Heterogeneous photocatalysed degradation of a herbicide derivative, isoproturon in aqueous suspension of titanium dioxide

Heterogeneous photocatalysed degradation of a herbicide derivative, N-(4-isopropylphenyl)-N',N'-dimethylurea (Isoproturon, 1) was investigated in aqueous suspensions of titanium dioxide by monitoring the change in absorption intensity and depletion in Total Organic Carbon content as a function of irradiation time. The degradation kinetics was studied under different conditions such as pH, catalyst concentration, substrate concentration, different types of TiO(2) and in the presence of electron acceptors such as hydrogen peroxide (H(2)O(2)), potassium bromate (KBrO(3)) and potassium persulphate (K(2)S(2)O(8)) besides molecular oxygen. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 was found to be more efficient as compared with other photocatalysts. An attempt was made to identify the degradation product through GC-MS analysis technique.     

Auditing non-hazardous wastes from golf course operations: moving from a waste to a sustainability framework

This paper provides non-hazardous solid waste audit procedures and bench mark audit data for golf courses (GCs). The paper also demonstrates the narrow scope of solid waste audit data, and the need to move towards a broader auditing scope such as that contained in sustainability auditing frameworks. A case study of Clear Lake Golf Course, located in southwestern Manitoba, Canada was completed. Annual waste generation rates at the GC were estimated to be 46.2 tonnes/year with 83% of this material compostable. Grass clipping material generated from the putting greens accounted for 79% of the waste stream. The GC achieved a solid waste diversion rate of 81% (waste generated not destined for landfill per total waste material generated). A future, realistic target of 97% diversion was also identified. The 7 day audit period was found to be unsuitable for estimating grass clipping generation rates. Implementation of a broader sustainability framework for future audits will harmonize many existing management functions such as solid waste auditing, waste characterizations, pollution prevention, green procurement, customer satisfaction, and the efficiency of the operations.     

A THEORETICAL TRAVEL TIME BASED ON WATERSHED HYPSOMETRY1

ABSTRACT: The time to hydrograph peak of a watershed basin has been found to correlate with various statistical attributes (e.g., skewness and kurtosis) of its hypsometric curve (treated as probability distribution). This paper presents a theoretical travel time that is conceptually analogous to the time to hydrograph peak and can be calculated directly from the hypsometric curve of a watershed basin based on gravity and acceleration. The theoretical travel times for 23 selected watersheds in the United States are found to correlate significantly with their corresponding hypsometric attributes. In addition, the theoretical travel times are consistent with the times of concentration estimated from the Federal Aviation Administration method. Thus, this paper offers a simple theoretical explanation to the empirically identified linkage between time to hydrograph peak and hypsometric attributes. This theoretical travel time can provide an alternative way of characterizing the effects of basin morphometry on hydrologic response.     

An environmental threshold for degree of phosphorus saturation in sandy soils

There is critical need for a practical indicator to assess the potential for phosphorus (P) movement from a given site to surface waters, either via surface runoff or subsurface drainage. The degree of phosphorus saturation (DPS), which relates a measure of P already adsorbed by a soil to its P adsorption capacity, could be a good indicator of that soil's P release capability. Our primary objective was to find a suitable analytical protocol for determining DPS and to examine the possibility of defining a threshold DPS value for Florida's sandy soils. Four farmer-owned dairy sprayfields were selected within the Suwannee River basin and soil profiles were randomly obtained from each site, as well as from adjacent unimpacted sites. The soil samples were divided either by horizon or depth, and DPS was determined for each soil sample using ammonium-oxalate (DPS(Ox)), Mehlich-1 (DPS(M1)), and Mehlich-3 (DPS(M3)) extracts. All methods of DPS calculations were linearly related to one another (r2 > 0.94). Relationships between water-soluble P and DPS indicate that the respective change points are: DPS(Ox) = 20%, DPS(M1) = 20%, and DPS(M3) = 16%. These relationships include samples from Ap, E, and Bt horizons, and various combinations thereof, suggesting that DPS values can be used as predictors of P loss from a soil irrespective of the depth of the soil within a profile. Taking into consideration the change points, confidence intervals, agronomic soil test values, and DPS values from other studies, we suggest replacing Mehlich-1 P values in the Florida P Index with the three DPS categories (DPS(M1) = <30, 30-60, and >60%) to assign different P loss ratings in the P Index.     

THE INFLUENCE OF CLIMATE VARIATION ON THE ESTIMATION OF LOW FLOWS USED TO PROTECT WATER QUALITY: A NATIONWIDE ASSESSMENT1

ABSTRACT: Historical flow records are used to estimate the regulatory low flows that serve a key function in setting discharge permit limits through the National Pollutant Discharge Elimination System, which provides a nationwide mechanism for protecting water quality. Use of historical records creates an implicit connection between water quality protection and climate variability. The longer the record, the more likely the low flow estimate will be based on a broad set of climate conditions, and thus provides adequate water quality protection in the future. Unfortunately, a long record often is not available at a specific location. This analysis examines the connection between climate variability and the variability of biologically based and hydrologically based low flow estimates at 176 sites from the Hydro‐Climatic Data Network, a collection of stream gages identified by the USGS as relatively free of anthropogenic influences. Results show that a record of 10 to 20 years is necessary for satisfactory estimates of regulatory low flows. Although it is possible to estimate a biologically based low flow from a record of less than 10 years, these estimates are highly uncertain and incorporate a bias that undermines water quality protection.     

