土壤中苯系物的吹扫捕集-气相色谱-质谱测定方法

采用吹扫捕集-气相色谱-质谱联用(PT-GC-MS)法,研究了污染土壤中苯系物(包括苯、甲苯、乙苯、对间二甲苯、邻二甲苯和异丙苯)的测定方法,优化了吹扫捕集作为北京潮土中苯系物预处理方法的参数. 结果表明,吹扫时间11 min,解吸温度190 ℃和解吸时间0.5 min为最佳的吹扫捕集方法参数. 采用PT-GC-MS法测定土壤中的苯系物的平均加标回收率为99.0%～103.9%,相对标准偏差为10.3%～17.5%(n=7);苯系物的检出限为1.6～2.8 μg/kg,定量限为5.4～9.6 μg/kg. 将研究结果与文献中的苯系物监测质量控制参数进行比较发现,由于采用有机质含量低、砂质壤土质地的北京潮土为研究对象,使该试验的回收率均高于文献中的结果;同时,相对标准偏差和检出限与文献中的结果也存在差异,主要是由于挥发性污染物所赋存的介质及实验仪器操作条件不同所致.      

沈阳地区地表水、浅层地下水及沿岸土壤中苯

对沈阳地区主要地表水(浑河、细河、蒲河、沈抚灌渠)及其沿岸地下水和土壤中苯系物(BTEX)的污染特点和分布特征进行了研究.结果表明:细河和沈抚灌渠地表水中BTEX检出率较高(33%～67%),苯和甲苯是该区域的主要污染物,ρ(苯)和ρ(甲苯)分别为<0.30～24.90和<0.30～354.00 μg/L;地表水检出的BTEX均未超过《生活饮用水卫生标准》(GB5749—2006)的限值(1 510 μg/L). 细河两岸的浅层地下水在一定程度上受到BTEX的污染,苯和甲苯的检出率分别为25%～33%和13%～25%,二甲苯和乙苯检出率较低(0～20%). 彰驿镇19个监测井中有2个浅层地下水监测井中的ρ(苯)超过GB5749—2006限值(10 μg/L),夏季ρ(苯)最大值为236.00 μg/L. 沿岸附近土壤中5种BTEX全部被检出,检出率均高于相应的河水. 研究区包气带土壤层虽具有良好的防污性能,但也具有储存和阻碍BTEX挥发和降解的负面效应,对当地的生态系统和人类健康构成了潜在的威胁.      

顶空-固相微卒取-气相色谱测定水体中痕量苯系物

对测定水体中痕量苯系物的顶空-固相微萃取-气相色谱法的固相微萃取条件进行了对比优化,经过对水体中的7种苯系物对比实验,确定了顶空-固相微萃取-气相色谱法的固相微萃取的最佳实验条件为：选用75μmCAR/PDMS萃取涂层,加入与水质量比为40%的氯化钠,于20℃温度下萃取40min,解析3min。方法检出限为0.12～0.19μg/L,相对标准偏差2.0%～3.9%。依据确定的优化条件,用不同类型的水样对优化后的试验条件进行了验证试验,回收率在96.2%～102.0%之间,表明优化后的试验条件适用于多类型水体中痕量苯系物的分析测定。     

耐低温混菌降解苯系物的特性及菌种鉴定研究

以吉化双苯厂被硝基苯、苯系物（BTEX）污染的土壤为菌源,经过筛选驯化得到一组在低温条件（10℃）下可降解苯系物（BTEX）的混菌。室内研究表明,在10℃,pH=6.8,苯系物（BTEX）总质量浓度200mg·L^-1的条件下,84h后该菌对苯、甲苯、乙苯、二甲苯的降解率依次为93.2%、95.6%、91%、88.4%、对6种质量浓度的苯系物（BTEX）污染物中最难降解的苯进行降解动力学曲线模拟,当苯质量浓度小于17.48mg·L-1时,降解符合一级降解动力学,当苯的质量浓度为17.48～195.30mg·L^-1时,降解符合零级降解动力学、该混菌降解效果稳定、适应环境能力强,经80次传代后仍能保持良好的降解效果,且在6个不同地区含有不同背景组成的地下水中降解效果稳定、应用Biolog细菌自动鉴定系统和16SrDNA序列分析方法对降解率较高的3株菌B2、B4、B6作菌种鉴定,B2为嗜麦芽糖寡养单胞菌（Stenotrophomonas maltophilia）,B4为斑生假单胞菌（Pseudomonas maculicola）,B6为多刺假单胞菌（Pseudomonas spinosa）。     

