黑麦草对土壤中苯并[a]芘动态变化的影响

本文通过盆栽试验初步研究了黑麦草 (LoliummultiflorumLam)对污染土壤中多环芳烃苯并 [a]芘动态变化的影响。盆栽试验设计 3种苯并 [a]芘处理浓度 ,分别为 1、10、10 0mgkg-1。将苗龄为 1周的黑麦草移植于受苯并 [a]芘污染的土壤中 ,同时设置有相同的苯并 [a]芘处理浓度但不种植物的对照试验。试验在2 0m3 的控温、控光的生长室内进行 ,土壤湿度维持在田间持水量的 6 0 %。通过 12 0d的温室盆栽试验 ,观察到土壤中苯并 [a]芘的可提取浓度随着时间逐渐减少 ,种植黑麦草加快了土壤中可提取态苯并 [a]芘浓度的下降。在 1、10、10 0mgkg-1苯并 [a]芘处理浓度下 ,黑麦草生长的土壤中苯并 [a]芘的减少率分别达 82 3%、74 0 %和 5 5 9%。结果还显示 ,随盆栽时间的延长 ,黑麦草根圈土壤中多酚氧化酶含量提高 ,这可能根圈土壤中可提取态苯并 [a]芘含量降低有关。黑麦草的地上部可以积累苯并 [a]芘 ,变幅在 0 0 6～ 3 6 0mgkg-1。初步认为 ,土壤具有缓解苯并 [a]芘污染的自然本能 ,促进黑麦草生长 ,增强土壤多酚氧化酶活性 ,可提高黑麦草对苯并 [a]芘污染土壤的修复能力。     

铅和苯并[a]芘混合污染酸性土壤上黑麦草生长及对污染物的吸取作用

设置铅(Pb)处理浓度为0、5001、0002、000 mg kg-1(烘干土计),苯并[a]芘(B[a]P)处理浓度为0、12.5、255、0 mg kg-1(烘干土计),完全组合设计,对每一处理通过种植和不种植黑麦草盆栽试验,研究了B[a]P和Pb混合污染酸性红砂土上黑麦草(Lolium perenneL.)的生长及对污染物积累的吸取作用。试验表明,铅是抑制黑麦草株高和产量的主要因素,在低Pb处理浓度下,B[a]P对黑麦草生长有一定的促进作用。在试验61 d内,黑麦草吸收的铅占土壤铅添加量的4.7%,黑麦草吸收的B[a]P占土壤B[a]P添加量的0.023%;种植黑麦草的土壤B[a]P残留率平均为42.6%;而未种植黑麦草的土壤B[a]P平均残留率为50.9%。该研究结果表明,当Pb-B[a]P混合污染土壤时,在一定的浓度范围内黑麦草能吸收土壤中的Pb和B[a]P,黑麦草对Pb-B[a]P混合污染土壤有一定的吸取修复作用。     

镉和苯并[a]芘胁迫对小麦幼苗生理指标的影响

采用水培方法研究了镉（Cd）和苯并[a1芘（BaP）污染对小麦幼苗生理指标的影响。营养液中镉和苯并[a]芘的浓度分别为10mg·L^-0和54mg·L^-0。结果表明：与对照组相比,各胁迫组小麦生物量下降,株高降低,复合胁迫组地上及地下干重分别下降13．1％和49．8％,株高增长最低;各组超氧化物歧化酶（SOD）活性呈现升高-降低-升高趋势,且低于对照,过氧化物酶（POD）和过氧化氢酶（cAT）活性先升高再降低,复合胁迫组POD活性最高,CAT活性最低。镉、苯并[a]芘及其复合胁迫下,小麦幼苗的生长受到了一定抑制,且以复合胁迫最为显著。镉、苯并[a]芘联合作用的结果表现为协同促进作用。     

真菌对污染水稻土中苯并[a]芘共代谢降解研究

在恒温和恒定转速培养条件下,模拟生物泥浆反应器法,选择从石油污染土壤中分离出来的青霉菌、黑曲霉、白腐真菌等3种真菌,在添加不同浓度菲和邻苯二甲酸作为共存底物情况下,研究其对水稻土中苯并[a]芘（B[a]P）的共代谢降解。结果表明,未灭菌土壤对B[a]P有降解能力。当土壤中添加菲时,提高了B[a]P在土壤中的降解率,100 mg kg-1浓度菲处理的降解率显著高于200 mg kg-1浓度菲处理,邻苯二甲酸对B[a]P降解影响不大。灭菌土壤中的B[a]P几乎没有降解。添加菲及邻苯二甲酸均促进了青霉菌对B[a]P的降解,其中菲浓度为100 mg kg-1处理效果最显著。与灭菌土壤相比,接种黑曲霉提高了B[a]P的降解率,但添加菲与邻苯二甲酸却均抑制了黑曲霉菌对B[a]P的降解。白腐真菌能有效地降解B[a]P,但高浓度菲抑制了白腐真菌对B[a]P的降解,同时邻苯二甲酸对促进白腐真菌降解B[a]P的效果不明显。     

