植被恢复对昆阳磷矿土壤有机碳储量的影响

植被恢复是既能保持磷矿开采同时又能有效扼制矿区生态环境的退化,并逐步恢复已退化的矿区生态系统最有效的生物措施。为揭示植被恢复对昆阳磷矿土壤有机碳和碳素积累的影响,研究探讨了昆阳磷矿不同恢复林地的土壤有机碳储量变化。结果表明:（1）不同恢复林地的土壤有机碳含量存在显著差异（p < 0.05）,7种不同植被恢复人工林土壤平均有机碳含量分别是废弃地的14.29倍、11.83倍、11.40倍、5.89倍、15.48倍、15.59倍、18.53倍。（2）土壤有机碳在剖面的含量表现出明显的“表聚作用”,均以表土层（0—20 cm）最大,且随土层厚度的增加,呈下降趋势。（3）不同恢复林地的土壤有机碳密度差别较大,变化趋势和土壤有机碳含量的变化趋势一致,且在同一林分土壤中,单位深度土壤各土层平均有机碳密度均以表层最大,随土层的增加而降低。（4）土壤有机碳主要存储于0—20 cm土层中,平均含量为53.60%,随着土层的加深,土壤有机碳所占比重急剧下降,经过植被恢复,7种人工林土壤有机碳储量较废弃地0—20 cm土壤有机碳储量提高了26.53%,20.39%,34.48%,10.81%,28.62%,39.52%,36.71%,说明目前矿区通过植被恢复后的土壤状况显著优于未进行恢复措施的废弃地。     

植被恢复和覆土厚度对砒砂岩区土壤水分及养分的影响

[目的]研究植被恢复对砒砂岩区土壤水分和养分的影响状况,明确对于砒砂岩地区土壤保水保肥效果最佳的植被恢复类型,为砒砂岩区的生态修复和区域水土流失治理提供理论依据。[方法]选取准格尔旗暖水乡裸露砒砂岩向覆土砒砂岩过渡区域,以黄土—砒砂岩交界带不同人工恢复植被和自然恢复草地的土壤为研究对象,测定土壤水分和养分含量,分析不同植被恢复和覆土厚度对砒砂岩区土壤水分和养分特征的影响(其中天然草地作为对照)。[结果](1)裸露砒砂岩向覆土砒砂岩过渡区域土壤水分含量主要受黄土厚度影响,黄土的持水性能优于砒砂岩土壤,养分含量主要受植被恢复类型影响;(2)研究区土壤各指标均属于中等变异程度,其中土壤水分、碳、氮含量自北向南随覆土厚度增加逐渐增加,磷素分布则相反;(3)对比天然草地,沙棘和油松恢复对砒砂岩区土壤碳、氮含量的提升效果最好,土壤有机质含量分别提高了43.12%和34.27%,全氮提高了78.95%和42.11%,铵态氮提高25.64%和46.15%,硝态氮提高69.44%和42.22%。其中油松恢复下土壤水分含量高于天然草地54.55%,但人工植被恢复后的土壤磷素水平并没有提升。[结论]黄土较砒...     

覆土处理对高寒矿区露天煤矿排土场植被和土壤特征的影响

[目的]探讨高寒矿区覆土处理对露天煤矿排土场植被恢复的影响,以评估覆土措施在露天煤矿排土场所达到的植被恢复效果,为高寒矿区生态保护和恢复提供技术依据.[方法]调查分析青海省木里煤田不同年限5个覆土处理和3个不覆土处理矿区排土场植被群落特征和土壤理化性质.[结果]在覆土处理下,随着建植年限的增加,木里煤矿排土场植被和幼苗...     

