Dixon H. Landers

Transient storage and hyporheic flow along the Willamette River, Oregon: Field measurements and model estimates

Transient storage is a measure of the exchange of main channel flow with subsurface hyporheic flow and surface water dead zones. Hyporheic flow, in which river water enters the channel bed and banks to reemerge downstream, promotes biochemical processes that are important for water quality and aquatic habitat. Previous studies have quantified transient storage and hyporheic flow on small streams but were not specifically developed to identify both of these processes over long reaches of large rivers. We studied transient storage on the eighth-order upper Willamette River, which flows through high- porosity gravel deposits conducive to hyporheic flow. We used main channel dye tracer studies and solute transport modeling to estimate transient storage on nine study reaches in a 26-km-long study area. We also took dye measurements within the transient storage zone to identify transient storage flow paths. We obtained estimates of transient storage exchange coefficient, αs (mean equals 1.6×10−4 s−1), and transient storage to main channel cross-sectional area, As/A (mean equal to 0.28), that show that significant amounts of water follow flow paths with 0.2–30 hour transient storage zone residence times. Our dye measurements from the transient storage zone itself showed the occurrence of both subsurface and surface flow paths, confirming that hyporheic flow is an important component of estimated transient storage. We found that the two highest As/Aestimates were for reaches that spanned the only length of active main channel in our study area that is unconstrained and where the river can rework large gravel deposits. Much of the natural channel complexity that historically promoted hyporheic flow no longer exists on the upper Willamette River. River management targeting the ecological functions provided by hyporheic flow might best focus on restoring historic hydrogeomorphic processes for creating sites conducive to hyporheic flow.

Chemical and physical characteristics of lakes in the southeastern United States

Rogalla, J. A,; Brezonik, P. L.; Glass, G. E. Water, Air, Soil Pollut. 1986, 31, 95-100. Wiener, J. E.; Eilers, J. M. Lake Reserv. Manage. 1987,3, 365-378. Charles, D. F.; et al. Water, Air, Soil Pollut. 1986, 30 355-365. Krug, E. C.; Isaacson, D. J.; Frink, C. R. J. Air Pollut. Control Assoc. 1985, 35, 109-114. of the National Acid Precipitation Assessment Program by the US. Environmental Protection Agency. This article was prepared at the EPAs Research Laboratory in Corvallis, OR, in part, through Contract 68-03-3246 with Northrop Services and Cooperative Agreement CR812653 with Western Washington University. This is a contribution from the National Surface Water Survey of the EPA’s Aquatic Effects Research Program. It has been subjected to the Agency’s peer and administrative review and awsroved for wublication. Mention of trade names Received for review February 9,1987. Accepted October 26,1987. The research described in this article has been funded as part or commerciai products-does not constitute endorsement or recommendation for use.

What data should we collect? A framework for identifying indicators of ecosystem contributions to human well-being

The lack of a clear framework identifying data to link ecosystems to analyses of human well-being has been highlighted in numerous studies. To address this issue, we applied a recently developed economic theory termed “final” ecosystem goods and services – the biophysical features and qualities that people perceive as being directly related to their well-being. The six-step process presented here enabled us to identify metrics associated with streams that can be used in the analysis of human well-being; we illustrate these steps with data from a regional stream survey. Continued refinement and application of this framework will require ongoing collaboration between natural and social scientists. Framework application could result in more useful and relevant data, leading to more informed decisions in the management of ecosystems.

Heavy metal contamination in the Taimyr Peninsula, Siberian Arctic

The Taimyr Peninsula is directly north of the worlds largest heavy metal smelting complex (Norilsk, Russia). Despite this proximity, there has been little research to examine the extent of contamination of the Taimyr Peninsula. We analyzed heavy metal concentrations in lichen (Cetraria cucullata), moss (Hylocomium splendens), soils, lake sediment, freshwater fish (Salvelinus alpinus, Lota lota and Coregonus spp.) and collared lemming (Dicrostonyx torquatus) from 13 sites between 30 and 300 km from Norilsk. Element concentrations were low in both C. cucullata and H. splendens, although concentrations of Al, Fe, Cu, Ni and Pb were significantly higher than those in Arctic Alaska, probably due to natural differences in the geochemical environments. Inorganic surface soils had significantly higher concentrations of Cd, Zn, Pb and Mg than inorganic soils at depth, although a lake sediment core from the eastern Taimyr Peninsula indicated no recent enrichment by atmospherically transported elements. Tissue concentrations of heavy metals in fish and lemming were not elevated relative to other Arctic sites. Our results show that the impact of the Norilsk smelting complex is primarily localized rather than regional, and does not extend northward beyond 100 km.

