水体铯污染的生物效应与修复植物筛选

研究铯对水生植物的生物效应,筛选对铯富集能力强的水生植物,能够为水体铯污染的修复治理提供方法依据。设计铯污染浓度为0、0.5、2.5和10 mg/L,9种水生植物,3次重复,研究铯对不同水生植物生物效应(BE)和不同水生植物对铯的吸收和富集情况。结果表明,不同植物对水体铯污染有不同的反应。就增加鲜重而言,绿萍、水花生、轮叶狐狸藻、水蓼、水葱增加鲜重大于对照;眼子菜、水葫芦、水稻增加鲜重小于对照;不同植物的铯含量不同。平均铯含量依次为水花生 >水蓼 >水稻 >水葫芦 >水葱 >眼子菜 >轮叶狐狸藻 >绿萍,其中水花生为935.12 mg/kg DW,水蓼为825.93 mg/kg DW,水稻为723.38 mg/kg DW;不同植物清除水体铯污染的能力不同。收获时水体铯浓度降低最多至最少的依次是水蓼、水花生、水稻、轮叶狐狸藻、水葱、水葫芦、绿萍和眼子菜。根据生物效应、植物铯含量、水体铯减少情况,水花生、水蓼、水葫芦和水稻可以作为铯污染水体修复植物。     

灯心草部分生理生化指标对土壤复合重金属胁迫的响应

通过盆栽试验,以叶绿素含量和POD、SOD、CAT3种抗氧化酶活性作为观测指标,研究了Cu、Cd、Pb、Zn和As复合重金属胁迫下灯心草部分生理生化指标的变化趋势和机理.结果表明,灯心草的生理毒害效应呈明显的剂量-效应关系.表现为与对照相比,叶绿素含量减少,叶绿素a/b值降低,叶片失绿现象明显.随着复合重金属胁迫浓度的增加,灯心草3种酶活性均呈先升后降的变化趋势,但出现抗性酶活性高峰所对应的重金属浓度不同,表现出不同的特征变化趋势.总体来说,在接近土壤环境质量标准低浓度设计范围内,酶活性有逐渐被激活的趋势.但在高浓度水平下,酶活性普遍受到抑制.生长在铅锌尾矿和模拟矿毒水污染土壤中的灯心草叶绿素合成受到显著抑制(P＜0.05),但POD和CAT两种酶活性均高于对照.     

钙对李氏禾富集和耐受铬的调控作用

通过水培实验,研究钙对铬胁迫下李氏禾幼苗生理生化、草酸分泌及铬吸收量的影响,考察钙对李氏禾体内草酸合成的调控,进而促进李氏禾的铬耐性富集能力的作用。结果显示,不同浓度Cr³⁺胁迫下缺钙处理,李氏禾生长受抑制及质膜过氧化作用加剧,体内总草酸含量为对照处理的113%~169%,且主要表现为水溶性草酸含量显著高于对照,水溶性草酸含量为对照处理的135%~197%;高钙处理,李氏禾细胞膜透性、丙二醛（MDA）含量低于对照,李氏禾叶部总草酸含量为对照处理的125%~155%,且主要表现为不溶性草酸含量显著高于对照,其含量为对照处理的181%~270%。低浓度（0.2、0.4 mmol/L）铬胁迫下,高钙处理总铬含量分别为对照处理的175%和215%,高浓度（0.8、1.0 mmol/L）铬胁迫下,总铬含量与对照处理无显著差异（P>0.05）。可见,添加Ca²⁺能在一定Cr³⁺浓度胁迫下,有效缓解铬对李氏禾的毒害,且能通过提高植物体内不溶性草酸含量达到促进植物富集和耐受铬的能力。     

