Category: Statewide

Nutrient enrichment is a critical issue affecting Iowa surface water bodies. The Upper Midwestern United States is heavily drained and subsurface drainage provides a direct pathway for nutrients to enter surface waters. Nitrogen is typically the focus of research on nutrients in drainage; however, current research has shown that drainage can be a significant source of phosphorous loading as well. The goal of the proposed project is to evaluate the impact of subsurface drainage on P concentrations in surface waters. Objectives of the study are (1) to determine intra-event contributions of different P pathways and (2) apply the ICECREAMDB phosphorous model to Iowa agricultural watersheds. ICECREAMDB is a graphical front-end for the ICECREAM model that also includes options to structure outputs. ICECREAMDB is a management oriented phosphorus loss model that quantifies runoff, erosion, and P losses at the field scale and has the capability to simulate phosphorus losses through drainage systems. Water quality monitoring and model simulations will be conducted on the Black Hawk Lake watershed located in Carroll and Sac counties in Iowa. The Black Hawk Lake watershed was selected for this study because its three unique monitoring locations allow comparison of overland surface flow to tile flow water quality. Results of the project include an intra-event analysis of total phosphorus and dissolved reactive phosphorus concentrations in grass waterway, surface runoff, and tile flow and testing of a new model for predicting phosphorous in tiles, ICECREAMDB, in the heavily drained Iowa landscape.

This project completes the final three months of a two year project. Soil moisture is the reservoir of water that supports agriculture. Soil moisture also affects the amount and variability of precipitation and hence the occurrence of drought. Remote sensing satellites that observe near–surface soil moisture have recently been launched or will be launched in the near future. Before measurements of near–surface soil moisture made from space can be used to estimate the amount of water stored in the soil and improve weather and climate predictions, the quantitative value of the measurements must be known. My long–term goal is to contribute to the construction of a water balance model for Iowa consisting of atmospheric and land surface models along with a data assimilation scheme. This model would ingest real–time information regarding soil moisture, river levels, precipitation, and atmospheric conditions, in order to give the best estimate of current and future soil water conditions throughout the state. Ultimately this system could be used to monitor the evolution of soil moisture, and as a tool to test actions that could be taken to ameliorate the impacts of drought and future climate variability. My objective in this proposal is to contribute to the validation of near–surface soil moisture observations made by current and future satellite remote sensors in order to assess the quantitative value of these space–based observations. My central hypothesis is that satellite observations of near–surface soil moisture are valid as determined by point–based in–situ observations of soil moisture scaled to match the size of the satellite footprint. My rationale for this project is two–fold: the quantitative value of remotely–sensed near–surface soil moisture must be known before it can be used effectively; and the state of Iowa should seize this opportunity to benefit from these new satellite measurements. My specific research objectives for this project are as follows: Improve and then validate SMOS near–surface soil moisture observations in Iowa; Initiate the validation of SMAP near–surface soil moisture observations in Iowa. The expected outcome of this project will be validated near–surface soil moisture observations that could be used by hydrologists and atmospheric scientists to estimate soil water storage and improve the prediction of weather and climate in Iowa. I will use professional relationships developed during this project to submit proposals to NASA that will support future research on SMAP mission observations and water cycle studies in Iowa. If we are successful at validating these new satellite soil moisture observations, Iowa scientists will have a unique opportunity to estimate current soil moisture reserves and better understand the conditions leading to drought and hence mitigate the impact of this type of natural disaster on the citizens of Iowa.

This study applies new approaches to understand the fate of soluble pollutants in the urban environment. Soil samples collected during warm season months as part of this field study compliment an existing effort to assess impacts of winter road maintenance on water quality by considering relationships between chlorides, soils and metals. The objective is to expand sampling and analysis from winter roadway runoff to also consider soil quality as a means of characterizing the fate and transport of soluble pollutants in winter road maintenance regimes; thus reducing water contamination potential from winter road maintenance activities. By sampling soils during warm- season months, data collected compliments winter runoff sampling and broadens the overall potential for data analysis. It expands the scope of an urban water quality monitoring project by incorporating warm-season soil analysis to quantify impacts from winter roadway runoff in two Eastern Iowa communities. By understanding the fate and transport of road salts from transportation systems, we gain further insight to environmental susceptibility to surface and groundwater contamination. As winter roadway runoff is diverted to infiltration-based stormwater management practices such as rain gardens and bioretention cells, potential for chloride contamination can increase. Metals are soluble in roadway runoff. Urban stormwater management practices for sediment and solids removal may perform poorly for treating such soluble pollutants. Results will verify urban watershed modeling tools implemented in project’s initial assessment phase, and determine needs for further analysis, data collection and scalability. Results will also inform local policy and practice regarding water quality concerns from road salts.

