REGIONAL SCALE TREND MONITORING OF INDICATORS OF TROPHIC CONDITION OF LAKES1

ABSTRACT: The U.S. Environmental Protection Agency has proposed a sample survey design to answer questions about the ecological condition and trends in condition of U.S. ecological resources. To meet the objectives, the design relies on a probability sample of the resource population of interest (e.g., a random sample of lakes) each year on which measurements are made during an index period. Natural spatial and temporal variability and variability in the sampling process all affect the ability to describe the status of a population and the sensitivity for trend detection. We describe the important components of variance and estimate their magnitude for indicators of trophic condition of lakes to illustrate the process. We also describe models for trend detection and use them to demonstrate the sensitivity of the proposed design to detect trends. If the variance structure that develops during the probability surveys is like that synthesized from available databases and the literature, then the trends in common indicators of trophic condition of the specified magnitude should be detectable within about a decade for Secchi disk transparency (0.5–1 percentiyear) and total phosphorus (2–3 percent/year), but not for chlorophyll-a (> 3–4 percent/year), which will take longer.     

Causes of ambient toxicity in the Calleguas Creek watershed of southern California

A combination of toxicity tests, chemical analyses, andToxicity Identification Evaluations (TIEs) were used toinvestigate receiving water toxicity in the Calleguas Creekwatershed of southern California. Studies were conductedfrom 1995 through 1999 at various sites to investigatecauses of temporal variability of toxicity throughout thissystem. Causes of receiving water toxicity varied by siteand species tested. Investigations in the lower watershed(Revolon Slough, Santa Clara Drain, Beardsley Wash)indicated that toxicity of samples to the cladoceran Ceriodaphnia dubia due to elevated concentrations ofthe organophosphate pesticide chlorpyrifos, while causes ofintermittent toxicity to fathead minnows (Pimephalespromelas) and the alga Selanastrum capricornutum wereless clear. Investigations at sites in the middle and upperreaches of the watershed (Arroyo Simi and Conejo Creek)indicated that the pesticide diazinon was the probable causeof receiving water toxicity to Ceriodaphnia. Elevatedammonia was the cause of toxicity to fathead minnows in theupper watershed sites. Results of these and previousstudies suggest that biota are impacted by degraded streamquality from a variety of point and non-point pollutionsources in the Calleguas Creek watershed. Water qualityresource manager's efforts to identify contaminant inputsand implement source control will be improved with thefindings of this study.     

Analyzing the carbon footprint from public services provided by counties

In this paper we investigate the Carbon Footprint (CF) resulting from the activities of the county of Sogn og Fjordane (SFK). An Environmentally Expanded Input-Output model is applied to develop a consumption-based Greenhouse Gas (GHG) inventory for this purpose. The model has previously been used for the assessment of municipal CFs, and is in this paper further developed for the purpose of assessing county CFs. Results show that a large fraction of the CF is caused by the purchase of services from private actors, especially the purchase of transportation services, of which a steady increase from the year 2002–2008, is found. In the same period of time, the CF resulting from the operation of county vehicles has been reduced to only 1/6. This outsourcing regarding the provision of services is found in several departments of the county municipality. It indicates a necessary shift in local mitigation strategies, as more focus needs to be on the environmental performance of suppliers. One important finding in the SFK case is the potential of introducing environmental requirements in tenders on providing transportation services. Another is to make environmental requirements to the companies receiving financial support from the county administration.     

Transfer of mercury in the marine food web of West Greenland

Total mercury (THg), methylmercury (MeHg) and stable isotopes of nitrogen (delta(15)N) and carbon (delta(13)C) were measured in three invertebrate, five fish, three seabird and three marine mammal species of central West Greenland to investigate trophic transfer of mercury in this Arctic marine food web. The food web magnification factor (FWMF) estimated as the slope of the regression between the natural logarithm of THg or MeHg concentrations (mg kg(-1) dw) and tissue delta(15)N ( per thousand) was estimated to 0.183 (SE = 0.052) for THg and 0.339 (SE = 0.075) for MeHg. The FWMFs were not only comparable with those reported for other Arctic marine food webs but also with quite different food webs such as freshwater lakes in the sub-Arctic, East Africa and Papua New Guinea. This suggests similar mechanisms of mercury assimilation and isotopic (delta(15)N) discrimination among a broad range of aquatic taxa and underlines the possibility of broad ecosystem comparisons using the combined contaminant and stable isotope approach.     