重金属Cr(Ⅵ)和Ni对旱伞草富集能力及其生理生化指标的影响

采用水培方法,研究了在不同重金属 Cr(Ⅵ)(0~50 mg/L)和Ni(0~50 mg/L) 浓度下旱伞草(Cyperus alternifolius)的富集能力及生理生化指标的变化规律。研究结果表明:(1)旱伞草中积累的重金属含量随处理浓度的增加逐渐增加, Cr(Ⅵ)在其地上部和根部富集量分别达到 958.00 mg/kg和2 874.44 mg/kg,Ni 在其地上部和根部富集量分别达到1 655.46 mg/kg和2 511.20 mg/kg;(2)在 Cr(Ⅵ)和Ni 胁迫下,随着 Cr(Ⅵ)和Ni 浓度的增加,旱伞草生物量、叶绿素含量、根系活力均呈先上升后下降的趋势;(3)脯氨酸的含量随着Cr(Ⅵ) 胁迫浓度的增加,呈现为先上升后降低的趋势,而随着Ni 胁迫浓度的增加,则为先缓慢上升而后急剧升高。旱伞草对 Cr(Ⅵ)和Ni 具有较强的富集能力且主要分布在根部,虽不是 Cr(Ⅵ)和Ni 超积累植物,但具有较强的稳定化能力,在污染水体的修复方面有一定应用潜力。     

镉胁迫对向日葵幼苗生长和生理特性的影响

采用溶液培养方法,研究了不同浓度镉(0、0.05、0.1、0.5和1 mg/L)处理7 d对向日葵幼苗生长和生理特性的影响。结果表明：随着镉处理浓度的增加,向日葵幼苗对镉的吸收显著增加。1 mg/L镉浓度处理时,叶、茎和根中镉浓度分别为0.05 mg/L镉处理时的16.3、19.2和581倍;根中积累的镉含量明显高于叶和茎, 各浓度根部积累的镉分别为叶和茎的37.8～63倍和29.4～41倍。镉胁迫显著抑制向日葵幼苗生长和叶绿素合成,当镉浓度达1 mg/L时,整株植物生物量和总叶绿素含量分别为对照的55.9%和52.6%。镉胁迫下向日葵幼苗游离脯氨酸和丙二醛（MDA）含量显著增加,1 mg/L镉浓度时,根中含量分别为对照的4和5.8倍。向日葵幼苗可溶性蛋白含量和过氧化物酶(POD)活性变化与镉胁迫浓度呈明显的倒U字型关系,可溶性蛋白含量在0.05 mg/L镉浓度时达到最大值,叶、茎、根中的POD活性分别在0.1、0.1和0.05 mg/L镉浓度时达到最大值。     

小分子有机酸诱导野苋菜修复Pb污染土壤

通过土培实验,研究小分子有机酸对野苋菜吸收重金属Pb的影响。结果表明,添加小分子有机酸处理能有效促进野苋菜的生长,显著提高野苋菜地上/下部Pb含量,柠檬酸、乙酸在15 mmol·kg-1,草酸在10 mmol·kg-1 时,植物Pb 积累量达到最大值,分别为15.625、18.732和9.072 mg·kg-1,高于对照166%、219%和54%;高浓度（20 mmol·kg-1）有机酸处理,对植株产生一定的毒害作用,影响植株富集Pb能力。3种有机酸均能促进植株地上部对Pb的吸收,作用表现为乙酸 > 柠檬酸 > 草酸,说明适当浓度的有机酸能增强土壤中重金属Pb的活性,提高植株修复Pb污染土壤的能力。     

石油烃对翅碱蓬生理特性的影响及植物-微生物联合降解

通过盆栽实验,测定在低浓度石油烃浓度下翅碱蓬的生长生理指标及沉积物和翅碱蓬中石油烃含量的变化,研究石油烃对翅碱蓬生理特性和抗氧化酶系统的影响及植物-微生物联合修复效果。结果表明,翅碱蓬抗氧化酶能够快速提高活性来抵御逆境,植株还可通过增加其叶绿素含量等来适应或补偿逆境造成的损失。同时还发现,当植物处于石油烃污染沉积物时,它体内污染物的分布会与自然情况下有所不同,自然情况下分布为茎>叶>根,受污染时分布为根>茎>叶,该结果可以作为判断沉积物是否受到污染的依据。实验的不同处理(加植物加菌组、只加菌未种植物组、种植物未加菌组)去除率分别为70.87%、63.66%和60.26%,翅碱蓬-降解菌处理的沉积物中石油烃残留浓度最低、去除量最高,表明植物-微生物联合作用更有利于石油烃污染沉积物的修复。     