Sources and Deposition of Polycyclic Aromatic Hydrocarbons to Western U.S. National Parks

Seasonal snowpack, lichens, and lake sediment cores were collected from fourteen lake catchments in eight western U.S. National Parks and analyzed for sixteen polycyclic aromatic hydrocarbons (PAHs) to determine their current and historical deposition, as well as to identify their potential sources. Seasonal snowpack was measured to determine the current wintertime atmospheric PAH deposition; lichens were measured to determine the long-term, year around deposition; and the temporal PAH deposition trends were reconstructed using lake sediment cores dated using (210)Pb and (137)Cs. The fourteen remote lake catchments ranged from low-latitude catchments (36.6 degrees N) at high elevation (2900 masl) in Sequoia National Park, CA to high-latitude catchments (68.4 degrees N) at low elevation (427 masl) in the Alaskan Arctic. Over 75% of the catchments demonstrated statistically significant temporal trends in SigmaPAH sediment flux, depending on catchment proximity to source regions and topographic barriers. The SigmaPAH concentrations and fluxes in seasonal snowpack, lichens, and surficial sediment were 3.6 to 60,000 times greater in the Snyder Lake catchment of Glacier National Park than the other 13 lake catchments. The PAH ratios measured in snow, lichen, and sediment were used to identify a local aluminum smelter as a major source of PAHs to the Snyder Lake catchment. These results suggest that topographic barriers influence the atmospheric transport and deposition of PAHs in high-elevation ecosystems and that PAH sources to these national park ecosystems range from local point sources to diffuse regional and global sources.

Inorganic contaminants in Arctic Alaskan ecosystems: long-range atmospheric transport or local point sources?

The moss monitoring technique (Hylocomium splendens) for tracking environmental concentrations of atmospheric contaminants is applied to arctic Alaska. Median 1990–1992 concentrations of Pb, Cd, Cu, V, and Zn are ≤ median 1990 concentrations in northernmost parts of the Nordic/European monitoring network. Extremely low Pb concentrations (median, 0.6 μg/g) indicate that long-range atmospheric transport (LRTAP) of Pb to arctic Alaskan ecosystems is neglible. However, samples taken adjacent to a local source point (the Dalton Highway) have elevated Pb, V, and Cu. Site-specific watershed studies indicate that natural within- and between-site variability does not affect the interpretation of our Alaskan data relative to the Nordic/European network for Pb, V and Cu. Variability is greater relative to regional data for Cd and Zn, but neither LRTAP nor the Dalton Highway appear to be significant contributors to local concentrations of Cd and Zn. Pilot studies of blueberries and other selected wildlife forage foods indicate that concentrations inH. splendens are generally comparable to those in a common carbou forage lichen, but thatH. splendens may underestimate Cu and overestimate Pb, Hg, and in some cases Cd, relative to selected forage fruits. More studies of contaminants in arctic Alaskan forage foods are needed to characterize potential exposure of human and wildlife populations to airborne contaminants in this region.

The Western Airborne Contaminant Assessment Project (WACAP): An Interdisciplinary Evaluation of the Impacts of Airborne Contaminants in Western U.S. National Parks

The National Park Service Organic Act of 1916 (1) required protection of the national parks for perpetuity by tasking the National Park Service (NPS) to maintain these lands “...unimpaired for the enjoyment of future generations.” Near the close of the last century, the NPS became aware of a new body of research describing a potential ecosystem threat that could not be ignored. Toxic airborne contaminants were increasingly being found in the world’s most pristine alpine and polar ecosystems, far from where such chemicals were produced or used, and the risks to the national parks of the western U.S. were unknown. Airborne contaminants present a broad range of potential risks to these ecosystems, largely due to bioaccumulation and or biomagnification of toxicants in biota, particularly vertebrates, that can result in loss of fecundity, unfit offspring, maladaptive behavior, and even death. As an outgrowth of these concerns, the Western Airborne Contaminants Assessment Project (WACAP) was initiated in 2002 to determine the risk from airborne contaminants to ecosystems and food webs in national parks of the U.S. The specific objectives that guided design and implementation of WACAP were the following: 1. Determine if contaminants were present in western national parks. 2. If contaminants were present, determine in what way and where they were accumulating (geographically and by elevation). EP A Environ. Sci. Technol. 2010, 44, 855–859