苯并[a]芘污染土壤的丛枝菌根真菌强化植物修复作用研究

研究了种植紫花苜蓿 (MedicagosativaL )在接种和不接种菌根真菌 (GlomuscaledoniumL )情况下对土壤中苯并 [a]芘 (B[a]P)的降解动态。历经 90天的温室盆栽试验表明 ,较高浓度 (10 0mgkg-1)B[a]P能降低菌根真菌对植物根的侵染率。种植紫花苜蓿和接种菌根真菌能促进土壤中可提取态B[a]P的降解 ,在接种情况下 ,有植物时对三种浓度 (1mgkg-1,10mgkg-1,10 0mgkg-1)B[a]P的降解率分别达 86 2 %、86 6 %、5 7 0 % ;而没有植物时B[a]P的降解率为 5 3 5 %、5 3 0 %、33 0 %。不接菌根真菌时的降解率比接菌根真菌的低得多 ,不接种菌根真菌时 ,有植物的B[a]P降解率分别达 75 9%、77 7%、5 3 4 % ;而不种植物的降解率分别为 5 4 9%、5 2 6 %、34 1% ,低、中浓度 (1mgkg-1,10mgkg-1)两处理的降解率明显地高于高浓度处理(p <0 0 5 )。B[a]P添加对土壤中多酚氧化酶活性有较大的影响 ,特别是高浓度B[a]P处理土壤的酶活性明显地低于其它三个处理 ,接种菌根真菌能够提高土壤中的酶活性 ,从而促进了土壤中B[a]P的降解。     

铜-苯并[a]芘复合污染体系中铜的微生物吸附特性

研究了铜-苯并[a]芘（BaP）复合污染体系中,嗜麦芽窄食单胞菌对铜的微生物吸附特性。实验结果表明,该菌可以选择性地吸附Cu^2＋,并把NO3^-还原为NO2^-,pH、投菌量、处理时间和铜浓度等因素及BaP均会对铜的生物吸附产生显著的影响,BaP和这4个因素的相互作用对铜的生物吸附也达到了显著的水平。投菌量会对铜吸附过程中F-、Cl^-、NO2^-、NO3^-、PO34^-和SO24-等离子的释放产生显著的影响,BaP则会显著的影响F^-、NO2^-、NO3^-和PO34^-的浓度水平。当BaP的浓度为0、0.1、1.0、10.0 mg.L^-1时,2.5 g.L^-1菌体对pH为6.0、浓度为2 mg.L^-1的铜溶液的吸附率分别高达97.1%、93.8%、94.0%和93.3%。BaP和铜在2 h内均没有造成菌体表面形态的明显变化;处理10 mg.L^-1 Cu^2＋及其与BaP的复合污染2 d后,菌体表面会产生突起结构。     

表面活性剂对东北黑土中苯并[a]芘的增溶洗脱作用

研究了4种常见表面活性剂十二烷基苯磺酸钠(SDBS)、十二烷基硫酸钠(SDS)、Tween80和TritonX-100对东北农田黑土土壤中苯并[a]芘的洗脱修复效果。增溶试验结果表明,非离子表面活性剂Tween80和TritonX-100对苯并[a]芘的增溶能力显著高于阴离子表面活性剂SDBS和SDS。4种表面活性剂在单一和混合处理条件下均能不同程度地洗脱土壤中的苯并[a]芘,且洗脱率随着表面活性剂浓度的增加而增大。各表面活性剂洗脱能力大小顺序为Tween80-SDS(3:1)Tween80-SDS(1:1)Tween80-SDS(10:1)Tween80TritonX-100SDSSDBS,当Tween80和SDS质量比为3:1时对两受试土壤中苯并[a]芘的去除率分别达到最高的42.3%和44.8%,可见阴-非离子混合表面活性剂对土壤苯并[a]芘的洗脱效果好于单一表面活性剂。土壤老化70 d后,Tween 80和Tween 80-SDS(3:1)处理对苯并[a]芘的洗脱率相比老化仅14 d的土壤分别下降了20.5%和12.9%,表明土壤老化时间的增加可降低表面活性剂对苯并[a]芘的洗脱去除效果。     

