Ceramic Aggregate Sorption and Desorption Chemistry: Implications for Use as a Component of Soilless Media

Ceramic aggregates (Turface® and Profile®) are common soilless media components, but their sorption/desorption chemistry is poorly understood. We investigated: labile (readily desorb-able or readily plant-available) ion concentrations; the effect of rinsing and soaking pretreatments on labile ions; sorption of applied nutrients; and nutrient uptake from the aggregates by plants. Variability in labile ions was extremely high among bags of aggregates. Manganese, boron, magnesium, calcium, sulfur and potassium were most likely to desorb in excess for plants. Phosphorus, iron, copper and zinc were sorbed by the aggregates; only copper was found nearly deficient in plant tissue. Rinsing and soaking pretreatments adjusted labile ions to more suitable concentrations for plants. However, growth data suggested a worst-case scenario of high levels of labile ions may not be mitigated by these pretreatments. With frequent leaching after planting or where the aggregates are a minor component of media, excessive nutrient uptake would likely be limited.     

Impact of Aluminum on Phosphate Uptake and Acid Phosphatase Activity in Root Tips of Lotus Japonicus

The effect of aluminum (Al) on phosphate homeostasis and induction of acid phosphatase activity and isoenzymes was analyzed in root tips of Lotus japonicus. The rapid uptake of phosphate as well as the decrease of soluble inorganic phosphate in tissues suggested, that the presence of Al in root apoplast causes precipitation of the most of absorbed phosphate. Acid phosphatase (ACP) isoenzymes are affected differentially during low pH and Al stress and both Al induced increases and decreases of ACP isoenzyme activities were observed.     

Determination of Phosphate in Selective Extractions for Soil Iron Oxides by the Molybdenum Blue Method in an Automated Continuance Flow Injection System

Phosphorus (P) mobility and bioavailability in soil depend on the pools in which it resides. The identification of such pools is essential for the full understanding of P behavior in soil. We evaluated the molybdenum-blue ascorbic-acid method in an automated continuous flow injection analyzer (MB-FIA) to analyze P in two selective soil extractions for soil iron oxide (i.e., the acid ammonium oxalate, AAO, and citrate–dithionite, CD, procedures). Uninterrupted development of the color reaction was obtained at citrate and oxalate concentrations less than 50 mM and 35 mM, corresponding to molybdate/citrate and molybdate/oxalate molar ratios of 2.4 and 3.4, respectively. High precision (% RSD, 1.7 ± 1.3% for CD and 2.9 ± 3.7% for AAO), accuracy, and recoveries (105.7 ± 1.0% for CD and 99.8 ± 3.8% for AAO) were obtained. This study demonstrates the utility of the MB-FIA system for the determination of AAO- and CD-extractable inorganic P.     

平原区水田改林地后土壤黏土矿物及氧化铁的变化

近年来水田改为林地在我国南方地区非常普遍,为了解这种转变对土壤矿物(黏土矿物和氧化铁)演变的影响,在浙江省平原地区构建了4个水田改林地系列土壤,采用野外调查和室内分析相结合的方法,研究水田改林地后土壤剖面中氧化铁形态和黏土矿物类型的演变规律。结果表明,改林地后,土壤剖面中全铁含量变化不明显,耕作层和犁底层土壤游离氧化铁有轻微增加趋势。改林地15～20 a后,4个系列土壤耕作层活性铁和活化度降幅分别在18.0%～38.4%和24.7%～48.9%;耕作层土壤铁氧化物的晶胶比增幅在0.73倍～1.62倍;耕作层土壤亚铁含量明显下降,降幅最高达95.8%,变异系数达到143.9%;耕作层络合铁降幅在21.3%～36.2%,并与有机质呈极显著正相关(P<0.01)。改林地后,犁底层土壤中绿泥石相对含量及其与高岭石的比值都呈降低趋势,其他黏土矿物相对含量变化规律不明显,土壤有机质显著下降,土壤明显酸化。土壤铁氧化物形态和数量的变化对土壤结构以及土壤重金属的迁移转化等产生重要影响。     

