Physical and Thermal Analysis of the Degradation of Poly(3-Hydroxybutyrate-<Emphasis Type="Italic">co</Emphasis>-4-Hydroxybutyrate) Coated Paper in a Constructed Soil Medium

The degradation of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB)) coated brown Kraft paper and its components in a constructed soil environment was investigated. Soil burial tests were carried out over 8 weeks. Weight loss measurements, photographic analysis, environmental scanning electron microscopy (ESEM), dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) were conducted to assess the physical, structural, mechanical and thermal behavior before and after the soil burial test. Paper showed the highest physical degradation and weight loss. With respect to the control samples, the stiffness of the partially degraded samples decreased. The overall crystallinity of the biopolymer and the coated paper was affected significantly by burial. The pure biopolymer’s weight loss was substantially enhanced when coated on paper. This result reveals a possible increased microbial population in the coated paper relative to the pure biopolymer.     

Changes in character of organics in the receiving environment of effluent from a sulphite pulp mill

Purpose

The characteristics of organics in sulphite pulp mill effluent and in the receiving environment of effluent discharge were investigated to assess the basis for the persistence or attenuation of colour.

Methods

Characterization of organics was conducted through determination of SUVA, specific colour, and molecular weight distribution of organics using high performance size exclusion chromatography and by solid-state ¹³?C cross polarization (CP) NMR. The characteristics of organics from mill wastewater before and after secondary aerobic treatment, followed by lime treatment and from the receiving environment, an enclosed brackish lake were compared. Changes in the character of organics in lake water over a period of 14?years were studied in the context of changes in mill processing and climate impacts.

Results

High colour in mill effluent and in receiving waters correlated with high SUVA and specific colour levels, high molecular weight range and aromatic content. Conversely, lake waters with low colour had UV absorbing compounds of much lower molecular weight range and low relative abundance of aromatic compounds. Attenuation of colour and changes in the character of organics in the receiving environment coincided with increased concentrations of metal cations.

Conclusions

These increased concentrations appear to be due to the effects of climate change, lake management and their presence in mill effluent, with subsequent discharge to the lake. Attenuation of colour was found to be predominantly through removal of high molecular weight aromatic compounds where the removal processes could be through adsorption and co-precipitation with divalent metals, as well as through dilution processes.     

Bioaccessibility of arsenic in various types of rice in an in vitro gastrointestinal fluid system

Rice can be a major contributor to dietary arsenic exposure because of the relatively high total arsenic concentration compared to other grains, especially for people whose main staple is rice. This study employed in vitro gastrointestinal fluid digestion to determine bioaccessible or gastrointestinal fluid extractable arsenic concentration in rice. Thirty-one rice samples, of which 60 % were grown in the United States, were purchased from food stores in New York City. Total arsenic concentrations in these samples ranged from 0.090 ± 0.004 to 0.85 ± 0.03 mg/kg with a mean value of 0.275 ± 0.161 mg/kg (n = 31). Rice samples with relatively high total arsenic (>0.20 mg/kg, n = 18) were treated by in vitro artificial gastrointestinal fluid digestion, and the extractable arsenic ranged from 53 % to 102 %. The bioaccessibility of arsenic in rice decreases in the general order of extra long grain, long grain, long grain parboiled, to brown rices.     

Assessing chlorinated ethene degradation in a large scale contaminant plume by dual carbon-chlorine isotope analysis and quantitative PCR

