沿阶草(Ophiopogon japanicus)对土壤中菲芘的修复作用

采用盆栽试验法,研究沿阶草对土壤中芘、菲的去除效果与修复机制.结果显示:在试验浓度范围(0～322mg · kg-1)内,植物-微生物系统对芘、菲的去除效果明显.种植沿阶草60d后,菲、芘去除率分别为77.58%～96.3%、65.25%～83.25%;平均去除率分别比对照1(加0.1%NaN3)高82.27%、72.73%,比对照2(无NaN3)高43.26%、46.27%.沿阶草能吸收积累土壤中的菲和芘,根部和茎叶部菲、芘含量随土壤中菲、芘浓度的提高而增大;生物浓缩系数随土壤中菲、芘含量的增加而减小,且根部大于茎叶部、芘大于菲.修复过程中,非生物因子、植物积累、植物代谢对菲、芘的去除率分别为6.61%、0.157%、6.54%和3.18%、1.21%、5.72%;微生物降解、植物-微生物间的交互作用对菲、芘的去除率分别为39.01%、26.47%和36.57%、39.34%.说明植物-微生物交互作用、微生物降解作用是土壤中菲、芘去除的主要原因.     

蚯蚓-菌根在植物修复镉污染土壤中的作用

以灰化土(Aquods)为供试土壤,分别加入4个浓度的Cd2 (0,5,10,20mg/kg)模拟土壤污染,设置每钵接种8条蚯蚓(Pheretimasp.)、接种菌根(InoculumEndorize-Mix2)和同时接种蚯蚓和菌根的处理,以不加蚯蚓和菌根为对照,并种植黑麦草(Loliummultiflorum),研究蚯蚓菌根相互作用对Cd污染土壤中黑麦草生长及土壤中Cd生物有效性的影响。结果表明菌根浸染率不受添加Cd浓度的影响,平均浸染率为22%,加入蚯蚓能使菌根的侵染率提高9%。在Cd污染土壤上,引进蚯蚓显著增加了黑麦草地上部的生物量,接种菌根对黑麦草地上部分产量没有明显影响,同时接种蚯蚓和菌根与只接种蚯蚓相比没有显著差异。蚯蚓活动显著提高了土壤中CaCl2-Cd的含量,而菌根只在低浓度Cd处理上增加了土壤中CaCl2-Cd含量,二者对H2O-Cd、DTPA-Cd均无显著影响,蚯蚓和菌根对增加土壤有效态Cd含量不存在协同作用。蚯蚓活动促进了黑麦草对Cd的吸收,但吸收的Cd积累于黑麦草根部。接种菌根不仅能促进黑麦草对Cd的吸收,而且还能促进Cd从植物的根部向地上部分转移,由于接种蚯蚓可以提高菌根的浸染率,所以二者具有促进Cd向地上部转移的协同作用。这对于重金属污染土壤的植物修复具有十分重要的意义。     

永定河沿河沙地杨树人工林生态系统呼吸特征

杨树是世界上广泛采用的人工造林树种之一,也是中国人工林面积最大的树种。研究杨树人工林生态系统呼吸(Re)及其分量土壤呼吸(Rs)的时间动态格局以及强度特征,分析两者对环境因子的响应是提高人工林生态系统净生产力和促进固碳减排等人工林经营管理中考虑的首要问题。采用开路式涡度相关系统、Licor-8150土壤呼吸测定系统以及小气候测定系统连续测定了位于北京大兴区永定河沿河沙地杨树人工林的生态系统呼吸、土壤呼吸和小气候特征。研究结果表明:(1)2007-2009年该生态系统的Re年总量分别为946.68、863.58、817.30gCm^-2a^-1,其中Rs年总量分别为642.11、629.29,609.05gCm^-2a^-1, Rs年总量约占Re年总量的70%;(2)Re和Rs月总量一般在7或者8月份达到最大值,Rs的变化趋势与土壤5cm温度(Ts5)相一致;(3)Ts5是Re和Rs两者的显著影响因子,但Re与空气相对湿度(RH)的相关性最显著。此外,Rs更容易受到Ts5和0-20cm土壤平均体积含水量(vwc)两者耦合效应的限制。     