Corn Wastes and Peanut Shell as Growing Media for Production of Red Radish Plants in Soilless System

ABSTRACT

Peat is considered the conventional growing medium in most soilless culture systems. The high cost of peat and the urgent need of agricultural wastes recycling encouraged the scientists and soilless culture users to search for an alternative growth medium where optimal growth conditions are achieved and help in the safe disposal of wastes. In the current study, peanut shell (PS) and corn wastes (CW) were used as growing media in comparison to peat moss (PM). The tested organic wastes and peat moss were examined with sand at three mixing ratios (1:1 “M₁”, 1:2 “M₂” and 1:3 “M₃” raw material: washed sand, respectively). Red radish (Raphanus raphanistrum subsp. sativus) plant were cultivated in 5 kg pots filled with the instigated growing media. Most of the recoded growth parameters were found in PS and PM growing media, while the lowest ones were found in CW. PS medium contained available N and P higher by 141 and 29% above the PM media. Although the peat moss gave the highest values in the measured growth characteristics, its high price decreased the net profit. The highest net profit value was obtained from PSM₂ followed by PSM₁ and PSM₃. According to the obtained results, the characteristics of the growth media derived from peanut shell qualify them for use in the production of red radish in soilless culture systems.     

Enhancement of callose production by a combination of aluminum and iron in suspension-cultured tobacco (Nicotiana tabacum) cells

In nutrient medium, aluminum (A1) enhances ferrous ion [Fe(II)] -mediated per oxidation of lipids, which results in the loss of the plasma membrane integrity and the accumulation of A1 in tobacco cells. Under these conditions, the mechanism of callose production and possible involvement of callose in the accumulation of Al were investigated. Callose production was enhanced by both Al and Fe(II), but not by A1 or Fe(II) alone, and the enhancement was inhibited by a lipophilic antioxidant, suggesting that the enhancement of callose production is caused by the A1-enhanced, Fe(II)-mediated peroxidation of lipids. The enhancement of callose production depended on the presence of external Ca²⁺ in the treatment medium. The activity of β-l,3-glucan synthase in the microsomes was increased several times by the addition of Ca²⁺ in the assay medium, although the activity in the microsomes was reduced by the treatment of cells with Al and Fe(II) together. Therefore, it is likely that callose production is enhanced by exogenous Ca²⁺ via the AI-enhanced, Fe(II)-mediated peroxidation of lipids. During the exposure of the cells to Al and Fe(II), callose production started and increased simultaneously with Al accumulation. However, the digestion of callose in the cell wall materials prepared from the A1-treated cells by laminarinase did not release A1, suggesting that callose is not involved in the binding or trapping of A1.     

Al and Fe in PM 2.5 and PM 10 Suspended Particles in South-Central Florida: The Impact of the Long Range Transport of African Mineral Dust

Aluminum and iron were measured in daily samples collected at urban and rural sites near Ft. Myers, Florida, in 1995–1996 using a dichotomous sampler. Al and Fe concentrations were low during most of the year but they increased dramatically duringsummer when African dust was advected into Florida. The ratioof fine (less than 2.5 m diameter) to coarse (2.5–10 m) Al and Fe is relatively constant in African dust events with the fine accounting for a third to a half of the total. Also the mass ratio of Al-to-Fe is relatively constant at 1.8, a value similar to average crustal material. In contrast, in non-African dust the fine-to-coarse and Al-to-Fe ratios are extremely variable and generally much lower than those duringAfrican events when dust concentrations ranged up to 86 g m^-3. The timing and magnitude of the Ft. Myers dust peaks closely matched those measured concurrently in Miami, 200 km to the southeast. Large areas of the eastern United States are frequently impacted by African dust every summer. Although dustconcentrations can reach very high values it seems unlikely that African dust events alone will cause a violation of the Environmental Protection Agency's standards for PM 2.5 or PM 10. However, African dust in conjunction with emissions from local and regional sources could conceivably present a problemwith compliance. The probability of such an occurrence is heightened by the fact that dust concentrations are highest in the summer when pollution levels are often at a maximum in theeastern states.     

