Organic geochemical parameters for estimation of petrogenic inputs in the coastal area of Kavala City,Greece

Background, aims, and scope  Sediments and soils in coastal areas are frequently polluted by anthropogenic contaminants as the result of both riverine or terrestrial discharge and autochthonic marine emissions. In order to determine petrogenic contamination in the coastal industrial area of Kavala City in northern Greece, a combination of polycyclic aromatic hydrocarbon (PAH) and organic geochemical petroleum biomarker analyses has been performed on marine and freshwater sediments as well as soils. Materials and methods  Soils, freshwater, and marine sediments have been treated by standard extraction methods. The dried and desulphurized sample extracts have been fractionated by column chromatography, followed by addition of surrogate standards. Qualitative and quantitative data were obtained by gas chromatograph connected with a flame ionization and electron capture detector (GC-FID/ECD) and by GC linked to a mass spectrometer (GC/MS), whereas identification of compounds was based on EI⁺-mass spectra and gas chromatographic retention times. Quantitative data were obtained by integration of specific ion chromatograms. Results  The total PAH concentrations measured in the area varied highly, showing different levels from 18 up to 318,000 ng g⁻¹ dry weight (dw). Several PAH ratios, as well as the ratio of pristane (Pr) to phytane (Phyt), have been considered. Out of 39 samples, 22 revealed a specific distribution of hopane fingerprints indicating petrogenic input. Finally, in numerous samples, the ratio of 17α(H)-22,29,30-trisnorhopane (Tm) and 18α(H)-22,29,30-trisnorhopane (Ts) was calculated, as well as the ratio of 22S-17α(H),21β(H)-30 homohopane (αβC₃₁-hopane 22S) and 22R-17α(H),21β(H)-30 homohopane (αβC₃₁-hopane 22R). Discussion  Based on the specific PAH ratios, a group of samples was clearly characterized to be contaminated dominantly by combustion-derived emissions, whereas a second group of samples exhibited mixed influence from petrogenic and pyrogenic PAHs. On the other hand, the exhibition of specific hopane fingerprints in many samples indicates a direct petrogenic input. Finally, the values of the ratio of Tm/(Ts + Tm) and of αβC₃₁-hopanes 22S/(22S+22R)-isomer demonstrated an input of highly mature organic matter that has to be clearly attributed to petroleum-derived contamination, while the ratio of Pr/Phyt showed that most samples exhibited an input of organic matter. Conclusions  The coastal area of Kavala is strongly affected by anthropogenic contaminants. Petrogenic emissions were pointed out firstly by PAH analyses that separated dominantly pyrogenic contaminated sites from areas affected by both pyrogenic and petrogenic emissions. However, analyses of organic geochemical biomarkers revealed a much higher sensitivity in identifying petroleum-derived contaminations and were successfully used to differentiate several petrogenic contaminations in the marine and terrestrial samples. Recommendations and perspectives  Based on this study, it was recommended to use a complementary approach of source-specific substances to successfully characterize petrogenic emissions. Generally, a PAH-based source identification of petrogenic versus pyrogenic contaminations should be combined with petroleum biomarker analysis. PAH and biomarker ratios as well as individual biomarker fingerprints revealed a more comprehensive view on the quality and quantity of petrogenic emissions in sediments and soils.     

Partitioning characteristics of PAHs between sediment and water in a shallow lake

Goal, Scope and Background

Distribution of hydrophobic organic contaminants in abiotic compartments is essential for describing their transfer and fate in aquatic ecosystems. Taihu Lake is the third largest freshwater lake in China. Water quality of Taihu Lake has deteriorated greatly during the last decades and has threatened the water supply. The aim of the present study was to investigate the partitioning of polycyclic aromatic hydrocarbons (PAHs) among overlying water, suspended particulate matter (SPM), sediments, and pore water in Meiliang Bay, Taihu Lake and to provide useful information for the ecological engineering in this area.