蚯蚓对湿地植物光合特性及净化污水能力的影响

以香蒲、芦苇和美人蕉为研究对象,并以土壤+沙子+有机质混合物为供试基质模拟人工湿地处理污水,采用向基质中加入蚯蚓与未加入蚯蚓2种处理。研究加入蚯蚓后,香蒲、芦苇和美人蕉光合速率、蒸腾速率、SPAD值和水分蒸发、蒸腾量的变化及其对净化污水能力的影响。结果表明:与未加入蚯蚓相比,加入蚯蚓后,香蒲、芦苇和美人蕉的净光合速率、蒸腾速率、SPAD值和水分蒸发、蒸腾量均增加,其中芦苇的净光合速率、蒸腾速率和水分蒸发、蒸腾量增加达到显著水平(P <0.05),而香蒲的水分蒸发、蒸腾量增加也达到显著水平(P <0.05);加入蚯蚓后,香蒲、芦苇和美人蕉对COD_Mn、NH₄⁺-N、NO₃^--N、TN和TP的去除率均增加,且香蒲和芦苇对COD_Mn的去除率显著增加 (P <0.05)。加入蚯蚓后,香蒲、芦苇和美人蕉的SPAD值均增加,说明蚯蚓能提高湿地植物对氮的吸收,增加植株中的氮含量,促进湿地植物的光合速率和蒸腾速率从而提高对污水的净化能力。     

广东西部云开山自然保护区蕨类植物多样性调查

野外调查和标本鉴定结果表明,云开山自然保护区共有185种蕨类植物,其中10种为广东新分布:中华桫椤(Alsophila costularis)、白桫椤(Sphaeropteris brunoniana)、有刺凤尾蕨(Pteris setulosacostulata)、禾秆亮毛蕨(Acystopteris tenuisecta)、高大短肠蕨(Allantodia muricata)、细裂铁角蕨(Asplenium tenuifolium)、无盖肉刺蕨(Nothoperanema shikokianum)、蓝色鳞毛蕨(Dryopteris polita)、云南舌蕨(Elaphoglossum yunnanense)和黑鳞剑蕨(Loxogramme assimilis)。该地蕨类植物区系主要由亚洲热带亚热带分布和东亚分布成分(各占约37%的种类)构成,以鳞毛蕨科(Dryopteridaceae)、水龙骨科(Polypodiaceae)、金星蕨科(Thelypteridaceae)、蹄盖蕨科(Athyriaceae)和铁角蕨科(Aspleniaceae)的植物最为丰富,包含13种中国特有种但缺乏本地特有成分。垂直分布的统计结果表明,绝大多数植物(143种)生活在海拔900~1300 m的常绿阔叶林下,局限分布于海拔800 m以下的植物有15种,而局限分布于海拔1400~1700 m的植物有23种。该地的珍稀蕨类植物有马尾杉(Phlegmariurus phlegmaria)、华南马尾杉(P. austrosinicu)、薄叶阴地蕨(Sceptridium daucifolium)、小黑桫椤(Gymnosphaera metteniana)、中华桫椤、白桫椤、长柄车前蕨(Antrophyum obovatum)、黑鳞复叶耳蕨(Arachniodes nigrospinosa)、两广鳞毛蕨(Dryopteris liangkwangensis)、云南舌蕨、燕尾蕨(Cheiropleuria bicuspis)、锯蕨(Micropolypodium okuboi)和穴子蕨(Prosaptia urceolaris)。     

干旱胁迫对高山柳和沙棘幼苗光合生理特征的影响

为了解干旱河谷-山地森林交错带植物光合生理特征对干旱胁迫的响应。以交错带两种典型植物高山柳(Salix paraqplesia)和沙棘(Hippophae rhamnoides)为研究对象,研究其在不同程度的干旱胁迫条件下植株气体交换参数的日变化特征。干旱胁迫显著降低了两种植物叶片数、叶面积、叶片生物量、比叶面积、色素含量、净光合速率(Pn)、气孔导度(gs)和气孔限制值(Ls)等与光合生理过程密切相关的叶片指标,但增大了胞间CO₂浓度(Ci)和内禀水分利用效率(WUEi)。植物叶片的气体交换参数(如:Pn和gs)日变化并未完全随着光合有效辐射的增强和温度的升高而增加,全天以11:00最大,"午休"现象明显。相对而言,沙棘在干旱胁迫条件下表现出相对较高的叶面积、Pn、gs和WUEi,具有相对更强的适应干旱环境的能力,而高山柳对干旱胁迫更为敏感。     