土壤环境质量指导值与标准研究Ⅳ.保护人体健康的土壤苯并[a]芘的临界浓度

：基于人体健康风险评估制定土壤环境质量指导值或标准是当前国际上广泛采用的方法.本文全面调研了国际上保护人体健康的土壤苯并[a]芘（B[a]P）的各类临界浓度,初步确定了量化土壤中B[a]P暴露剂量的暴露场景和暴露参数,率先提出了制定我国土壤中保护人体健康的B[a]P临界浓度的方法体系,这种方法可用来制定持久性有机污染物的土壤临界浓度.考虑了口腔摄入、皮肤接触、呼吸摄入和取食污染蔬菜摄入四个主要暴露途径,探讨了B[a]P的致癌风险水平为10-5或10-6时,农业用地、居住用地和工业用地方式下土壤中B[a]P的临界浓度,同时制定了保护地下水的土壤B[a]P的临界浓度.     

土壤苯并[a]芘多次叠加污染对蚯蚓体腔细胞抗氧化酶的毒性效应

苯并[a]芘(B[a]P)是具有典型"三致"效应的持久性有机污染物,在土壤中逐步累积,对土壤环境质量造成潜在的威胁。一次污染条件下,B[a]P进入土壤的过程与较低剂量逐步累积的污染过程存在一定差异,在一定程度上会高估B[a]P的环境风险。本试验采用一次污染和多次累积污染2种方法,模拟污染物在土壤中逐步累积的过程,研究土壤B[a]P叠加污染的有效性特征及其在蚯蚓(Eisenia foetida)体内的富集规律,分析蚯蚓体腔细胞超氧化物歧化酶(SOD)和过氧化物酶(POD)的毒性效应。结果表明,随着土壤中B[a]P培养时间的延长,B[a]P有效含量、蚯蚓富集量和蚯蚓体腔细胞SOD、POD活性均呈逐渐下降的趋势。在多次叠加污染和一次污染条件下,土壤B[a]P有效含量在培养前期(1~28 d)下降速率分别为2.37μg·kg-1·d-1和3.35μg·kg-1·d-1,后期(28~56 d)下降速率逐步减缓为0.24μg·kg-1·d-1和0.53μg·kg-1·d-1;蚯蚓体内B[a]P富集量在培养前期(1~28 d)下降速率分别为6.94μg·kg-1·d-1和14.84μg·kg-1·d-1,后期(28~56 d)逐步减缓为0.73μg·kg-1·d-1和1.64μg·kg-1·d-1。蚯蚓体内B[a]P富集量与土壤B[a]P有效含量(Tenax吸附提取量)之间呈极显著正相关(P0.01),相关系数(R2)为0.914 7。蚯蚓体腔细胞SOD和POD活性与土壤B[a]P有效含量和蚯蚓体内B[a]P富集量之间分别呈极显著正相关(P0.01),相关系数(R2)分别为0.754 3(SOD)、0.829 6(POD)和0.704 0(SOD)、0.727 1(POD)。在叠加污染条件下,土壤B[a]P有效含量比一次污染低17.1%~38.6%(P0.05),蚯蚓富集量比一次污染低22.6%~46.8%(P0.05),蚯蚓体腔细胞SOD和POD活性分别为一次污染酶活性的49.6%~82.7%和75.5%~109.6%,差异达到显著水平(P0.05)。这表明土壤B[a]P多次叠加污染对蚯蚓体腔细胞的毒性效应低于一次污染。     

噬氨副球菌HPD-2对苯并[a]芘的降解特性及代谢途径初探

通过溶液培养的方法初步探讨了噬氨副球菌HPD-2对苯并[a]芘(B[a]P)的降解特性及代谢途径。结果表明,噬氨副球菌HPD-2对B[a]P的降解率随其初始浓度的增大而逐渐减小。当HPD-2在B[a]P初始浓度分别为5.0、50.0mg/L的培养液中生长5天后,B[a]P的降解率分别为66.1%和31%。经衍生化后GC-MS鉴定结果发现,8-羧酸-7-羟基芘和双羟基菲为噬氨副球菌HPD-2降解B[a]P的两种主要代谢中间产物。     

Development of biomarkers inAporrectodea caliginosa andLumbricus rubellus for detecting exposure to benzo[a]pyrene

