THE STRUCTURE AND ROLE OF RIVER AUTHORITIES IN TEXAS1

ABSTRACT: Texas river authorities are a type of large, regional water district that must be financially self-sufficient. An institutional and historical study of Texas river authorities reveals the broad power of these organizations and their influence in water management. River authorities now control 25 percent of surface water deliveries in Texas. Over two-thirds of authority water was developed by river authorities; nearly one-third was purchased from private or public ventures. While river authority activities have been effective where these services are marketable, the provision of public good services is limited. Increased visibility of these organizations is paralleled by challenges to their traditional autonomy.     

The politics of leadership: The relationship between task-people leadership and subordinate influence

The purpose of the present research was to investigate the political nature of leadership by examining the association of the task-people leadership approach with strategies used by subordinates to influence their superiors. Forty-eight faculty members (31 males and 17 females) from a school of higher education completed the T-P Leadership Questionnaire and Profile of Organizational Influence Strategies. Reponses were analyzed using Pearson product-moment correlations. The results indicated that as perceived task-centered leadership increased, employees reported a significantly greater use of bargaining, assertiveness, higher authority, and coalition as strategies to influence their superiors. The relationships were observed only during second influence attempts. Further, it was observed that as the perceived level of people-centered leadership behavior rose, subordinates reported a significantly decreased use of bargaining and higher authority as influence strategies during first influence attempts. The findings are discussed in terms of the reciprocal and political character of managerial- subordinate relationships.     

Geologic emissions of methane to the atmosphere

The atmospheric methane budget is commonly defined assuming that major sources derive from the biosphere (wetlands, rice paddies, animals, termites) and that fossil, radiocarbon-free CH4 emission is due to and mediated by anthropogenic activity (natural gas production and distribution, and coal mining). However, the amount of radiocarbon-free CH4 in the atmosphere, estimated at approximately 20% of atmospheric CH4, is higher than the estimates from statistical data of CH4 emission from fossil fuel related anthropogenic sources. This work documents that significant amounts of "old" methane, produced within the Earth crust, can be released naturally into the atmosphere through gas permeable faults and fractured rocks. Major geologic emissions of methane are related to hydrocarbon production in sedimentary basins (biogenic and thermogenic methane) and, subordinately, to inorganic reactions (Fischer-Tropsch type) in geothermal systems. Geologic CH4 emissions include diffuse fluxes over wide areas, or microseepage, on the order of 10(0)-10(2) mg m(-2) day(-1), and localised flows and gas vents, on the order of 10(2) t y(-1), both on land and on the seafloor. Mud volcanoes producing flows of up to 10(3) t y(-1) represent the largest visible expression of geologic methane emission. Several studies have indicated that methanotrophic consumption in soil may be insufficient to consume all leaking geologic CH4 and positive fluxes into the atmosphere can take place in dry or seasonally cold environments. Unsaturated soils have generally been considered a major sink for atmospheric methane, and never a continuous, intermittent, or localised source to the atmosphere. Although geologic CH4 sources need to be quantified more accurately, a preliminary global estimate indicates that there are likely more than enough sources to provide the amount of methane required to account for the suspected missing source of fossil CH4.     

Fouling mechanisms in a laboratory-scale UV disinfection system.

The fouling of quartz sleeves surrounding UV disinfection lamps is a perennial problem affecting both drinking water and wastewater applications. The mechanisms of fouling are not fully understood, but factors promoting fouling are believed to include heat, high hardness and/or high iron concentrations, and hydrodynamic forces. The role of UV radiation itself is unclear. The goal of this paper is to attempt to isolate the fouling mechanisms and to provide key information about those induced by UV radiation, using a unique laboratory-scale continuous-flow UV reactor. Its design allowed for irradiated and nonirradiated zones and control of both temperature and UV intensity at the fouling surface. Synthetic wastewater samples were tested with two levels of calcium, iron, phosphorus, and biochemical oxygen demand (as beef broth), and constant levels of magnesium and nitrogen to assess the effects of the four key variables. Average UV fluence before fouling exceeded 35 mJ/cm2, based on collimated beam tests. Foulant accumulation was monitored by UV intensity measurements and by mass and composition of foulant collected after an average of 56 hours of continuous operation. Tests showed that relative UV intensity dropped by as much as 100% when iron was present. Detailed results were assessed and yielded support for the following three UV-induced fouling mechanisms: (a) precipitation of ferric hydroxide [Fe(OH)3], (b) release of calcium from calcium-organics complexes followed by precipitation of iron-organics complexes, and (c) calcium carbonate precipitation. Other fouling mechanisms, such as sedimentation of preformed particles and sorption of calcium onto preformed colloids of Fe(OH)3, occurred outside the zone of UV radiation. Hence, these could be confused with concurrent UV-induced mechanisms in full-scale reactors. Iron and/or calcium undoubtedly created the most favorable conditions for fouling to occur; in the absence of both, fouling would be unlikely. The rates of fouling were enhanced when organics were also present; however, when phosphorus was present, fouling in the UV section was reduced. Indeed, UV may be viewed as inhibiting the fouling caused by phosphate complexes.     