平茬对半干旱黄土丘陵区柠条林地土壤水分的影响

半干旱黄土丘陵区多年生柠条人工林地发生土壤旱化,研究柠条林平茬对土壤水分影响对于防治土壤旱化具有重要意义。采用中子仪测定土壤水分,对未平茬和平茬柠条林地土壤水分进行测定,分析了平茬对土壤水分的影响。结果表明:未平茬和平茬柠条林地降雨补给量(R₁,R₂)同降雨量(P)显著正相关(P<0.05)。定义降雨耗损量(林冠截留量和地表径流之和)占降雨量的百分比为降雨耗损率,未平茬林地降雨损耗率(L₁)和平茬柠条林地降雨损耗率(L₂)分别与其降雨前土壤表层(0-20 cm)含水量(S₁,S₂)呈明显指数关系(P<0.05):L₁=2.54exp(0.22S₁),L₂=2.40exp(0.27S₂),表层含水量相同时,平茬林地降雨损耗率明显高于未平茬林地。平茬后,林地降雨最大入渗深度减小,土壤水分利用深度减小;短时间内(2个月左右)林地20-160 cm含水量增加,之后平茬林地土壤含水量与未平茬林地土壤含水量接近;丰水年和丰水年后的第一年,平茬林地含水量低于未平茬林地,0-400 cm土壤储水量比未平茬林地最多低45.9 mm。平茬后200-400 cm土层土壤水分有少量增加,但是0-200 cm土层土壤含水量损失更严重。平茬3a后,平茬对柠条林地土壤水分的影响减弱。     

交通尾气污染对城市绿化乡土树种的影响:气孔、光合生理的响应

以生长在交通繁忙的东莞大道沿线的4种常见乡土绿化树种山杜英(Elaeocarpus sylvestris)、海南蒲桃(Syzygium hainanense)、小叶榕(Ficus microcarpa var. pusillifolia)和樟树(Cinnamomum philippinense)为材料,研究了城市交通尾气污染对植物的影响以及乡土植物在城市绿化中的适应特征。结果表明,4种植物的气孔形态没有明显差异,但污染环境中的气孔密度均显著增加,其中山杜英增加幅度最大。各树种的叶绿素和类胡萝卜素含量均发生了不同的适应性变化,但变化规律不一致。除樟树外,其它3种植物的最大净光合速率均提高,但气孔导度和胞间二氧化碳浓度的变化不一致。植物对大气污染的响应程度和方式存在种间差异。因此,4种植物通过形态和生理可塑性的改变以适应交通尾气污染环境。     

干旱胁迫对高山柳和沙棘幼苗光合生理特征的影响

为了解干旱河谷-山地森林交错带植物光合生理特征对干旱胁迫的响应。以交错带两种典型植物高山柳(Salix paraqplesia)和沙棘(Hippophae rhamnoides)为研究对象,研究其在不同程度的干旱胁迫条件下植株气体交换参数的日变化特征。干旱胁迫显著降低了两种植物叶片数、叶面积、叶片生物量、比叶面积、色素含量、净光合速率(Pn)、气孔导度(gs)和气孔限制值(Ls)等与光合生理过程密切相关的叶片指标,但增大了胞间CO₂浓度(Ci)和内禀水分利用效率(WUEi)。植物叶片的气体交换参数(如:Pn和gs)日变化并未完全随着光合有效辐射的增强和温度的升高而增加,全天以11:00最大,"午休"现象明显。相对而言,沙棘在干旱胁迫条件下表现出相对较高的叶面积、Pn、gs和WUEi,具有相对更强的适应干旱环境的能力,而高山柳对干旱胁迫更为敏感。     

