有机肥对土壤-小麦系统汞污染影响的研究

以冬小麦为试验对象,采用盆栽试验,研究了不同有机肥、不同外源汞施用量对土壤和小麦的汞污染、迁移和累积的影响。结果表明,随着汞施入量的增加,土壤全汞和有效汞含量逐渐增加,使小麦吸收汞增加。在小麦整个生育期,土壤有效汞与小麦根、茎叶、籽粒吸收的汞之间呈极显著正相关性。随着有机肥施用量的增加,土壤有效态汞含量逐渐减少,继而降低小麦对汞的吸收。相关分析表明,有机肥施用量与土壤有效汞呈显著负相关。有机肥对土壤有效汞的抑制效果以低汞高有机肥处理效果最为显著,苗期达到58.94%,收获期达到62.29%。有机肥施用量与苗期低汞处理下小麦茎叶和根部汞含量呈显著负相关,与收获期的所有汞处理下小麦茎叶、根部和籽粒汞含量呈极显著或显著负相关,在低汞处理,施用有机肥完全抑制了土壤中汞向籽粒中转移。所有处理小麦各器官汞含量的分布规律为根〉茎叶〉籽粒。     

高锌土壤上春小麦对~(65)Zn的吸收分布及其根际效应

利用６５ Ｚｎ 示踪法研究了高锌土壤春小麦对外源６５Ｚｎ 的吸收和６５ Ｚｎ 在小麦各器官中的累积分布。结果表明：外源６５ Ｚｎ 在小麦各器官的分配顺序为：茎叶＞ 籽粒＞根＞ 颖壳;６５Ｚｎ 在小麦各器官的比活度顺序为根＞ 籽粒＞ 颖壳≥茎叶;６５Ｚｎ 从土壤向小麦各器官的转移系数为：根＞ 籽粒＞ 颖壳≥茎叶。随着外源６５ Ｚｎ 浓度增加,小麦植株吸６５Ｚｎ 量及小麦籽粒中６５ Ｚｎ 量增加,６５ Ｚｎ 在小麦根部的分配比例也随之增加。小麦根际土对６５Ｚｎ 有富集作用。     

施用富Cu猪粪后潮土-小麦系统Cu的传递与积累

以华北地区典型土壤潮土为供试土壤,将猪粪(施用量占风干土重的0%,1%和3%)和不同Cu浓度(0,100,200,400,600和800 mg kg-1土)的CuSO4溶液腐化后与土壤混合均匀进行盆栽试验,以研究施用富Cu猪粪对土壤和小麦各器官(根、茎叶和籽实)Cu积累及对潮土—小麦系统Cu迁移转化的影响。结果表明,土壤全Cu、有效态Cu和小麦植株各器官Cu浓度均随着外源Cu浓度的增加而显著增加,在相同外源Cu浓度条件下,成熟期各指标浓度相对拔节期有所下降。外源Cu只有极少量从土壤向小麦转移,且在小麦各器官Cu浓度顺序为根>>茎叶/籽实。相对于拔节期,小麦成熟期根部Cu积累量显著上升,茎叶Cu积累量无显著变化,但根部和茎叶Cu浓度均显著下降。施用1%猪粪明显降低了Cu的可移动性,而3%猪粪在一定程度上增加了Cu的传递与积累。当外源Cu浓度≥200 mg kg-1时,0%和3%猪粪施用的处理籽实中Cu浓度超过了人体能接受的Cu毒性极限(20 mg kg-1),施用1%猪粪则潜在的降低了Cu在籽实中的积累。     

土壤中汞生物有效性的研究

小麦思苗实验表明,小麦幼苗根主要吸收土壤中小分子有机质结合的汞（ＦＡ结合态汞）,并在根部累积,其他开矿汞可以结合为ＦＡ结合态,表现为间接作用,残渣态汞是植物根吸收的库源。在实验条件下,小麦幼苗叶片可以很快吸收土壤中挥发出来的汞,并在茎叶中积累,土壤汞植物利用率氏,可被带出土主汞量有限。     