Objectives and Methods. The sensitivity of two biomarkers, the neutral red retention assay (NRRA) and cytochrome P450 were evaluated in the earthwormAporrectodea caliginosa for their potential to detect exposure to benzo[a]pyrene (BaP). Cytochrome P450 was also evaluated in the earthwormLumbricus rubellus, and measured using the substrate ethoxycoumarin. Optimal assay conditions (pH, and temperature) were determined, followed by exposure of earthworms to 20 mg/kg BaP (a typical concentration at contaminated sites in New Zealand). Ethoxycoumarin-O-dealkylase (ECOD) activity was measured after 7, 14, and 21 days exposure. The NRRA was evaluated in earthworms exposed to 0.2, 20, and 100 mg BaP/kg, and biomarker responses were compared with effects on body weight. Results and Discussion Benzo[a]pyrene failed to induce ECOD activity in either earthworm species, and therefore it is not useful as a biomarker of BaP exposure and was not evaluated further. In all cases, the NRRA was significantly affected in the absence of any effects on earthworm body weight, indicating that this assay can detect exposure to BaP at a range of concentrations comparable to those found at contaminated sites. The NRRA should be linked to reproductive endpoints, then it can be used as an early warning indicator of adverse effects. Establishing biomarker stability under environmental conditions is an important step in biomarker development. Therefore, the effects of soil type (sandy soil, silt loam, and a clay soil), moisture content (15–30%), and temperature (5–20°) on the NRRA were determined. In all cases, there was no effect on the NRRA, indicating that this assay is very stable under varying environmental conditions. Conclusion and Outlook In conclusion, cytochrome P450 activity does not appear to be a useful indicator of PAH exposure in eitherA. caliginosa or L.rubellus, and due to the inherently low activity, it is not suitable as a routine biomarker for detecting environmental contamination by these compounds. In contrast, the NRRA in the earthworm A.caliginosa is a promising indicator of PAH exposure at the concentrations likely to be found in contaminated sites in New Zealand, and therefore has potential for evaluating these contaminated sites. If the NRRA can be linked to ecologically important life-cycle endpoints, such as reproduction, then it could be used as an early warning indicator of adverse effects at contaminated sites, i.e., by measuring biomarker responses in earthworms from a ‘contaminated area’ and comparing these with earthworms from a matched control area.     

长江三角洲地区城市污泥中苯并[a]芘和菲的初步研究

To evaluate the contaminated conditions of benzo[a]pyrene (B[a]P) and phenanthrene (PA) in sludge and to ascertain whether B[a]P limit for land application of sludge exists, the contents of B[a]P and PA in 46 sludge samples from 15 cities in the Yangtze River Delta area of China were determined using high performance liquid chromatography (HPLC) coupled with a fluorescence detector after ultrasonic extraction and silica gel cleanup. B[a]P contents ranged from non-detectable to 1.693 mg kg^-1 dry weight (DW), averaged 0.402 mg kg^-1 DW, and were < 1.0 mg kg^-1 DW in most of the sludge samples. PA was found in all the sludge samples analyzed; its contents ranged between 0.028 and 1.355 mg kg^-1 DW, with an average value of 0.298 mg kg^-1 DW. Most of the sludge samples contained < 0.5 mg kg^-1 DW PA. All 46 municipal sludge samples analyzed in this study showed B[a]P contents < 3.0 mg kg^-1 DW, which is the limit value for sludge applied to agricultural lands in China. The contents and distributions of B[a]P and PA in municipal sludge were related to sludge types, sources and treatment technologies, along with the physical and chemical properties of these pollutants.     

有机污染土壤修复技术研究进展

苯并[a]芘（Bap）是一种由5个苯环组成的分布广泛、广受关注、“三致”毒性极强的多环芳烃,也是主要的环境污染物监测对象。Bap在土壤等环境中长期积累,可通过食物链的累积和放大效应威胁人体健康。Bap污染土壤的高效修复迫在眉睫,本文综述了Bap的产生、污染现状与毒性效应、不同修复技术的优缺点。物理/化学方法具有修复周期短、范围广,但成本高且易产生二次污染等特点;生物修复成本低、操作简单、环境效益好,但修复周期长、效果受多因素影响。在实际治理过程中应综合考虑成本和效果,重点关注微生物修复及相关联合修复技术的应用,将为今后开展Bap类有机污染土壤的绿色修复提供科学思路。

     

Hydrogen oxidation activities in soil as influenced by pH,temperature, moisture,and season