三江并流区水库消落带5种草本根系形态及抗拉特性

为揭示三江并流区水库消落带5种草本植物在浅层土壤中的根系形态及抗拉力学特性,筛选消落带优势固土草本,以澜沧江黄登水库消落带的花叶芦竹(Arundo donax var.versicolor)、风车草(Cyperus alternifolius L.)、美人蕉(Canna indica L.)、菖蒲(Acorus calamus L.)和芦苇(Phragmites communis Trin.)为对象,分析了根系形态,并进行室内单根拉伸试验。结果表明:(1)5种草本根系都发育良好,花叶芦竹和风车草根系的所有形态指标都位居前二,根系较为发达; 5种草本直径大于1 mm的根系长度、表面积和体积在各自总根系中占比最大,且除芦苇外,其余4种草本直径大于2 mm的根系体积占比最大,达到58.53%～92.86%。(2)5种草本根系的平均抗拉力、抗拉强度以花叶芦竹(33.04 N,34.33 MPa)最大,美人蕉(10.26 N,7.54 MPa)最小,根系抗拉力、抗拉强度分别随直径增大呈幂函数增大、减小。(3)5种草本根系平均极限延伸率以菖蒲(24.28%)最大,美人蕉(8.20%)最小; 平均杨氏模量以花叶芦竹(313.44 MPa)最大,菖蒲(70.47 MPa)最小,根系杨氏模量与直径呈幂函数负相关。综上,5种草本都适应了研究区环境,均可作为黄登水库消落带植被重建的候选物种; 直径大于1 mm的根系是5种草本根系的主体,直径大于2 mm的根系整体上对体积贡献最大; 花叶芦竹不仅根系发达,且其抵抗拉伸作用的能力最强,固土能力最强,是黄登水库消落带水土保持的优势草本。研究结果可适当推广到三江并流区和其他水库消落带。     

砒砂岩区三种沙棘根系特征与固土能力

[目的] 研究中国沙棘(Hippophae rhamnoides ssp.sinensis)、太阳沙棘(Hippophae rhamnoides ssp.taiyang)、乌兰沙林沙棘(Hippophae rhamnoides ssp.mongolica “Wulanshalin”)在砒砂岩区的根系分布特征及林下土壤抗蚀性特征,为改善当地生态环境提供新的树种选择。[方法] 在野外挖土壤剖面获取根土复合体,在室内进行根扫描及崩解试验。[结果] ①沙棘根系垂直分布规律大致相似。随土层深度的增加,根长、根体积逐步减少。根系主要分布在0—60 cm土层,占总根量比例分别为90.96%(中国沙棘),83.38%(太阳沙棘),74.93%(乌兰沙林沙棘);粗根主要分布在0—40 cm土层。水平方向粗根主要分布在距根基0—20 cm的范围内,细根主要分布在20—100 cm范围内,且距根基越远细根含量越少,根系整体呈浅层化分布。②沙棘林下土壤崩解速度变化趋势基本一致。以0—20 cm表层土平均崩解速度最低。随着深度增加逐步增大,水平方向距根基部越远土壤平均崩解速度越大。土壤崩解速度表现为：中国沙棘(3.18 g/s)＞太阳沙棘(1.27 g/s)＞乌兰沙林沙棘(1.21 g/s)。③土壤崩解速度与沙棘根系分布有显著相关关系。垂直方向上受到粗根和细根的共同影响,水平方向主要受到细根的影响,细根对固持水土的作用更大。[结论] 太阳沙棘的根系含量高于乌兰沙林沙棘,且根系分布特征和林下土壤崩解速度变化规律联系更密切,更适用于砒砂岩区的水土流失防治工作。     