Source Apportionment and Identification of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediment Cores of Selected Creeks in Delta State,Nigeria

Polycyclic aromatic hydrocarbons (PAHs) seasonal variation and sources in Ubeji, Ifie, and Egbokodo Creeks of the Niger Delta, Nigeria, were predicted using diagnostic ratios (DRs) of parent PAHs (Phe/Phe + Ant; Flu/Flu + Pyr; BaA/BaA + Chry, and Ind/Ind + BghiP) and principal component analysis (PCA). A total of 222 sediment core samples were collected during the wet (August 2010) and the dry seasons (January 2011). The samples were dried and Soxhlet extracted; sample extracts were fractionated and analyzed by gas chromatography/flame ionization detection (GC/FID) to identify individual PAHs. The diagnostic PAH ratios revealed that PAHs in the sediment cores at the three creeks, in both seasons, mainly stemmed from the combustion process (pyrogenic sources). Principal component analysis further confirmed that wood-burning, coal combustion, diesel, gasoline-powered vehicular emissions, and petroleum combustion were the dominant contributors of PAHs sources at the sampling location. This study provided information on the origin and sources of PAHs in sediment cores, which may be useful for regulatory actions, environmental quality management, contamination history, and environmental forensic studies.     

地下水中BTEX的原位生物修复研究进展

BTEX是苯、甲苯、乙苯和二甲苯的统称,存在于原油和石油产品中,其作为化工原料,广泛应用于农药、塑料及合成纤维等制造业.BTEX已成为地下水中普遍存在的污染物,自然衰减或生物修复工程已成功应用于地下水中BTEX的去除.自然衰减受BTEX污染的地下水具有良好的效果,但相比之下,生物修复工程更快、更有效.综述了在好氧和厌氧条件下,地下水中BTEX原位生物修复过程的微生物降解机制.     

Birth sex ratios in toque macaques and other mammals: integrating the effects of maternal condition and competition

Mammalian life histories suggest that maternal body condition and social dominance (a measure of resource-holding potential) influence the physical and social development of offspring, and thereby their reproductive success. Predictably, a mother should produce that sex of offspring which contributes most to her fitness (as measured by the number of her grandchildren) and that she is best able to raise within the constraints imposed by her condition, social rank, and environment. Such combined effects were investigated by monitoring variations in body condition (weight) and behavior of female toque macaques, Macaca sinica of Sri Lanka, in a changing forest environment over 18 years. Maternal rank, by itself, had no influence on offspring sex, but did affect maternal body condition. The combined effects of rank and condition indicated the following: mothers in robust condition bore more sons, whereas those in moderate condition bore more daughters, but both effects were expressed most strongly among mothers of high rank. Where the consequences of low rank were felt most acutely, as shown by poor condition, mothers underproduced daughters. Environmental quality directly influenced rank and condition interactions, and thus sex ratios. These relationships, and data from other mammals suggest an empirically and theoretically consistent pattern of sex allocation in mammals. New predictions integrate effects, proposed by Trivers and Willard, that are rooted in male mate competition, which is universal among polygynous mammals, with those of local resource competition (and/or female reproductive competition), which are not universal and differ in intensity between the socioecologies and local environments of different species. Received: 30 May 1998 / Accepted after revision: 29 August 1998     

Intraspecific parasitism and split sex ratios in a monogynous and monandrous ant (Leptothorax nylanderi)