砒砂岩改良风沙土对2种引进植物生长和氮磷营养的影响

通过室内盆栽模拟试验,设计风沙土、砒砂岩、黄绵土、覆土砒砂岩、覆沙砒砂岩和砒砂岩改良风沙土6个土壤处理,种植鲁冰花和墨西哥玉米草2种引进植物,研究2种植物在砒砂岩改良风沙土和晋陕蒙接壤区原有土壤类型中的生长和氮磷营养差异,为该区域植被恢复提供理论依据。结果表明:(1)植物在砒砂岩改良风沙土中根系生长好,总体生物量大,鲁冰花地上生物量相较于黄绵土增幅达到242%,地下生物量相较于风沙土增幅达到186%,根长和根体积相较于风沙土增幅达到388%和290%;(2)2种引进植物根系在不同的土壤环境中表现出不同的适应特征,鲁冰花比根长在砒砂岩改良风沙土中最大,风沙土中最小,墨西哥玉米草比根长在黄绵土中最大,砒砂岩改良风沙土中最小;鲁冰花和墨西哥玉米草根系中直径d≤0.45 mm的细根体积占总根体积的百分比在砒砂岩改良风沙土中均较小,分别为9.99%和13.94%;(3)所有处理中植物的氮和磷含量均低于植物在正常生长条件下的氮和磷含量,植物生长受到氮和磷养分限制,并且植物氮磷比小于14,植物生长受氮素限制更严重。与几种原有土壤类型相比,砒砂岩改良风沙土土壤理化性质更好,土壤生产力高,更适宜植物生长,可以应用于晋陕蒙接壤区的植被恢复,但在种植过程中应考虑适当施用氮肥和磷肥,以加快植被恢复进程。     

宁南山区退耕对土壤微生物生物量和酶活性的影响

在野外调查和室内实验分析的基础上,研究了宁夏黄土丘陵区农田退耕后不同植被恢复措施对土壤的微生物生物量碳、氮、磷和转化酶、碱性磷酸酶、过氧化氢酶和脲酶活性的影响.研究表明:农田退耕后通过不同的植被恢复措施,土壤的微生物生物量碳为农地的1.04～3.12倍;微生物生物量氮为农地偏高;微生物生物量磷则相对稳定,无显著差异;转化酶和碱性磷酸酶活性的提高主要表现在表层(0-5 cm土层)和5-20 cm土层,分别比农地高出1%～41%和1%～89%;过氧化氢酶活性变化幅度最小;土壤脲酶活性在表层提高的幅度最大,为农地的1.95倍.农田退耕后,通过不同的植被恢复措施,土壤的生物肥力有所提高.     

离子型稀土矿尾砂地植被恢复障碍因子研究

以江西省赣州市定南县不同废弃时间的离子型稀土矿尾砂地为研究对象,通过植被调查、土壤理化性质、微生物和酶活性分析,探讨稀土矿尾砂地植被恢复的障碍因子。结果表明,尾砂地植被覆盖度随着废弃时间增加而增加,在废弃10年后植被覆盖度达到72%,但其群落组成仍相对简单(仅3种);尾砂地土壤黏粒含量(6.00%~9.66%)和土壤有机质含量(0.5~1.5 g kg-1)均远低于周边正常植被区,而尾砂地土壤容重(1.26~1.43 g cm-3)则明显高于周边正常植被区。废弃1年的尾砂地土壤电导值显著高于废弃3~10年的尾砂地土壤和对照区土壤,土壤铵态氮和碱解氮含量则高达400 mg kg-1和500 mg kg-1,但废弃3~10年后碱解氮和铵态氮含量已趋于痕量,且在所调查的废弃3年和6年的尾砂地0~100 cm剖面内土壤铵态氮含量也极低,表明尾砂地土壤铵态氮在废弃3年内已流失殆尽,严重的水土流失及其导致的土壤氮素等营养匮乏也是尾砂地植被恢复的主要障碍之一;尾砂地土壤微生物生物量碳(26.7 mg kg-1)、土壤脲酶活性(29.9NH3-Nmg kg-1h-1)、土壤酸性磷酸酶活性(7.10 phenol mg kg-1h-1)均显著低于周边正常植被区土壤,表明尾砂地土壤氮、磷循环受到抑制。本研究表明,废弃3~10年内离子型稀土矿尾砂地的土壤理化生性质并未得到明显改善,尾砂地土壤面临土壤重建的问题,需要引入合适的人工干预如土壤改良才能加快尾砂地植被恢复。     