多环芳烃芘对小白菜生长和元素吸收及营养品质的影响

通过土培试验测定了不同浓度芘处理下小白菜根和茎叶的生物量、芘及其它矿质元素的含量和一些营养品质指标。结果表明:芘对小白菜根干重的影响显著,对茎叶干重和株高的影响不显著,全株干重由于根干重的下降而呈下降趋势;根中的芘含量和土壤中残留的芘含量随土壤中芘浓度增加而显著增加,茎叶芘含量与对照无显著差异,土壤芘降解率随芘浓度增加表现为先上升再下降的趋势;茎叶有机碳和根粗灰分含量随土壤芘浓度的增加而下降,茎叶粗灰分和根有机碳含量施芘处理显著高于对照,芘促进了根对土壤中N、P、K和S的吸收同化,并加速其向茎叶的转移。茎叶粗蛋白含量较对照有所增加,粗纤维和可溶性糖含量则随芘浓度增加而下降,其中可溶性糖含量各个处理与对照之间的差异达显著水平。     

锰改性猪粪炭对水稻吸收累积土壤中汞镉的影响

为了探明KMnO4改性猪粪炭对水稻吸收累积复合污染土壤中汞镉的阻控效果，通过盆栽试验研究添加不同量的锰改性猪粪炭（MZC）对水稻中汞镉累积分布特征、根际土壤有效态汞镉含量和土壤理化性质的影响，并探讨了MZC阻控水稻籽粒吸收累积汞镉的可能机制。结果表明：与空白对照相比，添加0.5%MZC使水稻籽粒的总汞、甲基汞和总镉含量分别降低了50.4%、58.4%和79.3%，同时降低了31.1%和39.9%根际土壤有效态汞和镉的含量，但增加了70.3%根际土壤总Mn含量；且添加0.5%的原始猪粪炭对水稻籽粒中总汞、甲基汞和镉含量的降幅显著小于锰改性猪粪炭的，表明经过KMnO4改性可以显著增强猪粪炭对土壤汞镉的钝化能力。水稻籽粒、茎叶中的汞镉含量和根际土壤有效态汞镉含量都随着MZC添加量的增加呈明显的降低趋势。统计分析显示水稻籽粒和茎叶中的汞镉含量与根际土壤中有效态汞、镉呈显著正相关性，而土壤中有效态汞镉含量与土壤的pH、CEC呈负相关。添加MZC使土壤pH、CEC升高，降低了根际土壤中汞、镉的生物有效性，从而减少了水稻地上部分对汞镉的吸收累积。因此，锰改性猪粪炭是一种具有应用潜力的能保障汞镉复合污染农田水稻安全生产的土壤修复剂。     

宝鸡燃煤电厂周围土壤环境Hg污染及其评价

通过对宝鸡燃煤电厂周围土壤环境的调查、采样,研究了土壤汞的污染状况。结果表明,电厂周围土壤中Hg的含量为0.137~2.105mg kg-1,平均值为0.606mg kg-1,高于陕西、全国和世界土壤中Hg的平均含量。单因子污染指数、地质累积指数和潜在生态危害系数评价结果表明,电厂周围土壤出现不同程度汞的污染。     

芜湖燃煤电厂周边土壤中砷汞的分布特征研究

探讨了芜湖燃煤电厂周边随距电厂水平方向、垂直剖面土壤中砷汞总量及形态分布特征,并分析了土壤中砷汞与理化性质之间的相关性。结果表明:土壤中As、Hg的变幅分别为3.821～19.264mg/kg,0.025～1.696mg/kg,平均含量分别为6.671mg/kg和0.212mg/kg。As、Hg含量总体分布特征为:距电厂1km处最大,距电厂1km距离内次之,距电厂1km以外,随距离增大而减小,其中汞随距离衰减明显。土壤汞含量在东南-西北(SE-NW)主导风向上明显大于东北-西南(NE-SW)非主导风向,而As含量在不同风向上基本无差异;土壤汞含量随剖面深度的增加明显减少,而砷在剖面上的分布规律不明显。土壤中砷主要以硫化物态和残渣态存在,而汞以残渣态和腐殖酸结合态为主。表层土中As、Hg与理化性质之间存在不同程度的相关性。     

