Assessing inter-laboratory comparability and limits of determination for the analysis of cyclic volatile methyl siloxanes in whole Rainbow Trout (Oncorhynchus mykiss)

Cyclic volatile methyl siloxanes (cVMS) are high volume production chemicals used in a wide range of industrial and consumer products. Three cVMS compounds (D4, D5, and D6) have and are undergoing environmental risk evaluations in several countries and have been proposed for legal regulation in Canada. As interest in monitoring concentrations of these chemicals in the environment increase, there is a need to evaluate the analytical procedures for cVMS in biological matrices in order to assess the quality of data produced. The purpose of this study was to determine laboratory testing performance for measuring residues of D4, D5, and D6 in a standard set of fish homogenate samples and to estimate limits of determination for each substance. The samples sent to each laboratory consisted of homogenized whole body tissues of hatchery raised rainbow trout which were fed food fortified with D4, D5, and D6 (dosed) and trout that were fed standard food rations (control). The participants analyzed each sample using their analytical method of choice using their own standards and procedures for quantification and quality control. With a few exceptions, participating laboratories generated comparable results for D4, D5, and D6 in both the dosed and control samples having z-scores between 2 and −2. Method detection limits for the whole fish matrix were on average 2.4 ng g⁻¹ ww for D4, 2.3 ng g⁻¹ ww for D5, and 1.8 ng g⁻¹ ww for D6.     

Solar driven nitrous acid formation on building material surfaces containing titanium dioxide: A concern for air quality in urban areas?

The photoenhanced uptake of nitrogen dioxide (NO₂) to the surface of commercially available self-cleaning window glass has been studied under controlled laboratory conditions. This material is one of an array of modern building products which incorporate titanium dioxide (TiO₂) nanoparticles and are finding increasing use in populated urban areas. Amongst the principal drivers for the use of these materials is that they are thought to facilitate the irreversible removal of pollutants such as NO₂ and organic molecules from the atmosphere and thus act to remediate air quality. While it appears that TiO₂ materials do indeed remove organic molecules from built environments, in this study we show that the photoenhanced uptake of NO₂ to one example material, self-cleaning window glass, is in fact accompanied by the substantial formation (50–70%) of gaseous nitrous acid (HONO). This finding has direct and serious implications for the use of these materials in urban areas. Not only is HONO a harmful respiratory irritant, it is also readily photolysed by solar radiation leading to the formation of hydroxyl radicals (OH) together with the re-release of NO_x as NO. The net effect of subsequent OH initiated chemistry can then be the further degradation of air quality through the formation of secondary pollutants such as ozone and VOC oxidation products. In summary, we suggest that a scientifically conceived technical strategy for air quality remediation based on this technology, while widely perceived as universally beneficial, could in fact have effects precisely opposite to those intended.     

ITERATIVE EVALUATION OF A LAKE WATER QUALITY MANAGEMENT PROGRAM1

ABSTRACT: Local governments often face environmental problems that cross political boundaries. The onus for solution usually falls on the moat severely affected jurisdiction, others do nothing until impacted. Resolution of these problems requires cooperation across political boundaries which means that local governments must be persuaded first that there is a problem, and second that action is required to solve it. This paper presents a method to supply low cost, credible information that can be used to achieve consensus on problem solution. A case study of a lake water quality management problem is described. Formative evaluation techniques was adapted to provide a minimum of evidence which was then used to persuade less impacted local jurisdictions to cooperate in the problem solution.     

Long-term depletion of calcium and other nutrients in eastern US forests

Both harvest removal and leaching losses can deplete nutrient capital in forests, but their combined long-term effects have not been assessed previously. We estimated changes in total soil and biomass N, Ca, K, Mg, and P over 120 years from published data for a spruce-fir site in Maine, two northern hardwood sites in New Hampshire, central hardwood sites in Connecticut and Tennessee, and a loblolly pine site in Tennessee. For N, atmospheric inputs counterbalance the outputs, and there is little long-term change on most sites. For K, Mg, and P, the total pool may decrease by 2%–10% in 120 years depending on site and harvest intensity. For Ca, net leaching loss is 4–16 kg/ha/yr in mature forests, and whole-tree harvest removes 200–1100 kg/ha. Such leaching loss and harvest removal could reduce total soil and biomass Ca by 20%–60% in only 120 years. We estimated unmeasured Ca inputs from rock breakdown, root-zone deepening, and dry deposition; these should not be expected to make up the Ca deficit. Acid precipitation may be the cause of current high leaching of Ca. Although Ca deficiency does not generally occur now in acid forest soils, it seems likely if anthropogenic leaching and intensive harvest removal continue.     

