Airborne observations of vegetation and implications for biogenic emission characterization

Measuring hydrocarbons from aircraft represents one way to infer biogenic emissions at the surface. The focus of this paper is to show that complementary remote sensing information can be provided by optical measurements of a vegetation index, which is readily measured with high temporal coverage using reflectance data. We examine the similarities between the vegetation index and in situ measurements of the chemicals isoprene, methacrolein, and alpha-pinene to estimate whether the temporal behavior of the in situ measurements of these chemicals could be better understood by the addition of the vegetation index. Data were compared for flights conducted around Houston in August and September 2000. The three independent sets of chemical measurements examined correspond reasonably well with the vegetation index curves for the majority of flight days. While low values of the vegetation index always correspond to low values of the in situ chemical measurements, high values of the index correspond to both high and low values of the chemical measurements. In this sense it represents an upper limit when compared with in situ data (assuming the calibration constant is adequately chosen). This result suggests that while the vegetation index cannot represent a purely predictive quantity for the in situ measurements, it represents a complementary measurement that can be useful in understanding comparisons of various in situ observations, particularly when these observations occur with relatively low temporal frequency. In situ isoprene measurements and the vegetation index were also compared to an isoprene emission inventory to provide additional insight on broad issues relating to the use of vegetation indices in emission database development.     

Free phosphine from the anaerobic biosphere

The possible liberation of highly toxic and mutagenic phosphine from putrefying media raises the question of its significance as a problem of hygiene. Free phosphine was established by gas chromatography as a universal trace component in gas emitted from the anaerobic biosphere. Sources of phosphine include landfills, compost processing, sewage sludge, animal slurry and river sediments. We detected maximum concentrations in the order of 20 ppb(v/v).     

Sources of airborne CC14

Atmospheric mixing ratios of chlorinated C₁ and C₂ hydrocarbons (CHCs) were measured at the mountain Wank (Garmisch-Partenkirchen, Bavarian Alps) in autumn 1992. The data lead to the assumption that at least part of the observed CC1₄ originates from a source different to the other CHCs measured (C₂HCL₃, C₂C1₄, CHCl₃ and CH₃CCl₃). The nature of this source is discussed.     

Intrageneric differences in the four stereoisomers of stenusine in the rove beetle genus, Stenus (Coleoptera, Staphylinidae)

Most species of the rove beetle genus Stenus employ the spreading alkaloid stenusine as an escape mechanism on water surfaces. In the case of danger, they emit stenusine from their pygidial glands, and it propels them over the water very quickly. Stenusine is a chiral molecule with four stereoisomers: (2′R,3R)-, (2′S,3R)-, (2′S,3S)-, and (2′R,3S)-stenusine. The percentile ratio of these four isomers is only known for the most common species of the genus: Stenus comma. With the intention of determining the stereoisomer ratios of five additional species from the two subgenera, Stenus and Hypostenus, we used GC/mass spectrometry measurements with a chiral phase. The results showed that the ratio differs among the genus. These findings can be a basis for chemotaxonomy. It is also possible that the biological function of stenusine, e.g., as antibiotic or fungicide, varies with changing stereoisomer composition.

Commercialization of Perennial GE Crops: Looming Challenges for Regulatory Frameworks

Overall, the deregulation of genetically engineered (GE) crops for commercial cultivation in North America has been a success story. In several cases, however, GE crops have sparked concerns and disagreements among the stakeholders and there are incidences of court lawsuits, including a recent one on glyphosate resistant (GR) alfalfa (Medicago sativa, L.). While GE crops can provide operational benefits to farmers, challenges are looming from commercialization of perennial GE crops. The unique ecology and biology of these crops and GE alfalfa in particular can facilitate adventitious presence (AP) of GE traits and it makes more visible that economic risks for conventional growers and food/feed producers have not been adequately addressed by the GE regulatory system in the United States (US). Asynchronous market approvals and the existence of a number of GE sensitive export markets create uncertainties among the exporters. Policy development in these fields may be helpful for ensuring a broader acceptance and market success of GE agriculture in general. The analysis is focusing on the US, although many diagnosed problems are also relevant to other jurisdictions—in particular if no co-existence policy is in place.     

Levels of persistent organic pollutants in the Neretva River (Bosnia and Herzegovina) determined by deployment of semipermeable membrane devices (SPMD)

The main objective of this study was to determine levels of certain persistent organic pollutants (POPs) in Neretva River, Bosnia and Herzegovina (BiH), which is currently facing implementation of the Stockholm Convention on persistent organic pollutants (POPs) and environmental protection strategies. This is the very first report on the deployment of semipermeable membrane devices (SPMDs) in BiH. SPMDs were used for continuous 3-weeks sampling of POPs at three locations, covering 220 km long stream of the Neretva River. Water concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polybrominated diphenylethers (PBDEs) were calculated using performance reference compounds (PRCs). The total OCP concentrations ranged from 40 to 140 pg L^?1 and most of compounds were detected only in lower course of the river. Total PAH ranged from 160 to 4000 pg L^?1 and show a clear spatial variation. Dominant PAHs were phenanthrene, fluoranthene, fluorene and acenaphthene. Total PCB ranged from undetectable to 120 pg L^?1. From the group of 15 PBDE congeners investigated, only PBDE-47 and PBDE-99 were detected. Since the concentrations of broad spectrum of POPs found in the Neretva River are quite low, future actions should be focused on preservation rather than on sanitation measures. Regular monitoring should anyhow be established.     

