Establishing a standard Sonoran Reference Plant and its application in monitoring industrial and urban pollution throughout the Sonoran Desert

Using analyses from honey mesquite (Prosopis glandulosa) leaves from nearly pristine locations in Arizona, an inorganic plant concentration standard is proposed for use as a Sonoran Reference Plant (SRP). Such a standard can be used as a monitoring device for different anthropogenic pollution sources throughout the Sonoran Desert. To test the application of the SRP, honey mesquite leaves were collected at different sites in southern Arizona and their chemical fingerprints compared to SRP. Sources of element origin were identified through factor analysis and correlation matrices. A terrestrial factor was found in leaves from all sites. Anthropogenic factors varied for different sites. Mesquite leaves accumulated significant amounts of elements originating from copper smelters (As, Sb) and urban pollution (La, Sm, Ce, V). These pollutants are small-sized and have been linked to human lung diseases. Mesquite is a deciduous tree; the yearly comparison of mesquite leaf element concentration spectra to the SRP standard can be used to determine seasonal improvement or deterioration of environmental quality in a particular area.     

Diversity, Seasonality, and Context of Mammalian Roadkills in the Southern Great Plains

Thousands of mammals are killed annually from vehicle collisions, making the issue an important one for conservation biologists and environmental managers. We recorded all readily identifiable kills on or immediately adjacent to roads in the southern Great Plains from March 2004–March 2007. We also recorded distance traveled, whether a road was paved or divided, the number of lanes, and prevailing habitat. Surveys were opportunistic and were conducted by car during conditions of good visibility. Over our 239 surveys and >16,500 km traveled, we recorded 1412 roadkills from 18 different mammal species (size ranged from Sciurus squirrels to the white-tailed deer, Odocolieus virginianus). The overall kill rate was 8.50 / 100 km. Four species were prone to collisions: the Virginia opossum (Didelphis virginiana), nine-banded armadillo (Dasypus novemcinctus), striped skunk (Mephitis mephitis), and northern raccoon (Procyon lotor). Together they accounted for approximately 85% (1198) of all roadkills. Mortality rate differed significantly between 2- and 4-lane roads (8.39 versus 7.79 / 100 km). Kill rates were significantly higher on paved versus unpaved roads (8.60 versus 3.65 / 100 km), but did not depend on whether a road was divided. Roadkills were higher in spring than in fall (1.5×), winter (1.4×), or summer (1.3×). The spring peak (in kills / 100 km) was driven chiefly by the armadillo (2.76 in spring/summer versus 0.73 in autumn/winter) and opossum (2.65 versus 1.47). By contrast, seasonality was dampened by a late winter/early spring peak in skunk mortalities, for which 41% occurred in the 6-week period of mid-February through March. The raccoon did not exhibit a strong seasonal pattern. Our data are consistent with dispersal patterns of these species. Our results underscore the high rate of highway mortality in the southern plains, as well as differences in seasonality and road type that contribute to mortality. Conservation and management efforts should focus on creating underpasses or using other means to reduce roadkill rates.     

Projecting Cumulative Benefits of Multiple River Restoration Projects: An Example from the Sacramento-San Joaquin River System in California

Despite increasingly large investments, the potential ecological effects of river restoration programs are still small compared to the degree of human alterations to physical and ecological function. Thus, it is rarely possible to “restore” pre-disturbance conditions; rather restoration programs (even large, well-funded ones) will nearly always involve multiple small projects, each of which can make some modest change to selected ecosystem processes and habitats. At present, such projects are typically selected based on their attributes as individual projects (e.g., consistency with programmatic goals of the funders, scientific soundness, and acceptance by local communities), and ease of implementation. Projects are rarely prioritized (at least explicitly) based on how they will cumulatively affect ecosystem function over coming decades. Such projections require an understanding of the form of the restoration response curve, or at least that we assume some plausible relations and estimate cumulative effects based thereon. Drawing on our experience with the CALFED Bay-Delta Ecosystem Restoration Program in California, we consider potential cumulative system-wide benefits of a restoration activity extensively implemented in the region: isolating/filling abandoned floodplain gravel pits captured by rivers to reduce predation of outmigrating juvenile salmon by exotic warmwater species inhabiting the pits. We present a simple spreadsheet model to show how different assumptions about gravel pit bathymetry and predator behavior would affect the cumulative benefits of multiple pit-filling and isolation projects, and how these insights could help managers prioritize which pits to fill.     

A geophysical perspective of value of information: examples of spatial decisions for groundwater sustainability