铀胁迫对植物光合特性的影响及植物对铀的吸收转移

在铀污染土壤的二次修复中,采用7科12种植物,研究铀胁迫对植物光合作用、叶绿素荧光特性的影响以及植物对铀的吸收、富集情况,为铀污染土壤的植物修复提供理论和方法依据。结果表明:(1)铀胁迫显著影响红圆叶苋、苍耳、美洲商陆、刺天茄和苘麻5种植物的光合效率,具体表现为叶片净光合速率(Pn)降低,胞间CO2浓度(Ci)增加,初始荧光(F0)增加,光系统II最大光化学效率(Fv/Fm)、光化学猝灭(qP)和最大相对电子传递速率(rETRmaxr)降低;而反枝苋、菊苣、鬼针草、向日葵和牛皮菜则对铀胁迫表现出较好的耐性。(2)酸模、鬼针草、苍耳和向日葵吸收富集铀的能力较强,在铀含量为485 mg/kg的二次修复土壤中生长3个月,体内积累的铀含量分别为363.57、91.87、75.80和65.42 mg/kg;而反枝苋、牛皮菜和美洲商陆吸收富集铀的能力较弱,体内的铀含量分别为16.20、15.11和12.36 mg/kg。(3)铀在植物体内的转移能力较差,器官间的铀富集能力一般表现为根叶茎果。综合比较而言,酸模、向日葵和鬼针草对铀的耐性较强、体内铀含量高,可作为铀污染土壤二次修复植物。     

不同氮磷比对多年生水生植物生长特性影响的研究

从氮、磷等植物生长的环境因子出发,研究了高低氮磷营养水平下,不同氮／磷比例的富营养化水体对聚草（Myriophyllum spicatum）、黄花水龙（Jussiaea stipulacea Ohwi）、喜旱莲子草（Alternanthera philoxeroides）生长特性的影响。结果表明,聚草在氮磷比2：1时生物量最大,且生物量在高浓度水平处理明显大于低浓度水平处理（P〈0．01）;黄花水龙在氮磷比10：1～20：1时生物量最大,高低浓度水平处理问生物量无显著性差异;喜旱莲子草在较高氮磷比20：l～40：1时生物量最大,高浓度水平处理时生物量显著性高于低浓度水平处理（P〈0．05）。在低浓度水平处理时,氮为黄花水龙和喜旱莲子草生长的主要限制因子,磷为聚草生长的主要限制因子,且喜早莲子草叶绿素增长期较其他处理提前,而黄花水龙的叶绿素变化在高低营养水平下差异不显著。营养盐水平对聚草茎长和生物量的影响较对黄花水龙和喜旱莲子草的影响明显。     

高浓度汞污染土壤低温工程性修复复垦的可行性

低温热解技术修复高浓度汞污染土壤（≥100 mg·kg-1）工程除汞效果可达70%以上,仍残留20%~30%的惰性汞,是否对农作物安全存在一定风险仍属未知。为此,以低温热解工程性修复前的高浓度汞污染农田土壤为对照,研究修复后土壤在原位大田条件下残留汞的形态变化及对几种常见作物生物产量、质量及汞在植物组织间迁移的影响。结果表明：低温热解过程未对土壤肥力造成影响,经低温热解修复后土壤中有机结合态汞降低64.07%,残渣态汞降低56.38%;高浓度汞污染抑制了作物生长,修复后土壤耕种作物生长状况得以明显改善,作物产量提高了2~3倍;所研究作物可食部分土豆肉、玉米粒及稻米,汞含量分别降低了51.2%、43.8% 和53.79%;汞在植株中的分布情况为：根 > 叶 > 茎,残留汞对植株根系的胁迫最为严重,且植株的根和叶汞含量,相比修复前明显降低了2~5倍。     

Hydrogen sulfide ameliorates lead-induced morphological, photosynthetic, oxidative damages and biochemical changes in cotton

