Dechlorination after thermal treatment of a TCE-contaminated aquifer: laboratory experiments

A microcosm study was conducted to evaluate dechlorination of trichloroethene (TCE) to ethene and survival of dechlorinating bacteria after a thermal treatment in order to explore the potential for post-thermal bioremediation. Unamended microcosms containing groundwater and aquifer material from a contaminated site dechlorinated TCE to cis-1,2-dichloroethene (cDCE), while lactate-amended microcosms dechlorinated TCE to cDCE or ethene. A thermal treatment was simulated by heating a sub-set of microcosms to 100 degrees C for 10d followed by cooling to 10 degrees C over 150 d. The heated microcosms demonstrated no dechlorination when unamended. However, when amended with lactate, cDCE was produced in 2 out of 6 microcosms within 300 d after heating. Dechlorination of TCE to cDCE thus occurred in fewer heated (2 out of 12) than unheated (10 out of 12) microcosms. In unheated microcosms, the presence of dechlorinating microorganisms, including Dehalococcoides, was confirmed using nested PCR of 16S rRNA genes. Dechlorinating microorganisms were detected in fewer microcosms after heating, and Dehalococcoides were not detected in any microcosms after heating. Dechlorination may therefore be limited after a thermal treatment in areas that have been heated to 100 degrees C. Thus, inflow of groundwater containing dechlorinating microorganisms and/or bioaugmention may be needed for anaerobic dechlorination to occur after a thermal treatment.     

Quantification of biotransformation of chlorinated hydrocarbons in a biostimulation study: added value via stable carbon isotope analysis

Stable carbon isotope analysis of chlorinated aliphatic compounds was performed at an in situ biostimulation pilot test area (PTA) at a site where 1,2-dichloroethane (1,2-DCA) and trichloroethene (TCE) were present in groundwater. Chlorinated products of TCE reductive dechlorination (cis-dichloroethene (cDCE) and vinyl chloride (VC)) were present at concentrations of 17.5 to 126.4 micromol/L. Ethene, a potential degradation product of both 1,2-DCA dihaloelimination and TCE reductive dechlorination was also present in the PTA. Emulsified soybean oil and lactate were added as electron donors to stimulate anaerobic dechlorination in the PTA. Stable carbon isotope analysis provided evidence that dechlorination was occurring in the PTA during biostimulation, and a means of monitoring changes in dechlorination efficiency over the 183 day monitoring period. Stable carbon isotope analysis was also used to determine if ethene production in the PTA was due to dechlorination of TCE, 1,2-DCA, or both. Fractionation factors (alpha) were determined in the laboratory during anaerobic biotransformation of 1,2-DCA via a dihaloelimination reaction in four separate enrichment cultures. These alpha values (as well as the previously published ranges of alpha for the dechlorination of TCE, cDCE and 1,2-DCA) were used, along with isotopic values measured during the pilot test, to derive quantitative estimates of biotransformation during the pilot test. Dechlorination was found to account for 10.7 to 35.9%, 21.9 to 74.9%, and 54.4 to 67.8% of 1,2-DCA, TCE and cDCE concentration loss respectively in the PTA. Stable carbon isotope analysis indicates that dechlorination of 1,2-DCA, TCE and cDCE were all significant processes during the pilot test, while ethene production during the pilot test was dominated by 1,2-DCA dihaloelimination. This study demonstrates how stable carbon isotope analysis can provide more conservative estimates of the extent of biotransformation than do conventional protocols. In addition, in a complex mixed plume such as this, compound specific isotope analysis is shown to be one of the few methods available for clarifying dominant biotransformation pathways where breakdown products are non-exclusive (i.e. ethene).     

An inexpensive light-scattering particle monitor: field validation

We have developed a small, light, passive, inexpensive, datalogging particle monitor called the "UCB" (University of California Berkeley particle monitor). Following previously published laboratory assessments, we present here results of tests of its performance in field settings at high particle concentrations. We demonstrate the mass sensitivity of the UCB in relation to gravimetric filter-based PM(2.5) mass estimates as well as commercial light-scattering instruments co-located in field chamber tests and in kitchens of wood-burning households. The coefficient of variation of the unadjusted UCB mass response in relation to gravimetric estimates was 15%. Although requiring adjustment for differences in sensitivity, inter-monitor performance was consistently high (r(2) > 0.99). Moreover, the UCB can consistently estimate PM(2.5) mass concentrations in wood-burning kitchens (Pearson r(2) = 0.89; N = 99), with good agreement between duplicate measures (Pearson r(2) = 0.94; N = 88). In addition, with appropriate cleaning of the sensing chamber, UCB mass sensitivity does not decrease with time when used intensively in open woodfire kitchens, demonstrating the significant potential of this monitor.     

EFFECTS OF SCALE ON LAND USE AND WATER QUALITY RELATIONSHIPS: A LONGITUDINAL BASIN‐WIDE PERSPECTIVE1

ABSTRACT: Human land use is a major source of change in catchments in developing areas. To better anticipate the long‐term effects of growth, land use planning requires estimates of how changes in land use will affect ecosystem processes and patterns across multiple scales of space and time. The complexity of biogeochemical and hydrologic interactions within a basin makes it difficult to scale up from process‐based studies of individual reaches to watershed scales over multiple decades. Empirical models relating land use/land cover (LULC) to water quality can be useful in long‐term planning, but require an understanding of the effects of scale on apparent land use‐water quality relationships. We empirically determined how apparent relationships between water quality and LULC data change at different scales, using LIJLC data from the Willapa Bay watershed (Washington) and water quality data collected along the Willapa and North Rivers. Spatial scales examined ranged from the local riparian scale to total upstream catchment. The strength of the correlations between LTJLC data and longitudinal water quality trends varied with scale. Different water quality parameters also varied in their response to changes in scale. Intermediate scales of land use data generally were better predictors than local riparian or total catchment scales. Additional data from the stream network did not increase the strength of relationships significantly. Because of the likelihood of scale‐induced artifacts, studies quantifying land use‐water quality relationships performed at single scales should be viewed with great caution.     