Sound Survey Designs Can Facilitate Integrating Stream Monitoring Data Across Multiple Programs1

Abstract: Multiple agencies in the Pacific Northwest monitor the condition of stream networks or their watersheds. Some agencies use a stream “network” perspective to report on the fraction or length of the network that either meets or violates particular criteria. Other agencies use a “watershed” perspective to report on the health or condition of watersheds. The agencies often use the same indicators and measurement protocols for data collection and often conduct monitoring in overlapping geographic regions. In these situations, agencies would like to combine data across different monitoring studies in a statistically sound manner to make regional estimates of condition. Three statistical survey design principles will facilitate combining such studies: (1) a clearly specified statistical target population of interest, including elements that comprise the population, (2) a consistent representation of that target population (such as a digital map of the stream network and watersheds), and (3) rules that incorporate randomization to guide the selection of the sample of sites on which measurements will be made. A case study illustrates the application of these design principles using two agency monitoring programs interested in combining stream channel data for different purposes: one for making network summaries and the other for evaluating watershed condition.     

A European model for waste and material flows

The use of materials and the generation of waste are linked to economic activities and in many projections these are assumed to be a constant ratio of the economic activities. This may be the case considering detailed economic activities and unchanged technology. However, the assumption of constant coefficients is questionable when linking material use and waste generation to aggregated economic activities. Therefore, in this paper, econometrics is used to test the assumption of constant waste coefficients empirically. The analyses show that an assumption of constant waste coefficients is not supported, generally, and a model allowing for trendwise changing coefficients is developed and used for projections of waste and material flows in 25 European countries.     

Occurrence of Sediment-Bound Pyrethroids in Danish Streams and their Impact on Ecosystem Function

In a total of 189 water samples collected from Danish streams no traces of the pyrethroid esfenvalerate were detected. However, pyrethroids have previously been found in sediments in 9 out of 30 streams investigated. We found that the shredding activity of the Trichopteran Sericostoma personatum and the amphipod Gammarus pulex was significantly reduced with increased concentration of the pyrethroid lambda-cyhalohtrin adsorbed to the leaves on which they fed. Predation rate on the Plecopteran Leuctra nigra by the leech Erpobdella octoculata increased significantly with increasing concentration of lambda-cyhalothrin on the leaves on which L. nigra was fed. Our results clearly indicate that the ongoing monitoring of pesticides is likely to underestimate pyrethroid occurrence and that sediment-bound pyrethroids have a potential negative impact on ecosystem function and biotic interactions in streams.     

Potential mineralization of four herbicides in a ground water--fed wetland area

Herbicides may leach from agricultural fields into ground water feeding adjacent wetlands. However, only little is known of the fate of herbicides in wetland areas. The purpose of the study was to examine the potential of a riparian fen to mineralize herbides that could leach from an adjacent catchment area. Slurries were prepared from sediment and ground water collected from different parts of a wetland representing different redox conditions. The slurries were amended with O2, NO3-, SO4(2-), and CO2, or CO2 alone as electron acceptors to simulate the in situ conditions and their ability to mineralize the herbides mecoprop, metsulfuron-methyl, isoproturon and atrazine. In addition, the abundance of bacteria able to utilize O2, NO3-, SO4(2-) + CO2, and CO2 as electron acceptors was investigated along with the O2-reducing and methanogenic potential of the sediment. The recalcitrance to bacterial degradation depended on both the type of herbicide and the redox conditions pertaining. Mecoprop was the most readily degraded herbicide, with 36% of [ring-U-14C]mecoprop being mineralized to 14CO2 under aerobic conditions after 473 d. In comparison, approximately 29% of [phenyl-U-14C]metsulfuron-methyl and 16% of [ring-U-14C]isoproturon mineralized in aerobic slurries during the same period. Surprisingly, 8 to 13% of mecoprop also mineralized under anaerobic conditions. Neither metsulfuron-methyl nor isoproturon were mineralized under anaerobic conditions and atrazine was not mineralized under any of the redox conditions examined. The present study is the first to report mineralization of meco-prop in ground water in a wetland area, and the first to report mineralization of a phenoxyalcanoic acid herbicide under both aerobic and anaerobic conditions.     

Mitigation of methane emission from an old unlined landfill in Klintholm,Denmark using a passive biocover system

Methane generated at landfills contributes to global warming and can be mitigated by biocover systems relying on microbial methane oxidation. As part of a closure plan for an old unlined landfill without any gas management measures, an innovative biocover system was established. The system was designed based on a conceptual model of the gas emission patterns established through an initial baseline study. The study included construction of gas collection trenches along the slopes of the landfill where the majority of the methane emissions occurred. Local compost materials were tested as to their usefulness as bioactive methane oxidizing material and a suitable compost mixture was selected. Whole site methane emission quantifications based on combined tracer release and downwind measurements in combination with several local experimental activities (gas composition within biocover layers, flux chamber based emission measurements and logging of compost temperatures) proved that the biocover system had an average mitigation efficiency of approximately 80%. The study showed that the system also had a high efficiency during winter periods with temperatures below freezing. An economic analysis indicated that the mitigation costs of the biocover system were competitive to other existing greenhouse gas mitigation options.