Monitoring organic contaminants in eggs of glaucous and glaucous-winged gulls (Larus hyperboreus and Larus glaucescens) from Alaska

Gull eggs have been used to monitor contaminants in many parts of the world. The Seabird Tissue Archival and Monitoring Project (STAMP) is a long-term program designed to track trends in pollutants in northern marine environments using seabird eggs. Glaucous and glaucous-winged gull (Larus hyperboreus and Larus glaucescens) eggs collected in 2005 from seven Alaskan colonies were analyzed for organic contaminants. Concentrations ranged from below detection limits to 322 ng g⁻¹ wet mass in one egg for 4,4′-DDE and differed among the samples collected in the Gulf of Alaska and Bering and Chukchi Seas. Chick growth and survival rates may be affected by the contaminant levels found in the eggs, but the eggs should be safe for human consumption if they are eaten in small quantities. STAMP plans to continue collecting and banking gull eggs for future real-time and retrospective analyses.     

Sensitivity of a molecular marker based positive matrix factorization model to the number of receptor observations

To investigate the impact of the number of observations on molecular marker-based positive matrix factorization (MM-PMF) source apportionment models, daily PM_2.5 samples were collected in East St. Louis, IL, from April 2002 through May 2003. The samples were analyzed for daily 24-h average concentrations of elemental and organic carbon, trace elements, and speciated particle-phase organic compounds. A total of 273 sets of observations were used in the model and consisted of all valid sets of observations from the year long data set minus one sixth of the measurements, which were collected every 6th day and were analyzed by different chemical analysis techniques. In addition to the base case of 273 samples, systematic subsets of the data set were analyzed by PMF. These subsets of data included 50% of the observations (135–138 days), 33% of the observations (90–92 days) and 20% of the observations (52–56 days). In addition, model runs were also examined that used 48-h, 72-h, 6-day, and weekly average concentrations as model inputs. All MM-PMF model runs were processed following the same procedures to explore the stability of the source attribution results. Consistent with previous MM-PMF results for East St. Louis, the main sources of organic aerosol were found to be mobile sources, secondary organic aerosols (SOAs), resuspended soil and biomass combustions, as well as an n-alkane dominated point source and other combustion sources. The MM-PMF model was reasonably stable when the number of observations in the input was reduced to ninety, or approximately 33% of observations present in the base case. In these cases, the key factors including resuspended soil, mobile and secondary factors, which accounted for more than 70% of the measured OC concentrations, were stable as defined by a relative standard deviation (RSD) of less than 30%. Similar results were obtained from the smaller data subsets, but resulted in larger uncertainties, with several of these factors yielding RSD of greater than 30%. The three factors with the largest OC contributions were more stable than the other minor factors, even when the number of observations was nominally 50 days. Secondary organic aerosol (SOA) was the most stable factor observed in the model runs. Since it is unclear if these results can be broadly applied to all MM-PMF models, additional studies of this nature are needed to assess the broader applicability of these conclusions. Until such studies are implemented, this paper provides a foundation to design future studies in sampling strategies for source apportionment using MM-PMF.     

Safety management by use of laser mass spectrometry of polychlorinated biphenyls (PCBs) in the processed gas and work environment of a PCB disposal plant

This study demonstrates the applicability of laser mass spectrometry for safety management of the processed gas and the work environment in a polychlorinated biphenyl (PCB) disposal plant. By utilization of laser ionization/ion trapping storage/time-of-flight mass spectrometry (LI-IT-TOFMS), we analyzed gaseous PCBs from scrap capacitors with on-line detection. It was confirmed that few contaminants were detected in the spectrum. By the effect of laser-induced selective ionization, it was considered that there was little interference with the mass range of PCBs. The accuracy of LI-IT-TOFMS when analyzing environmental gas was almost the same as that for the PCB standard gas. It was possible to perform on-line analysis of the work environment for over 2000 h (120 000 data points). LI-IT-TOFMS was thus shown to be a very useful method for ensuring the safety of the work environment in disposal plants for PCBs.     