西北地区种植甘草对土壤次生盐渍化的影响

[目的]研究西北地区植被特征指标与土壤表层盐含量、碱性间的相互关系,为该区土壤次生盐渍化防治工作提供科学依据。[方法]以甘草(Glycyrrhiza uralensis)植被和其下部土壤为研究对象,通过测定甘草植被的盖度、高度、地上生物量和其下部土壤表层(0—5cm)的含水率、pH值、电导率、盐含量等指标,并利用SPSS统计软件进行分析。[结果]甘草植被的盖度、高度、地上生物量和其下部土壤的含水率均随甘草生长年限的增加呈显著升高的趋势(p0.05),而土壤的pH值、电导率、盐含量正好相反,均表现出显著降低的趋势(p0.05);相关分析结果显示,耕地表层土壤的pH值、盐含量与甘草植被特征指标间呈显著的负相关关系,相关系数的大小顺序均为:植被盖度植株高度地上生物量;回归分析显示,土壤pH值和盐含量与甘草植被的这3个性状指标间均表现为负线性函数关系,甘草植被的盖度、高度、地上生物量每提高1个单位,可使土壤表层的pH值分别下降0.012,0.011和0.002,盐含量分别降低0.108,0.107,0.015g/kg。[结论]西北干旱地区耕地中种植甘草对其下部土壤表层的盐含量和碱性(pH值)影响显著,其中植被的盖度对表层土壤的盐碱影响最大;从耕地表层抑盐角度考虑,应优先选择种植枝叶稠密、植株高大的作物。     

封育年限对干旱河谷灌丛土壤理化性质的影响

[目的]探讨不同封育年限对干旱河谷灌丛土壤理化性质的影响,为该地区的天然植被恢复与管理提供理论依据。[方法]采用野外调查和实验室分析相结合的方法开展研究。[结果](1)封育后灌木层的盖度、密度、平均冠幅、高度明显升高,而草本层则相反。(2)随着封育年限的增加,土壤容重呈V形变化,封育13a达到最小值,而群落植被特征、土壤孔隙度、土壤持水量、土壤养分,呈倒V形变化,封育13a达到最大值。0—40cm,封育13a的土壤平均速效N,P,K较未封育草地分别增加26.42%,107.35%,33.92%;全量N,P,K含量分别增加了168.42%,47.62%和31.12%。(3)封育后,土壤理化性质有所改善,具有明显的表聚现象,土壤固碳能力有所提高,土壤有机碳密度表现为:F_(13)F_(22)F_(30)F_5CK;土壤有机碳储量表现为:F_5F_(13)F_(22)F_(30)CK,说明在狼牙刺群落封育恢复过程中,土壤环境有较为明显的改善。(4)采取封育措施后,外界干扰减少,狼牙刺灌丛覆盖度增加,从而增加地上生物量,使生产力得到提升,生物量与封育年限存在线型关系。[结论]采取封育措施后,干旱河谷地带的狼牙刺群落植被特征和土壤理化性质及有机碳密度和储量均优于未封育,植被自然恢复状态良好。     

不同治理措施对秦巴山区渣场土壤养分与植被恢复的影响

通过对不同治理措施下渣场土壤养分状况的差异性进行分析,系统地探讨不同治理措施对渣场土壤养分含量和植被恢复的影响。结果表明:渣场形成初期土壤养分含量比较贫乏,但随着恢复年限的增加会有一定程度的增加趋势,不同恢复年限之间渣场土壤全氮、铵态氮、速效钾和有机质含量差异极显著(P<0.01),硝态氮含量差异显著(P<0.05),速效磷含量差异不显著;不同覆土厚度的渣场除了速效磷含量差异显著以外,其他土壤养分含量差异极显著,说明覆土厚度对渣场土壤养分含量和植被恢复有一定的作用;渣场形成初期,若进行人工恢复植被,会使渣场土壤养分在短期内小于自然恢复植被的渣场,但是随着恢复年限的增加,以及人工植被改良土壤的作用,从而使进行人工恢复植被的渣场土壤养分含量大于自然恢复植被的渣场。     

