香根草和水花生对垃圾污水中N、P、Cl的吸收效果

香根草和水花生对垃圾污水中不同“污物”的吸收能力差别较大。二者对N的吸收量均超过了各自净化的总N量,对P的吸收率亦较高,但植株体内的P浓度却随介质P浓度的升高而下降。和净化量相比,植物对低浓度污水中Cl的吸收率较高,但对高浓度中的吸收率较低。和原液中的“污物”量相比时,根系对元素的吸收率都明显降低。这表明,植物净化系统中的去污方式除了根系的吸收外,还有其他方式,即根系是通过根际微生态系统的综合作用来达到净化目的。总的来说,香根草对“污物”的吸收能力不比水花生强,尽管他比水花生有更强的净化能力。     

垃圾污水的植物毒性和植物净化效果之研究(英文)

广州李坑拉圾卫生填埋场的渗滤污水含有高浓度的污染物,经过人工净化后仍未达到排放标准,对植物产生毒害。在被观测的４种植物中,水葫芦（Ｅｉｃｈｈｏｒｎｉａｃｒａｓｉｐｅｓ）在高浓度和低浓度２种污水中均被毒害致死;百喜草（Ｐａｓｐａｌｕｍｎｏｔａｔｕｍ）在高浓度的渗滤液中不能存活,在低浓度中受严重伤害;水花生（Ａｌｔｅｒｎａｎｔｈｅｒａｐｈｉｌｏｘｅｒｏｉｄｅｓ）在高浓度污水中受较重伤害,但在低浓度形成庞大生物体,这可能是污水的“富营养化”所致;香根草（Ｖｅｔｉｖｅｒｉａｚｉｚａｎｉｏｉｄｅｓ）在这２种污水中亦受伤害,但受害程度为４种植物中最轻。在污水中表现相对较好的２种植物中,水花生对低浓度污水的净化效果总体上好于香根草,尤其对总氮和硝态氮的净化效果明显好于香根草,但香根草对高浓度污水中的７种“污物”的净化效果均优于水花生,且对低浓度污水中的磷与ＣＯＤ的净化亦优于水花生。在被观测的７种水质指标中,植物对氨态氮的净化效果最好,净化率在７７％～９１％之间。此外,香根草对磷也表现出了较强的净化能力,净化率高达７０％以上。香根草和水花生可分别作为高、低２种浓度垃圾污水的净化植物来辅助净化污水。     

四种湿地植物在人工湿地的生长特性研究

研究了表面流人工湿地中香根草(Vetiveria zizanioides)、风车草(Cyperus flabelliformis)、芦苇(Phrogmites australis)和水鬼蕉(Hymenocallis littoralis)4种植物的根生物量和生长量、根系分布、地上部分的生长情况.风车草、香根草和水鬼蕉根系及地上部分的生长节律相似,9月或10月前生长较快,以后生长减慢甚至停止;芦苇则不同,7月以前生长缓慢,以后生长加速,冬季也保持较快的生长.全年根生长量和根生物量以水鬼蕉最大,显著高于其它植物(P<0.01),香根草最小,显著低于其它3种植物(P<0.01).香根草的根系垂直向下生长,分布较深,而其它3种植物的根系主要分布在浅层土壤中.风车草分株最多,叶面积指数最大.香根草叶面积指数最小.结果表明,在构建多种植物人工湿地群落时,可以考虑将芦苇与大多数湿地植物搭配以保证湿地全年保持较好的净化效果;水鬼蕉可以作为底层植物,和风车草等生长早、植株较高的植物构建多种湿地群落.     