The fate of chlorinated ethenes in a large contaminant plume originating from a tetrachloroethene (PCE) source in a sandy aquifer in Denmark was investigated using novel methods including compound-specific carbon and chlorine isotope analysis and quantitative real-time polymerase chain reaction (qPCR) methods targeting Dehaloccocoides sp. and vcrA genes. Redox conditions were characterized as well based on concentrations of dissolved redox sensitive compounds and sulfur isotopes in SO(4)(2-). In the first 400 m downgradient of the source, the plume was confined to the upper 20 m of the aquifer. Further downgradient it widened in vertical direction due to diverging groundwater flow reaching a depth of up to 50 m. As the plume dipped downward and moved away from the source, O(2) and NO(3)(-) decreased to below detection levels, while dissolved Fe(2+) and SO(4)(2-) increased above detectable concentrations, likely due to pyrite oxidation as confirmed by the depleted sulfur isotope signature of SO(4)(2-). In the same zone, PCE and trichloroethene (TCE) disappeared and cis-1,2-dichloroethene (cDCE) became the dominant chlorinated ethene. PCE and TCE were likely transformed by reductive dechlorination rather than abiotic reduction by pyrite as indicated by the formation of cDCE and stable carbon isotope data. TCE and cDCE showed carbon isotope trends typical for reductive dechlorination with an initial depletion of (13)C in the daughter products followed by an enrichment of (13)C as degradation proceeded. At 1000 m downgradient of the source, cDCE was the dominant chlorinated ethene and had reached the source δ(13)C value confirming that cDCE was not affected by abiotic or biotic degradation. Further downgradient (up to 1900 m), cDCE became enriched in (13)C by up to 8 ‰ demonstrating its further transformation while vinylchloride (VC) concentrations remained low (<1 μg/L) and ethene was not observed. The correlated shift of carbon and chlorine isotope ratios of cDCE by 8 and 3.9 ‰, respectively, the detection of Dehaloccocides sp genes, and strongly reducing conditions in this zone provide strong evidence for reductive dechlorination of cDCE. The significant enrichment of (13)C in VC indicates that VC was transformed further, although the mechanism could not be determined. The transformation of cDCE was the rate limiting step as no accumulation of VC occurred. In summary, the study demonstrates that carbon-chlorine isotope analysis and qPCR combined with traditional approaches can be used to gain detailed insight into the processes that control the fate of chlorinated ethenes in large scale plumes.     

Altered vegetative assemblage trajectories within an urban brownfield

Recognizing the growing importance of both structure (maintenance of biodiversity) and function (fostering natural cycles) of urban ecologies, we examine coarse scale (herbaceous, shrub and forest) beta guild trajectory in an urban brownfield. The distribution of the pioneer forest assemblage dominated by Betula populifolia Marsh. and Populus spp. could be correlated positively with total soil metal load (arsenic, cadmium, chromium, copper, lead, zinc, lead and vanadium),whereas herbaceous and shrub guilds were negatively correlated. Distinct assemblage development trajectories above and below a critical soil metal threshold are demonstrated. In addition, we postulate that the translocation of metals into the plant tissue of several dominant species may provide a positive feedback loop, maintaining relatively high concentrations of metals in the litter and soil. Therefore assembly theory, which allows for the development of alternate stable states, may provide a better model for the establishment of restoration objectives on degraded urban sites.     

Outdoor and indoor cadmium distributions near an abandoned smelting works and their relations to human exposure

The relationship of measured or modelled Cd concentrations in soil, house dust and available to plants with human urinary Cd concentrations were assessed in a population living around a Cd/Pb/Zn smelter in the UK. Modelled air concentrations explained 35% of soil Cd variation indicating the smelter contributed to soil Cd loads. Multi-variate analysis confirmed a significant role of biological and life-style factors in determining urinary Cd levels. Significant correlations of urinary Cd with soil, house dust and modelled plant available Cd concentrations were not, however, found. Potential reasons for the absence of clear relationships include limited environmental contact in urban populations; the role of undefined factors in determining exposure; and the limited spatial scope of the survey which did not sample from the full pollution gradient. Further, the absence of any significant relationship indicates that environmental measures provide limited advantage over atmospheric model outputs for first stage human exposure assessment.     

Metrics for integrating sustainability evaluations into remediation projects

The US Sustainable Remediation Forum (SURF) created a compilation of metrics (Metrics Toolbox) in response to a need for a broad set of metrics that could be used to assess and monitor the effectiveness of remedies in achieving sustainability goals. Metrics are the key impacts, outcomes, or burdens that are to be assessed or balanced to determine the influences and impacts of a remedial action. Metrics can reflect any of the three aspects of sustainability (i.e., environmental, social, or economic) or a combination of these aspects. Regardless, metrics represent the most critical sustainable outcomes from the perspective of the key stakeholders. The Metrics Toolbox is hosted online at www.sustainableremediation.org/library/guidance‐tools‐and‐other‐resources . By selecting metrics from the Metrics Toolbox as a starting point and considering a potentially wider suite of metrics in remedial program decisions, appropriate assessments can be made. Qualitative and quantitative metrics are tabulated for each remedial phase: remedial investigation, remedy selection, remedial design, remedial construction, operation and maintenance, and closure. Attributes for each metric are described so that remediation practitioners and key stakeholders can view the universe of metrics available and select the most relevant, site‐specific metrics for a particular site. For this reason, SURF recommends that remediation practitioners consider the metrics compiled in the Metrics Toolbox as a companion to the sustainable remediation framework published elsewhere in this journal and other sustainability evaluations. © 2011 Wiley Periodicals, Inc.     