镉在土壤-金丝垂柳系统中的迁移特征

以金丝垂柳为试验对象,采用盆栽试验方式,设置无植物和金丝垂柳两组试验,分别对两组试验的土壤做梯度浓度Cd处理:0(无镉处理)、2(低浓度处理)、20(中浓度处理)、80(高浓度处理) mg/kg 土壤干重,无植物组各处理分别定义为CK(无镉处理)、L(低浓度处理)、M(中浓度处理)、H(高浓度处理),金丝垂柳组各处理分别定义为CKP(无镉处理)、LP(低浓度处理)、MP(中浓度处理)、HP(高浓度处理)。通过对土壤中各形态Cd含量及金丝垂柳叶、韧皮部、木质部、根部的Cd含量测定,分析了金丝垂柳及不同浓度Cd处理对土壤中中性交换态、螯合态和残渣态Cd含量的影响,并评价了富集指数(BCF)、转移系数(TF)和生物有效性(BF),明确了Cd在土壤-金丝垂柳系统中的转移特征及金丝垂柳对土壤中Cd的清除效果。结果表明:(1)金丝垂柳对土壤中中性交换态、有效态Cd含量及总Cd量的降低具有极显著影响,HP组与无植物H组相比,中性交换态及有效态Cd含量分别降低了52.73%、25.34%,MP、HP组与对应的无植物处理组的总Cd量相比分别降低了11.33%、13.89%;(2)金丝垂柳各处理组的Cd积累量随Cd处理浓度的增加和处理时间的延长而增加,处理90 d后,HP处理中木质部和根部的Cd含量可达170.64 mg/kg、212.49 mg/kg;(3)各浓度Cd处理下,金丝垂柳各部位生物富集系数呈根>木质部>韧皮部、叶,且随着Cd处理浓度的增加而显著降低,随处理时间的延长而升高;与40 d相比,90 d时LP组叶的生物富集系数增加了6.90倍,增幅最大。(4)各部分转移系数均随处理时间的延长而降低,90 d时LP、MP的转移系数分别比40 d时的结果低47.94%、41.34%。(5)金丝垂柳LP、HP组土壤Cd的生物有效性显著低于相应的无植物处理L、H组,分别低70.73%、88.46%,MP组与M组无显著差异。研究结果表明,金丝垂柳能有效地吸收土壤中的有效态Cd,降低土壤中Cd的生物有效性及总Cd量,提高土壤的安全性,并能将吸收的Cd有效地转移至地上部分,尤其是木质部储存。随着植株不断生长,生物量的增加,金丝垂柳可有效地清除土壤中的Cd,适用于对Cd污染地区进行长期植物修复。     

芘对黑麦草根系几种低分子量有机分泌物的影响

植物根系释放分泌物与有机污染物的植物修复机制密切相关,研究具有有机污染物修复潜力植物在污染胁迫条件下的根系分泌物特征有助于揭示其修复机制.以多环芳烃修复研究中常用的黑麦草为材料(Lolium perenneL.)为材料,在营养液栽培方式下研究了在芘胁迫处理下,黑麦草根系几种低分子量有机物分泌特征.结果表明,黑麦草对芘具有较强的耐受能力,芘胁迫处理下,生物量无显著变化.黑麦草根系分泌的低分子量有机酸主要为草酸.3、6 mg/L和9 mg/L芘胁迫处理下,低分子量有机酸的组成无明显变化,但含量随芘胁迫处理浓度上升而显著增加(P＜0.05);总糖分泌量随着芘胁迫处理浓度升高而呈现先略微上升后下降的趋势,相对高峰值出现在芘胁迫处理浓度3 mg/L,但差异不显著;氨基酸分泌总量随着芘胁迫处理浓度的增加而显著增多,芘胁迫浓度在3、6 mg/L和9 mg/L时,根系氨基酸的分泌总量分别是空白的1.37、2.02倍和2.65倍,但根系分泌的氨基酸组成无明显变化,19种常见氨基酸分泌的数量变化情况却不相同,分泌量总体均随着芘胁迫处理浓度的提高而增加,其中苏氨酸、丝氨酸、脯氨酸、甘氨酸、丙氨酸、亮氨酸、组氨酸和鸟氨酸的分泌量显著增多,差异显著(P＜0.05).     