Association of reproductive traits with captive- versus wild-sourced birds in trade

The wildlife trade is a billion-dollar global business, involving millions of people, thousands of species, and hundreds of millions of individual organisms. Unravelling whether trade targets reproductively distinct species and whether this preference varies between captive- and wild-sourced species is a crucial question. We used a comprehensive list of all bird species traded, trade listings and records kept in compliance with the Convention on International Trade in Endangered Species (CITES), and a suite of avian reproductive parameters to examine whether wildlife trade is associated with particular facets of life history and to examine the association between life-history traits and captive- and wild-sourced traded volumes over time. Across all trade, CITES listing, and CITES trade, large birds were more likely to be traded and listed, but their longevity and age at maturity were not associated with CITES listing or trade. We found species across almost the full range of trait values in both captive and wild trade between 2000 and 2020. Captive trade volumes clearly associated with relatively longer lived and early-maturing species; these associations remained stable and largely unchanged over time. Trait–volume associations in wild-sourced trade were more uncertain. Only body mass had a clear association, and it varied from negative to positive over time. Although reproductive traits were important in captive-sourced trade, species-level variation dominated trade, with even congeneric species varying greatly in volume despite similar traits. The collection and incorporation of trait data into sustainability assessments of captive breeding facilities are crucial to ensure accurate quotas and guard against laundering.     

建筑产品与生命周期思考

生命周期理念,在与建筑和建设部门的关系中,特别应该进行建筑产品分析、在提高建筑物能源效率并为经济繁荣有所贡献的时候,这些产品发挥着基本的作用,已经做出的要算披露,在从自然索取的物质资源和产生的垃圾总量中,有一半来自建筑部门,为了对建筑产品的影响进行和理并把综降到最低,就必须利用生命周期的方法对所产生的影响进生检测,本文评论了生命周期理念并思考了最新的发展.材料与可持续建筑,环境产品宣言,所体现的能源以及北方与南言建筑产品评估中产生的差异,都是要讨论的话题.     

Reduced-impact logging and biodiversity conservation: a case study from Borneo

A key driver of rain forest degradation is rampant commercial logging. Reduced-impact logging (RIL) techniques dramatically reduce residual damage to vegetation and soils, and they enhance the long-term economic viability of timber operations when compared to conventionally managed logging enterprises. Consequently, the application of RIL is increasing across the tropics, yet our knowledge of the potential for RIL also to reduce the negative impacts of logging on biodiversity is minimal. We compare the impacts of RIL on birds, leaf-litter ants, and dung beetles during a second logging rotation in Sabah, Borneo, with the impacts of conventional logging (CL) as well as with primary (unlogged) forest. Our study took place 1-8 years after the cessation of logging. The species richness and composition of RIL vs. CL forests were very similar for each taxonomic group. Both RIL and CL differed significantly from unlogged forests in terms of bird and ant species composition (although both retained a large number of the species found in unlogged forests), whereas the composition of dung beetle communities did not differ significantly among forest types. Our results show little difference in biodiversity between RIL and CL over the short-term. However, biodiversity benefits from RIL may accrue over longer time periods after the cessation of logging. We highlight a severe lack of studies investigating this possibility. Moreover, if RIL increases the economic value of selectively logged forests (e.g., via REDD+, a United Nations program: Reducing Emissions from Deforestation and Forest Degradation in Developing Countries), it could help prevent them from being converted to agricultural plantations, which results in a tremendous loss of biodiversity.     

Tissue nutrient concentrations in aquatic macrophytes: comparison across biophysical zones,surface water habitats and plant life forms

Aquatic plant tissue (nitrogen) N and phosphorus (P) concentrations, together with the N:P ratio in general, respond poorly to ambient nutrient supply. The variability in plant tissue nutrient concentrations appears to be highly conditioned by taxonomic (mostly species) effects. The significant role that other attributes of the surrounding environment may have in modifying the degree of taxonomic dependence on plant nutrient concentration is yet to be tested with a broader characterisation of plant life forms (bryophytes, helophytes, hydrophytes), so as to investigate implications for ecosystem processes. Plant samples (378) were collected across 65 sites spanning a wide range of aquatic habitats (lotic and lentic) and biophysical zones (floodplain, glacial terraces, mountains) located in NE Scotland. Significant differences in plant tissues N, P and the N:P were found after grouping sampling sites by either habitat or biophysical zones; the latter even after removing the largest taxonomic effect. The range in plant tissue N and P was relatively wide within habitats and zones, reflecting the high species diversity of the studied area. As a group, bryophytes had smaller N and P concentrations, and consequently wider biomass C:N and C:P ratios, a situation which may impose constraints on the flow of energy through food-webs of the mountain and bog areas where they dominate.     

Nitrate Status of Two Major Rivers in N. E. Scotland with Respect to Land Use and Fertiliser Additions

Land Use and the influence it has upon river water nitrate levels is discussed, for two large relatively unpopulated river systems in the N.E. of Scotland. the catchment areas for the rivers Dee and Don have been further subdivided into a number of sub catchments. Substantial differences in land use and agricultural potential exist both within and between the two areas. Greater agricultural production down stream is associated with increased river nitrate concentrations.