Validation of an evacuated canister method for measuring part-per-billion levels of chemical warfare agent simulants

The National Institute for Occupational Safety and Health (NIOSH) research on direct-reading instruments (DRIs) needed an instantaneous sampling method to provide independent confirmation of the concentrations of chemical warfare agent (CWA) simulants. It was determined that evacuated canisters would be the method of choice. There is no method specifically validated for volatile organic compounds (VOCs) in the NIOSH Manual of Analytical Methods. The purpose of this study was to validate an evacuated canister method for sampling seven specific VOCs that can be used as a simulant for CWA agents (cyclohexane) or influence the DRI measurement of CWA agents (acetone, chloroform, methylene chloride, methyl ethyl ketone, hexane, and carbon tetrachloride [CCl4]). The method used 6-L evacuated stainless-steel fused silica-lined canisters to sample the atmosphere containing VOCs. The contents of the canisters were then introduced into an autosampler/preconcentrator using a microscale purge and trap (MPT) method. The MPT method trapped and concentrated the VOCs in the air sample and removed most of the carbon dioxide and water vapor. After preconcentration, the samples were analyzed using a gas chromatograph with a mass selective detector. The method was tested, evaluated, and validated using the NIOSH recommended guidelines. The evaluation consisted of determining the optimum concentration range for the method; the sample stability over 30 days; and the accuracy, precision, and bias of the method. This method meets the NIOSH guidelines for six of the seven compounds (excluding acetone) tested in the range of 2.3-50 parts per billion (ppb), making it suitable for sampling of these VOCs at the ppb level.     

Particulate matter in new technology diesel exhaust (NTDE) is quantitatively and qualitatively very different from that found in traditional diesel exhaust (TDE)

Diesel exhaust (DE) characteristic of pre-1988 engines is classified as a "probable" human carcinogen (Group 2A) by the International Agency for Research on Cancer (IARC), and the U.S. Environmental Protection Agency has classified DE as "likely to be carcinogenic to humans." These classifications were based on the large body of health effect studies conducted on DE over the past 30 or so years. However, increasingly stringent U.S. emissions standards (1988-2010) for particulate matter (PM) and nitrogen oxides (NOx) in diesel exhaust have helped stimulate major technological advances in diesel engine technology and diesel fuel/lubricant composition, resulting in the emergence of what has been termed New Technology Diesel Exhaust, or NTDE. NTDE is defined as DE from post-2006 and older retrofit diesel engines that incorporate a variety of technological advancements, including electronic controls, ultra-low-sulfur diesel fuel, oxidation catalysts, and wall-flow diesel particulate filters (DPFs). As discussed in a prior review (T. W. Hesterberg et al.; Environ. Sci. Technol. 2008, 42, 6437-6445), numerous emissions characterization studies have demonstrated marked differences in regulated and unregulated emissions between NTDE and "traditional diesel exhaust" (TDE) from pre-1988 diesel engines. Now there exist even more data demonstrating significant chemical and physical distinctions between the diesel exhaust particulate (DEP) in NTDE versus DEP from pre-2007 diesel technology, and its greater resemblance to particulate emissions from compressed natural gas (CNG) or gasoline engines. Furthermore, preliminary toxicological data suggest that the changes to the physical and chemical composition of NTDE lead to differences in biological responses between NTDE versus TDE exposure. Ongoing studies are expected to address some of the remaining data gaps in the understanding of possible NTDE health effects, but there is now sufficient evidence to conclude that health effects studies of pre-2007 DE likely have little relevance in assessing the potential health risks of NTDE exposures.     

Characterizing long-term hydrologic-response and sediment-transport for the R-5 catchment

Recently there have been several calls to establish long-term data collection networks to monitor near-surface hydrologic response and landscape evolution. The focus of this paper is a long-term dataset from the International Hydrologic Decade (1965-1974). The small upland catchment, known as R-5, located near Chickasha, Olahoma, has been the subject of considerable attention within the event-based hydrologic modeling community for more than 30 yr. Here, for the first time, 8 yr of continuous near-surface hydrologic-response and sediment-transport data are analyzed to show trends in the catchment's long-term behavior. The datasets include precipitation, temperature, solar radiation, soil-water content, infiltration, water discharge, and sediment discharge. Potential and actual evapotranspiration rates were estimated and used to calculate an average annual water balance for the catchment. Findings include, for example, that rainfall intensity rarely exceeds the threshold for Horton-type runoff, soil-water content is both spatially and temporally variable, and the water and sediment discharge rates are positively correlated. The R-5 data provide a unique opportunity to test (and refine) process-based models of continuous hydrologic response and sediment transport at the catchment scale for applications in the emerging fields of hydroecology and hydrogeomorphology.