蚯蚓-秸秆及其交互作用对黑麦草修复Cu污染土壤的影响

以高沙土为供试土壤,加入Cu^2＋以模拟成：0,100,200,400mg／kgCu^2＋的Cu污染土壤,设置接种蚯蚓（E）、表施秸秆（M）,同时加入蚯蚓和秸秆（ME）及不加蚯蚓和秸秆的对照（CK）4个处理,并种植黑麦草。研究蚯蚓、秸秆相互作用对黑麦草吸收、富集铜的影响。结果表明：加入秸秆显著提高了蚯蚓的生物量,一定程度上缓解了重金属对蚯蚓的毒害,同时蚯蚓显著提高了秸秆的分解率,较无蚯蚓对照提高了58．11％～77．32％。接种蚯蚓（E,ME）还提高了土壤有效态重金属（DTPA-Cu）含量,秸秆处理（M）则降低了土壤有效态重金属含量。研究还发现,E处理促进了黑麦草地上部生长,而M和ME处理均显著提高了黑麦草地下部的生物量。E和ME处理同时提高了植物地上部和地下部的Cu浓度及Cu吸收量,M处理则只对植物的地下部Cu浓度和Cu吸收量有显著促进作用。总体来看,E处理、M处理及ME处理分别使黑麦草地上部Cu富集系数提高了31．22％～121．07％．2．12％～61．28％和25．56％～132．64％。     

Role of earthworm-straw interactions on phytoremediation of Cu contaminated soil by ryegrass

It is well known that the earthworm's activities can increase the availability of soil nutrients, improve soil structure, and enhance the biomass of plants in uncontaminated soil. Recently, many researchers found that some metal-tolerant earthworms can survive and even change the fractional distribution of heavy metals in contaminated soil. Furthermore, it has been revealed that earthworms are able to increase metal availability, and therefore, accumulate more metals in plants through their burrowing and casting activity. It is clear that the influence of soil animals is an important factor for phyto-remedation that must be taken into account. ~In this article, the authors studied some effects of addition of earthworms (Metaphire guillelmi), corn straw, and in combinations of earthworms and corn straw on the growth and Cu uptake by ryegrass in Cu contaminated pot soils. The experiment consisted of four levels of Cu addition (0, 100, 200, 400 mg·kg?1) and four treatments. The treatments were 1. control (CK); 2.straw mulching only (M); 3. earthworm additions to soil only (E); and 4.straw mulching plus earthworm additions (ME). Each treatment had three replicates. 10 seeds of ryegrass (Lolium multiflorum) were sowed in each pot and harvested after 30 days. After 30 days of incubation, all earthworms were found to be alive and the pot soils were burrowed through by earthworms. Results showed that the biomass of earthworm declined with the increase of the dosage of Cu additions. The biomass of earthworm increased significantly in treatment 4 (ME) as compared with treatment 3 (E). Not only the earthworms could get more food from the straw, but also could counteract some negative effects of Cu on the earthworms. The rates of straw decomposition in ME treatment increased by about 58.11% ?77.32%. The earthworm activities increased root biomass of ryegrass significantly, but did not show the effect on plant root growth. On the contrary, straw enhanced roots biomass significantly instead of shoots biomass. It was also found that the concentration of Cu in the plant shoot and the plant root, as well as plant Cu uptake were enhanced by earthworm's activities and straw mulching. The increased amount by straw mulching was lower than that of earthworms (E). The treatment of the earthworm–straw mulching combinations enhanced plant Cu concentration, and the amount increased by it was lower than that of the earthworm treatment (E) but higher than that of straw mulching treatment (M). The accumulation factors of copper in the shoots of ryegrass were increased by 31.22% ?121.07%, 2.12% ?61.28% and 25.56% ?132.64%, respectively, in treatment 3(E), 2(M), and 4(ME), respectively. In conclusion, the earthworm activities, straw-mulching and their interactions may have potential roles in elevating phyto-extraction efficiency in low to medium level Cu contaminated soil.     

Remediation of benzo[a]pyrene and chrysene-contaminated soil with industrial hemp (Cannabis sativa)

The phytoremediation, with industrial hemp (Cannabis sativa), of a Hawaiian silty clay soil contaminated with two polycyclic aromatic hydrocarbons (PAHs), chrysene and benzo[a]pyrene, was studied. Hemp showed a very high tolerance to the contaminants. The growth rates of hemp, compared with control, in soils fortified with chrysene and benzo[a]pyrene at concentrations of each varying from 25 to 200 micrograms/g were consistently above 100%. The plants grew from seed for 45 days in soil fortified with PAHs at concentrations of 25, 50, and 75 micrograms/g. Controls were pots with contaminated soil but no plant. PAHs levels were significantly reduced in all pots (control and seeded pots), expect for one set at a high concentration of chrysene, which may be due to uneven spiking. A time course study over 28 days was done to monitor changes of microbial count and levels of chrysene. Little changes were observed for the total microbial count in the soil, and the concentration of chrysene in the soil decreased slightly in the pots containing plants. However, the chrysene levels in those pots were consistently lower than those in the pots without plants.     