Summary Hydrogen oxidation in soil was measured at low (1 ppmv) and high (300 ppmv) H₂ concentrations to distinguish between the activities of abiontic soil hydrogenases and Knallgas bacteria, respectively. The two activities also showed distinctly different pH optima, temperature optima, and apparent activation energies. The pH optima for the soil hydrogenase activities were similar to the soil pH in situ, i.e., pH 8 in an slightly alkaline garden soil (pH 7.3) and pH 5 in an acidic cambisol (pH 4.6–5.4). Most probable number determinations in the alkaline acidic soils showed that Knallgas bacterial populations grew preferentially in neutral or acidic media, respectively. However, H₂ oxidation activity by Knallgas bacteria in the acidic soil showed two distinct pH optima, one at pH 4 and a second at pH 6.4–7.0. The soil hydrogenase activities exhibited temperature optima at 35–40°C, whereas the Knallgas bacteria had optima at 50–60°C. The apparent activation energies of the soil hydrogenases were lower (11–23kJ mol^-1) than those of the Knallgas bacteria (51–145 kJ mol^-1). Most of the soil hydrogenase activity was located in the upper 10 cm of the acidic cambisol and changed with season. The seasonal activity changes were correlated with changes in soil moisture and soil pH.     

Soil moisture controls on temperature sensitivity of soil organic carbon decomposition for a mesic grassland

We examined relationships between soil moisture and the temperature sensitivity of decomposition of labile soil organic carbon at a central North American grassland. For soils collected from shallow, xeric uplands, temperature sensitivity was greatest at intermediate soil moisture. For soils collected from the deeper, mesic lowlands, temperature sensitivity increased with increasing soil moisture. For example, lowland soils incubated at 75% WHC exhibited an apparent activation energy (E_a) that was 15 kJ mol⁻¹ greater than soils incubated at 30% WHC, the equivalent of a Q₁₀ of 2.8 vs. 2.3. Although further research is still needed to understand why moisture-temperature sensitivity relationships would differ between topographic positions, the magnitude of the soil moisture effect is large enough to alter soil C budgets and should be considered explicitly when predicting ecosystem responses to global change scenarios.     

培养温度和土壤类型对土壤硝化特性的影响

采用室内恒温好气培养方法,研究了温度(15℃、20℃、25℃和30℃)和土壤类型(黑土、潮土和红壤)对土壤硝化率的影响。氮素加入比率为N 200 mg kg-1土壤。结果表明:在15～30℃培养范围内,随着培养温度的升高,硝化率呈升高趋势;硝态氮累积量和培养积温(培养温度×培养天数,温度以0℃为基准)之间的关系可用单参数指数模型表示。在相同培养温度条件下,供试土壤硝化率从大到小的顺序为:高有机质含量潮土>低有机质含量潮土>高有机质含量黑土>低有机质含量黑土>低有机质含量红壤>高有机质含量红壤。硝化率(25℃恒温培养)与土壤全磷含量、全钾含量、黏粒含量及pH呈极显著相关;土壤pH和全磷含量解释了硝化率差异的98.1%。土壤pH是影响其硝化率的主要因素,并抑制土壤有机质含量及温度对硝化率的影响。     

Interacting effects of temperature, soil moisture and plant biomass production on ecosystem respiration in a northern temperate grassland

Chamber measurements of total ecosystem respiration (TER) in a native Canadian grassland ecosystem were made during two study years with different precipitation. The growing season (April–September) precipitation during 2001 was less than one-half of the 30-year mean (1971–2000), while 2002 received almost double the normal growing season precipitation. As a consequence soil moisture remained higher in 2002 than 2001 during most of the growing season and peak aboveground biomass production (253.9 g m⁻²) in 2002 was 60% higher than in 2001. Maximum respiration rates were approximately 9 μmol m⁻² s⁻¹ in 2002 while only approximately 5 μmol m⁻² s⁻¹ in 2001. Large diurnal variation in TER, which occurred during times of peak biomass and adequate soil moisture, was primarily controlled by changes in temperature. The temperature sensitivity coefficient (Q₁₀) for ecosystem respiration was on average 1.83 ± 0.08, and it declined in association with reductions in soil moisture. Approximately 94% of the seasonal and interannual variation in R₁₀ (standardized rate of respiration at 10 °C) data was explained by the interaction of changes in soil moisture and aboveground biomass, which suggested that plant aboveground biomass was good proxy for accounting for variations in both autotrophic and heterotrophic capacity for respiration. Soil moisture was the dominant environmental factor that controlled seasonal and interannual variation in TER in this grassland, when variation in temperature was held constant. We compared respiration rates measured with chambers and that determined from nighttime eddy covariance (EC) measurements. Respiration rates measured by both techniques showed very similar seasonal patterns of variation in both years. When TER was integrated over the entire growing season period, the chamber method produced slightly higher values than the EC method by approximately 4.5% and 13.6% during 2001 and 2002, respectively, much less than the estimated uncertainty for both measurement techniques. The two methods for calculating respiration had only minor effects on the seasonal-integrated estimates of net ecosystem CO₂ exchange and ecosystem gross photosynthesis.