PAH and PCB in soils of Switzerland--status and critical review

The surface soil concentrations (0-20 cm) of the Swiss soil monitoring network (NABO) with 105 observation sites representing all major land use types ranged for the sum of 16 EPA PAH (PAH(16)) from 32 to 8465 microg kg(-1) (median 163 microg kg(-1)), for benzo[a]pyrene (BaP) from 0.5 to 1129 microg kg(-1) (median 13 microg kg(-1)) and for the sum of seven IRMM PCB (PCB(7)) from 0.5 to 12 microg kg(-1) (median 1.6 microg kg(-1)). The legal guide values of Switzerland were exceeded for PAH(16) at only three and for BaP at two sites. The PCB(7) concentrations were clearly below any assessment value. The concentration ranges were overlapping between all land use types. Tendencies for higher concentrations were observed at urban and viticulture sites. The overall measurement precision at repeatability conditions ranged from 1 to 37% RSD for PAH(16), BaP and PCB(7). The median bias for the chemical analysis was around zero for PAH(16), +5% for BaP and -5% for PCB(7) with spreads ranging from less than -20% up to more than +30%. The PAH profiles were clearly dominated by phenanthrene. Stratification by land use revealed a prevalence of benzo[a]pyrene at urban and naphthalene at conservation sites. For PCB, the general congener rank order was PCB no. 153 > 138 > 101 > 180. From a broad correlation screening only PAH(16)/BaP (r = 0.88**) were relevant for practical soil protection. The extensive comparison with other studies was severely biased by the lack of harmonisation, especially concerning sampling depth, sampling support, analytical method and the sum calculation procedure.     

Critical evaluation of PAH source apportionment tools using data from the Swiss soil monitoring network

In this study a large dataset on the polycyclic aromatic hydrocarbon (PAH) content of Swiss soils was analysed to evaluate two source apportionment tools, i.e., characteristic PAH ratios/molecular markers and a linear mixing model. Population density and total organic carbon (TOC) content were identified by a multiple regression model as independently and positively influencing the PAH concentrations in Swiss background soil. Specifically, TOC was more strongly positively correlated with the sum of light PAH (naphthalene to phenanthrene) than with the sum of heavy PAH (anthracene to benzo[ghj]perylene), whereas population density was more strongly positively correlated with the sum of heavy PAH than with light PAH. In addition, the sum of the heavy PAH as well as the total sum correlated negatively with sample site altitude. It is therefore hypothesised that heavy PAH are less mobile, whereas light PAH were closer to equilibrium with TOC in the soil. Similar results were found for polychlorinated biphenyls (PCB). The characteristic ratios and molecular markers pointed to pyrogenic origin of PAH in Swiss background soil but did not allow for further differentiation of individual fuel contributions, even though attempts to take environmental fractionation processes into account were made. The comparison of three soil profiles identified with a linear mixing model from the pattern of 16 PAH with >300 PAH emission profiles from the literature suggested urban dust, wood combustion and binders from asphalt as PAH sources. However, also here, environmental fractionation processes probably obscured source characteristic PAH ratios and fingerprints, which thus need to be interpreted with caution.     

Remediation of a Former Dry Cleaner Using Nanoscale Zero Valent Iron

Nanoscale zero valent iron (nZVI) was evaluated in a laboratory treatability study and subsequently injected as an interim measure to treat source area groundwater impacts beneath a former dry cleaner located in Chapel Hill, North Carolina (the site). Dry cleaning operations resulted in releases of tetrachloroethene (PCE) that impacted site soil at concentrations up to 2,700 mg/kg and shallow groundwater at concentrations up to 41 mg/L. To achieve a design loading rate of 0.001 kg of iron per kilogram of aquifer material, approximately 725 kg of NanoFe? (PARS Environmental) was injected over a two‐week period into a saprolite and partially weather rock aquifer. Strong reducing conditions were established with oxidation–reduction potential (ORP) values below –728 mV. pH levels remained greater than 8 standard units for a period of 12 months. Injections resulted in near elimination of PCE within one month. cis‐1,2‐Dichloroethene accumulated at high concentrations (greater than 65 mg/L) for 12 months. MAROS software (Version 2.2; AFCEE, 2006 ) was used to calculate mass reduction of PCE and total ethenes at 96 percent and 58 percent, respectively, compared to baseline conditions. Detections of acetylene confirmed the presence of the beta‐elimination pathway. Detections of ethene confirmed complete dechlorination of PCE. Based on hydrogen gas generation, iron reactivity lasted 15 months. © 2013 Wiley Periodicals, Inc.