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以柚、柠檬、红江橙等作砧木,化州橘红作接穗.研究了激素处理砧木、接穗灭菌和培养基配方、砧木苗龄等因素对化州橘红茎尖嫁接成活率的影响.柚作砧木时,任何激素处理的成活率均高于对照,以0.1 mg/L的GA3处理10 min的成活率最高,为31%.不同砧木其成活率不同,成活率最高的为柚,达19.0%,最低的为宽皮橘,为5.0%.灭菌方法对成活率和污染率也有影响,污染率最低的是0.1%升汞灭菌10 min,为5.7%,成活率最高的是0.15%升汞灭菌8 min,为25.0%.培养基配方对嫁接苗的成活率也有影响,MS基本培养基最有利于嫁接苗的成活,添加6-BA、Ad和NAA都会降低成活率.16d苗龄的砧木最有利于嫁接苗的成活,成活率可达36.5%. 相似文献
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Background, aim, and scope Contaminated mine drainage water has become a major hydrogeological and geochemical problem. Release of soluble metal contaminants
and acidity from mining sites can pose serious chemical risks to surface and groundwater in the surrounding environment, and
it is an important socio-economic factor addressed by working groups like SUITMA Morel and Heinrich (J Soils Sediments 8:206–207,
2008). The release of Zn and Pb from sulfide-bearing flotation residues of a small scale mine in Western Germany is investigated
with focus on metal transfer to soil solution. Total contents of the soil material as well as soil water sampled with suction
cups were analyzed. The influence of pH on leaching behavior was investigated with pHstat tests. Isotopic analyses helped assessing seepage water velocity. The aim of this study was the assessment of the environmental
behavior of zinc and lead caused by the weathering of sulfide-bearing mine tailings. Especially, we address in this paper
the dissolution of sphalerite (ZnS) in contrast to the well-known dissolution processes of pyrite (FeS2).
Materials and methods Total metal contents of the soil samples were analyzed by energy-dispersive X-ray fluorescence spectroscopy, total C concentration
was measured using a CHNS elemental analyzer. X-ray diffraction (XRD) spectra were recorded from powdered soil samples. Soil
water was sampled in nylon suction cups. Electrical conductivity (EC), pH, and temperature of the soil water samples were
measured in the field immediately after sampling. Major anions (F, Cl, NO2, NO3, SO4) were analyzed by ion chromatography, major cations (Ca, Na, K, Li) were analyzed by flame photometry, heavy metals (Zn,
Pb, Fe, Mn, and Mg) by flame atomic absorption spectrometry. Tritium was analyzed by liquid scintillation counting (LSC),
18O and 2H were analyzed by isotope ratio mass spectrometry (IRMS). pHstat tests were performed at four different pH values between 2 and 5.
Results Total Zn contents of the soil samples averaged 10 g kg−1, Pb contents averaged 2.5 g kg−1, Fe 22 g kg−1, S 8.0 g kg−1, and total carbon 4.0 g kg−1. Below 2-m depth, soil samples had neutral pH values. Toward the surface, pH decreased down to pH 5.4 in P1 and P3, and to
pH 5.9 in core P2, respectively. Dissolved contents of major ions (Mg, Ca, K, SO4, and HCO3) in the soil solution increased with depth. Metal concentrations (Fe, Mn, Zn) decreased with depth. The solution pH was neutral
to slightly alkaline in samples below 2 m and slightly acidic (pH 6) at 1 m depth. Tritium values are around 7 TU and correspond
to modern rain, i.e., after 1975. Stable isotope values plot on the global meteoric water line. The pHstat tests provide two kinds of information, the acid neutralization capacity after 24 h (ANC24) and the release of metals depending
on pH. The ANC24 increases linearly with decreasing pH from about 60 mmol(eq) kg−1 at pH 5 to about 460 mmol(eq) kg−1 at pH 2. Zn and Fe release show a strong increase with decreasing pH to 126 and 142 mmol(eq) kg−1, respectively. Pb release increases at pH <4 and Mn release at pH <5, both to about 10 mmol(eq) kg−1.
Discussion With an average of 10 g kg−1, this field site is highly enriched in Zn. In the oxidized topsoil, Zn concentrations are significantly lower than in the
anoxic subsoil. The distribution pattern of total Zn contents and soil pH values indicate that the topsoil, which is prone
to oxidation and acidification, is already depleted in Zn. Only in soil core P2, Zn (and Fe) contents in the topsoil were
higher than in the subsoil. Oxidation of the sulfidic material leads to redistribution into mobilizable species. High soil
water concentrations (10 to 15 mg L−1) can be found at acidic pH. The dominant Zn species in the soil solution is Zn2+. At neutral pH, Zn concentrations are below 0.001 mg L−1. During the soil passage, the contaminated seepage water enters the anoxic subsoil with pH buffering carbonates. Results
indicate that Zn is immobilized there. However, when the acid neutralization capacity is exhausted, a breakthrough of dissolved
Zn to the groundwater has to be expected. Lead averages 2.5 g kg−1 inside the flotation dump. In contrast to Zn, the first centimeters of the oxidized topsoil with high TOC contents show higher
Pb contents than the anoxic subsoil. About 80% of the cation exchange capacity in the topsoil is occupied by Pb. In contrast
to Zn, Pb is not abundant as aqueous species at slightly acidic pH. Values lower than pH 4 are necessary to mobilize Pb in
higher amounts, as pHstat experiments confirm. Hence, Pb is not expected to be leached out until the buffer capacity of the soil is exhausted.
