The Hourglass: A Conceptual Framework for the Transport of Biologically Active Compounds from Agricultural Landscapes

Recent research has suggested that the fate of biologically active compounds (BACs) originating from point sources such as wastewater treatment plants is fundamentally different from that of similar compounds released from nonpoint sources through runoff from agricultural landscapes. Downstream from wastewater treatment plants, BACs will degrade via a variety of mechanisms; however, their concentration in the water adjacent to the point of discharge may not decrease over time, as the compounds are continually released. In contrast, in agricultural systems, BACs are episodically introduced to surface water during snowmelt and rainstorm events, and under these circumstances, may be found in water for only hours or days after a storm event. Recent research in our laboratories as well as others, has suggested that sediments play an important role in the persistence of herbicides and steroids in watersheds after nonpoint source loading events. Conceptually, the sediment serves as both a sink and a source, equilibrating with BACs during storm events then slowly releasing them back into the water over time, long after the initial pulse of chemicals has moved downstream.     

Salps in the Lazarev Sea, Southern Ocean: II. Biochemical composition and potential prey value

Two species of salps, Salpa thompsoni and Ihlea racovitzai, were sampled during three cruises to the Lazarev Sea, Southern Ocean, in summer (December–January) 2005/2006, Autumn (April–May) 2004 and Winter (July–August) 2006. Dry weight, carbon, nitrogen, protein, lipid and carbohydrate contents were measured to characterize the potential value of salps as a food source for predators in the Antarctic ecosystem. Biochemical composition measurements showed that despite having a high percentage of water (~94% of wet weight), both species had relatively high carbon and protein contents in their remaining dry weight (DW). In particular I. racovitzai showed high carbon (up to 22% of DW) and protein (up to 32% of DW) values during all seasons sampled, compared to lower values for S. thompsoni (carbon content only about 15% of the DW, protein content about 10% of the DW). At the same time, carbohydrates (CH) and lipids (Lip) only accounted for a small portion of salp DW in both species (1.4% CH and 3.6% Lip for I. racovitzai; 2.1% CH and 2.9% Lip for S. thompsoni). There was little variability in the biochemical composition of either salp species between the seasons sampled. Both biochemical composition and life cycle characteristics suggest that Antarctic salps, especially I. racovitzai, may be important prey items for both cold and warm-blooded predators in an environment where food is often very scarce.     

Use of toxicity identification evaluations to determine the pesticide mitigation effectiveness of on-farm vegetated treatment systems

Evidence of ecological impacts from pesticide runoff has prompted installation of vegetated treatment systems (VTS) along the central coast of California, USA. During five surveys of two on-farm VTS ponds, 88% of inlet and outlet water samples were toxic to Ceriodaphnia dubia. Toxicity identification evaluations (TIEs) indicated water toxicity was caused by diazinon at VTS-1, and chlorpyrifos at VTS-2. Diazinon levels in VTS-1 were variable, but high pulse inflow concentrations were reduced through dilution. At VTS-2, chlorpyrifos concentrations averaged 52% lower at the VTS outlet than at the inlet. Water concentrations of most other pesticides averaged 20-90% lower at VTS outlets. All VTS sediment samples were toxic to amphipods (Hyalella azteca). Sediment TIEs indicated toxicity was caused by cypermethrin and lambda-cyhalothrin at VTS-1, and chlorpyrifos and permethrin at VTS-2. As with water, sediment concentrations were lower at VTS outlets, indicating substantial reductions in farm runoff pesticide concentrations.     

Birmingham's Eastside story: Making steps towards sustainability?

Abstract

Sustainability has come to play a dominant discursive role in the UK planning system, particularly relating to urban regeneration. The purpose of this paper is to evaluate the role that sustainability plays in a major regeneration programme, known as Eastside, currently underway in Birmingham, the UK. That this £6 billion redevelopment is now widely talked about by such key players as Birmingham City Council and the Regional Development Agency, Advantage West Midlands, as having a central sustainability agenda points to the growing importance of the ideal of sustainability in planning and regeneration agendas. In this paper, we investigate in detail how and why sustainability has become part of the planning discourse for Eastside and critically evaluate what impact, if any, this is having on public policy decision-making.     