水稻土镉污染与水稻镉含量相关性研究

采用盆栽试验的方法,考察了水稻土中重金属镉（Cd）的浓度对水稻生长及Cd富集的影响以及Cd在水稻植株的分布情况,并进一步研究了糙米（可食部位）对Cd的富集量与土壤中Cd总量的关系。结果表明,在各个浓度Cd胁迫下,根、茎叶、稻壳、糙米相比,2个品种水稻都是根累积的Cd含量要高于茎叶和稻壳、糙米,即根〉茎叶〉稻壳〉糙米;在水稻的茎叶细胞中,Cd主要分布在细胞壁,细胞可溶性成分,细胞器Cd的分布量较少,即细胞壁〉可溶性部分〉细胞器及膜部分;随Cd浓度增加,茎叶中的Cd积累量极显著增加,各细胞组分中的Cd含量均显著增加;根据国标GB 2762—2005对大米中Cd的限量标准（≤0.2 mg.kg^-1）,水稻土土壤总Cd临界值分别为2.0 mg.kg^-（1博优225）、3.1 mg.kg^-（1矮糯）。因此,在污染土壤上宜选种食用部位重金属积累低的水稻品种,以减少人类吸收重金属的风险。     

烟草对土壤铅的吸收、转运及分配特征

采用室外盆栽试验方法,开展烟草不同生育期铅吸收转运及分配特征的研究。结果表明：土壤铅处理对烟草生长有较明显的抑制作用,且生育前期比生育后期更明显;烟草根系对铅的阻滞作用较强,以限制铅由根系向地上部运输。烟草各生育期根、茎和叶中铅含量均随土壤铅浓度的增加而升高,其中根部的上升幅度最大,随着生育期的推进,烟草各器官铅含量从团棵期至现蕾期呈现先降低后升高的趋势,根部铅含量从现蕾期至成熟期呈现下降趋势。土壤添加外源铅后,烟草生育期内茎和叶的铅转运系数分别介于0．35—1．00和0．25～0．91之间,茎和叶的转运系数随着铅浓度的增加和生育期的推进呈下降趋势。烟草各器官中铅含量介于13．8～180．74mg·kg^-1之间,各器官铅含量的分布规律为根〉茎〉叶,各器官铅积累量总体为叶〉根〉茎,但成熟期在T2和T3处理下表现为根〉叶〉茎。在土壤铅浓度较低时,烟草体内铅较易向地上部分转运,旺长期至现蕾期阶段是烟草体内铅向地上部分转运的关键时期。     

Season-Dependent Fruit Loading: Effect on Nutrient Homeostasis of Tomato Plants

ABSTRACT

Greenhouse tomato plants were grown hydroponically during the period of lower temperatures of winter (LT) versus the period of higher temperatures of summer (HT). In these plants, the effect of season on fruit load was dramatic. In order to study the alterations season introduces to the developmental allocation of nutrients within the various organs, concentrations of total nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) were determined during each season at weekly intervals in the dry mass of leaves and roots and in the extract of upper, middle, and lower parts of the stem. The level of N/P ratio was always higher in the leaves than in the roots, and these differences were more intense during HT. The short-term changes of ratio in the leaves during HT and LT were positively related with the changes in temperature (r = 0.59 and 0.51 for HT and LT, respectively). In contrast, such correlations in the root were negative (r = ?0.54 and r = ?0.33 for HT and LT, respectively). The increase of temperature increased P uptake but not its translocation to upper plant parts. HT affected the translocation of N, K, Mg, and Ca more and their uptake less. Fruit load differentially affected the concentration of nutrients. In contrast to total N and K, Ca concentration in plant parts presented a positive relation with the increase of fruit load. Calcium and total N concentration (as opposed to P and micronutrient concentrations) were always higher in the leaves than in the roots. Under HT conditions, P was accumulated in roots in combination with high concentrations of Fe, Zn, and Mn. On the other hand, K and N were accumulated in the roots during the period of low temperature in winter. Calcium and K compared with other nutrients presented a pronounced tendency to be transported toward the top of the stem during HT, and their extractable concentration in the upper part of stem presented a significant increase during summer. Extractable K concentration was two to nine times higher than that of the other macronutrients. Our data suggest that the extractable concentration of nutrients of the stem is a good index for the diagnosis of the mineral nutritional status of the plant.     

