm2范围内,玉米苗期、拔节期、吐丝期、灌浆期、成熟期的植株和籽粒含锌量都有显著增加的趋势,并且施用量与锌含量呈极显著正相关,正常施锌和超高量施锌在植物体内各个生育期锌含量都呈增加的趋势,且同一浓度施锌量,玉米植株积累的锌量随植株生长而增加,说明玉米在不同生长期从土壤中吸取的锌元素也在不断增加。玉米地上部分各生育阶段对锌的吸收速率总体趋势为,随着施锌量的增加各个生育阶段对锌的吸收速率呈增加趋势,其中,拔节期-吐丝期对锌的吸收速率最高。随着施锌量的增加,玉米产量呈现先增加后降低的趋势,最适合的施锌量为50kg/hm2,相比正常施锌量有所提高,并且高施锌肥可以增加玉米产量、提高玉米籽粒和植株锌含量。     

重金属对安氏伪镖水蚤的急性毒性及摄食的影响

[目的]研究桡足类浮游动物在重金属作用下的中毒效应以及摄食压力的变化。[方法]探究了Cu2＋、Zn2＋、Cd2＋3种重金属离子对安氏伪镖水蚤的急性毒性,并研究了安氏伪镖水蚤在3种重金属影响下的摄食率变化。[结果]Cu2＋、Zn2＋、Cd2＋对安氏伪镖水蚤的96 h LC50分别为0.1577、0.8941、0.1695mg/L,急性毒性由强至弱为Cu2＋〉Cd2＋〉Zn2＋;急性中毒后,重金属离子对安氏伪镖水蚤摄食率的影响为：Cd2＋〉Cu2＋〉Zn2＋,慢性中毒后,重金属离子对安氏伪镖水蚤摄食率的影响为Cu2＋〉Cd2＋〉Zn2＋。且雄性成体的摄食率普遍低于雌性成体。[结论]3种重金属对安氏伪镖水蚤均有毒性效应。