Materials and Methods

Overlying water and surface sediment were sampled from six sites in Meiliang Bay, Taihu Lake, China. Within 72 h of sampling, sediments were centrifuged to obtain the pore water. Overlying water samples were filtered to separate dissolved and SPM samples. After extraction, samples were purified following a clean-up procedure. PAH fraction was obtained by elution with a mixture of hexane: DCM (7:3, V/V) and analyzed by GC/MS.

Results

PAHs concentrations in overlying water varied from 37.5 ng/L to 183.5 ng/L. Concentrations of PAHs in pore water were higher than those in overlying water. The total concentrations of 16 priority PAHs in sediments ranged from 2091.8 ng/g-dw to 4094.4 ng/g-dw. PAHs concentrations on SPM were decreased with suspended solid concentrations (SSC). Total PAHs concentrations on SPM varied in the range of 3369.6 ng/g-dw to 7531.1 ng/g-dw. The partition coefficients between sediment and overlying water (log K _oc) for PAHs with log K _ow<5 were positively correlated with their octanol-water partition coefficients (log K _ow) (n=39, r=0.79, p<0.0001). Partition coefficients between sediment and pore water (log K _oc′) for all PAHs were also significantly correlated with their log K _ow values (n=48, r=0.82, p<0.0001).

Discussion

In general, PAHs derived from combustion sources tend to bind strongly to soot particles in natural sediment. Consequentially, K _oc values observed in the natural environment could be orders of magnitude higher than those predicted by linear correlation relationships under laboratory conditions. In the present study, the ratio of log K _oc values to log K _ow values falls consistently above 1, indicating that the sediment soot carbon in the bay was more attractive for PAHs than n-octanol. The log K _oc′ was also higher than that predicted under laboratory conditions, suggesting that the measured pore water PAH concentrations were lower than those predicted. That is to say, not all the sediment PAHs can be available to partition rapidly into sediment pore waters. A variation in soot content is a possible reason. Furthermore, concentrations of PAHs on SPM were higher than those in sediments. The compositions of PAHs on SPM and in sediments were similar, indicating the importance of re-suspension process of sediments in the partitioning process of the shallow lake.

Conclusions

The results indicated the equilibrium partitioning model could be used to predict PAHs distribution in various phases of a shallow lake in the stagnation period, but re-suspension processes should be considered to modify the relationship between log K _ocs and log K _ows.

Recommendations and Perspectives

Concentration, particle size and composition of resuspended particles could affect the relationship between log K _ocs and log K _ows. Further work should be done under field conditions, especially where a steady thermodynamic equilibrium state could be assumed.

     

十氯酮污染土壤上根茎作物收割部分的污染状况

A bacterial strain, Arthrobacter oxydans (B4), capable of degrading benzo[a]pyrene (BaP) in water body, was isolated from a polycyclic aromatic hydrocarbons-contaminated site. Effects of different factors, such as reaction time, pH value, temperature and organic nutrients, on BaP biodegradation by the strain B4 were studied. After 5 d treatment, the concentration of BaP in mineral salts medium was reduced to 0.318 mg L-1 , compared to the initial concentration of 1.000 mg L-1 . There was a process of acid formation during the degradation with pH falling from initial 7.01 to 4.61 at 5 d, so keeping the water body under slightly alkaline condition was propitious to BaP degradation. Strain B4 efficiently degraded BaP at 20 to 37 ℃ with addition of organic nutrients. The biodegradation and transformation of BaP mainly occurred on cell surfaces, and extracellular secretions played an important role in these processes. Fourier transform infrared spectroscopy and gas chromatograph-mass spectrometer analyses of metabolites showed that ring cleavage occurred in the BaP degradation process and the resulting metabolically utilizable substrates were generated as sole carbon sources for B4 growth. Furthermore, mineralization extent of metabolites was verified by determining the total organic carbon and inorganic carbon in the degradation system.     

