Initial investigation on the use of waterjets to place amendments in the subsurface

Quasi‐passive in situ remediation technologies, such as the use of permeable reactive barriers to treat contaminated groundwater or applications of granular activated carbon to treat polychlorinated biphenyl (PCB)‐contaminated, near‐surface sediments, are proven or promising technologies that may be limited in application due to the traditional construction techniques normally used for placement in the environment. High‐pressure waterjets have traditionally been used to excavate material during mining operations or to cut rock or other durable material. Waterjets have the potential to place amendments in the subsurface at depths greater than those that can be obtained using traditional construction techniques. Likewise, waterjets may have less negative impact on near‐surface utilities and/or sensitive ecological systems. Laboratory experiments were performed to characterize the placement of two solid amendments in a simulated saturated aquifer. A second set of experiments was performed to characterize the effectiveness of waterjets for placing a third amendment in simulated intertidal sediments. The laboratory work focused on characterizing the nature of the waterjet penetration of the aquifer matrix and the saturated sediments, as well as the corresponding waterjet parameters of pressure, nozzle size, and injection time. The laboratory results suggest that field trials may be appropriate for future investigations. © 2005 Wiley Periodicals, Inc.     

Apatite and phillipsite as sequestering agents for metals and radionuclides

Laboratory and greenhouse studies were conducted to quantify apatite and phillipsite (zeolite) sequestration of selected metal contaminants. The laboratory batch study measured the sorption of aqueous Co2+, Ba2+, Pb2+, Eu3+, and UO2(2+). Apatite sorbed more Co2+, Pb2+, Eu3+, and UO2(2+) from the spike solution than phillipsite, resulting in distribution coefficients (Kd values) of >200,000 L kg(-1). Phillipsite was more effective than apatite at sorbing aqueous Ba2+. Results from the laboratory study were used to design the greenhouse study that used a soil affected by a Zn-Pb smelter from Pribram, Czech Republic. Two application rates (25 and 50 g kg(-1)) of phillipsite and apatite and two plant species, maize (Zea mays L.) and oat (Avena sativa L.), were evaluated in this study. There was little (maize) to no (oat) plant growth in the unamended contaminated soil. Apatite and, to a slightly lesser extent, phillipsite additions significantly enhanced plant growth and reduced Cd, Pb, and Zn concentrations in all analyzed tissues (grain, leaves, and roots). The sequestering agents also affected some essential elements (Ca, Fe, and Mg). Phillipsite reduced Fe and apatite reduced P and Fe concentrations in oat tissues; however, the level of these elements in oat leaves and grains remained sufficient. Sequential extractions of the soil indicated that the Cd, Pb, and Zn were much more strongly sorbed onto the amended soil, making the contaminants less phytoavailable.     

Evaluation of a conceptual model for the subsurface transport of plutonium involving surface mediated reduction of PuV to PuIV

A conceptual model is proposed to explain the transport behavior of plutonium in laboratory columns packed with a sandy coastal soil from the U.S. Department of Energy (DOE)'s Savannah River Site. The column transport experiments involved the introduction of a finite step input of plutonium, predominately in the +5 oxidation state, into the columns followed by elution with a low-carbonate solution of 0.02 M NaClO4 at pH 3, 5, and 8. Total plutonium concentrations were measured in the effluent as a function of time. These elution profiles suggest at least two distinct physical/chemical forms of plutonium, each with a different mobility. To explain the observed behavior, the following conceptual model was evaluated: [1] equilibrium partitioning of plutonium (V) and plutonium (IV) between the aqueous and sorbed phases as defined by pH-dependent, oxidation-state specific distribution coefficients and [2] kinetic reduction of plutonium (V) to plutonium (IV) in the sorbed phase. The conceptual model was applied to the column experiments through a one-dimensional advective/dispersive mathematical model, and predictions of the mathematical model were compared with the experimental data. Overall, the model was successful in predicting some of the major features observed in the experiments. It also yielded quantitative estimates of the rate constant for surface mediated reduction of plutonium (V) to plutonium (IV) that were of the same order (10(-4) to 10(-5) s(-1)) as those calculated from batch data both for this soil and for goethite.     