不同价态外源硒对冬小麦生长及生理代谢的影响

用盆栽试验研究了不同浓度外源硒（四价和六价）处理土壤对小麦生长和生理代谢的影响,旨在为富硒小麦的种植和开发提供理论依据。结果表明：外源硒抑制了苗期小麦的生长（株高和生物量）;而在生长后期,随外源硒浓度增加表现为先促进后抑制作用。Se（Ⅳ）和Se（Ⅵ）处理对小麦生物量影响的EC10分别从苗期的1.40mg·kg-1和0.28mg·kg-1增加到收获期的28.48mg·kg-1和4.56mg·kg-1,表明小麦对硒的耐受浓度随生长时间的延长逐渐增大。Se（Ⅵ）低浓度（≤1mg·kg-1）对小麦生长的促进作用及高浓度（≥2.5mg·kg-1）对小麦生长的抑制作用均大于Se（Ⅳ）。小麦籽粒产量随外源Se（Ⅳ）和Se（Ⅵ）浓度的增大先升高而后降低,分别在2.5mg·kg-1和1mg·kg-1浓度处理时达到最大。低浓度硒处理（Se（Ⅳ）≤5mg·kg-1和Se（Ⅵ）≤0.5mg·kg-1）能促进拔节期小麦叶片中GSH和POD等抗氧化酶活性,显著降低叶片过氧化物质MDA（Se≤2.5mg·kg-1）含量,高浓度硒处理则与之相反。     

Leaf chlorophyll content as a possible diagnostic mean for the evaluation of plant nitrogen uptake from the soil

The influence of temperature, irradiance, and soil humidity on the nitrogen (N) concentration in some organs, chlorophyll in the leaves, N uptake and accumulation of dry matter in plants of winter wheat was investigated. In the plants grown under equal initial N supplement but in contrasting conditions of the evironment, the correlation between concentration of total N and chlorophyll in the leaves was absent. No interrelationship was found between concentration of total N in the leaves and accumulation of N and dry matter in the whole plants. There is a close correlation between chlorophyll in the leaves, accumulation of total N, and dry matter of the whole plant. It was concluded that chlorophyll is a more stable informative parameter for the estimation of the N uptake from the soil under different growth conditions than leaf N concentration.     

大豆植株苗期至结荚初期对肥料氮的吸收与分配

采用砂培与15N分阶段标记的方法,研究了苗期至结荚初期大豆植株对氮素的同化吸收,尤其是肥料氮在不同器官和节中的积累与分配。结果表明:(1)苗期至结荚初期大豆植株氮素积累量逐渐增加,由标记试验Ⅰ的64.08g/plant逐渐增加到标记试验Ⅴ的307.17mg/plant;(2)不同器官中肥料氮积累存在差异,叶是苗期至结荚初期肥料氮积累的主要器官,所占比例为55.2%,根系次之为25.9%,茎最小为18.9%;(3)苗期至结荚初期肥料氮积累量和所占比例逐渐减小,而根瘤固氮则逐渐增加,其中苗期至盛花期肥料氮是大豆植株氮素主要来源,盛花期以后以根瘤固氮为主;(4)不同成长程度叶对肥料氮的积累存在差异,表现为成长中叶>新生叶>成熟叶;(5)新生茎叶氮素构成随全株氮素构成的变化而变化,苗期至初花期以肥料氮为主,初花期至结荚初期根瘤固氮逐渐转为主体。     

Impact of the state-of-the-art of flue gas cleaning on mercury species emissions from coal-fired steam generators