ZSM-5催化生物质三组分和松木热解生物油组分分析

为了更清晰地研究三大组分(纤维素、木聚糖、木质素)在介孔ZSM-5参与下的催化热解过程,该研究首先对生物质的三大基本组分和云南松木粉进行热解,然后在介孔ZSM-5催化剂存在的条件下对微晶纤维素、木聚糖、碱性木质素三大组分和云南松进行催化热解。采用气质联用仪对生物油的化学组分进行分析。通过对比ZSM-5参与前后的生物油的主要化学组分的变化,对催化剂的催化机理进行探究。研究结果表明,催化热解过程中,介孔ZSM-5将纤维素直接热解得到的β-D阿洛糖、糠醛、3-丙基戊二酸和2,4-戊二烯酸转化为1-甲基萘、2,6-二甲基萘,纤维素催化热解得到的生物油中的芳烃含量为63.89%。半纤维素催化热解过程中,催化剂将生物油中的糠醛从67.78%降低为2.66%,有效提高芳烃化合物,包括萘、2-甲基萘的含量,催化热解后得到的生物油中总芳烃含量达到36.81%。木质素催化热解过程中,介孔ZSM-5有效降低生物油中2,6-二叔丁基对甲酚的量(从82.33%降至77.97%),并大幅地提高1,8-二甲基萘和1,7-二甲基萘的量,生物油中总芳烃相对含量达到14.14%。云南松催化热解过程中,催化剂有效降低云南松直接热解得到生物油中2-甲氧基-4-甲基苯酚和(Z)-异丁子香酚的含量,并将芳烃化合物总量提高到53.99%(主要是1-甲基萘、1-亚甲基-1氢-茚和2,6-二甲基萘)。随着催化剂使用次数的增加,生物油中含氧化合物相对含量增加,烃类化合物的相对含量明显降低,从53.99%降至43.32%,元素分析结果表明生物油中的碳含量逐渐减少,氧含量逐渐增加。但是,催化剂经过焙烧再生后,催化活性基本完全恢复。     

木糖氧化无色杆菌反硝化亚种细菌的分离鉴定及其菲降解特性研究

利用选择性富集培养及升华法,从石油污染的土壤中分离到2株菲降解细菌,它们在以菲为唯一碳源的培养基上生长良好。应用BIOLOG细菌鉴定系统和分子生物学方法对两株细菌进行鉴定,两株菌分别为坚强芽孢杆菌(Bacillus.firmus)和木糖氧化无色杆菌反硝化亚种(Achromobacter.xylosoxidanssub.sp.denitrificans),两株菌均具有邻苯二酚氧化酶活性。两株细菌在液体培养条件下都表现较强降解菲的能力,液体培养60.h约90%的加入菲被降解。通过测定液体培养基中菲浓度和菌体密度变化发现,菌株降解菲的量与其生长密度相关;随着菌体浓度(吸光度)的增加,代谢底物菲的浓度明显降低,两株菌混合使用能够大幅度提高降解菲的能力。     

海湾扇贝对柴油的富集与消除规律

采用半静态动力学富集实验方法,分别以石油烃、多环芳烃及含硫芳烃、烷烃为指标,通过分析海湾扇贝(Argopecten irradians)对轻柴油(–10#柴油)、重柴油的富集与消除规律,探讨柴油污染对海湾扇贝食用安全性的影响。实验结果表明:海湾扇贝体内石油烃、多环芳烃及含硫芳烃、烷烃含量与富集时间及水中石油烃浓度呈正相关。海湾扇贝不同组织对柴油的富集能力不同,累积量由高到低依次是内脏外套膜及鳃等其他组织闭壳肌。海湾扇贝对柴油的富集量与柴油的种类有关,相同条件下海湾扇贝对重柴油的富集量更高且消除速率比轻柴油慢,说明重柴油溢油污染对贝类质量安全的危害更大,更值得关注。受污染的扇贝移入清洁的海水中,体内的石油烃可以逐渐消除,消除速度要慢于富集速度。海湾扇贝对烷烃的富集倍数比多环芳烃低,消除速率比多环芳烃要快。海湾扇贝体内石油烃的消除主要是烷烃的贡献。受污染的海湾扇贝体内多环芳烃以2~3环为主,其消除速率比高环数多环芳烃快。受污染的海湾扇贝移入清洁的海水中,短时间内虽然石油烃残留量能下降至正常水平,但多环芳烃(尤其是高环数多环芳烃)残留仍会存在。因此建议在发生石油污染后,跟踪监测不仅要关注海水中石油烃,更要关注贝类体内石油烃,要将多环芳烃与石油烃的检测结果综合考虑。此外,出于食品安全考虑,食用扇贝时尽量去除内脏。     

