Land Use and Climate Variability Amplify Carbon,Nutrient, and Contaminant Pulses: A Review with Management Implications

Nonpoint source pollution from agriculture and urbanization is increasing globally at the same time climate extremes have increased in frequency and intensity. We review >200 studies of hydrologic and gaseous fluxes and show how the interaction between land use and climate variability alters magnitude and frequency of carbon, nutrient, and greenhouse gas pulses in watersheds. Agricultural and urban watersheds respond similarly to climate variability due to headwater alteration and loss of ecosystem services to buffer runoff and temperature changes. Organic carbon concentrations/exports increase and organic carbon quality changes with runoff. Nitrogen and phosphorus exports increase during floods (sometimes by an order of magnitude) and decrease during droughts. Relationships between annual runoff and nitrogen and phosphorus exports differ across land use. CH₄ and N₂O pulses in riparian zones/floodplains predominantly increase with: flooding, warming, low oxygen, nutrient enrichment, and organic carbon. CH₄, N₂O, and CO₂ pulses in streams/rivers increase due to similar factors but effects of floods are less known compared to base flow/droughts. Emerging questions include: (1) What factors influence lag times of contaminant pulses in response to extreme events? (2) What drives resistance/resilience to hydrologic and gaseous pulses? We conclude with eight recommendations for managing watershed pulses in response to interactive effects of land use and climate change.     

Explicitness of consequence information in warnings

Four experiments were carried out to assess effects of product warning explicitness on purchase preferences and caution in use. Explicitness was defined as the specificity or detail with which potential injury consequences were described. All experiments employed a paradigm in which warnings varying in explicitness were described for familiar products. Subjects rated various perceptions of the products, purchase preferences, and intent to act cautiously in using the product. Results indicated that more explicit warnings were associated with greater levels of perceived dangerousness, hazard understanding, injury severity, and manufacturers' concern. While explicit warnings were also associated with an increased intent to act cautiously in using products, no clear relationship was found between explicitness and purchase preferences. It is recommended that product warnings should be explicit regarding injury consequences, especially where injuries may be severe. Given such information, product users, particularly those less familiar with a product, are more likely to exercise greater caution during use. Further, manufacturers' concern that explicit warnings may negatively impact sales appears to be unwarranted.     

Characterization and pilot‐scale studies for chemical oxidation remediation of fractured shale

The distribution of volatile organic compounds (VOCs) in fractured shale overlain by thin (< 10 feet) overburden at the Watervliet Arsenal near Albany, New York, was initially determined by sampling water from the fracture network using packer systems in boreholes and also using conventional monitoring wells. Furthermore, short‐term pumping and injection tests were conducted and the boreholes were logged using a variety of geophysical and hydrophysical tools. Tetrachloroethene is the dominant VOC in the groundwater, with lesser concentrations of trichloroethene and degradation products (cis‐1,2‐dichloroethene, trans‐1,2‐dichloroethene, and vinyl chloride). The vertical VOC distributions in the rock matrix were obtained from continuous‐cored holes from which small rock samples, collected at many depths between 18 and 150 feet below ground surface, were analyzed. The rock core VOC concentrations were determined by methanol extraction of crushed rock followed by direct methanol injection onto a gas chromatograph and subsequent estimation of rock porewater VOC concentrations. The rock core data support the concept that diffusion‐driven mass transfer has caused nearly all the VOC mass initially present in the fractures to now reside in the rock matrix, which has a porosity three or four orders of magnitude larger than the bulk fracture porosity. The results of the site characterization indicate that an effective site investigation strategy in fractured shale must include characterization of both the fracture and matrix contaminant distribution. These results also indicate that the most favorable remediation technologies for this fractured shale are those that will destroy VOCs in the rock matrix, particularly contaminants in the sorbed phase, and also destroy the VOC mass in the fractures including both dissolved and immiscible phases. The site characterization resulted in the selection of potassium permanganate for an in situ chemical oxidation pilot study. © 2004 Wiley Periodicals, Inc.     

Real-time PCR with molecular beacons provides a highly accurate assay for detection of Tay-Sachs alleles in single cells

The results presented here provide the first single-cell genetic assay for Tay-Sachs disease based on real-time PCR. Individual lymphoblasts were lysed with an optimized lysis buffer and assayed using one pair of primers that amplifies both the wild type and 1278 + TATC Tay-Sachs alleles. The resulting amplicons were detected in real time with two molecular beacons each with a different colored fluorochrome. The kinetics of amplicon accumulation generate objective criteria by which to evaluate the validity of each reaction. The assay had an overall utility of 95%, based on the detection of at least one signal in 235 of the 248 attempted tests and an efficiency of 97%, as 7 of the 235 samples were excluded from further analysis for objective quantitative reasons. The accuracy of the assay was 99.1%, because 228 of 230 samples gave signals consistent with the genotype of the cells. Only two of the 135 heterozygous samples were allele drop-outs, a rate far lower than previously reported for single-cell Tay-Sachs assays using conventional methods of PCR. Copyright © 2002 John Wiley & Sons, Ltd.     