Poisonous lead (Pb), among heavy metals, is a potential pollutant that readily accumulates in soils and thus adversely affects physiological processes in plants. We have evaluated how exogenous H₂S affects cotton plant physiological attributes and Pb uptake under Pb stress thereby understanding the role of H₂S in physiological processes in plants. Two concentrations (0 and 200 μM) of H₂S donor sodium hydrosulfide (NaHS) were experimented on cotton plants under Pb stress (0, 50, and 100 μM). Results have shown that Pb stress decreased plant growth, chlorophyll contents, SPAD value, photosynthesis, antioxidant activity. On the other hand, Pb stress increased the level of malondialdehyde (MDA), electrolyte leakage (EL), and production of H₂O₂ and uptake of Pb contents in all three parts of plant, viz. root, stem, and leaf. Application of H₂S slightly increased plant growth, chlorophyll contents, SPAD value, photosynthesis, and antioxidant activity as compared to control. Hydrogen sulfide supply alleviated the toxic effects of lead on plant growth, chlorophyll contents, SPAD value, photosynthesis, and antioxidant activity in cotton plants. Hydrogen sulfide also reduced MDA, EL, and production of H₂O₂ and endogenous Pb levels in the three mentioned plant parts. On the basis of our results, we conclude that H₂S has promotive effects which could improve plant survival under Pb stress.     

The role of bacteria in the heavy metals removal and growth of Sedum alfredii Hance in an aqueous medium

This study was the first attempt to examine the possible role of the naturally occurring rhizospheric bacteria in heavy metal removal by Sedum alfredii Hance, a terrestrial Zn/Cd hyperaccumuluator, from Zn, Cd, Cu and Pb contaminated water using antibiotic ampicillin. Moreover, the toxicity symptom in plants under heavy metal stress expressed as total chlorophyll, chlorophyll a and b content, growth inhibition, root length, and N, P contents were studied, and the possible relationship among them were also discussed. These results indicate that rhizospheric bacteria may play an important role in the uptake of N and P by S. alfredii, and consequently result in the increase of Chlorophyll content in the leaves and plant biomass due to improved photosynthesis. At the same time, root length significantly decreased under the treatment with ampicillin, which suggested that rhizospheric bacteria appeared to protect the roots against heavy metal toxicity. The Pb, Zn, Cu and Cd concentrations in the roots, stems and leaves of S. alfredii were much higher than those exposed to ampicillin. Accordingly, metal concentrations in the contaminated water without ampicillin treatment were lower than those treated with ampicillin. These results suggest that the rhizospheric bacteria may be useful in plant tolerance to heavy metal toxicity, and also accelerate the metal removal from contaminated water.     

Effect of exogenous abscisic acid on the level of antioxidants in Atractylodes macrocephala Koidz under lead stress

This study hypothesized that the positive or negative effects of exogenous abscisic acid (ABA) on oxidative stress caused by lead were dose dependent. The effects of different levels of ABA (2.5, 5, and 10 mg L^?1) on lead toxicity in the leaves of Atractylodes macrocephala were studied by investigating plant growth, soluble sugars, proteins, lipid peroxidation, and antioxidative enzymes. Excess Pb inhibited root dry weight, root length, and the number of lateral roots, but increased shoot growth. In addition, lead stress significantly decreased the levels of chlorophyll pigments, protein, and activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD). Different levels of ABA significantly increased SOD, CAT, POD, and APX activities, but decreased the level of hydrogen peroxide and malondialdehyde in nonstressed plants. Exogenous application of 2.5 mg L^?1 ABA detoxified the stress-generated damages caused by Pb and also enhanced plant growth, soluble sugars, proteins, and all four antioxidant enzyme activities but reduced Pb uptake of lead-stressed plant compared to lead treatment alone. However, the toxic effects of Pb were further increased by the applications of 5 and 10 mg L^?1 ABA. The levels of antioxidants caused by a low concentration of exogenous ABA might be responsible for minimizing the Pb-induced toxicity in A. macrocephala.     

Calcium protects roots of Sedum alfredii H. against cadmium-induced oxidative stress

Sedum alfredii is a well-known Cd (cadmium) hyperaccumulator native to China. The impacts of exogenous Ca on Cd-induced oxidative stress and antioxidant systems in roots of S. alfredii were investigated by using cellular and biochemical approaches. Supplementation of the medium with higher Ca levels resulted in alleviated growth inhibition and decreased Cd concentration, as well as increased Ca concentration in roots. Cadmium induced lipid peroxidation and loss of plasma membrane integrity, reactive oxygen species overproduction, as well as ultrastructural changes of root cells were largely reversed by Ca supplementation in the medium. Calcium application significantly altered the Cd effects on antioxidant enzymes and non-enzyme antioxidants (non-protein thiols), and significantly increased glutathione (GSH) biosynthesis. The results suggest that Ca is able to protect the roots of S. alfredii against Cd toxicity by restoration of Cd-displaced Ca, alleviation of the metal induced oxidative stress, as well as promotion of GSH biosynthesis.     