高寒矿区排土场不同坡向植被和土壤特征研究

针对高寒矿区排土场人工植被恢复问题,选取青海江仓矿区南北2个排土场的4个坡面(南坡、北坡、东南坡与东坡)为研究对象,进行了不同坡向立地条件下植被与土壤的调查分析。结果显示:除幼苗高度外,不同坡向植被高度、盖度、地上生物量、生殖枝数量具有显著差异(P0.05),东南坡与南坡(阳坡)长势较好。土壤全氮、有效磷含量及pH在不同坡向差异不显著(P0.05),土壤全磷、碱解氮、速效钾、有机质、含水量在不同坡向具有显著差异(P0.05)。北坡土壤有机质含量比其他3个坡面平均高出127.95 g/kg(P0.05),土壤含水量在北坡与东坡(阴坡)显著高于南坡与东南坡(P0.05)。土壤细菌与放线菌数量在东南坡显著高于其他3个坡面(P0.05)。利用随机森林方法得出,土壤细菌数量、含水量、碱解氮含量、全磷含量、有机质含量及植被高度是影响露天煤矿排土场不同坡向立地条件下植被与土壤特性的主要因子。因此,为减小矿区排土场复绿过程中坡向不同带来的影响,在人工建植初期应加大东坡与北坡(阴坡)的种子播量,适时追施氮肥,并选择加厚无纺布(50 g/m~2)覆盖。     

Bioavailability of As,Cd, Co,Cr, Cu,Hg, Mo,Ni, Pb,Se, and Zn from Biosolids Amended Compost

Appropriate compost standards are being considered in Canada. Five aspects of compost safety and quality are being evaluated; probably the most controversial aspect is the standards for metals in compost. In order to assist in the development of appropriate standards, the authors began an extensive research project in October, 1993 to determine the bioavailability of metals from compost and compost-metal mixtures. Swiss chard was grown in compost-amended soils or compost in a growth room using five treatments of increasing percentages of compost in the media (0, 25 percent, 50 percent, 75 percent, 100 percent compost (v/v)). A Truro loamy sand and a race-track manure-biosolids compost (RTM-biosolids) supplemented with a high metal biosolids were used in a completely randomized design with five replicates. Dry matter yield, metal content in plant tissue, and total metal uptake were evaluated as well as the total and DTPA-extractable metal content in the compost-soil mixes. The results of this and five other experiments conducted by the authors will help determine whether the suggested limits for As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se and Zn in composts are appropriate.     

Variation of N,P, K,Ca, Mg,Mn, Zn,and al in slash pine foliage

Abstract

The seasonal patterns of foliage nutrient concentrations and contents were monitored for two growing seasons in an 11‐year—old Pinus el1iottii stand. In the first growing season after needle initiation, N, P, K, Mg, and Zn concentrations decreased, but this was followed by an increase in the fall and winter months. Another drop in concentration of all elements, except P, occurred in the second growing season. Decreases in total contents indicated that this drop was a result of translocation to other tissues. In contrast to the mobile elements, the concentration and fascicle contents of Ca, Mn, and Al increased with aging of the needles.

Between‐tree variability was least for N, P, and Zn and the N, K, Mg, Mn, and Zn in the current foliage had consistently lower variation than that in the 1‐year‐old foliage. Between‐tree variation for K was lower in the winter than the spring.

For pine foliage, recommended sampling period for N, P, Mg, and Zn is mid to late summer and for the other elements it is late fall to late winter.

There are several sources of variation that influence the level of nutrients in tree foliage. The most important of these, apart from the tree nutrient status, are seasonal fluctuations, variation between trees, and age of needles . Smaller sources of variation are associated with position of the needles within the crown, diurnal changes, year to year variation, and analytical errors^1,2. These variables must be studied in order to develop suitable sampling techniques and in Pinus this has been undertaken for P. banksiana ¹, P. taeda ³, P. strobus ⁴, P. resinosa ⁴, P. sylvestris ⁵, and P. radiata ^6,7. However, foliage sampling has not been studied in detail for slash pine (Pinus elliottii Englem var. elliottii) and earlier studies with other pines have been largely confined to temperate or cool climates.

