Announcements
- Affiliate Standouts! Alida Cantor, Geography faculty, received the Professional Geographer Award from the Energy and Environment Specialty Group of the American Association of Geographers.
- Heejun Chang, Geography Faculty and Associate Dean for Research and Graduate Programs, and Alexander Ross, Geography faculty, published a book titled “Climate Change, Urbanization, and Water Resources.”
Partner Publications
Andres Holz (PSU) contributed to the paper “Patterns, drivers, and implications of postfire delayed tree mortality in temperate conifer forests of the western United States” which investigates the impact of increasing wildfire activity on conifer forest resilience in western North America. Using high-resolution satellite imagery, the researchers mapped and quantified delayed mortality of conifer trees between 1 and 5 years after 30 large wildfires across three montane ecoregions. They found that delayed mortality reduced live conifer tree cover by 5%–25% at the fire perimeter scale and 12%–15% at the ecoregion scale. Burn severity one year after the fire was the strongest predictor of delayed mortality, indicating that patch-level fire effects can indicate the severity of fire injury among surviving trees that eventually die. Delayed mortality rates were also influenced by long-term and short-term postfire climate moisture deficits, highlighting the impact of drought on fire-injured tree survival. This paper demonstrates that delayed mortality in conifer forests in the western United States can be remotely quantified at a fine grain and landscape scale, and is driven by interactions between fire, climate, and the environment, with significant ecological implications.
In the publication, “Timing and source of recharge to the Columbia River Basalt groundwater system in northeastern Oregon” research hydrologist Hank Johnson (USGS) and colleagues characterize groundwater flow within the Columbia River Basalt Group (CRBG) groundwater system in northeastern Oregon. By analyzing isotopic, gas, and age-tracer samples from wells, springs, and stream base flow, researchers found that most groundwater samples were late-Pleistocene to early-Holocene, with a median age of 11,100 years. They observed a consistent relationship between mean groundwater age and well depth across the study area, despite differences in precipitation, topography, and geologic units. Recharge rates calculated from age-depth relations were found to be less than 3 mm/yr and were independent of the modern precipitation gradient, contrasting with previous estimates. This highlights the uncertainty in current models used to estimate recharge to the CRBG groundwater system and suggests that recharge is a slow and localized process.
Jennifer Morse (PSU), Associate Professor of Environmental Science and Management, had several presentations at the Urban Ecosystem Research Consortium of Portland/Vancouver in March.
- Effects of Urbanization on Dissolved Carbon and Nutrients in the Johnson Creek Watershed on Long-term Temporal Scales: This paper focuses on dissolved organic carbon (DOC), a crucial metric in urban stream ecology often overlooked on seasonal scales. The Johnson Creek watershed in the Portland metro area was studied to understand the effect of urbanization on DOC and water quality due to channelization and urban land. The hypothesis was that DOC would increase downstream with increasing impervious surface cover and urbanization. Weekly surface water samples were collected from three locations from July to November 2023. Results showed a significant three-fold decrease in DOC concentrations downstream, accompanied by an increase in total dissolved nitrogen (TDN) concentrations, as imperviousness and developed land cover increased. Crystal Springs Creek in the lower Johnson Creek watershed exhibited similar DOC and TDN values to the downstream site at Milwaukie, indicating a point source of increased nitrogen. Ongoing sampling will provide further insights into longitudinal and seasonal patterns in urban stream carbon and nitrogen chemistry.
- Soil Biogeochemical Changes in Response to Irrigation with Treated Wastewater: This study investigates the impact of recycled wastewater irrigation on soil carbon (C) and nitrogen (N) cycling, including greenhouse gas (GHG) emissions, in the Tualatin River watershed. Elevated summer water temperatures in the river, partly due to effluent from wastewater treatment plants, pose a threat to temperature-sensitive species like salmonids. Clean Water Services aims to reduce heat input by irrigating restored wetlands near their facilities with treated wastewater, potentially providing ecosystem benefits like carbon sequestration and improved habitat quality. However, there's concern about increased GHG emissions. The study, conducted over two years, measures soil GHG emissions in irrigated and control areas of the project site. Preliminary results show no significant differences in GHG emissions, likely due to low irrigation rates to prevent surface ponding.
- Green Stormwater Infrastructure Effects on Pollutant Retention and Water Quality: Recent years have seen a surge in the adoption of green stormwater infrastructure (GSI) in urban planning and environmental management. GSI, which includes bioretention structures, aims to manage urban flooding, enhance water quality in receiving waters, and provide green spaces for aesthetics and recreation. While the benefits of peak flow attenuation through bioretention structures are well-documented, the water quality improvements associated with GSI are less understood. Several projects in Portland, Oregon, explored the role of GSI in processing nitrogen, phosphorus, and metals. Findings indicated that GSI soils could serve as strong nitrogen sinks but exhibited variability. Soil phosphorus was prone to release following drying and flooding cycles. Additionally, GSI impacts on water quality during storms revealed decreases in total suspended solids and most metals from inflow to outflow, but notable increases in nitrate and phosphate concentrations in effluent waters. These results suggest that water quality improvements from GSI are not guaranteed, highlighting the need for further study to understand pollutant retention mechanisms and inform design processes and planning expectations.
Cassandra Smith’s (USGS) paper, “Comparing modern identification methods for wild bees: Metabarcoding and image-based morphological taxonomic assignment” compared two methods of identifying wild bees: morphological identification by experienced taxonomists using images and genetic analysis using metabarcoding. Bees were collected from conservation grasslands in eastern Iowa in 2019 and identified to the lowest taxonomic unit using both methods. Morphological identification resulted in 36 unique taxa among 22 genera, with over 80% of Bombus specimens identified to species. Metabarcoding provided genus-level assignments among 18 genera but didn't consistently detect all genera, including kleptoparasitic bees. Morphological identification was more successful in detecting genus-specific taxa, while metabarcoding was limited by tissue proportion in composite samples and databases. The study highlights the complementary nature of these methods, providing valuable genus- and species-level information for wild bee conservation research.
News Articles
The Environmental Protection Agency (EPA) has set the first federal rules for six types of harmful PFAS chemicals found in drinking water. These chemicals, often called "forever chemicals," don't break down and can cause serious health issues. The new rules will impact around 4,100 to 6,700 water utilities in the U.S., affecting about 100 million people. The regulations aim to reduce exposure to PFAS and prevent illnesses like cancer and birth complications. While some utilities have already installed treatment systems, others are still working to comply with the new standards. The EPA's move has been praised for protecting public health, but some argue that more needs to be done to hold companies accountable for pollution.
The Bureau of Reclamation has announced how much water farmers in the Klamath Basin will get this year, but it's not enough to meet their needs. Despite average snowpack, the water supply is still short. Farmers are getting about two-thirds of the water they need, which makes it hard for them to plan their crops. There might be more water later in the season, but farmers have to make decisions now. Some areas will get enough water, but others might not. The Bureau is also limited in how much water it can release down the Klamath River because of restoration work happening there. This means there could be extra water available for other uses. The local tribes and water users are working together on projects to improve water efficiency and sustainability. The Bureau is also providing funding for drought resilience and ecosystem restoration projects in the Klamath Basin.