浮床植物净化生活污水中N、P的效果及N2O的排放

在温室内采用浮床无土栽培技术,研究了黑麦草(Lolium mutliflorum)、水芹(Oenanthe javanica)和香根草(Vetiveria Zizanioides)3种植物对生活污水中N、P的去除效果及净化过程中N2O的排放特征。结果表明,浮床植物系统对生活污水的TN、NH4 -N和TP具有良好的净化效果。同对照系统相比,浮床黑麦草、水芹和香根草系统对TN的平均去除率分别提高了26.2%,22.9%,4.1%;对NH4 -N的去除率分别提高了31.4%,14.5%,3.0%;对TP去除率分别提高了33.1%,54.2%,15.5%。净化周期内,浮床各系统的TN、NH4 -N和TP浓度随着污水停留时间的延长直线下降,而NO3-N浓度却因系统内硝化强度大于反硝化强度而产生了累积;植物的存在明显的促进了浮床系统的N2O排放,浮床黑麦草、水芹、香根草和对照系统N2O的平均排放通量分别为174.44μg/(m2.h),82.19μg/(m2.h),112.49μg/(m2.h)和44.81μg/(m2.h)。浮床系统N2O排放通量的日变化呈现出夜间下降而白天增加的规律,与温度的昼夜变化规律基本相同,表明温度的升降直接影响了N2O的生成及排放。     

3种观赏植物对室内甲醛污染的净化及生长生理响应

在密封条件下,采取熏蒸法研究了常春藤、绿萝、驱蚊草对不同浓度梯度的甲醛气体胁迫的吸收能力及其生理响应。结果显示:(1)3种植物对室内甲醛气体均有不同程度的吸收能力,其吸收率随室内甲醛气体浓度的升高而逐渐增加,且吸收能力表现为常春藤>驱蚊草>绿萝。(2)与对照相比,随着室内甲醛气体胁迫浓度的增加,驱蚊草、绿萝、常春藤的叶绿素含量先升高再降低,而叶绿素a/b值的变化趋势各有不同。(3)不同浓度甲醛气体胁迫下,3种植物的超氧化物歧化酶(SOD)活性和过氧化物酶(POD)活性均显著升高,并以常春藤的增加量最大(分别为113.21%和120.84%),驱蚊草的增加量最小(分别为69.04%和60.76%);而3种植物的过氧化氢酶(CAT)活性与对照相比显著降低,并以驱蚊草的变化量最大(49.54%),绿萝的变化量最小(14.66%)。(4)驱蚊草、绿萝、常春藤的丙二醛(MDA)含量和脯氨酸含量随着甲醛气体浓度的增加呈升高趋势。综合分析表明,3种室内植物耐受甲醛胁迫的能力存在显著差异,常春藤属于吸收多、耐性强的植物,驱蚊草属于吸收多、耐性弱的植物,而绿萝属于吸收少、耐性强的植物。     

香根草和百喜草对铅锌尾矿重金属的抗性与吸收差异研究

铅锌尾矿是一类重金属含量极高,对植物生长产生毒害的生境.盆栽实验的结果显示,香根草和百喜草在纯尾矿或由尾矿和垃圾组成的混合基质上都能生长,但植物的长势随基质中重金属含量的增加而减弱,其中香根草的生物量所受的影响比百喜草的更大,即百喜草有比香根草更强的重金属抗性.2种植物体内的重金属含量高低均为Zn＞Pb＞Cu,但二者对它们的富集能力大小分别是,香根草为Zn＞Cu＞Pb,百喜草则为Cu＞Zn＞Pb.香根草和百喜草的根系对3种重金属都有较强的滞留效应,滞留率均在50%以上;其中香根草对重金属的滞留率又明显高于百喜草;而且,同一植物对不同的重金属的滞留率也明显不同,香根草对Pb的滞留率最高,而百喜草对Cu的滞留率显著高过对Zn和Pb.由于香根草的生物量明显大于百喜草,结果香根草对Pb、Zn的吸收量比百喜草高.当用25%的垃圾改良金属尾矿时,百喜草对重金属的吸收量即达最大;而香根草则在尾矿和垃圾各占50%的基质中吸收最多的重金属;因此,添加一定量的垃圾(25%～50%左右)用于尾矿改良时,不仅能使尾矿得到更快的植被恢复与更高的植物修复效果,而且能使垃圾资源得到充分合理的利用.总之,当开展对金属尾矿的植被恢复时,可选择种植抗性强、覆盖快的百喜草,但如果要对尾矿中的重金属进行生物净化,则应选择种植生物量大的香根草,种植香根草还可较好地防止重金属的二次污染或生物富集.     

