Effect of the spionid polychaeteBoccardia syrtis on the distribution and survival of juvenileMacomona liliana (Bivalvia: Tellinacea)

The tellinid bivalveMacomona liliana (Iredale) occurs at relatively low densities on a sandbank (Te Tau bank) in Manukau Harbour, New Zealand. Te Tau bank is dominated by polychaetes, including the tube-building spionidBoccardia syrtis (Rainer). JuvenileM. liliana are known to disperse as post-settlement juveniles by byssus-drifting. Laboratory experiments were conducted to assess whether the low abundance ofM. liliana on Te Tau bank was due to the presence ofB. syrtis, or to some reaction to the sediment itself. In particular, we, examined how juvenileM. liliana survived after exposure to Te Tau bank sediments with and without the spionid tube-mat for 1 mo in still-water conditions, and how they responded when given a choice of different sediment/tube-mat treatments in moving water. JuvenileM. liliana did not appear to have a strong aversion to settling and burrowing in sediments from Te Tau bank. Sediments without the tube-mat did not adversely affect the survivorship of the bivalves, but survival was significantly lower amongst theB. syrtis tube-mat. In the presence of a current, the juvenile bivalves settled in Te Tau bank sediments without a tube-mat, but avoided settling amongst liveB. syrtis. An artificial tube-mat enhanced settlement. Avoidance of liveB. syrtis appears to be an avoidance of the worms themselves rather than a response to the physical presence of their tubes.     

Annual average radon concentrations in California residences.

A study was conducted to determine the annual average radon concentrations in California residences, to determine the approximate fraction of the California population regularly exposed to radon concentrations of 4 pCi/l or greater, and to the extent possible, to identify regions of differing risk for high radon concentrations within the state. Annual average indoor radon concentrations were measured with passive (alpha track) samplers sent by mail and deployed by home occupants, who also completed questionnaires on building and occupant characteristics. For the 310 residences surveyed, concentrations ranged from 0.10 to 16 pCi/l, with a geometric mean of whole-house (bedroom and living room) average concentrations of 0.85 pCi/l and a geometric standard deviation of 1.91. A total of 88,000 California residences (0.8 percent) were estimated to have radon concentrations exceeding 4 pCi/l. When the state was divided into six zones based on geology, significant differences in geometric mean radon concentrations were found between several of the zones. Zones with high geometric means were the Sierra Nevada mountains, the valleys east of the Sierra Nevada, the central valley (especially the southern portion), and Ventura and Santa Barbara Counties. Zones with low geometric means included most coastal counties and the portion of the state from Los Angeles and San Bernardino Counties south.     

Integrierte Treibhausgasbewertung der Prozessketten von Erdgas und industriellem Biomethan in Deutschland

Background The use of natural gas has increased in the last years. In the future, its import supply and transport structure will diversify (longer distances, higher share of LNG (liquefied natural gas), new pipelines). Thus the process chain and GHG emissions of the production, processing, transport and distribution might change. Simultaneously, the injection of bio methane into the natural gas grid is becoming more important. Although its combustion is regarded as climate neutral, during the production processes of bio methane GHG emissions are caused. The GHG emissions occurring during the process chain of energy fuels are relevant for the discussion on climate policy and decision making processes. They are becoming even more important, considering the new Fuel Quality Directive of the EU (Dec. 2008), which aims at controlling emissions of the fuel process chains. Aim In the context of the aspects outlined above the aim is to determine the future development of gas supply for Germany and the resulting changes in GHG emissions of the whole process chain of natural gas and bio methane. With the help of two gas consumption scenarios and an LCA of bio methane, the amount of future emissions and emission paths until 2030 can be assessed and used to guide decision processes in energy policy. Results and discussion The process chain of bio methane and its future technical development are outlined and the related emissions calculated. The analysis is based on an accompanying research study on the injection of bio methane to the German gas grid. Two types of biogas plants have been considered whereof the “optimised technology” is assumed to dominate the future market. This is the one which widely exploits the potential of process optimisation of the current “state of the art” plant. The specific GHG emissions of the process chain can thus be nearly halved from currently 27.8?t CO₂-eq./TJ to 14.8?t CO₂-eq./TJ in 2030. GHG emissions of the natural gas process chain have been analysed in detail in a previous article. Significant modifications and a decrease of specific emissions is possible, depending on the level of investment in the modernisation of the gas infrastructure and the process improvements. These mitigation options might neutralise the emission increase resulting from longer distances and energy intensive processes. In the last section two scenarios (low and high consumption) illustrate the possible development of the German gas supply until 2030, given an overall share of 8–12?% of bio methane. Considering the dynamic emission factors calculated in the former sections, the overall gas emissions and average specific emissions of German gas supply can be given. The current emissions of 215.4 million t CO₂-eq. are reduced by 25?% in the low-consumption scenario (162 million t CO₂-eq.), where consumption is reduced by 17?%. Assuming a consumption which is increased by 17?% in 2030, emissions are around 7?% higher (230.9 million t CO₂-eq.) than today. Conclusions Gaseous fuels will still play a significant role for the German energy supply in the next two decades. The GHG emissions mainly depend on the amount of gas used. Thus, energy efficiency will be a key issue in the climate and energy related policy discussion. A higher share of bio methane and high investments in mitigation and best available technologies can significantly reduce the emissions of the process chain. The combustion of bio methane is climate neutral compared to 56?t CO₂/TJ caused by the direct combustion of natural gas (or 111?t CO₂/TJ emitted by lignite). The advantage of gaseous energy carriers with the lowest levels of GHG emissions compared to other fossil fuels still remains. This holds true for fossil natural gas alone as well as for the expected future blend with bio-methane.     