Effect of humic matter on metal adsorption onto clay materials: Testing the linear additive model

Migration of contaminants with low affinity for the aqueous phase is essentially governed by interaction with mobile carriers such as humic colloids. Their impact is, however, not sufficiently described by interaction constants alone since the humic carriers themselves are subject to a solid–liquid distribution that depends on geochemical parameters.In our study, co-adsorption of the REE terbium (as an analogue of trivalent actinides) and humic acid onto three clay materials (illite, montmorillonite, Opalinus clay) was investigated as a function of pH. ¹⁶⁰Tb(III) and ¹³¹I-labelled humic acid were employed as radiotracers, allowing experiments at very low concentrations to mimic probable conditions in the far-field of a nuclear waste repository. Humate complexation of Tb was examined by anion and cation exchange techniques, also considering competitive effects of metals leached from the clay materials.The results revealed that desorption of metals from clay barriers, occurring in consequence of acidification processes, is generally counteracted in the presence of humic matter. For all clay materials under study, adsorption of Tb was found to be enhanced in neutral and acidic systems with humic acid, which is explained by additional adsorption of humic-bound Tb.A commonly used composite approach (linear additive model) was tested for suitability in reconstructing the solid–liquid distribution of Tb in ternary systems (Tb/humic acid/clay) on the basis of data determined for binary subsystems. The model can qualitatively explain the influence of humic acid as a function of pH, but it failed to reproduce our experimental data quantitatively. It appears that the elementary processes (metal adsorption, metal–humate complexation, humic acid adsorption) cannot be considered to be independent of each other. Possible reasons are discussed.     

Aniline and 2,4,6-trinitrotoluene associate preferentially to low molecular weight fractions of dissolved soil organic matter

Aniline and 2,4,6-trinitrotoluene (TNT) were equilibrated with particulate (POM) and dissolved organic matter (DOM) from an organic soil at different compositions of adsorbed major cations (Na, Al) and pH (aniline: 3.7–5.1, TNT: 4.8–5.0). After separation of POM, concentrations of ¹⁴C-labelled aniline and TNT* (including TNT degradation products) were determined in DOM size fractions using size-exclusion chromatography (SEC) and UV-detection. Concentrations in the <3.5 kDa size fraction were 2.8–6.0 and 8.5–9.5 times higher for aniline and TNT*, respectively, as compared to the >40 kDa fraction. Thus, both aniline and TNT* were preferentially associated to the smallest DOM size fraction. The significant binding to DOM (similar extent as to POM) and the fact that the <3.5 kDa DOM fraction was less susceptible to flocculation by major metals suggests that the mobility of aniline and TNT is highly affected by the solubility of soil organic matter.     

Historical record of black carbon in urban soils and its environmental implications

Energy use in urbanization has fundamentally changed the pattern and fluxes of carbon cycling, which has global and local environmental impacts. Here we have investigated organic carbon (OC) and black carbon (BC) in six soil profiles from two contrast zones in an ancient city (Nanjing) in China. BC in soils was widely variable, from 0.22 to 32.19 g kg⁻¹. Its average concentration in an ancient residential area (Zone 1) was, 0.91 g kg⁻¹, whereas in Zone 2, an industrial and commercial area, the figure was 8.62 g kg⁻¹. The ratio of BC/OC ranged from 0.06 to 1.29 in soil profiles, with an average of 0.29. The vertical distribution of BC in soil is suggested to reflect the history of BC formation from burning of biomass and/or fossil fuel. BC in the surface layer of soils was mainly from traffic emission (especially from diesel vehicles). In contrast, in cultural layers BC was formed from historical coal use. The contents of BC and the ratio of BC/OC may reflect different human activities and pollution sources in the contrasting urban zones. In addition, the significant correlation of heavy metals (Cu, Pb, and Zn) with BC contents in some culture layers suggests the sorption of the metals by BC or their coexistence resulted from the coal-involved smelting.     

添加小麦秸秆对猪粪高温堆肥腐熟进程的影响

选用猪粪与小麦秸秆为堆肥原料进行高温好氧堆肥实验,研究添加小麦秸秆对猪粪高温好氧堆肥过程中堆体温度、pH值、种子发芽指数、碳氮比和养分等理化指标的影响,寻求猪粪高温堆肥时的最佳秸秆配比,旨在为猪粪快速资源化利用提供科学依据。结果表明,猪粪高温堆肥时添加小麦秸秆可以缩短进入高温发酵阶段的时间,减少氮素损失,加快C/N的降低速率,加速有毒有害物质分解。其中猪粪和小麦秸秆6∶4处理各层温度在2~5 d内上升至50℃,并持续37~46 d,在堆肥结束时,有机质和速效氮含量较堆肥初期下降幅度最小,分别为33.90%和23.76%,全氮、全磷、全钾、速效磷和速效钾含量较堆肥初期提高幅度最大,分别为13.34%、20.24%、53.19%、41.53%和16.57%。若以种子发芽指数80%作为堆肥腐熟的评价指标,猪粪和小麦秸秆6∶4配比堆肥的腐熟速度比纯猪粪快18 d,36 d即可腐熟。综合判断,实际应用中,猪粪与小麦秸秆按体积6∶4进行堆肥较为适宜。     