水培条件下两种植物根系分泌特征及其与污染物去除的关系

分别以黑臭河涌污水和霍格兰营养液作为培养液,选取种内个体大小基本一致的风车草(Cyperus alternifolius)和美人蕉(Canna indica)各2株分别水培于2种培养液中,研究经污水驯化和营养液培养后植物的生长状况、根系分泌物、根系径向泌氧以及污水净化效果。结果表明,美人蕉在营养液中的增长速率明显高于污水,而风车草在2种培养液中的增长速率相差不大。2种植物在2种培养液中的单位重量分泌能力存在显著差异。在经过污水及营养液培养后,风车草单位重量分泌能力均高于美人蕉;就单种植物而言,污水水培的植株单位重量分泌能力均高于营养液水培的植株。风车草(营养液)、风车草(污水)、美人蕉(营养液)和美人蕉(污水)的最大分泌量分别为2.89、34.76、1.28、1.82 mg·g-1·d-1。在2种培养液中,风车草的根系泌氧速率均明显高于美人蕉。就单种植物而言,经污水驯化的植物,其泌氧速率均高于营养液中培植的植物,风车草(污水)泌氧速率最大,为0.92μmol O2·h-1·g-1(植株)或6.69μmol O2·h-1·g-1(根),美人蕉(营养液)泌氧速率最小,为0.20μmol O2·h-1·g-1(植株)或1.15μmol O2·h-1·g-1(根)。植物经过一段适应期后,对氨氮、TN、TP的去除率稳定达到90%以上;COD的去除率整体不高,单位重量的风车草和美人蕉对COD的去除量分别为6.95±1.78和1.35±0.52 mg·g-1,而对TP的去除量最小,分别为0.28±0.06和0.06±0.02 mg·g-1。对于COD、氨氮、TN和TP,风车草的单位重量去除量显著高于美人蕉,这与风车草根系分泌有机物能力及根系泌氧能力较美人蕉强有明显的一致性。研究表明,采用风车草作为浮床植物应用于污染水体修复,能达到更佳的效果。     

香根草对土壤中几种重金属离子富集能力的比较研究

用组织培养的香根草无菌苗作为试验材料,进行香根草对Cd、Cr、Pb和Ni四种重金属离子的富集能力比较试验,分别测定了香根草体内的重金属含量、香根草与重金属元素的相关性、香根草对重金属的富集系数和根系滞留率.结果表明：香根草对四种重金属离子都具有较高的富集能力.其中,香根草植物体中元素总含量表现为Ni＞Cr＞Pb＞Cd,在茎叶和根中的分含量,均表现为根＞茎叶;香根草与重金属元素的关系中,Cd的相关性最显著;富集系数与重金属浓度呈负相关,以Ni最为明显;从滞留率的角度来看,以Cr在香根草根系的滞留率最大,但对同一种重金属来说,随浓度的变化,香根草根系对它的滞留率却几乎是恒定的.     

河岸美人蕉和香根草的生长繁育及其腐烂规律

以河岸带中的美人蕉、香根草为对象,研究了河岸带生态恢复过程中植物的生长及其作用。结果表明:美人蕉和香根草二者对水深的耐受性均不强,不适合在深水中生长与繁殖;与美人蕉相比,香根草对水深的耐受性更强;美人蕉不适合在水深>20cm的水域生长;美人蕉地上的生物量比地下高27.5%,香根草地上的生物量比地下高79%;通过收割美人蕉分别带走美人蕉所固定的全部氮、磷的59%和55%,收割香根草带走香根草所固定的全部氮和磷的57%;经过130d的浸泡,美人蕉、香根草质量损失率分别为31.89%和19.8%,全氮、全磷的损失美人蕉分别为49.43%和77.30%,香根草分别为47.54%和86.06%;植物浸泡释放有机物、氮和磷,但水中COD、NH4 -N和TP浓度并不持续增加。     