The value of information (VOI) can be used to determine what kind of spatial information maybe relevant and useful for groundwater sustainability decisions. In this paper, the unique challenges for applying VoI to spatial information from geophysical data are described. The uncertainty regarding the spatial structure or continuity of the subsurface properties can be described with geostatistical sample models. Using these models, one can quantify the prior value given our present state of uncertainty and a set of decision alternatives and outcomes. Because geophysical techniques are a type of remote-sensing data, assuming “perfect” information is not realistic since the techniques usually are indirectly sampling the aquifer properties. Therefore, the focus of this paper is describing how the data reliability (the measure of imperfectness) can be quantified. One of the foremost considerations is the non-unique relationship between geological parameters (which determine groundwater flow) and geophysical observables (what determines the response of the technique). Another is to have the information in a form such that it is useful for spatial decisions. This will often require inversion and interpretation of the geophysical data. Inversion reconstructs an image of the subsurface from the raw geophysical data. How closely the image reproduces the true subsurface structure or property of interest depends on the particular technique’s resolution, depth of investigation and sensor locations. Lastly, in some cases, interpretation of the geophysical data or inversion will be necessary to link the data to the variables that determine the outcome of the decision. Three examples are provided that illustrate different approaches and methods for addressing these challenges. In the examples, time-domain electromagnetic and electrical resistivity techniques are evaluated for their ability to assist in spatial decisions for aquifer management. The examples considered address these three situations: aquifer vulnerability to surface–borne contaminants, managed aquifer recharge and CO₂/brine leakage (related to CO₂ geologic sequestration activities). The methods presented here are transferable to other subsurface sciences and decisions that involve risk. Recent work has been applied to geothermal well-siting using electromagnetic techniques. These approaches can also be applied for oil and mining spatial decisions, and they offer advantages over previous VOI work done for oil applications: they explicitly include the geologic uncertainty modeling and simulate the physics of the considered geophysical technique.     

Structure of pathways in ecological networks: relationships between length and number

In ecosystems network, structure determines adjacent (direct) and non-adjacent (indirect) pathways over which energy, matter, and information can flow. The more pathways, the more possible ways the conservative substance can move in zero-sum transactions between network nodes that the pathways interconnect, and the more possible non-conservative, nonzero-sum relations can be secondarily derived from these. Structural analysis is a tool we employ, from a family of input–output methods for exploring zero- and nonzero-sum attributes of environmental networks, to count pathways of varying length between network nodes. In this paper, we examine the relationship between pathway length (k) and number (P_k) as determined by system size (n, number of nodes) and extent and pattern of connectance (C). We develop a measure (m_a) of pathway growth in numbers with increasing length, and then normalize this to the maximum rate possible (m_a/m_c) for a given system size. These measures apply to two pathway types—paths, m_a(0) and m_a(0)/m_c(0), which forbid adjacent node repetitions, and walks, m_a(1) and m_a(1)/m_c(1), which allow them. We find that network size has a curvilinear effect on the pathway number versus length relationship, and extent and pattern of connectance are convolved. Values computed for the paths and walks of three ecosystem models (oyster reef, freshwater marsh, and reservoir cove) are used to compare their pathway structure.     

Injuries causing death: Their nature,external causes,and associated diseases

This article provides national data on the types of injuries reported on death certificates, the external causes of these injuries, and diseases that are frequently reported with them. Injuries were a factor in 11 % (213,366 deaths) of the deaths to residents of the United States in 1978. Of 11 broad categories of injuries, three (fractures, sprains, strains, and dislocations, intracranial injuries, and adverse effects) were mentioned on almost 50,000 deaths each. There was considerable variation in the distribution of injury types by age, sex, and race. The most notable example was fractures of the lower limb which were mentioned on 29% of the deaths involving an injury to 65 + year olds but no less than 5% of such deaths for all other age groups. For white females, the percentage with a fracture of the lower limb was 23 % compared to 12 % overall. In 25 % of the deaths involving an injury, the immediate cause was a motor vehicle accident. In 51 %, the immediate cause of the injury was a non-motor-vehicle accident. In 73 % of the deaths involving non-motor-vehicle accidents, disease conditions as well as injuries were a factor; and, 69% of the time, the disease condition was actually the underlying cause of the death with the injury being a contributing factor or complication. For example, over 14,000 deaths in 1978 involved a circulatory condition as the underlying cause of death which was complicated by an accidental fracture, sprain, or dislocation. Although diseases more often assumed the role of the underlying cause of death, they were also a nonunderlying cause in 24,000 non-motor-vehicle accident deaths. Over 12,000 of such deaths involved circulatory diseases.     

The effects of corona electrode geometry on the operational characteristics of an ESP

Experiments were run in a pilot scale electrostatic precipitator (ESP) to determine the effects of corona wire-to-wire spacing on the operating conditions. Tests were run, using a reentrained low sulfur fly ash at both hot- and cold-side conditions. The effects of varying wire-to-wire spacing were determined. Results are given which show that varying wire spacing at cold-side conditions has little operational effect on the ESP while improved efficiency can be obtained at hot-side (low resistivity) conditions by reducing wire spacing. The increased efficiency results from a higher average operating voltage. The effects of back ionization are clearly demonstrated by a set of experiments in which dust was selectively removed from the wires or plate. These tests show that the lower operating voltage caused by back ionization is a combined effect of high resistivity dust on both the wires and plate.     

Fungi of the Bay of Fundy

During the spring and summer of 1979, 48 species of geofungi and several sterile, unidentified fungi were isolated from two off-shore stations on the Bay of Fundy, Canada. Isolations were made from subsurface water and surface slicks on 6 agar media including one containing hexadecane, and from subsurface water baited with hemp seeds. Numbers of fungi were 10 to 100 times higher than those reported for other offshore stations and similar to those reported for a saltmarsh outflow. Species isolated during a high freshwater flow largely corresponded to a typical soil flora. Species isolated during a reduced freshwater flow were either marine in character or noted for association with area littoral seaweeds. Three fungi (Cladosporium cladosporioides, Trichoderma viride, and Gliocladium rosium) were tested for growth on media of increasing salinity. Growth was measured by dry weight production, pH drop and glucose used in liquid culture. C. cladosporioides showed responses typical of a marine fungus, T. viride of a terrestrial fungus and G. roseum was intermediate. The results are discussed in relation to the role of geofungi in the sea.