陕北黄土区土壤石油污染物对玉米生长影响研究

为研究陕北黄土区土壤石油污染物对玉米种子出苗率和幼苗生长的影响,采用盆栽试验的方法,设置土壤不同石油浓度处理组,培养玉米2个月,测定了各处理组玉米的出苗率、株高、茎宽、生物量和叶片叶绿素浓度.结果表明:(1)土壤石油质量浓度即使为30 g/kg时,各处理组出苗率最终均为100％;土壤石油质量浓度达到20 g/kg及以上时,在一定程度上会推迟玉米种子的出苗时间.(2)土壤石油质量浓度达到1 g/kg就会对玉米茎的生长产生抑制作用,可以显著降低玉米株高,但对玉米茎宽影响不显著.随着土壤石油浓度的升高,对玉米株高的抑制作用显著增加.玉米茎宽总体上是随着土壤石油浓度的升高而减小,但土壤石油质量浓度为0～1g/kg或20～30 g/kg时,玉米茎宽没有显著差异.(3)当土壤石油质量浓度达到5 g/kg以上时,植株干质量随石油浓度升高而减少.土壤石油质量浓度达到20 g/kg时,会显著降低玉米根的含水率;达到30 g/kg时,会显著降低茎和叶的含水率.(4)土壤石油质量浓度为1、5 g/kg时,叶绿素a和叶绿素b浓度与土壤石油质量浓度为0 g/kg时没有显著差异;土壤石油质量浓度为10、20、30 g/kg时,叶绿素a和叶绿素b浓度显著低于土壤石油质量浓度为0 g/kg时,并且随土壤石油浓度的升高呈降低趋势.     

Combined effects of lanthanum ion and acid rain on growth, photosynthesis and chloroplast ultrastructure in soybean seedlings

Rare earth elements (REEs) have been accumulated in the agricultural environment. Acid rain is a serious environmental issue. In the present work, the effects of lanthanum ion (La³⁺) and acid rain on the growth, photosynthesis and chloroplast ultrastructure in soybean seedlings were investigated using the gas exchange measurements system, chlorophyll fluorometer, transmission electron microscopy and some biochemical techniques. It was found that although the growth and photosynthesis of soybean seedlings treated with the low concentration of La³⁺ was improved, the growth and photosynthesis of soybean seedlings were obviously inhibited in the combined treatment with the low concentration of La³⁺ and acid rain. At the same time, the chloroplast ultrastructure in the cell of soybean seedlings was destroyed. Under the combined treatment with the high concentration of La³⁺ and acid rain, the chloroplast ultrastructure in the cell of soybean seedlings was seriously destroyed, and the growth and of photosynthesis were greatly decreased compared with those of the control, the single treatment with the high concentration of La³⁺ and the single treatment with acid rain, respectively. The degree of decrease and destruction on chloroplast ultrastructure depended on the increases in the concentration of La³⁺ and acid rain (H⁺). In conclusion, the combined pollution of La³⁺ and acid rain obviously destroyed the chloroplast ultrastructure of cell and aggravated the harmful effect of the single La³⁺ and acid rain on soybean seedlings. As a new combined pollutant, the harmful effect of REEs ions and acid rain on plant should be paid attention to.     

Bioaccumulation and physiological effects of excess lead in a roadside pioneer species Sonchus oleraceus L

Seedlings of Sonchus oleraceus L. were transplanted to soil supplied with lead acetate at dosages of 0, 800, 1600 and 3200 mg kg(-1) DW. Measures of chlorophyll content, peroxidase (POD) activity, shoot length, biomass and Pb content in the plant tissues were obtained from the experimental plants. With increasing amounts of Pb in the soil, the chlorophyll content, shoot length and biomass decreased, while POD activity and Pb content in the plant tissues increased. At 3200 mg kg(-1) Pb treatment, Pb content in the plant leaf, stem and root were 65.67, 149.82 and 1113.24 mg kg(-1), respectively. Only at 3200 mg kg(-1) Pb treatment did chlorophyll content, shoot length and biomass significantly increase by 18, 15 and 44%, respectively, while POD decreased by 39% over the control. The potential of applying this species in phytoremediation of Pb contaminated roadside soils and thus restoration of the roadside vegetation are discussed.     