This study reports the variation in elemental concentrations with season, age of foliage, and between slash pine trees growing in a subtropical climate in Florida.     

Phytotoxicity of cobalt,vanadium, titanium,silver, and chromium

Abstract

The phytotoxicity of five nonessential elements (Co, V, Ti, Ag, Cr) to higher plants was studied in solution culture experiments with bush beans (Phaseolus vulgaris L. C.V. Improved Tendergreen). All, but in varying degrees, tended to concentrate in roots with a decreasing gradient to stems and leaves. Cobalt was one of the more mobile of the five trace metals. Its toxicity was expressed as severe chlorosis; 43 (with 10^‐5 M) and 142 (with 10^‐4 M) μg Co/g dry weight in leaves resulted in severe chlorosis. Vanadium as 10^‐4 M vanadate resulted in smaller plants but not in chlorosis. Leaf, stem, and root V, respectively, were 13, 8, and 881 μg/g dry weight. Titanium was somewhat mobile with considerable yield decrease at 10^‐4 M; leaf, stem, and root Ti concentrations, respectively, were 202, 48, and 2420 μg/g. Symptoms were chlorosis, necrotic spots on leaves, and stunting. Silver was very lethal at 10^‐4 M AgNO₃; at 10^‐5 M yields were greatly decreased, but plants were grown without symptoms. Leaf, stem, and root concentrations of Ag for this treatment, respectively, were 5.8, 5.1, and 1760 μg/g dry weight. Plants grown with 10^‐5 N Cr₂O₇ were decreased in yield by about 25% with or without EDTA (ethylenediamine tetraacetic acid) while the same level of Cr₂(SO₄)₃ was essentially without effect. For the two salts, the leaf, stem, root concentrations for Cr, respectively were 2.2 and 1.3, 0.7 and 0. 7, and 140 and 104 μg/g. Most of the trace metals studied here had interactions in the uptake and/or distribution of other elements.     

Thin layer chromatographic determination of aflatoxins, ochratoxins, sterigmatocystin, zearalenone, citrinin, T-2 toxin, diacetoxyscirpenol, penicillic acid, patulin, and penitrem A.

A general method is described for determining 16 mycotoxins in mixed feeds and other food products used in the manufacture of these feedstuffs. The mycotoxins are extracted and cleaned up by extracting with solvents of different pH. Thin layer chromatography is used to separate the toxins; toxins are then quantitated by the limit detection method. The minimum detectable concentration of mycotoxins in various products is: aflatoxin B1 or G1, 4--5 micrograms/kg; ochratoxin A or ethyl ester A 140--145 micrograms/kg; citrinin 600--750 micrograms/kg; zearalenone, 410--500 micrograms/kg; sterigmatocystin, 140--145 micrograms/kg; diacetoxyscirpenol, 2400--2600 micrograms/kg; T-2 toxin, 800--950 micrograms/kg; patulin, 750--800 micrograms/kg; penitrem A 14,000--14,500 micrograms/kg; penicillic acid 3400--3650 micrograms/kg.     

Organochlorine pesticide residues in different Indian cereals, pulses, spices, vegetables, fruits, milk, butter, Deshi ghee, and edible oils.