Effects of earthworm (Pheretima sp.) on three sequential ryegrass harvests for remediating lead/zinc mine tailings

Farm soil and artificial soil were mixed separately with Pb/Zn mine tailings and placed in the ratios (w/w) of 0, 12.5, 25, and 50% in pots, together with 0.33 g KH2PO4 and 0.35 g urea/pot. Each pot contained 15 ryegrass seedlings (Lolium multiflorum) and 7 earthworms (Pheretima sp.). At the end of the experiment (after the third harvests of ryegrass), the earthworms were all found to be alive and burrowed completely at the bottom of the pots in all treatments. Earthworm activity increased plant biomass significantly in artificial soil/tailings mixtures in the second and third harvests as compared with the control (without addition of earthworms), but not in the farm soil/tailings mixture. The biomass of ryegrass in both soil/tailings mixtures decreased with increase of tailings, especially those containing 50% tailings. In general, the plant biomass obtained from farm soil/tailings mixtures was lower than that from artificial soil/tailings mixtures. Earthworm activity did not significantly increase DTPA-extracted Zn or Pb, in both soil/tailings mixtures. However, the concentrations in farm soil/tailings mixtures were lower in the second and third harvests, compared with the first harvest. The Zn and Pb uptake by ryegrass shoots in the two soils/tailings mixtures did not increase significantly (compared with the control) in the first and second harvests. However, in the third harvest, Zn and Pb uptake increased significantly in farm soil/tailings mixtures, but decreased significantly in artificial soil/tailings mixtures (compared with the control). The results indicated that the presence of earthworms and sequential plant harvesting could be a viable strategy for the remediation of Pb/Zn tailings.     

BIODEGRADATION OF PAHS IN LONG-TERM CONTAMINATED SOIL CULTIVATED WITH EUROPEAN WHITE BIRCH (BETULA PENDULA) AND RED MULBERRY (MORUS RUBRA) TREE

The ability of birch (Betula pendula) and mulberry (Morus rubra), cultivated either separately or together with perennial ryegrass (Lolium perenne), to enhance the biodegradation of 15 selected polycyclic aromatic hydrocarbons (PAHs) in long-term contaminated soil was studied in a greenhouse experiment. The microecosystems (MESs) were cultivated for either 12 or 18 months at a natural photoperiod. The fact that the soil chosen for cultivation had been contaminated for over 50 years was expected to be the main factor limiting biodegradation. Extracts of both planted and unplanted soil were analyzed using HPLC. After 1 year of cultivation, the overall content of the investigated compounds had declined to 50%. The concentrations of fluoranthene and pyrene, the PAHs originally present in the soil in the highest concentrations (103.5 and 83.3 mg/kg, respectively), had decreased to 28.0 and 18.0 mg/kg, respectively. In addition, other compounds were successfully degraded, including even benzo[a]pyrene. Benzo[ghi]perylene and indeno[1,2,3-cd]pyrene were the only PAHs remaining and were almost entirely undegraded. Because few significant differences were found between the various types of MESs studied, degradation can primarily be attributed to the presence of degrading microorganisms in the soil.     

蚯蚓和铁处理对苹果根铁营养影响

试验于2007～2009年在河北省永年县曹庄村和中国农业大学曲周实验站进行。在苹果树根际用不同价态的2500、5000、10000、20000mg/kg的铁处理玉米秸秆后接种蚯蚓,研究蚯蚓和铁对苹果根系生长、蚯蚓对铁的富集转移及根质外体铁的影响。结果表明:蚯蚓对铁有很大的富集量,在20000mg/kg(试验所用最高浓度)二价铁和三价铁处理的秸秆中可以成活并把秸秆转化为蚯蚓粪,促进根系生长,提高根的质外体铁含量,蚯蚓对二价铁的适应性高于三价铁。蚯蚓可将有机物料中的铁转移到果树根系内,5000mg/kg铁处理增加蚯蚓体内Fe2+含量和根质外体铁含量效果最好,蚯蚓、蚯蚓粪和根中的全铁含量随铁处理浓度的增加而增加。铁显著促进果树根系生长,没有用铁处理过的秸秆接种蚯蚓诱导的新根量明显少于用铁处理的,两种不同价态的铁都是以5000mg/kg的新根量最多。蚯蚓显著促进根系生长,没有接种蚯蚓的处理新根量显著少于接种蚯蚓的处理。     