Effects of pre-exposure to ultraviolet-B radiation on responses of tomato (Lycopersicon esculentum cv. New Yorker) to ozone in ambient and elevated carbon dioxide

Patterns of environmental change in the biosphere include concurrent and sequential combinations of increasing ultraviolet (UV-B) and ozone (O(3)) at increasing carbon dioxide (CO(2)) levels; long-term changes are resulting mainly from stratospheric O(3) depletion, greater tropospheric O(3) photochemical synthesis, and increasing CO(2) emissions. Effects of selected combinations were evaluated in tomato (Lycopersicon esculentum cv. New Yorker) seedlings using sequential exposures to enhanced UV-B radiation and O(3) in differential CO(2) concentrations. Ambient (7.2 kJ m(-2 )day(-1)) or enhanced (13.1 kJ m(-2) day(-1)) UV-B fluences and ambient (380 microl l(-1)) or elevated (600 microl l(-1)) CO(2) were imposed for 19 days before exposure to 3-day simulated O(3) episodes with peak concentrations of 0.00, 0.08, 0.16 or 0.24 microl l(-1) O(3) in ambient or elevated CO(2). CO(2) enrichment increased dry mass, leaf area, specific leaf weight, chlorophyll concentration and UV-absorbing compounds per unit leaf area. Exposure to enhanced UV-B increased leaf chlorophyll and UV-absorbing compounds but decreased leaf area and root/shoot ratio. O(3) exposure generally inhibited growth and leaf photosynthesis and did not affect UV-absorbing compounds. The highest dose of O(3) eliminated the stimulating effect of CO(2) enrichment after ambient UV-B pre-exposure on leaf photosynthesis. Pre-exposure to enhanced UV-B mitigated O(3) damage to leaf photosynthesis at elevated CO(2).     

The effects of 2,4-D herbicide and organophosphorus insecticides on growth, photosynthesis, and chlorophyll a synthesis of Chlamydomonas reinhardtii (mt +)

The effects of the herbicide (2,4-D) and six organophosphorus insecticides (Diazinon, Dimethoate, Fenitrothion, Malathion, Phenthoate and Quinalphos) on growth, photosynthesis and chlorophyll a synthesis of the fresh water green alga Chlamydomonas reinhardtii (mt +) were studied. At low concentrations (1 and 5 ppm), the herbicide and all six orgnophosphorus insecticides stimulated photosynthesis of the alga. The stimulating effects on algal growth and chlorophyll a synthesis were only observed in the presence of low concentration (1 ppm) of 2,4-D and Fenitrothion, Growth, photosynthesis and chlorophyll a synthesis of the alga were inhibited in the presence of high concentrations (10, 20 and 40 ppm) of the herbicide and all the six organophosphorus insecticides. Results also indicated that the toxicities of these organophosphorus insecticides on the tested alga were dependent on their chemical structures.     

Changes in photochemical and antioxidant enzyme activities in maize (Zea mays L.) leaves exposed to excess copper

Changes in photosynthetic and antioxidant activities in maize (Zea mays L.) leaves of cultivars 3223 and 31G98 exposed to excess copper (Cu) were investigated. Cu treatment reduced the shoot and root length of both cultivars. No significant difference of Cu accumulation in the roots of both cultivars was observed while the cultivar 3223 accumulated significantly higher Cu in leaves than 31G98. The observed decreases in effective quantum efficiency of PSII, ETR and qP indicate an over excitation of photochemical system in 3223 compared to 31G98. The leaf chlorophyll and carotenoid contents of both cultivars decreased with increasing Cu concentration. A far higher production of anthocyanins in 31G98 has been observed than that of 3223. At 1.5 mM Cu concentration, all antioxidant enzyme activities increased in leaves of the cultivar 31G98 while there were no significant changes in SOD and GR activities in 3223 compared to the control except increased APX and POD activities. The lower Cu accumulation in leaves and higher antioxidant enzyme activities in 31G98 suggested an enhanced tolerance capacity of this cultivar to protect the plant from oxidative damage.