人工湿地处理炼油废水的生态效益研究

来自茂名石化公司的炼油废水含有较高浓度的污染物 ,超过广东省规定的排放标准 ,未经处理不能直接排放。 4种草本植物 ,香根草、芦苇、宽叶香蒲和蒲草被用来测试建植人工湿地的效果以及所建植的人工湿地处理炼油废水的效果。在为期 2个月的处理过程中 ,人工湿地在前期对炼油废水的净化效率很高 ,它们对第一批高浓度废水中氨氮、COD、BOD和油的去除率分别是 97.7%、78.2 %、91 .4%和 95 .3% ,对第一批低浓度污水分别是 97.1 %、71 .5 %、73.7%和 89.8%。但是 ,随着时间的推移 ,湿地的净化效果会有一定程度的下降 ,然后逐渐趋于稳定。湿地对氨氮、COD、BOD和油类的去除效率始终表现为氨氮 >油类 >BOD>COD,但植物对它们的净去除量却是 COD>BOD>氨氮和油类。湿地建植之初 ,植物的净化功能很弱 ,但随植物的生长和生物量的增加而逐渐增强。然而 ,不同植物种对废水的净化率很接近 ,基本上无显著性差异。被测试的 4种植物在污水湿地中的生长表现都好过在清水湿地中的 ,但香根草、芦苇和宽叶香蒲在高浓度废水的分蘖数比在低浓度的废水少些 ,而蒲草相反 ,表明高浓度污水相对于低浓度污水而言已经对前面 3个种产生了伤害 ,却仍促进蒲草生长。在清水培养阶段 ,香根草产生分蘖的速度是 4个种中最低的 ;进入污水培养阶     

长期水淹条件下香根草(Vetiveria zizanioides)、菖蒲(Acorus calamus)和空心莲子草(Alternanthera philoxeroides)的存活及生长响应

人工构建三峡库区消落区植被是控制消落区水土流失、保护消落区生态环境的重要措施,选择能够耐受长时间完全水淹的植物物种是该措施实施的关键.为了验证香根草、菖蒲、空心莲子草能否用于消落区植被的构建,实验模拟消落区的长期完全水淹条件,设置30d、60d、90d、120d、150d和180d等6个完全水淹时间水平,研究了3种植物在完全水淹条件下生长、生物量积累及存活状况.结果发现:(1)3种植物在经受长时间的完全水淹后有较高的存活率,180d全淹处理后,香根草、菖蒲和空心莲子草的存活率分别为87.5%、100%和50%.(2)这3种植物有不同的水下生长能力.全淹条件下,香根草生长缓慢,几乎没有产生新的叶片,总叶长也没有显著变化;菖蒲能够持续产生较对照植株更为细长的叶片,空心莲子草只在水淹初期(30d内)能够快速伸长地上部分的枝条,并迅速产生新叶片,但随水淹时间的延长,总枝条长及总叶片数没有再显著增加.(3)与对照植株相比,全淹处理抑制了3种植物总生物量的增加,但对3种植物的地上、地下部分生物量抑制程度不同.全淹条件下,香根草的地上部分和地下部分生物量与水淹0d水平(水淹处理开始前一天,下同)相比无显著变化,根冠比高于对照植株;菖蒲的地上部分生物量随水淹时间延长而降低,但却高于对照植株,地下部分生物量始终低于水淹0d水平,根冠比低于对照植株;空心莲子草的地上部分生物量与水淹0d水平相比无显著差异,但地下部分生物量与水淹0d水平相比大幅降低,根冠比低于对照植株.结果表明,这3种植物都有很强的水淹耐受能力,可应用于三峡库区消落区植被的构建.同时,发现植物对长期完全水淹的耐受能力很大程度上与植株在水下的生长情况及植株的营养储备水平相关,剧烈的水下生长会消耗大量的营养储备,进而造成植株存活率降低.植株在全淹条件下有限的生长能力及丰富的营养储备可能是耐淹物种的重要特征.     

Studies on the chemical composition of isolated soil solution and the cation absorption by plants

Summary The effects were studied of varying amounts and forms of N fertilizers on the chemical composition of soil solution and on the uptake of N, K, Na, Ca and Mg by barley.In isolated soil solution the concentrations as well as the ratios of individual cations depended on form and amount of added nitrogen. The concentration of cations increased proportionally with applications of nitrate+sulphate. Cation-activity ratios in isolated soil solution were governed by the ratios of corresponding exchangeable cations. During the entire growth period the absorption by the plants of individual as well as of cations was independent of their concentrations in soil solution. So long as NH₄ ions were present in the soil solution, plants with NH₄ addition contained less cations than those with NO₃ addition. Thereafter the amounts of cations in the plant were closely correlated with N absorption, but not affected by form of applied N. The ratios K/(Ca+Mg) and Ca/Mg in the plant were closely correlated with corresponding activity ratios but independent of concentration ratios of these ions in isolated soil solution. It is postulated that uptake of cations is governed by N-metabolic processes in the plant, whereas ratios of absorbed cations are influenced by cation-activity ratios in the soil solution.     