红壤侵蚀区不同植被类型土壤磷垂直分布特征及影响因素研究

为探讨红壤侵蚀区不同植被类型下土壤磷素有效性,选取福建长汀红壤丘陵生态系统国家定位观测研究站的裸地(CK)、针叶林(CF)、针阔混交林(CB)以及阔叶林(BF)4种植被类型,分别测定其铁氧化物、各级磷素形态,并采用高通量测序技术对解磷菌(PSM)进行测定。结果表明:随着植被类型的转变,中等活性磷含量增加,低活性磷含量总体上减少,游离态氧化铁(Fe_d)含量逐渐减少。土壤中解磷菌的丰富度和多样性随植被类型的转变增加。在门分类水平上,优势类群主要有变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、异常球菌—栖热菌门(Deinococcus-Thermus)等。变形菌门和酸性磷酸酶的含量随植被类型的转变总体呈现出增加趋势,变形菌门与ACP呈极显著正相关。综上所述,随着植被类型转变,稳定态磷逐渐向可利用态磷转化,土壤潜在磷源增加;游离态氧化铁含量的减少有利于有机磷的解吸和矿化,进而增加磷的有效性;解磷菌群落结构与多样性变化会受到土壤理化性质的影响,解磷微生物可通过分泌酸性磷酸酶的方式水解有机化合物并降解固定在土壤的无机磷,进而提高磷的有效性。     

The Effects of Cow Manure and Vermicompost on Availability and Desorption Characteristics of Zinc in a Loamy Calcareous Soil

The application of organic fertilizers in soils not only increases soil organic matter but also introduces essential nutrients to soil. Therefore, applying these fertilizers can affect the availability and desorption characteristics of nutrients. The main objective of this research is to study the effects of cow manure (CM) and vermicompost (VC) on availability and desorption characteristics of zinc (Zn) in a loamy calcareous soil. In this study, concentration of available Zn (using DTPA-TEA, AB-DTPA, and Mehlich 3) and desorption characteristics of Zn (using successive extraction with DTPA-TEA For 1–504 h at 25 ± 1°C) in amended soil with 0, 0.5, and 1% (w/w) of CM and VC were investigated in a completely randomized design. Results of this research showed that concentration of Zn extracted by using three methods was higher in amended soils with 1% CM and VC than those with 0.5% of these fertilizers. Furthermore, the difference between concentration of available Zn in amended soils with CM and VC was not found to be significant (p > 0.05). The results of kinetics study illustrated that the effect of organic fertilizers on Zn desorbed after 504 h was found to be significant (p < 0.01). Amount of cumulative of Zn desorbed in amended soils was significantly (p < 0.05) higher than unamended soil. Concentration of Zn desorbed after 504 h in 0.5 and 1% of CM and VC compared with unamended soil increased 26, 54, 12, and 46%, respectively. In addition, Zn desorption rate in amended soils with CM was higher than those with VC. It can be concluded that organic fertilizers applied to loamy calcareous soils enhance source of available Zn for the plant. Moreover, the results of this study showed that the ability of amended soils with VC to supplying Zn for plants was lower than those with CM.     

排土场土体裂缝区植被根系及抗剪强度分布特征

为揭示排土场土体裂缝区植物根系和抗剪强度分布特征,采用根钻法、WinRHIZO根系分析系统和直剪仪研究了0—60 cm土层植物根系、黏聚力和内摩擦角随土层深度的变化规律。结果表明:3个样地根系特征参数不同,随土层深度增加而减小,主要分布在0—20 cm土层,根密度和根重密度为88.81～303.03个/10³cm³,0.15～2.69 mg/cm³。根系以径级d≤0.1 mm和0.1 mm相似文献   