Uptake and transformation of arsenic during the reproductive life stage of Agaricus bisporus and Agaricus campestris

Fruiting bodies from the Agaricus genus have been found to contain non-toxic arsenobetaine (AB) as a major compound. It is unknown whether AB is formed during the vegetative or reproductive life stages of the fungus, or by the surrounding microbial community, but AB''s structural similarity to glycine betaine has led to the hypothesis that AB may be adventitiously accumulated as an osmolyte. To investigate the potential formation of AB during the reproductive life stage of Agaricus species, growth substrate and fungi were collected during the commercial growth of Agaricus bisporus and analyzed for arsenic speciation using HPLC-ICP-MS. AB was found to be the major arsenic compound in the fungus at the earliest growth stage of fruiting (the primordium). The growth substrate mainly contained arsenate (As(V)). The distribution of arsenic in an A. bisporus primordium grown on As(V) treated substrate, and in a mature Agaricus campestris fruiting body collected from arsenic contaminated mine tailings, was mapped using two dimensional XAS imaging. The primordium and stalk of the mature fruiting body were both found to be growing around pockets of substrate material containing higher As concentrations, and AB was found exclusively in the fungal tissues. In the mature A. campestris the highest proportion of AB was found in the cap, supporting the AB as an osmolyte hypothesis. The results have allowed us to pinpoint the fungus life stage at which AB formation takes place, namely reproduction, which provides a direction for further research.     

The Great Decoupling: Why Minimizing Humanity’s Dependence on the Environment May Not Be Cause for Celebration

Characterizations of the Anthropocene often indicate both the challenges that our new epoch poses for human well-being and a sense of loss that comes from a compromised environment. In this paper I explore a deeper problem underpinning both issues, namely, that decoupling humanity from the world with which we are familiar compromises human flourishing. The environmental conditions characteristic of the Anthropocene do so, I claim, by compromising flourishing on two fronts. First, the comparatively novel conditions of the Anthropocene risk rupturing our narratives, putting at risk our sense of self and connections to familiar environments. Second, by undermining the connections between our environmental background and the sense of well-being conditioned by that background our ability to exercise options that constitute a recognizable good life are compromised. This paper argues that to the extent humanity is decoupled from their environments humans are not only less able to access opportunities our understanding of who we are, our identities, and our capacity to make sense of the world around us through those identities is compromised. I conclude that the Anthropocene does more than challenge our ability to utilize resources, it challenges our understanding of who we are in the world.     

Effect of arsenic contaminated irrigation water on Lens culinaris L. and toxicity assessment using lux marked biosensor

Contamination of irrigation water represents a major constraint to Bangladesh agriculture, resulting in elevated levels in the terrestrial systems. Lux bacterial biosensor technology has previously been used to measure the toxicity of metals in various environmental matrices. While arbuscular mycorrhizal fungi have their most significant effect on phosphorus uptake, but showed alleviated metal toxicity to the host plant. The study examined the effects of arsenic and inoculation with an arbuscular mycorrhizal fungus, Glomus mosseae, on lentil (Lens culinaris L. cv. Titore). Plants were grown with and without arbuscular mycorrhizal inoculum for 9 weeks in a sand and terra-green mixture (50:50, V/V) and watered with five levels of arsenic (0, 1, 2, 5, 10 mg As/L arsenate). The results showed that arsenic addition above 1 mg/L significantly reduced percentage of mycorrhizal root infection. On further analysis a close relationship was established with the vegetative and reproductive properties of lentil (L. culinaris) plants compared to the percentage bioluminescence of the soil leachate. However, arbuscular mycorrhizal fungal inoculation reduced arsenic concentration in roots and shoots. Higher concentrations of arsenic (5, 10 mg As/L arsenate) reduced the mycorrhizal efficiency to increase phosphorus content and nitrogen fixation. Therefore, this study showed that increased concentration of arsenic in irrigation water had direct implications to the lentil (L. culinaris) plants overall performance. Moreover the use of bioassay demonstrated that mycorrhiza and clay particle reduced arsenic bioavailability in soil.     

Ozone Air Quality Models Prepared Discussion

The APCA Critical Review entitled “Ozone Air Quality Models” was presented by John H. Seinfeld, Louis E. Nohl Professor and Executive Officer for Chemical Engineering at the California Institute of Technology, Pasadena, California. Dr. Seinfeld presented his review at the 81st APCA Annual Meeting & Exhibition, held in Dallas, Texas in June 1988. The Critical Review paper, published in the May 1988 issue of JAPCA, highlighted recent advances and continuing problem areas in photochemical air quality modeling. Prepared discussions and floor comments presented during the Critical Review session in Dallas are published here, along with additional comments and closing remarks by Dr. Seinfeld. Howard M. Ellis, Chairman of the Critical Review Subcommittee of the Publications Committee, served as moderator of the 1988 APCA Critical Review session.     

CRC-APRAC Vehicle Emissions Modeling Workshop

A conference was held on October 30-31,1990 to examine discrepancies between the output of vehicle emission factor models (MOBILE and EMFAC), field and laboratory measurements of vehicle emissions, and observed ratios of pollutants in urban atmospheres dominated by vehicle emissions. There was a general consensus that significant discrepancies exist and that these discrepancies must be resolved. A number of research recommendations were made as to how models and model inputs could be improved, and what additional laboratory and field work should be conducted.