Comparison of total mercury and methylmercury cycling at five sites using the small watershed approach

The small watershed approach is well-suited but underutilized in mercury research. We applied the small watershed approach to investigate total mercury (THg) and methylmercury (MeHg) dynamics in streamwater at the five diverse forested headwater catchments of the US Geological Survey Water, Energy, and Biogeochemical Budgets (WEBB) program. At all sites, baseflow THg was generally less than 1ng L(-1) and MeHg was less than 0.2ng L(-1). THg and MeHg concentrations increased with streamflow, so export was primarily episodic. At three sites, THg and MeHg concentration and export were dominated by the particulate fraction in association with POC at high flows, with maximum THg (MeHg) concentrations of 94 (2.56)ng L(-1) at Sleepers River, Vermont; 112 (0.75)ng L(-1) at Rio Icacos, Puerto Rico; and 55 (0.80)ng L(-1) at Panola Mt., Georgia. Filtered (<0.7microm) THg increased more modestly with flow in association with the hydrophobic acid fraction (HPOA) of DOC, with maximum filtered THg concentrations near 5ng L(-1) at both Sleepers and Icacos. At Andrews Creek, Colorado, THg export was also episodic but was dominated by filtered THg, as POC concentrations were low. MeHg typically tracked THg so that each site had a fairly constant MeHg/THg ratio, which ranged from near zero at Andrews to 15% at the low-relief, groundwater-dominated Allequash Creek, Wisconsin. Allequash was the only site with filtered MeHg consistently above detection, and the filtered fraction dominated both THg and MeHg. Relative to inputs in wet deposition, watershed retention of THg (minus any subsequent volatilization) was 96.6% at Allequash, 60% at Sleepers, and 83% at Andrews. Icacos had a net export of THg, possibly due to historic gold mining or frequent disturbance from landslides. Quantification and interpretation of Hg dynamics was facilitated by the small watershed approach with emphasis on event sampling.     

Estimating different order polynomial logarithmic environmental Kuznets curves

Environmental Science and Pollution Research - This paper contributes to the environmental literature by (i) demonstrating that the estimated coefficients and the statistical significance of the...     

Transport of Sewage Sludge From the 106-Mile Site - Results From an October Survey

Approximately 8 million tons of sewage sludge were disposed of annually at the 106-Mile Deepwater Municipal Sludge Dump Site (106-Mile Site) between 1987 and 1990. Beginning in 1988 and continuing to the present, the focus of monitoring at the 106-Mile Site moved towards improved understanding of the fate of the sludge. A survey conducted in October 1989 was designed to (1) detect the presence of any sludge particles that settle rapidly following disposal, (2) determine if sludge could be detected in the surface waters at locations away from the immediate disposal site, and (3) determine if water quality was degraded, by assessing whether the Environmental Protection Agency's marine water quality criteria were being exceeded.

The survey showed that the sludge does have a rapidly settling component composed of organic floc. mineral grains, and other heavy, gritlike particles, all of which are relatively large. These particles may settle at rates of between 8 and 180 m h^-1 and may reach the sea floor within 1 to 13 days following disposal. Even though a rapidly settling component is present in the sludge, a significant fraction of the sludge was detectable in the form of intact sludge plumes in the upper 35 m of the water column at least 15 km from the Site. in addition, unique tracers of sludge such as xylem tracheids and Clostridium perfringens plus elevated total suspended solids and trace metals concentrations, were found at locations up to 40 km from the Site. the presence of these tracers correspond with in situ transmissometry data suggesting that a fraction of the sludge was remaining in the near-surface waters above the seasonal pycnocline. Concentrations of metals were below EPA chronic marine water quality criteria, which indicates that the water quality downstream of the Site was not impaired. the detection of sludge downstream of the 106-Mile Site is consistent with the southwestward movement of the surface water mass during the survey, as recorded by satellite-tracked surface drifters and current vectors derived from a current meter moored at 100-m depth immediately west of the Site. Near-surface transport was generally towards the southwest at a speed of approximately 22 cm s^-1*.     

The structure of work values: A cross cultural comparison

Several years ago a research project on work values was originated. The study strived to examine the relative importance of work value items and to analyze the structure of the domain for samples from various cultural environments. A facet definition of work values was suggested that provided guidelines for constructing the Work Values Questionnaire and the formulation of hypotheses regarding the structure of relationships among components of work values. Based on data collected from 2280 respondents in eight countries the hypotheses were tested by means of Guttman's Smallest Space Analysis. The results support the hypotheses. An empirical double-ordered conceptual system, a radex structure, was obtained in each of the samples reflecting the facets of the definition: modality of outcome — cognitive, affective and instrumental, and system - performance contingency — reward, resource. In terms of the issue of cultural differences the results indicate the presence of cultural differences in the rating of a limited number of specific values. These differences are only minor variations within a much broader pattern of structural similarity. The fact that essentially the same structure was obtained in eight independent samples lends substantial support to the definitional framework of work values suggested.