The International Drinking Water Supply and Sanitation Decade in retrospect and implications for the future

In global terms this paper reviews the progress made during the International Drinking Water Supply and Sanitation Decade. There has been considerable progress. In terms of percent receiving water services, the urban areas made good progress: 77% in 1980 to 82% in 1990. In the rural areas progress was even greater, 30% had water services in 1980 versus 63% in 1990. There was also considerable progress in institutional terms. A positive trend towards better linkage betweeen authorities dealing with water supply and sanitation and those dealing with economic development, was one. Another was the awareness of the need for community involvement. In some cases progress was hampered by fragmentation of governmental authorities dealing with water and sanitation at the rural and/or urban level. In the 1990s an important issue will be financing the infrastructure needed to bring water and sanitation services to those not already covered and to an increasing population. Institutional issues will continue to be important as well.     

A framework for understanding the consumptive orientation of recreational fishermen

Fishermen were aggregated into high-, mid-, and low-consumptive groups according to the importance they placed on catching fish. Analysis of variance indicated that each consumptive group was unique in the importance it placed on other fish-related variables. Low-consumptive fishermen rated most other aspects of the fishing experience, such as interacting with nature, relaxation, and escaping the daily routine, more important than did high-consumptive fishermen. Low-consumptive fishermen also fished more frequently and were generally more satisfied with their most recent fishing trip than were high-consumptive-oriented fishermen. The three groups can be viewed as different fishing constituencies. By understanding their characteristics, we can gain additional insights into the impacts of management decisions on recreational fishermen and their experiences.     

Riera de Caldes new town: the restriction of growth

The historical and regional context to the development of a planning strategy for Barcelona is examined, providing an explanation of the obstacles to development of new towns in the region, and that of Riera de Caldes in particular. The paper analyses the reasons for the failure to develop the new town, and its subsequent reversion to rural uses and a place of pilgrimage for environmentalists.     

NITRATE CONTAMINATION IN OREGON WELL WATER: GEOLOGIC VARIABILITY AND THE PUBLIC'S PERCEPTION1

ABSTRACT: Approximately 4.5 million people in the United States who rely on well water are exposed to nitrate‐N concentrations exceeding the 10 mg/l standard. In this study in the Southern Willamette Valley in Oregon we reassessed nitrate‐N in rural wells sampled in 2000–2001, compared nitrate‐N concentrations among geological units, and surveyed residents about their perceptions of well water quality. Nitrate‐N concentrations were again sampled in 2002 and found to have increased significantly from the previous period. With rapid population growth in the area, the potential health risk in drinking well water that exceeds 10 mg/l nitrate‐N warrants continued public education. Nitrate‐N concentrations were found to be higher in the Holocene alluvium of the Willamette River and the Pleistocene sand and gravel post‐Missoula Flood deposits. Researchers conducting future studies may choose to stratify and monitor wells by geologic unit and by other parameters that estimate input of nutrients to the environment. Opinions differed between agricultural landowners and nonagricultural landowners with regard to the impact that agricultural fertilizers may have on water quality. Participants were supportive of a range of regulatory actions that might be used by homeowners or landowners to address ground water contamination. Given that the area is now designated a Groundwater Management Area, understanding local stakeholders’perceptions is critical and strategic and has the potential to help public agencies manage potential conflicts of opinion among stakeholders, build consensus, and help guide the approach to restoring ground water quality.     

Studies on enhanced degradable plastics: 1. The geographic variability in outdoor lifetimes of enhanced photodegradable polyethylenes

Studies on three types of enhanced photodegradable polyethylenes showed tensile elongation at break to be a suitable parameter for assessing disintegration due to outdoor weathering. Disintegration rates varied greatly with exposure location, with Arizona the harshest environment and Washington and New Jersey the mildest. The rate of breakdown of the enhanced degradable polyethylenes relative to unmodified plastic was termed an enhancement factor. For the materials studied, average enhancement factors generally ranged from five to fifteen. The location-dependent variability in rate parameters can be mostly explained in terms of different average radiation levels and temperatures at these locations. A duplicate exposure protocol was developed to determine if the test data were complicated by short-term fluctuations in sunlight or temperature during exposure.     

Degradation of Polylactic Acid (PLA) Plastic in Costa Rican Soil and Iowa State University Compost Rows

In this study the degradation of polylactic acid (PLA) plastic films in Costa Rican soil and in a leaf composting environment was investigated. Three types of PLA films were used: Ch-I, (PLA monolayer plastic films from Chronopol, Golden, CO), GII (PLA trilayer plastic films from Cargill Dow Polymers LLC, Minnetonka, MN), and Ca-I (PLA monolayer plastic films from Cargill Dow Polymers LLC). The average soil temperature and moisture content in Costa Rica were 27°C and 80%, respectively. The average degradation rate of PLA plastic films in the soil of the banana field was 7675 M _w/week. Two compost rows were set up at the Iowa State University (ISU) (Ames) compost site. Temperature and relative humidity of the compost rows were kept at 55 ± 5°C and 50 ± 10% RH, respectively. The degradation rates of GII and Ca-I in the compost rows were 113,290 and 71,283 M _w/week, respectively. Therefore, it was estimated that in Costa Rican soil and in compost rows, PLA would be visibly degraded in 6 months and in 3 weeks, respectively.