夏玉米和冬小麦秸秆对石灰性土壤磷吸附特性及磷素形态的影响

本文对夏玉米秸秆(MR)和冬小麦秸秆(WR)单施或者与P肥混施(在等P量条件下)对石灰性土壤P的吸附特性及其形态转化进行了为期15周的室内模拟培养研究,结果表明,无论是MR和WR单施,还是秸秆与P肥混施,都可以减少土壤对P的吸附量,提高土壤P的活性,其中秸秆单施处理的活性无机磷(Pi)和有机磷(Po)(NaHCO3-P或者NaOH-P)提高较大,夏玉米秸秆单施时,比对照(CK)增加Pi、Po的量分别达6.0、5.6mgkg-1(NaHCO3-P),增加NaOH-Po为12.7mgkg-1。并通过Langmuir方程求得P的最大吸附量(b)、P吸附结合能常数(k)、P素最大缓冲量(MPBC)、标准需P量(SPR)的值,进一步说明了两种秸秆均可使土壤对P的吸附能力降低,增加土壤中P的活性。     

Magnetic Solid-Phase Extraction Based on Modified Iron Oxide Nanoparticles for the Preconcentration of Ultra-Trace Amounts of Copper Ions in the Environmental and Plant Samples and its Determination Using FAAS

In the present work, magnetic iron oxide nanoparticles (MIONPs) coated with sodium dodecyl sulfate (SDS) and modified with 1-(2-pyridylazo)-2-naphthol (PAN) as a new nanoparticle were prepared and used as an adsorbent for the extraction and preconcentration of copper ions. After adsorption, copper ions were desorbed with nitric acid (HNO₃), followed by determination with flame atomic absorption spectrometry (FAAS). The extraction conditions0. were investigated systematically. The linear range 3.0–500.0 ng mL^?1 and the detection limit of 0.6 ng mL^?1 were obtained. The relative standard deviation (RSD) of the method for seven replicate determinations of 0.1 µg mL^?1 of Cu(II) was 2.2%. The method was applied for the determination of Cu(II) in different water samples with good trueness. The accuracy was also evaluated through analyses of a certified reference material (CRM TMDW-500).     

2种水土保持灌木的根系数量特征研究

以内蒙古自治区准格尔煤田黑岱沟露天矿排土场2种人工栽植的4龄水土保持灌木柠条和沙棘的根系为对象,通过研究根系数量特征,确定其代表根,为2种灌木根系的生物力学性质和抗蚀研究提供了基础数据和相关参数.代表根的确定将根系以0.5 mm为1个径级进行分级,计算每个径级组的累计根数量、累计根长、累计根表面积和累计根干重等4个方面,取这4个值百分比相对较大的径级组作为各自的代表根.结果表明:柠条代表根径级为0～0.5 mm,0.5～1 mm,1～1.5 mm;沙棘代表根径级是0.5～1 mm和1～1.5 mm.在根系固土抗蚀生物力学性质的研究中,建议在内蒙古准格尔露天矿排土场及相似地区柠条和沙棘2种水土保持灌木主要研究的根茎范围以其代表根径级为主要研究范围.     

三峡库区中部移民安置区土壤养分特征及变化评价

为揭示移民迁建对三峡库区中部土壤养分的长期影响,本研究在库区中部不同地貌类型移民安置区选择3种(耕地、果园和林地)典型土地利用方式,通过主成分分析和内梅罗指数法,揭示1998~2015年各区域的土壤养分特征及年际变化规律。结果表明,库区中部移民安置区的土壤养分总体水平较低;不同地貌类型区及土地利用方式土壤养分特征及变化存在差异性,整体呈现降低-增加-降低的趋势;2008年、2012年是土壤养分综合指数的最低和最高点,条状低山区土壤养分指数最高,浅丘区次之,单斜深丘区最低,但变化幅度较大;耕地土壤养分指数变化较显著,而林地、果园较为稳定。     

Molecular weight spectra of dissolved organic carbon in a rewetted Welsh peatland and possible implications for water quality