Impact of selective herbicide right-of-way vegetation treatment on birds

Power line rights-of-way provide a major portion of the shrub habitat in New York. Since this habitat type is on the decline, many of the birds dependent on shrub habitat are also declining. The methods used to control right-of-way vegetation could therefore have serious impacts on several birds of conservation concern. Since New York is increasingly using selective herbicide treatments in vegetation management, we sought to investigate the potential impacts of these treatments on nesting birds. The study looked at plots in two adjacent rights-of-way before and after a selective herbicide treatment in one of the rights-of-way. We investigated three bird species: alder flycatcher (Empidonax alnorum), chestnut-sided warbler (Dendroica pensylvanica), and gray catbird (Dumetella carolinensis). All three species exhibited a preference for shrub vegetation around nest sites. The selective herbicide treatment did not significantly decrease that shrub vegetation, and neither the density nor the nesting success of the three species declined following the treatment. We conclude that selective herbicide vegetation management encourages the development of shrub habitat without negatively impacting the birds nesting in the habitat.     

STREAM DISCHARGE PREDICTION VIA A GRID BASED SOIL WATER ROUTING WITH PADDY FIELDS1

ABSTRACT: A grid based daily hydrologic model for a watershed with paddy fields was developed to predict the stream discharge. ASCII formatted elevation, soil, and land use data supported by the GRASS Geographic Information System are used to generate distributed results such as surface runoff and subsurface flow, soil water content, and evapotranspiration. The model uses a single flow path algorithm and simulates a water balance at each grid element. A linear reservoir assumption was used to predict subsurface runoff components. The model was applied to a 75.6 km² watershed located in the middle of South Korea, and observed stream flow hydrographs from 1995 and 1996 were compared to model predictions. The stream flow predictions of 1995 and 1996 generally agreed with the observed flow, resulting in a Nash‐Sutcliffe efficiency R² of 0.60 and 0.62, respectively. The hydraulic conductivity for percolating water through the saturated layer affected baseflow generation. The levee height of the paddy influenced the time and magnitude of the surface runoff, depending on irrigation management. The model will be used for making low flow management decisions by evaluating the role of each land use to stream flow, especially in case of paddy decrease by gradual urbanization of a watershed.     

INSTANTANEOUS PEAK FLOW ESTIMATION PROCEDURES FOR NEWFOUNDLAND STREAMS1

ABSTRACT: A procedure of estimating instantaneous flood flows for various return periods on the Island of Newfoundland is presented. The procedure is based on annual maximum instantaneous flows rather than annual maximum daily-mean flows, as the latter requires the conversion of estimated daily-mean flows into instantaneous flows. Regression equations were developed for each of three homogeneous regions for the desired return periods. The flood flow estimation capability of the presented procedure is demonstrated to be better than any other currently available procedure on the Island.     

RUNOFF RESPONSE FROM TWO RECLAIMED WATERSHEDS1

ABSTRACT: Detailed studies of the surface hydrology of reclaimed surface-mined watersheds for both rainfall and snowmelt events are non-existent for central Alberta yet this information is crucial for design of runoff conveyance and storage structures. A study was initiated in 1992 with principal objectives of quantifying surface runoff for both summer rainfall and spring snowmelt events and identifying the dominant flow processes occurring in two reclaimed watersheds. Snowmelt accounted for 86 and 100% of annual watershed runoff in 1993 and 1994, respectively. The highest instantaneous peak flow was recorded during a summer rainfall event with a return period of greater than 50 years. Infiltration-excess overland flow was identified as the dominant flow process occurring within the Sandy Subsoil Watershed, whereas saturation overland flow was the principal runoff process occurring within the West Watershed.     

ANALYSIS OF NITROGEN MANAGEMENT STRATEGIES USING EPIC1

ABSTRACT: This paper illustrates a method of using a hydrologic/water quality model to analyze alternative management practices and recommend best management practices (BMPs) to reduce nitrate-nitrogen (NO₃^--N) leaching losses. The study area for this research is Tipton, an agriculturally intensive area in southwest Oklahoma. We used Erosion Productivity Impact Calculator (EPIC), a field-scale hydrologic/water quality model, to analyze alternative agricultural management practices. The model was first validated using observed data from a cotton demonstration experiment conducted in the Tipton area. Following that, EPIC was used to simulate fertilizer response curves for cotton and wheat crops under irrigated and dryland conditions. From the fertilizer response functions (N-uptake and N-leaching), we established an optimum fertilizer application rate for each crop. Individual crop performances were then simulated at optimum fertilizer application rates and crop rotations for the Tipton area, which were selected based on three criteria: (a) minimum amount of NO₃^--N leached, (b) minimum concentration of NO₃^--N leached, and (c) maximum utilization of NO₃^--M. Further we illustrate that by considering residual N from alfalfa as a credit to the following crop and crediting NO₃^--N present in the irrigation water, it is possible to reduce further NO₃^--N loss without affecting crop yield.     

NONLINEAR MODELING AND PREDICTION OF A RIVER FLOW SYSTEM1

ABSTRACT: Model estimation and prediction of a river flow system are investigated using nonlinear system identification techniques. We demonstrate how the dynamics of the system, rainfall, and river flow can be modeled using NARMAX (Nonlinear Autoregressive Moving Average with eXogenuous input) models. The parameters of the model are estimated using an orthogonal least squares algorithm with intelligent structure detection. The identification of the nonlinear model is described to represent the relationship between local rainfall and river flow at Enoree station (inputs) and river flow at Whitmire (output) for a river flow system in South Carolina.