REGION,LANDSCAPE, AND SCALE EFFECTS ON LAKE SUPERIOR TRIBUTARY WATER QUALITY1

ABSTRACT: In 1998 and 1999, third‐order watersheds in high mature forest (HMF) and low mature forest (LMF) classes were selected along gradients of watershed storage within each of two hydrogeomorphic regions in the Lake Superior Basin to evaluate threshold effects of storage on hydrologic regimes and watershed exports. Differences were detected between regions (North and South Shore) for particulates, nutrients, and pH, with all but silica values higher for South Shore streams (p < 0.05). Mature forest effects were detected for turbidity, nutrients, color, and alkalinity, with higher values in the LMF watersheds, that is, watersheds with less that 50 percent mature forest cover. Dissolved N, ammonium, N:P, organic carbon, and color increased, while suspended solids, turbidity, and dissolved P decreased as a function of storage. Few two‐way interactions were detected between region and mature forest or watershed storage, thus threshold based classification schemes could be used to extrapolate effects across regions. Both regional differences in water quality and those associated with watershed attributes were more common for third‐order streams in the western Lake Superior drainage basin as compared with second‐order streams examined in an earlier study. Use of ecoregions alone as a basis for setting regional water quality criteria would have led to misinterpretation of reference condition and assessment of impacts in the Northern Lakes and Forest Ecoregion.     

Why Won’t They Come? Stakeholder Perspectives on Collaborative National Forest Planning by Participation Level

Collaboration has taken root in national forest planning, providing expanded opportunities for stakeholder participation in decision-making, but are these processes considered meaningful by key stakeholders? Do the processes result in increased participation by key stakeholders? We present results of a study of stakeholder perspectives of a collaborative planning process on the Grand Mesa, Uncompahgre, and Gunnison National Forests in Western Colorado, U.S.A. The stakeholders were stratified by participation levels in order to explore a possible relationship between participation and perceptions of the collaborative process. We used a Q-methodology approach to compare and contrast perspectives across participant levels in the North Fork Valley Landscape Working Group process. The results demonstrate four distinct perspectives on the collaborative process: 1) The collaborative process is valued by the Forest Service and will directly influence planning decisions; 2) The Forest Service, the collaborative process, and other stakeholders are not to be trusted; 3) The collaborative process is most effective when emphasizing place-specific dialogue that primarily involves stakeholders educating the Forest Service about issues; and 4) Forest planning involves issues requiring the application of scientific knowledge and expertise rather than collaboration. These perspectives were not strongly associated with participation levels, with time constraint being the primary mediating factor affecting participation. There are several possible actions policymakers and planners can take to enhance participation and overcome high rates of nonparticipation.     

Metals in vineyard soils of the Penedès area (NE Spain) after compost application

The application of organic wastes to improve soil physical characteristics in mechanized vineyards planted after land levelling is becoming a common practice in Mediterranean areas. It may be useful as an additional source of organic matter and nutrients, but these wastes could also have negative effects due to their metal content. The aim of the study was to evaluate the influence of compost application on soil metal contents in mechanized vineyard soils of the Spanish Mediterranean area, where this practice is repeated every three years. The study was carried out in a ten-year-old vineyard where the main soil type is Typic Calcixerept. Composted cattle manure was applied in alternate rows, at a rate of 40 Mgha(-1) dry-weight. Nine sampling points were located along the slopes of two plots: a levelled plot prepared for mechanization with large soil disturbance movements within the plot, and a plot of undisturbed soil. At each location, soil samples were taken in both treated and untreated soils. Total concentrations (digestion with aqua regia) and the extractable DTPA (Diethylene-triaminepentacetic)-CaCl2-TEA (Triethanolamine) fractions of Cu, Zn and Mn were analyzed in each sample. For Cu and Zn, the initial concentration was higher in the undisturbed plot. In both cases, total Cu and total Zn were positively affected by manure input and the concentration in treated soils was significantly higher than in untreated soil. For Mn, the initial concentration was higher in disturbed soils than in undisturbed ones, and although in both scenarios the concentrations increased with manure, no significant differences were found between treated and untreated soils. The extractable fraction also increased in treated versus untreated soils, although for Cu and Mn the extractable/total metal ratio was similar in treated and untreated soils. After one compost application, total metal contents increased significantly, particularly for Zn. Most of those metals are accumulated in the soil, due to the soil characteristics.