Differential mobilization and metal uptake versus leaching in multimetal soil columns using EDTA and three metal bioaccumulators

Tannery waste is a major environmental concern that needs proper management. Tannery solid waste (TSW) can be added to the soil as an organic amendment but needs metal removal. Chelant-assisted phytoremediation hastens the process of metal removal but also poses risk of leaching at the same time. This research evaluates Ethylenediaminetetraacetic acid (EDTA)-assisted phytoextraction and associated leaching hazard using metal-tolerant plants. Greenhouse trials were carried out with sunflower, spinach, and marigold using columns of uniform diameter packed with field soil and multimetal contamination of TSW (5% and 10%) with four EDTA doses. The amounts of metal absorbed or leached conformed to amounts in the soil amendment and the dose of EDTA. The mobilization of metals by EDTA was however metal-specific. The metals that were extracted in greater amounts by the plants were leached less compared to Cr and Cu. A significant amount of other metals was leached down and thus less amount was phytoextracted by the plants e.g. Cd and Ni. A high correlation was observed between the amount of metal absorbed by the plant and the amount in leachate except for Cr in all the plants. Antioxidant activities like SOD and catalase were also found to be high in sunflower and spinach.     

Potassium uptake by Chinese cabbage (Brassica pekinensis Rupy.) from fused potassium silicate,a slow-releasing fertilizer

Fused potassium silicate (FPS), which contains K₂Ca₂Si₂O₇, has been prepared as a slow-releasing potassium fertilizer. Moreover, it is difficult to estimate the proportion of nutrients utilized by plants that come from the soil versus the slow-releasing fertilizer applied. To trace the uptake of potassium (K) by plants from FPS supplied to the soil, the fertilizer K was partially replaced with rubidium (Rb). The growth and K+Rb uptake (moles) of Chinese cabbage (Brassica pekinensis Rupy. cv. Kekkyu) plants in sand culture experiments were not affected by the replacement of K with Rb. In pot experiments using a volcanic ash Ando soil, Chinese cabbage was grown with no application of K, with K and Rb salts, or with Rb-containing FPS for three cycles of 40 days each. The amounts of fertilizer-derived K in the shoots estimated by the Rb-tracer method were smaller than those estimated by the difference of K accumulation between K fertilized and unfertilized plants. Such result suggests the involvement of `K priming', a process by which the addition of K fertilizers enhances plant K uptake from the soil. The amount of K absorbed from FPS, calculated by the Rb-tracer method, indicated that the sparingly soluble K, that is soluble in 0.2 g L^–1 citric acid solution but not in water, was absorbed at least partly through direct contact with the roots without prior exchange with soil K. Moreover, the plant absorption of sparingly soluble K from FPS was also confirmed by the difference method in K uptake.     

Municipal sludge-induced phytotoxicity

Municipal sludge (MS), containing various types of environmental pollutants, can exert phytotoxic effects in plants. Seed germination, chlorophyll content, plant weight, root and shoot growth, and metal levels, were measured as endpoints to assess the phytotoxic effects of leachates of MS from Lucknow city in three plants, Triticum aestivum, Brassica campestris and Phaseolus aureus. Among the five metals analysed, lead was found to be present at the highest concentration, and chromium at the lowest. Aqueous MS leachates had lower amounts of metals than pure MS. Seed germination was inhibited significantly in all three plants. The greatest inhibition of root and shoot growth was observed in B. campestris and T. aestivum. Total chlorophyll was depleted in all three plants, but the maximum depletion was observed in T.aestivum exposed to 10% leachate. Symptoms such as necrosis, leaf discoloration and root curling were also observed after exposure to 10% leachate, and plant weight was reduced significantly. It is evident that MS from Lucknow city exerted phytotoxic effects on all three test plant species.     