芳香植物在高尔夫球场中的应用分析

21世纪以来,中国经济快速增长,带动了体育产业的发展,高尔夫运动也得到了快速的发展。然而,高尔夫运动伴随着较高风险的运动性肌肉疲劳与运动性心理疲劳。指出了芳香植物能在一定程度上预防并治疗运动性肌肉疲劳与心理疲劳,但相关研究多集中于临床治疗和医疗保健等方面。高尔夫球场上芳香植物的应用多以园林美化为目的,未能充分发挥其在运动性疲劳方面的预防与保健功效。因此,芳香植物在高尔夫球场上的应用前景亟待开发。     

北京东南郊再生水灌区土壤PAHs污染特征

采用Eijkelkamp土壤采样器对北京东南郊再生水灌区进行了3个钻孔剖面采样,同时采集了灌溉用水及地下水样品,并采用气相色谱-质谱联用仪对16种多环芳烃(PAHs)进行定量分析。结果表明,表层土壤中有14种PAHs检出,浓度在0.4～53.1μg·kg-1之间,∑PAHs平均含量为206.7μg·kg-1,达到了土壤污染临界值;表层以下PAHs的检出种类和含量显著减少,以中、低环的萘、菲、芴、荧蒽、芘为主,∑PAHs仅占表层的3.8%～12.0%,从剖面PAHs含量变化可以判断,低环PAHs较易迁移,迁移性强弱顺序为萘、芴>菲>芘、荧蒽;污灌区表土中PAHs组成与大气降尘接近,但与再生灌区有明显差异,这种差异主要由于灌溉用水不同所造成;再生水灌区表土以下土壤剖面检出的PAHs与再生水中的PAHs一致,说明再生水灌溉是导致土壤剖面PAHs污染的主要原因,同时地下水中检出的PAHs种类也与土壤剖面基本一致,但含量较高,可能是早期污水灌溉所造成。     

香稻品种2-乙酰-1-吡咯啉多样性及籽粒分布特征的研究

采用田间试验方法研究同一地点和时间种植、同一栽培条件下2-乙酰-1-吡咯啉在11个香稻品种间差异性及籽粒分布特征.结果表明,桂香丝糯、中健2号、清香米、泰国香稻1号R207和Texmati等5个品种含有2-乙酰-1-吡咯啉,精米与糠中的2-乙酰-1-吡咯啉含量在上述5个品种间存在显著差异(P<0.05),其中Texma...     

分蘖期水分对香稻香气及生理特性的影响

以常规香稻品种桂香占和美香占为材料,采用盆栽试验,研究了分蘖期水分对香稻香气及生理特性的影响。结果表明,分蘖期土壤水势维持在0～(-25±5)kPa时,显著增加了二香稻品种糙米的香气成分和籽粒的游离脯氨酸以及成熟期叶片、茎鞘和籽粒的脯氨酸氧化酶活性。分蘖期土壤水势维持在0～(-50±5)kPa时,降低了二品种籽粒脯氨酸氧化酶活性、糙米的香气成分和有效分蘖。因此,适当的分蘖期节水灌溉模式能有效提高香稻香气成分,且不影响水稻后期生理特性。