Conclusions The environmental fate and behavior of Zn and Pb in the flotation dump is strongly depending on pH and redox conditions. Oxidation
of sphalerite leads to a transfer of Zn from immobile to easily mobilizable species. Sulfide oxidation leads to an acidification
of the topsoil where the buffer capacity is already exhausted due to the leaching of carbonates. At acidic pH, Zn is transferred
to the aqueous phase and leached to the subsoil where soil pH is neutral. Electron supply and the buffer capacity of the material
are found to be the main factors controlling the mobility of Zn. In contrast, the transfer of comparable amounts of Pb to
the aqueous phase requires pH values <4. Since Pb is enriched in the topsoil, not leaching to the groundwater, but direct
uptake (e.g., children, animals) and uptake by plants is the highest environmental risk. If the acidification of the soil
proceeds with the same rate as in the last 40 years, it will reach the bottom of the tailing in about 200 years and a breakthrough
of metals to the groundwater has to be expected.
Recommendations and perspectives The behavior of the different metals and their environmental impact depends on the different metal properties as well as on
external conditions, e.g. pH, redox conditions, buffer capacity, and groundwater recharge. To assess the future release of
metals from a flotation dump it is crucial to determine the main processes leading to acidification, the buffer capacity,
and heavy metal binding forms. The release of heavy metals to the groundwater could be prevented by liming or other buffering
techniques de Andrade et al. (J Soils Sediments 8:123–129, 2008).
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
27.
南京郊区某菜地土壤镉污染水平及其来源调查 总被引:2,自引:0,他引:2
通过南京郊区某菜地表层土壤、土壤剖面、大气降尘、灌溉水、土壤溶液、化肥的Cd含量研究,结果表明,菜地表层土壤存在一定程度的Cd污染,且土壤剖面由深及浅表现出累积趋势。表层土壤Cd的总体含量水平为0.30mgkg-1,其中自然背景含量为0.20mgkg-1,人为作用叠加含量为0.10mgkg-1。在人为污染来源中,大气降尘对菜地的贡献率为79%,化肥的贡献率为17%,而灌溉水仅为4%。工厂应采取适当措施避免废气直接排入大气中,菜农应施用有机肥,因为这些措施会有效控制进入菜地的镉含量。 相似文献
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为了探明铅冶炼污染区田块尺度下农田土壤重金属含量的空间变异及其对污染农田土壤安全利用的意义,在某冶炼厂附近一面积为4800 m2的农田用网格法采集120个0~20 cm土样,测定样品镉、铅和砷含量。研究表明,研究区土壤中存在砷、镉和铅的积累。从平均污染指数来看,以镉的积累程度最大,铅次之、砷最小。土壤全镉含量的变化范围为1.10~3.84 mg kg^-1,镉含量处于1.10~2.27 mg kg^-1之间的样品占97.50%。从重金属空间分布上看,镉和铅含量的空间分布有较高的一致性,均是研究区北部和南部含量较高,中间区域含量较低。相关分析表明,土壤镉和铅含量之间存在显著正相关(P <0.01)。根据土壤铅含量计算稳定铅时所用普通过磷酸钙的用量范围为0.312~0.419 kg m^-2,平均值为0.367 kg m^-2。根据其他研究者得到的土壤全镉含量与小麦籽粒镉含量的相关方程计算,不同方程得到的小麦籽粒镉含量结果有很大差异,较可信的小麦籽粒镉含量变化范围为0.095~0.814 mg kg^-1。采样区中部为小麦籽粒镉含量较低且铅稳定剂需要量较低区域。以上结果表明,研究区田块尺度下土壤镉含量存在较大的空间变异,且土壤镉含量的空间变异导致小麦籽粒镉含量可能存在较大的空间变异。 相似文献
29.
研究以大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)、沙门氏菌(Salmonella)、枯草芽孢杆菌(Bacillussubtilis)、巨大芽孢杆菌(Bacillus magaterium)、蜡状芽孢杆菌(Bacillus magaterium)为指示菌,采用纸片法评估了臭柏(Sabina vulgaris Ant)精油废液对食品污染细菌的抑菌效果.结果表明,精油废液对大肠杆菌、金黄色葡萄球菌、沙门氏菌有抑制效果,且对大肠杆菌和沙门氏菌的抑菌效果较好;水蒸气蒸馏后的废液比共水蒸馏后的废液抑菌效果好.水蒸气蒸馏的废液随着蒸馏次数的增加,所含的有效成分越多,抑菌效果越好. 相似文献
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