Enhanced Microbial Removal of Pyrene in Soils in the Presence of Earthworms

Microbial degradation of pyrene was studied in soils in the presence and absence of earthworms (Eisenia foetida) to demonstrate an integrated innovative strategy for bioremediation of sites lightly polluted by polycyclic aromatic hydrocarbons. Desorption of pyrene and soil microbial respiration were measured to elucidate the mechanism of enhanced microbial degradation. The results showed that both soil properties and contact time could influence pyrene biodegradation. The introduction of E. foetida enhanced pyrene removal significantly both in freshly spiked and aged soils. The percentage pyrene removal in the presence of E. foetida was 45.5–91.0% after 14 d of incubation, which were 2.1 to 2.8 times greater than those without the worms. The enhanced pyrene removal is attributed to both enhanced microbial degradation and uptake by the worms. Microbial degradation of pyrene increased by 1.2 to 1.6 times in the presence of the worms. Overall, the introduction of live worms could improve both pyrene bioavailability and microbial activity, which leads to enhanced microbial degradation of pyrene.     

Ecotoxicity of soils contaminated with industrial and domestic wastewater in western Shenyang, China

Soil samples were collected from 7 sites in the up-, mid- and down-reach along and nearby the wastewater irrigation channel, western Shenyang of China. The concentrations of selected pollutants (mineral oil, PAHs - polycycle aromatic hydrocarbons and Cd) were determined by UV spectrometer, HPLC and AAS (atomic adsorption spectrometer) spectrometer, respectively. Toxicity effects of soils were evaluated by seedling emergence test with root length of wheat as the end-point and by earthworms test with the mortality rate and inhibition rates of body weight as endpoints. Results showed accumulation of pollutants for most soils with concentration of 200.2 mg.kg-1 ～1600 mg.kg-1 for mineral oil, 0.33 mg.kg-1～1.81 mg.kg-1 for Cd and 900.16 mg.kg-1～ 2737.91 mg.kg-1 for PAHs. The inhibition rates of root elongation were from -20% up to 40 %, and mortality rates of earthworms ranged from 0%～40% from the exposure period of two weeks to eight weeks by sampling interval of two weeks, the inhibition rates of earthworm growth were from -19.36% to 34.53%, showing effects of stimulation at 2 weeks to an increasing effects of inhibition at 4, 6 and 8 weeks, respectively. Mortality rates correlated with the loss of body weight of earthworms.This study indicated the potential risk of pollutants of environmental low content in soil by the determination of selected chemicals combined with toxicity indexes.     

Toxicity and Bioaccumulation of Petroleum Mixtures with Alkyl PAHs in Earthworms

The toxicities of three oil products with boiling-point ranges representative of petroleum hydrocarbons were tested on earthworms (Eisenia fetida) to investigate the correlation between bioaccumulated concentrations of polycyclic aromatic hydrocarbons (PAHs) and toxicity. The toxicities to earthworms were in the sequence: kerosene > diesel > bunker-C. After 14 days, the LC50s of the soils contaminated with kerosene, diesel, and bunker-C were 1079, 9135, and 15,609 mg/kg, respectively. Analysis of the body residue concentrations of PAHs in the earthworms showed that the accumulation of alkyl PAHs predominated that of the 16 priority PAHs. Principal component analysis (PCA) identified 12 PAHs, including four alkylated naphthalenes, as the oil constituents that affected mortality in the kerosene-contaminated soil. For the diesel-contaminated soil, eight PAHs were identified, including dibenzothiophene. It was not clear which compounds affected mortality in the bunker-C soil. Across the three series, biota-to-soil accumulation factors (BSAFs) ranged from 10^–2.05 to 10^3.98, and generally increased as the hydrophobicity (K_ow) or molecular weight of the alkyl PAHs increased. The toxicity endpoints of each oil product can be used as reference values in the risk assessment of soils contaminated with petroleum, and individual PAHs screened out have implications for future toxicity assessment of petroleum hydrocarbons.