牛粪堆肥腐殖质的动态变化研究

牛粪堆肥实质是有机物质分解的同时形成腐殖质的过程。本研究通过向牛粪中接种发酵微生物进行堆肥,研究分析了总有机碳含量、总腐殖酸、游离腐殖酸和水溶性腐殖酸等的腐殖质物质含量的动态变化。研究结果表明：在牛粪发酵过程中,总有机碳含量呈明显降低趋势,发酵微生物处理下的下降幅度明显大于不接种发酵微生物的处理;总腐殖酸、游离腐殖酸和水溶性腐殖酸含量在发酵前期呈明显的降低趋势,但至发酵腐熟期又逐渐升高。发酵前期,外源微生物的处理,使其下降幅度明显大于不接种外源微生物的处理,但在发酵腐熟期变化不大。     

Reduction of Cr(VI) by malic acid in aqueous Fe-rich soil suspensions

Detoxification of Cr(VI) through reduction by organic reductants has been regarded as an effective way for remediation of Cr(VI)-polluted soils. However, such remediation strategy would be limited in practical applications due to the low Cr(VI) reduction rate. In this study, the catalytic effect of two Fe-rich soils (Ultisol and Oxisol) on Cr(VI) reduction by malic acid was evaluated. As the results shown, the two soils could obviously accelerate the reduction of Cr(VI) by malic acid at low pH conditions, while such catalytic effect was gradually suppressed as the increase in pH. After reaction for 48 h at pH 3.2, Oxalic acid was found in the supernatant of Ultisol, suggesting the oxidization of hydroxyl in malic acid to carboxyl and breakage of the bond between C₂ and C₃. It was also found that the catalytic reactivity of Ultisol was more significant than that of Oxisol, which could be partly attributed to the fact that the amount of Fe(II) released from the reductive dissolution of Ultisol by malic acid was larger than that of Oxisol. With addition of Al(III), the catalytic effect from Ultisol was inhibited across the pH range examined. On the contrary, the presence of Cu(II) would increase the catalytic effect of Ultisol, which was more pronounced with the increase in pH. This study proposed a potential way for elimination of the environmental risks posed by the Cr(VI) contamination by use of the natural soil surfaces to catalyze Cr(VI) reduction by the organic reductant such as malic acid, a kind of organic reductant originating from soil organic decomposition process or plant excretion.     

Sorption, desorption, and degradation of (4-chloro-2-methylphenoxy)acetic acid in representative soils of the Danubian Lowland, Slovakia

Herbicide leaching through soil into groundwater greatly depends upon sorption-desorption and degradation phenomena. Batch adsorption, desorption and degradation experiments were performed with acidic herbicide MCPA and three soil types collected from their respective soil horizons. MCPA was found to be weakly sorbed by the soils with Freundlich coefficient values ranging from 0.37 to 1.03 mg^1−1/n kg⁻¹ L^1/n. It was shown that MCPA sorption positively correlated with soil organic carbon content, humic and fulvic acid carbon contents, and negatively with soil pH. The importance of soil organic matter in MCPA sorption by soils was also confirmed by performing sorption experiments after soil organic matter removal. MCPA sorption in these treated soils decreased by 37-100% compared to the original soils. A relatively large part of the sorbed MCPA was released from soils into aqueous solution after four successive desorption steps, although some hysteresis occurred during desorption of MCPA from all soils. Both sorption and desorption were depth-dependent, the A soil horizons exhibited higher retention capacity of the herbicide than B or C soil horizons. Generally, MCPA sorption decreased in the presence of phosphate and low molecular weight organic acids. Degradation of MCPA was faster in the A soil horizons than the corresponding B or C soil horizons with half-life values ranging from 4.9 to 9.6 d in topsoils and from 11.6 to 23.4 d in subsoils.