When balancing the element mercury (Hg) two coal-fired power plant units — one with slag tap boilers (ST, 2 × 220 MW) and one with a dry bottom boiler (DB, 475 MW) were compared. Both systems are provided with electrostatic precipitators (ESP), nitrogen oxides removal (DeNO_x) and flue gas desulfurization (FGD) systems. The Hg in the flue gas is predominantly in gas phase. Only 15 % of the Hg introduced by the coal leaves the unit with the bottom or fly ash. Depending on the operating mode, 30 to 40 % of the Hg is separated in the FGD systems. The overall separation rate for the total system ranges between 45 to 55 %, the residue is emitted in the form of gaseous Hg species. At full load, the Hg concentration in the cleaned gas is less than 6 μg/m³. In the flue gas path of another dry bottom boiler (DB1, 480 MW) the concentrations of the gaseous species of bivalent mercury (Hg²⁺), elemental mercury (Hg⁰), and total mercury content (Σ Hg) were determined. The sum of the concentrations of Hg²⁺ and Hg⁰ is in agreement with the measurement of Σ Hg. Directly downstream of the boiler Hg²⁺ dominates with 77 %, while Hg⁰ amounts to 23 %. In the high-dust DeNO_x system Hg⁰ is oxidized almost completely to Hg²⁺ (96 %). Air heater and electrostatic precipitator do not influence the Hg species concentrations. The FGD system eliminates approximately 80 % of the Hg²⁺. At the same time the quantity of Hg⁰ increases by the factor 10. In the cleaned gas Hg⁰ dominates with 76 % as compared to Hg²⁺ with 24 %. At full load the concentration of Σ Hg in the cleaned gas is also below 6 μg/m³.     

Season-Dependent Fruit Loading: Effect on Dry Mass,Water, and Nitrogen Allocation in Tomato Plants

Tomato plants were grown hydroponically in greenhouse under common commercial cultivation practice during two seasons: winter, with lower temperatures (LT) and summer, with higher temperatures of (HT), and results were compared. The effect of season on fruit load was drastic and the hypothesis was advanced that nitrogen (N) homeostasis at the whole plant level might be significantly affected, as measured by the extractable N of the stem. During LT, dry-mass accumulation occurred more or less at the same rate in all plant parts. The high fruit load at HT altered the picture, with dry-mass accumulation present at different rates in the various plant organs. Low temperatures positively affected root weight, which was significantly higher; influenced root morphology; and negatively affected fruit load. There were significant differences between the two seasons at the time of flowering, fruit setting, and fruit maturation in terms of the number of leaves and inflorescences on the main stem and in the rate of their appearance. In summer, water content of leaves and roots was lower, but not that of stem. Also, water content of roots increased considerably increase in the last five weeks, which coincided with the temperature and fruit-load decrease at the end of the season. Nitrogen concentration of leaves was higher than that of roots throughout HT, while extractable N concentration increased significantly at the middle part of the stem, where it bore the main fruit load. This effect was more profound when more fruits were ripening. Low temperature conditions were characterized by a significant decrease of root water content, while extractable N allocation was not significantly affected and root total N was higher.     

腐植酸对冬小麦种子的生理调节作用

通过对两个不同品种冬小麦用与不用腐植酸处理种子的对比试验，研究了冬小麦的发育形态与生理变化特点。结果表明，腐植酸能提高冬小麦的出苗率，对植株的生长和生物量积累有明显的促进作用，能提高越冬期冬小麦叶中ABA含量，增强根系活力，提高产量。     

Estimation of Water Content in Winter Wheat (Triticum aestivum L.) and Soil Based on Remote Sensing Data–Vegetation Index