A total of 244 samples of cereals (wheat flour, rice, and maize), pulses (arhar, moong, gram, lentil, and black gram), spices (turmeric, chili, coriander, and black pepper), vegetables (potato, onion, spinach, cabbage, brinjal, and tomato), fruits (mango, guava, apple, and grape), milk, butter, Deshi ghee, and edible oils (vegetable, mustard, groundnut, and sesame) collected from different cities of Northern Province (Utter Pradesh) were analyzed by gas liquid chromatography for the presence of organochlorine pesticide residues. Residues of hexachlorocyclohexane (HCH) and 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) were detected in about 85% of the total samples of cereals, spices, milk, butter, Deshi ghee, and edible oils analyzed in the present study. However, the residue levels were either very small (less than 0.06 ppm) or not detected at all in pulses, vegetables, and fruits as compared with very high concentrations in wheat flour (4.42 and 0.12 ppm), butter (1.19 and 4.85 ppm), mustard oil (1.26 and 2.42 ppm), Deshi ghee (1.10 and 3.84 ppm), vegetable oil (1.02 and 0.59 ppm), groundnut oil (0.51 and 1.49 ppm), and chili (0.48 and 1.92 ppm). The levels of HCH and DDT residues detected in rice, maize, turmeric, corlander, black pepper, and all the vegetables and fruits were also lower than those found in wheat flour, oil, and fat samples analyzed in the present study. These findings suggest that a restricted and controlled use of such persistent pesticides may be useful for decreasing their contamination levels in different food items.     

Evaluation of Decomposition Procedure to Determine Ba,Co, Cr,Cu, Ni,Mn, V,and Zn Total Content in Soil Samples

Different procedures have been proposed to decompose soil samples. Most of them regard determination with fertility aims. In this case, the contents available to the plants are considered. On the other hand, there are procedures to determine total content. The objective of this work was to propose a new decomposition procedure to determine barium (Ba), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), vanadium (V), and zinc (Zn) total content in tropical soils with high content of oxides and silicate. According to the results, the digestion procedure proposed in this study provided satisfactory results for the contents recovery for the elements Ba, Co, Cr, Cu, Mn, Ni, V, and Zn, above 90%, and the use of inverted aqua regia, hydrogen peroxide (H₂O₂), hydrofluoric acid (HF), pre-digestions and agitation was shown as a new alternative for the high silicate content soil sample total digestion, such as the oxisols.     

Estimation of Reference Values for Cadmium,Cobalt, Chromium,Copper, Nickel,Lead, and Zinc in Brazilian Soils

Abstract

The objectives of this study were 1) to recommend reference values (RVs) and tolerance limits (TLs) for representative Brazilian soils and 2) to propose a model to calculate natural contents of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in a soil from the silt, clay, manganese (Mn), iron (Fe), and cation exchange capacity (CEC) values. A set of 256 soil samples was classified by similarity in seven groups, and the concentrations corresponding to the upper quarter of data collected were then calculated. These concentrations are proposed as RVs for Brazilian soils. Additionally, TLs were obtained for each group from the antilog expression (m+2s), where m=mean value and s=standard deviation of data transformed in log₁₀. The classification functions of discriminant analysis proved to be suitable to allocate new samples in the established groups. Thus, it is possible to evaluate soils under anthropic activity and, by comparison with reference values, to be aware of pollution risks in a given area.     

Caimans,Capybaras, otters,manatees, and man in amazonia

Amazonia, the world's largest tropical rain forest, is often assumed to be a virtually untouched wilderness. The region is often referred to as a demographic void; there is on average only about one person per sq. km. Yet in response to international market forces, the hand of man has penetrated deep into the imposing forests. Since colonial times, wildlife, particularly along rivers, has been exploited on a large-scale basis for commercial purposes. This paper focuses on the effects of the trade on some aquatic animals.     

Total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone

The total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone, were determined. Grape seed and green tea were analyzed for their phenolic constituents using high-performance liquid chromatography. The total phenolics of the plant extracts, determined by the Folin-Ciocalteu method, ranged from 24.8 to 92.5 mg of chlorogenic acid equivalent/g dry material. The antioxidant activities of methanolic extracts determined by conjugated diene measurement of methyl linoleate were 3.4-86.3%. The antioxidant activity of the extracts using chicken fat by an oxidative stability instrument (4.6-10.2 h of induction time) followed a similar trend in antioxidant activity as determined by the Folin-Ciocalteu method. Seven phenolics in grape seed and green tea extracts were identified that ranged from 15.38 to 1158.49 and 18.3 to 1087.02 mg/100 g of extract, respectively. Plant extracts such as green tea and grape seed extracts can be used to retard lipid oxidation in a variety of food products.