Sex ratios were bimodally distributed in a population of the monogynous and monandrous ant Leptothorax nylanderi during each of 3 study years. The population-wide investment ratios suggested worker control of sex allocation. Nest-level variation in the proportional investment in virgin queens was not affected by the presence or absence of a queen and only slightly by collecting year, but was correlated with nest size, total sexual investment and, unexpectedly, with differences in nestmate relatedness: small, low-investment nests and nests with several worker lineages produced male-biased sex ratios. Colonies containing several worker lineages arise from usurpation of mature colonies by unrelated founding queens and the fusion of unrelated colonies under strong nest site limitation. In contrast to facultatively polygynous and polyandrous species of social insects, where workers can maximize their inclusive fitness by adjusting sex ratios according to the degree of relatedness asymmetry, workers in mixed colonies of L. nylanderi do not benefit from manipulating sex allocation, as here relatedness asymmetries appear to be the same as in homogeneous colonies. Received: 7 December 1999 / Received in revised form: 29 February 2000 / Accepted: 13 March 2000     

The independent origin of a queen number bottleneck that promotes cooperation in the African swarm-founding wasp, Polybioides tabidus

When cooperation is based on shared genetic interests, as in most social insect colonies, mechanisms which increase the genetic similarity of group members may help to maintain sociality. Such mechanisms can be especially important in colonies with many queens because within-colony relatedness drops quickly as queen number increases. Using microsatellite markers, we examined the Old World, multiple-queen, swarm-founding wasp Polybioides tabidus which belongs to the ropalidiine tribe, and found that relatedness among the workers was four times higher than what would be expected based on queen number alone. Relatedness was elevated by a pattern of queen production known as cyclical oligogyny, under which, queen number varies, and daughter queens are produced only after the number of old queens has reduced to one or a very few. As a result, the queens are highly related, often as full sisters, elevating relatedness among their progeny, the workers. This pattern of queen production is driven by collective worker control of the sex ratios. Workers are three times more highly related to females than to males in colonies with a single queen while they are more equally related to males and females in colonies with more queens. As a result of this difference, workers will prefer to produce new queens in colonies with a single queen and males in colonies with many queens. Cyclical oligogyny has also evolved independently in another group of swarm-founding wasps, the Neotropical epiponine wasps, suggesting that collective worker control of sex ratios is widespread in polistine wasps. Received: 22 May 2000 / Revised: 24 August 2000 / Accepted: 4 September 2000     

Anaerobic biodegradation of benzene series compounds by mixed cultures based on optional electronic acceptors

A series of batch experiments were performed using mixed bacterial consortia to investigate biodegradation performance of benzene, toluene, ethylbenzene and three xylene isomers （BTEX） under nitrate, sulfate and ferric iron reducing conditions. The results showed that toluene, ethylbenzene, m-xylene and o-xylene could be degraded independently by the mixed cultures coupled to nitrate, sulfate and ferric iron reduction. Under ferric iron reducing conditions the biodegradation of benzene and p-xylene could be occurred only in the presence of other alkylbenzenes. Alkylbenzenes can serve as the primary subs＇rates to stimulate the transformation of benzene and p-xylene under anaerobic conditions. Benzene and p-xylene are more toxic than toluene and ethylbenzene, under the three terminal electron acceptors conditions, the degradation rates decreased with toluene 〉 ethylbenzene 〉 m-xylene 〉 o-xylene〉 benzene 〉 p- xylene. Nitrate was a more favorable electron acceptor compared to sulfate and ferric iron. The ratio between sulfate consumed and the loss of benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene was 4.44, 4.51, 4.42, 4.32, 4.37 and 4.23, respectively; the ratio between nitrate consumed and the loss of these substrates was 7.53, 6.24, 6.49, 7.28, 7.81, 7.61, respectively; the ratio between the consumption of ferric iron and the loss of toluene, ethylbenzene, o-xylene, m-xylene was 17.99, 18.04, 18.07, 17.97, respectively.