In this study, a suitable and near-real-time water status monitoring approach for winter wheat before harvest was developed with remotely sensed satellite data. Seven vegetation indices were extracted as remote-sensing parameters by making full use of the land surface reflection and land surface temperature transmitted by moderate resolution imaging spectroradiometer (MODIS) data. The correlation of each vegetation index and measured values of winter wheat and soil water contents in different crop growth periods was established. The simulation models, combining vegetation index, soil water content (SWC), and plant water content (PWC) in different winter wheat growth periods, were constructed to predict water content by using remote-sensing data. We found that the correlations between the difference vegetation index (DVI) and the perpendicular vegetation index (PVI) in the beginning of the stem elongation period with SWC were highly significant (P < 0.01); the correlation between the global environmental monitoring index (GEMI) in the ear emergency period and SWC was highly significant (P < 0.01). Furthermore, the correlation between the PVI in maturing period and SWC was highly significant (P < 0.01). Data of different coefficients of vegetation indices and PWC in different winter wheat growth periods illustrated that correlation between the DVI in the beginning of stem elongation period and PWC was highly significant (P < 0.01), while the correlation between the PVI in the maturing period and PWC was highly significant. Our results indicated that spatial and temporal vegetation indices were closely related to soil moisture and winter wheat water content in Wenxi County, Shanxi Province (P. R. China). The vegetation index is conceptually and computationally straightforward and may be used in prediction of environmental hydrological status.     

Nitrogen uptake and allocation by field‐grown ‘Arapaho’ Thornless blackberry

Spring surface applications of ¹⁵nitrogen (N)‐labeled urea were made in March 1995 and 1996 on one and two‐year‐old, field‐grown ‘Arapaho’ blackberry (Rubus subgenus Rubus) plants. Individual whole‐plant samples were collected at pre‐harvest (late May), post‐harvest (mid‐July), and early dormancy (late October). Plant parts separated for analysis were roots, primocanes, floricanes, primocane leaves, floricane leaves; and fruits. Soil samples were also taken from within the plant drip line at each sample date. Plant tissues were washed, dry weights measured, ground for acid digestion, total N determined, and ¹⁵N analyzed. Plants collected in October had more total dry matter, with roots, primocanes, and primocane leaves contributing most to this total. Total N content decreased in all vegetative tissues (leaves and canes) from May to October. Compared to other plant tissues, floricane leaves and primocanes recovered significantly more fertilizer N in May while roots and primocane leaves contained more in October of each year. Floricanes and fruits did not increase in fertilizer N levels during the sampling period. Overall, the lowest percent fertilizer N recovery for whole plants was 12.8% for May 1995 and the highest was 32.4% for October 1996. Recovery of fertilizer N in the topsoil ranged from a low of 12.9% in October 1995 to a high of 38.6% in May 1996. There were no statistical differences in percent recovery of fertilizer N from topsoil among sample dates. Recovery of fertilizer N from subsoil in the October sample was much lower than that in May, probably due most to plant uptake, but also possibly to a downward movement out of the sample area by leaching or from other loss mechanisms. Averaging all sample dates, recovery was 59.5% in 1995 and 75.8% in 1996 for the plant and soil combined, with the remainder probably lost via volatilization, leaching, and/or denitrification.     

冬小麦苗期叶绿素含量检测光谱学参数寻优

光谱分析技术是作物生长检测的主要手段,为了解决大田漫反射采集所造成的光谱基线漂移和偏移问题,研究采集了冬小麦冠层325~1 075 nm范围反射光谱,采用多元散射校正方法对小麦原始光谱进行预处理。采取遗传算法对光谱特征参数寻优并结合相关分析结果,选取486、599、699和762 nm波长处反射率值并组合计算了RVI(ratio vegetation index),DVI(difference vegetation index),NDVI(normalized difference vegetation index)和SAVI(soil-adjusted vegetation index)共12个植被指数,分析了各植被指数与叶绿素含量值之间的相关关系,结果显示:DVI和SAVI可抑制苗期土壤背景干扰并对叶绿素含量响应较为敏感,与叶绿素含量相关性最优的参数分别为DVI(762,599)、SAVI(762,599)、DVI(762,699)和SAVI(762,699),与叶绿素含量的相关系数都达到0.6以上。基于相关性最优光谱植被指数DVI(762,699)和SAVI(762,599)利用最小二乘-支持向量回归建立冬小麦叶绿素含量预测模型,建模集决定系数为0.681,验证集决定系数为0.611。该模型可用于无损检测冬小麦苗期叶绿素含量,以期为后续施肥决策提供支持。