Comparison of Lichen, Conifer Needles, Passive Air Sampling Devices, and Snowpack as Passive Sampling Media to Measure Semi-Volatile Organic Compounds in Remote Atmospheres

A wide range of semivolatile organic compounds (SOCs), including pesticides and polycyclic aromatic hydrocarbons (PAHs), were measured in lichen, conifer needles, snowpack and XAD-based passive air sampling devices (PASDs) collected from 19 different U.S. national parks in order to compare the magnitude and mechanism of SOC accumulation in the different passive sampling media. Lichen accumulated the highest SOC concentrations, in part because of its long (and unknown) exposure period, whereas PASDs accumulated the lowest concentrations. However, only the PASD SOC concentrations can be used to calculate an average atmospheric gas-phase SOC concentration because the sampling rates are known and the media is uniform. Only the lichen and snowpack SOC accumulation profiles were statistically significantly correlated (r = 0.552, p-value <0.0001) because they both accumulate SOCs present in the atmospheric particle-phase. This suggests that needles and PASDs represent a different composition of the atmosphere than lichen and snowpack and that the interpretation of atmospheric SOC composition is dependent on the type of passive sampling media used. All four passive sampling media preferentially accumulated SOCs with relatively low air-water partition coefficients, while snowpack accumulated SOCs with higher log K(OA) values compared to the other media. Lichen accumulated more SOCs with log K(OA) > 10 relative to needles and showed a greater accumulation of particle-phase PAHs.

The rates of accumulation and chronologies of atmospherically derived pollutants in Arctic Alaska, USA

Abstract Anthropogenically derived pollutants (e.g. trace metals, organochlorines, radionuclides) are deposited upon arctic ecosystems. To determine the range of probable biotic effects of these pollutants, one must know the rate at which they enter and are retained within an ecosystem. However, unknown deposition mechanisms and the complexity of quantifying atmospheric concentrations of constituents of interest make direct measurements of pollutant flux to arctic terrestrial and aquatic ecosystems difficult and/or impractical. Methods of indirectly measuring rates of pollutant accumulation, such as lake sediment stratigraphic analyses, can fill this void. Present in the sediment of two Alaskan lakes sampled in April 1991 were quantifiable concentrations of numerous organochlorine compounds, including DDT and its metabolites (Sum, 0.05-0.60 ng/g), PCBs (Sum, 0.20–30 ng/g), and lindane (0.20-0.80 ng/g). These surface concentrations correspond to estimated deposition rates of 2–6 ng/m2/year ( ∑DDT + metabolites), 10–300 ng/m2/year ( ∑PCBs), and 8–10 ng/m2/year (lindane). The rates and chronologies of accumulation of these pollutants and others are discussed with regard to the process of long-range atmospheric transport.

Variability in Pesticide Deposition and Source Contributions to Snowpack in Western U.S. National Parks

Fifty-six seasonal snowpack samples were collected at remote alpine, subarctic, and arctic sites in eight Western U.S. national parks during three consecutive years (2003-2005). Four current-use pesticides (CUPs) (dacthal (DCPA), chlorpyrifos, endosulfans, and gamma-hexachlorocyclohexane (HCH)) and four historic-use pesticides (HUPs) (dieldrin, alpha-HCH, chlordanes, and hexachlorobenzene (HCB)) were commonly measured at all sites, during all years. The mean coefficient of variation for pesticide concentrations was 15% for site replicate samples, 41% for intrapark replicate samples, and 59% for interannual replicate samples. The relative pesticide concentration profiles were consistent from year to year but unique for individual parks, indicating a regional source effect. HUP concentrations were well-correlated with regional cropland intensity when the effect of temperature on snow-air partitioning was considered. The mass of individual CUPs used in regions located one-day upwind of the parks was calculated using air mass back trajectories, and this was used to explain the distribution of CUPs among the parks. The percent of the snowpack pesticide concentration due to regional transport was high (>75%) for the majority of pesticides in all parks. These results suggest that the majority of pesticide contamination in U.S. national parks is due to regional pesticide use in North America.