Seasonal variation in the degree of heterospecific association of two syntopic hyraxes (<Emphasis Type="Italic">Heterohyrax</Emphasis><Emphasis Type="Italic">brucei </Emphasis>and <Emphasis Type="Italic">Procavia capensis</Emphasis>) exhibiting synchronous parturition

Adult rock hyrax (Procavia capensis) and bush hyrax (Heterohyrax brucei) allocate much of their surface activity to being vigilant for vertebrate predators. Individuals of the two species associate for thermoregulatory basking on rock outcrops (koppies) and, in the Matobo National Park, Zimbabwe, frequently constitute heterospecific groups that produce offspring synchronously. Exposure to predators during basking is thought to put a high premium on vigilance, particularly during the presence of dependent offspring in nurseries. We predicted, therefore, an increase in the association of the two species of hyraxes when offspring were present because this would lead to larger groups, thus enhancing the ability to detect predators. Koppie aggregations of hyraxes were classified as homospecific or heterospecific according to basking group composition. Heterospecific association increased when offspring were present, and heterospecific groups were larger than homospecific ones. Fifty-one percent of nurseries were heterospecific for adults/subadults. During the pre-weaning phase (<2 months after birth), 85% of P. capensis and 65% of H. brucei juveniles were in nurseries of heterospecific basking groups. Heterospecific groups had more offspring than homospecific groups. Juvenile mortality is most evident after young are weaned and heterospecific associations break down. Heterospecific aggregation, through increased group size, may result in a higher probability of avoiding predators, thereby reducing the vulnerability of young.     

Land change in the southern Yucatán and Calakmul biosphere reserve: effects on habitat and biodiversity.

The southern Yucatán contains the largest expanse of seasonal tropical forests remaining in Mexico, forming an ecocline between the drier north of the peninsula and the humid Petén, Guatemala. The Calakmul Biosphere Reserve resides in the center of this region as part of the Mesoamerican Biological Corridor. The reserve's functions are examined in regard to land changes throughout the region, generated over the last 40 years by increasing settlement and the expansion and intensification of agriculture. These changes are documented from 1987/1988 to 2000, and their implications regarding the capacity of the reserve to protect the ecocline, forest habitats, and butterfly diversity are addressed. The results indicate that the current landscape matrix serves the biotic diversity of the reserve, with several looming caveats involving the loss of humid forests and the interruption of biota flow across the ecocline, and the amount and proximity of older forest patches beyond the reserve. The highly dynamic land cover changes underway in this economic frontier warrant an adaptive management approach that monitors the major changes underway in mature forest types, while the paucity of systematic ecological and environment-development studies is rectified in order to inform policy and practice.     

Heavy metal contamination in the Tanat Valley,North Wales

The Tanat Valley area of North Powys, Wales, has a long history of metalliferous mining, the most active period of extraction being during the 18th century, while the largest mine, Llangynog, was in production until 1899. Ore minerals found in the area include galena (PbS), sphalerite (ZnS) and chalcopyrite (CuFeS2). Below the Llangynog mine the valley is heavily contaminated with elevated levels of Pb, Zn, Cu and Cd in soils and river sediments. On the valley floor subsoil metal levels frequently greatly exceed those of topsoils which probably reflects contamination of the floodplain during the peak period of mining. High levels of base metals in the stream sediments some 2 km downstream of the mine area are thought to be due to river erosion of the contaminated bank material. Contamination derived from the old mine tips results in extremely high levels of heavy metals in soils and stream sediments in the immediate vicinty of the old workings. Some metal contamination is also thought to derive from previously undetected mineralisation.     

Analysis of Historical Salinity and Boron Surface Water Monitoring Data from the San Joaquin River Watershed: 1985–2002

The objectives of this study were to use both parametric and probabilistic approaches to analyze water column concentrations of both salinity (24,845 measurements) and boron (13,028 measurements) from numerous investigations conducted in the San Joaquin River watershed from 1985 to 2002 to assess spatial and temporal trends and determine the probability of exceeding regulatory targets during both the irrigation and non-irrigation season. Salinity and boron concentrations from 26 mainstem and tributary sites were highly correlated based on this 17 yr data set. Generally, salinity and boron concentrations were higher in winter/spring and lower in summer/fall; higher concentrations of both constituents were reported in tributary sites when compared with the mainstem San Joaquin River. Approximately half the sites showed showed a negative correlation between flow and both constituents. Concentrations of both salinity and boron were somewhat variable with flow conditions for the other sites. Both linear and curvilinear trends were inconsistent over time. The salinity 90th centiles for the 26 sites ranged from 143 to 7,559 micros cm(-1) with the highest 90th centiles in tributary sites. Probabilistic analysis of salinity 90th centiles by year for five sites with extensive data showed a significant decrease over time at two sites and no significant trend for the other three sites. The probability of exceeding the salinity targets during either the irrigation (700 microm cm(-1)) or non-irrigation (1,000 micros cm(-1)) season was greater than 19% for all but three sites. The boron 90th centiles for the 26 sites ranged from 0.41 to 13.6 mg L(-1) with the highest 90th centiles from tributary sites. Probabilistic analysis of the boron 90th centile values by year for the five sites with the most extensive data showed a significant decrease over time at two sites and no significant trend for the other three sites. The probability of exceeding the boron target during the irrigation season (0.80 mg L(-1)) and non-irrigation (1.0 mg L(-1)) season was greater that 18% for all but three sites. Results from this analysis have important regulatory implications as targets for both salinity and boron are frequently exceeded at various sites in the San Joaquin River watershed.