Integrated Assessment of Abatement Strategies to Improve Air Quality in Urban Environments, the USIAM Model

Planning effective strategies to combat air pollution in amajor city such as London requires integration ofinformation on atmospheric concentrations and where theyexceed prescribed air quality standards, detailed data onemissions and potential measures to reduce them includingcosts, and a good understanding of the relativecontributions of different emission sources to pollutantconcentrations plus the remaining background. The UrbanScale Integrated Assessment Model (USIAM) is designed as atool to integrate such information, and to explore andassess a variety of potential strategies for improving airquality. It is based on the same principles as theAbatement Strategies Assessment Model (ASAM) that has beenused in the UN Economic Commission for Europe. To startwith the USIAM model is being developed with respect to theparticulate PM₁₀ only, and in particular the primaryparticulate contribution. The secondary particulate istreated as part of the background superimposed on theprimary particulate concentrations; this may need to betreated more specifically at a later stage, particularlywith respect to nitrate formation over the city. The USIAMmodel therefore sets out to examine a selection of severeepisode conditions as well as long-term annual averageconcentrations, and aims to find strategies that aresuccessful in eliminating exceedance of the prescribedtarget concentrations. By ranking different options forabatement of emissions, for example in terms of cost orease of implementation, the USIAM model can also select andprioritise different potential strategies.     

USING TECHNICAL ADAPTIVE MANAGEMENT TO IMPROVE DESIGN GUIDELINES FOR URBAN INSTREAM STRUCTURES1

ABSTRACT: Adaptive management is a heuristic approach to treating stream restoration projects as continuous, cyclic experiments, yielding results to be incorporated into future decisions. This comprehensive assessment views failures as surprises that are valuable lessons. Monitoring, evaluation of data, and communication of results are critical; the monitoring results trigger feedback mechanisms to invoke adaptation to the newly acquired information and communication of new hypotheses, treatments, or policies. The principles of adaptive management were applied to a monitoring study of three urban stream restoration sites in Maryland. Data were collected and evaluated for various restoration techniques, including vanes, cross vanes, step pools, root wads, imbricated riprap walls, and coir fiber rolls. Improvements to the existing Maryland design guidelines and policies were developed as the feedback mechanism. With the increasing application of adaptive management in stream restoration efforts, it is likely that repeated failures will be prevented and future restoration projects will be more successful in achieving their goals.     

On averting the tragedy of the commons

One of the enduring facts of the human condition is that the earth's resources are finite and its environment fragile. It is also evident that human behavior is rarely based on an appreciation of these facts. While the outlook may be bleak, so are some of the proposed solutions. Reasonable people have suggested that, to survive, an environmentally enlightened authoritarian government must be adopted. This article suggests that such a solution is unworkable, in part because it fails to consider critical aspects of human nature. A framework is proposed for developing solutions compatible with human capabilities.     

Kin discrimination in the spotted hyena (<Emphasis Type="Italic">Crocuta crocuta</Emphasis>): nepotism among siblings

We examined patterns of affiliation, association, and aggression to inquire whether spotted hyenas (Crocuta crocuta) can distinguish among various groups of maternal and paternal siblings. If so, and if these animals conform to predictions of kin selection theory, then behavioral interactions among hyenas should vary with relatedness. We also considered familiarity-based recognition and phenotype matching as mechanisms hyenas might use to recognize kin. Patterns of affiliative behavior indicated that hyenas favored full-sibling littermates over half-sibling littermates or any other group of half-siblings. Rates of dyadic aggression generally did not vary with kinship. Hyenas associated more closely with half-sibling littermates than with non-littermate half-siblings, and hyenas affiliated more with maternal half-siblings than with paternal half-siblings, suggesting that familiarity-based cues might mediate discrimination among these sibling classes. In addition, operation of a phenotype-matching mechanism was suggested by the preference hyenas demonstrated during affiliative interactions for full- over half-sibling littermates, and by their lack of preference in these interactions for half-sibling littermates over non-littermate half-siblings. Phenotype matching was also suggested by our observation that paternal half-siblings cooperated more, and fought less, than did non-kin. Our data indicate that hyenas can discriminate among various types of siblings, that their social behavior conforms to predictions of kin selection theory, and that they recognize kin using mechanisms of both familiarity and phenotype matching.Communicated by S. Alberts     

Fetal marfan syndrome: Prenatal ultrasound diagnosis with pathological confirmation of skeletal and aortic lesions

Sonography was performed during the second trimester in two pregnancies at risk for the Marfan syndrome. In one, the limbs were significantly longer than expected (p < 0·0025) and a diagnosis of the Marfan syndrome was established. Pathological examination of the fetus after pregnancy interruption showed typical foci of cystic medial necrosis in the ascending aorta.