Abstracts of Platform Presentations from the Phytoremediation Session at the 14th Annual West Coast Conference on Contaminated Soils,Sediments, and Water (March 15–18, San Diego,CA)

Previous field studies indicate that zucchini (Cucurbita pepo) has a unique ability to phytoextract persistent organic pollutants from soil. It is unlikely that C. pepo evolved a unique mechanism favoring POP extraction and uptake, but all plants have evolved means to facilitate nutrient acquisition from soil. We have hypothesized that the exudation of organic acids as a means to acquire phosphorus could facilitate the uptake of persistent organic pollutants by increasing contaminant bioavailability to the plants. In one study, we assessed DDE uptake and organic acid exudation by zucchini (an uptaker of POPs) and cucumber (a non-uptaker of POPs) under various cultivation and nutrient conditions. Under dense planting (5 plants in a 5-kg pot of DDE-contaminated soil), zucchini accumulated significant and expected amounts of DDE but surprisingly, under these stressed conditions, cucumber phytoextracted greater amounts of DDE. The cucumber rhizosphere concentrations of organic acids were significantly higher than that of zucchini, suggesting that the increased organic acid exudation promoted DDE uptake by cucumber. Conversely, under non-stressed conditions zucchini phytoextracted significantly greater quantities of pollutant than cucumber but no differences in organic acid content of the rhizosphere of the two species were observed. Separately, zucchini and other species were grown under field conditions and weekly amendments of different nutrients were made (nitrogen, phosphorus, nitrogen/phosphorus, aluminum sulfate to bind phosphorus in the soil). The uptake and translocation of the weathered pollutant and inorganic elements was found to vary with nutrient amendments. Lastly, data will be presented from rhizotron units constructed to facilitate not only the direct in situ isolation of exuded organic acids but also the isolation of xylem sap and rhizosphere soil pore water from individual plants. The role of cultivation conditions and nutrient availability in controlling root morphology, organic acid exudation, and contaminant uptake will be discussed.     

Root exudates of wetland plants influenced by nutrient status and types of plant cultivation

The present study investigated the amounts of root exudates and composition of organic acids released from two wetland plants (Typha latifolia and Vetiver zizanioides) under two nutrient treatments: low level (0.786 mM N and 0.032 mM P) and high level (7.86 mM N and 0.32 mM P) and two types of plant cultivation: monoculture and co-culture of the two plants. Low nutrient treatment significantly (p < 0.05) increased the root exudates of T. latifolia during the initial growth period (1-21 d) and those of V. zizanioides and the co-culture during the whole growth period. The concentrations of dissolved organic carbon in the root exudates of the co-culture in the low nutrient treatment were 3.23-7.91 times of those in the high nutrient treatment during the medium growth period (7-28 d). The compositions of organic acids varied between the two plant species and between the two nutrient treatments. The pattern of organic acids was also different between the co-culture and the monoculture. Oxalic acid was by far the major organic acid exuded from the two wetland plants. The present study on root exudates suggests that co-culture of wetland plant species would be more useful in the reclamation of waste water than a monoculture system.     

Interactive effects of herbivory and competition intensity determine invasive plant performance

Herbivory can reduce plant fitness, and its effects can be increased by competition. Though numerous studies have examined the joint effects of herbivores and competitors on plant performance, these interactive effects are seldom considered in the context of plant invasions. Here, we examined variation in plant performance within a competitive environment in response to both specialist and generalist herbivores using Chinese tallow as a model species. We combined tallow plants from native and invasive populations to form all possible pairwise combinations, and designated invasive populations as stronger neighbours and native populations as weaker neighbours. We found that when no herbivory was imposed, invasive populations always had higher total biomass than natives, regardless of their neighbours, which is consistent with our assumption of increased competitive ability. Defoliation by either generalist or specialist herbivores suppressed plant growth but the effects of specialists were generally stronger for invasive populations. Invasive populations had their lowest biomass when fed upon by specialists while simultaneously competing with stronger neighbours. The root/shoot ratios of invasive populations were lower than those of native populations under almost all conditions, and invasive plants were taller than native plants overall, especially when herbivores were present, suggesting that invasive populations may adopt an "aboveground first" strategy to cope with herbivory and competition. These results suggest that release from herbivores, especially specialists, improves an invader's performance and helps to increase its competitive ability. Therefore, increasing interspecific competition intensity by planting a stronger neighbour while simultaneously releasing a specialist herbivore may be an especially effective method of managing invasive plants.