Abstract. Demand for water from catchments dominated by upland peat as a source of drinking water supplies in the UK is likely to increase in the future as demand per capita continues to rise (Thomsen 1990) and/or summer droughts increase in frequency (Arnell 1992). Concern has been expressed in recent years over rising colour levels (related to dissolved organic carbon (DOC) and iron (Fe)) from such catchments (e.g. Kay et al. 1989) causing reduced drinking water quality. One of the major causes of increased DOC concentrations is rewetting following periods of relative drought (Mitchell & McDonald 1992). Experimental rewetting of a naturally drained wetland in Mid‐Wales over four years was found to substantially increase the concentrations of DOC, and Fe in the pore‐water, with peak values of >60 mg dm^–3 (Fe) and >300 mg dm^–3 (DOC) after rewetting, compared with typical values of <1 mgdm^–3 (Fe) and <15 mg dm^–3 (DOC) under the drained conditions. Seasonal peak concentrations of Fe and DOC have since remained at these higher levels. Rewetting produced a selective enrichment of the >5000 to <90 000 apparent molecular weight (AMW) material and this fraction was found to yield peak Fe concentrations. Two additional peaks of DOC were also found in the experimental wetland (not present in the control wetland), of >90 000 to <200 000 AMW and >200 000 AMW material. The AMW spectrum of DOC in the experimental wetland changed with season, and the >90 000 to <200 000 AMW fraction could only be seen in spring, representing a transient pool of carbon that is rapidly transformed in or transported from the wetland. These findings suggest that rewetting of peatland following drought (e.g. due to climate change) has the potential to reduce water quality. Moreover, recent interest in restoration (rewetting) of drained peatlands (Wheeler & Shaw 1995) could create an additional source of DOC rich water.     

Iron and/or acid foliar spray versus soil application of Fe-EDDHA for prevention of iron deficiency in Valencia orange grown on a calcareous soil

A two-year experiment was conducted in an iron(Fe)-deficient orchard with calcareous soil to find out an alternate method for soil application of Fe ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) (Fe-EDDHA) in orange trees. Foliar sprays of Fe-EDDHA (5 g l^?1, pH = 7.8), sulfuric acid (pH = 3), citric acid (5 g l^?1, pH = 2.4), Fe (II) sulfate solutions (250, 500, and 750 mg Fe l^?1) with their initial pH (6.5, 6.35, and 6.12) and reduced ones to pH of 3 were compared with soil applied (75 g tree^?1) Fe-EDDHA and a control test. Although optimum chlorophyll content, leaf Fe concentration, fruit quantitative and qualitative attributes were resulted from soil application of Fe-EDDHA, repeated sprays of Fe-EDDHA or acidified Fe solutions created suitable results. Acidification of Fe solutions made them more effective in alleviation of leaf Fe concentration and Fe chlorosis, probably due to remobilization of inactive Fe within the plant and prevention of Fe oxidation and precipitation in foliar solutions.     

Genetic Effects on Grain Characteristics of <Emphasis Type="Italic">indica</Emphasis> Black Rice and their Useson Indirect Selections for some Mineral Element Contents in Grains

Complete diallel crosses with Oryza sativa L., six varieties of black rice and one variety of aromatic white rice were conducted to study the seed, maternal and cytoplasmic genetic effects on grain characteristics such as 100-grain weight, length, width and shape and their genetic correlations with Fe, Zn, Mn and P mineral contents in kernels by using the genetic model on quantitative traits of seed in parents and their F₁s and F₂s. The seed genetic effects were found more important than the maternal genetic effects for grain characteristics, and seed additive effects constituted a major part of their genetic effects. The heritabilities of seed effects were high for 100-grain weight, width and shape and moderate for grain length. Single seed selection based on the 100-grain weight, width and shape was advocated in early generations, whereas single plant and seed selection based on grain length were advocated in late generations. Significant genetic correlations including seed additive, dominance, cytoplasmic, maternal additive and dominance between 100-grain weight, length, width and shape and Fe, Zn, Mn and P mineral contents were observed. Indirect selection of grain characteristics may be one of the breeding methods to select for higher contents of Fe, Zn, Mn and P in black pericarp indica rice.