Nitrate contamination from agriculture is a major water-quality problem in Iowa and a contributor to hypoxia in the Gulf of Mexico. In Iowa’s till-dominated watersheds, previous studies on nitrate transport in groundwater have relied on black box or unfractured porous media models, despite studies showing fracture control of nitrate transport. To investigate the role of fracture flow on watershed-scale nitrate transport, I will utilize a 3-D, fully-coupled, distributed-parameter, fracture-flow hydrologic model with a sophisticated, equivalent porous media (EPM) approach. Fracture flow parameters will be derived from X-ray computed tomography (CT) and laboratory column experiments conducted on 6.4- to 15-cm-diameter till core sampled from both drill core and 6-m-deep trenches associated with the recent installation of the Dakota Access Pipeline in central Iowa. Industry-developed fracture analysis programs and discrete fracture network (DFN) models will be used to compute the properties of the EPM. Results will be compared to existing nitrate-transport models for a watershed in central Iowa.

Nutrient enrichment of Iowa’s water bodies is one of the most critical issues the state is currently facing. Intensive farming and heavy nutrient application in the Midwest coupled with an extensive subsurface tile drainage network leads to excessive nutrients entering surface waters. Of the nutrients entering Iowa’s surface waters, nitrate is one of the most critical due to its contribution to harmful algal blooms (HABs) not only in the Midwest, but also in the Gulf of Mexico. Nitrate receives attention from researchers, farmers, and the general public because it travels in subsurface tile drainage and causes HABs. There is a long history of research conducted to reduce nitrate transport to water bodies from drainage. Phosphorous (P) also contributes to HABs and at lower concentrations, but its pathways are less understood by researchers. Recent work has begun to document the significant export of phosphorous through drainage systems. Woodchip bioreactors are one of the most cost effective and least invasive methods to remove nitrate from subsurface drainage. By installing these systems at the edge-of-the field, there is potential to expand the range of pollutants removed by woodchip bioreactors to include phosphorous. The goal of the proposed project is to evaluate the ability of woodchip bioreactors to remove phosphorous by adding biochar as a P amendment to the bioreactor. Objectives of the study are (1) to assess the effectiveness of different amendments on P removal in bioreactors and (2) to analyze the effect of influent P on overall removal. The study will be carried out in the Water Quality Research Laboratory (WQRL) at Iowa State University where there are three bioreactor columns available for use to complete a P amendment column study. We will analyze a range of enhanced biochars as an amendment, including three types of pyrolysis, biochar treated with Magnesium, and organic material sourced from corn stover, hardwood, and softwood. Results of the proposed project will include identification of viable P amendments to enhance the nutrient removal of woodchip bioreactors suitable for a range of applications.

Iowa’s waterways receive excessive nitrogen from agricultural lands. This project aims to identify the spatial specifics of a conservation practice that has demonstrated abilities to promote denitrification within agricultural fields, perennial vegetation filter strips. We have a strategy to identify the locations with the greatest potential for denitrification due to interactions between the filter strip and landscape processes resulting in changes in the soil environment. To do so, we will create and use a linear, fuzzy logic model to predict potential denitrification areas (PDA). The framework includes the spatial distribution of environmental factors which are conducive for denitrification following the following form: PDA= f (OC, T, pH, θv) where OC is a measure of accessible, oxidable carbon, T is a measure of favorable thermal conditions, pH is hydrogen ion activity, and θv is a measure of water holding capacity. In our current work, we have already observed the impact these filter strips are having on soil properties, affecting a greater area than generally assumed. Among those impacts, is a strong increase in θv within and surrounding the filter strips. This change in the soil environment suggests that if the other factors are present in the right combinations the capacity for denitrification in unsaturated hillslopes with perennial vegetation filter strips may also be increasing. Our research is unique in that it quantitatively accounts for the interaction between the hillslope morphology, hydrology, and the filter strips, which allows us to pinpoint the spatial interactions. Although impacts of perennial vegetation filter strips on water quality at the small catchment scale have been documented, the spatial distribution of the processes producing those impacts within the field has yet to be explored. By adding the soil sample analysis proposed here, our spatial modelling will create a map of PDA. The production and analysis of this map will assist in identify optimal filter strip design for increasing PDA.

Since 2006, the Iowa Department of Natural Resources has issued 190 advisories at state park beaches because of high levels of microcystin produced by harmful algae. Among those advisories, 142 were issued in the last five years, with a record 37 advisories issued in 2016. Microcystin was also detected in treated drinking water of Des Moines in 2016. While harmful algal blooms (HABs) can have adverse impacts, such as increased drinking water treatment costs and limiting recreational usage of waterbodies, the economic impacts of HABs in Iowa have not been studied. The proposed two-year project will conduct a comprehensive assessment of the economic benefits of mitigating HABs in Iowa. The benefits from improved drinking water safety, recreational opportunities, property values, and water aesthetics will be monetized using state-ofthe-art economic valuation methods. In the first year of the project, we will conduct a survey of Iowa citizens to gauge their awareness and attitude toward HABs and related issues including concerns about lake beach advisories and excessive levels of microcystin in drinking water. The survey data will also be used to monetize the benefits of mitigating HABs. In the second year, we will integrate the housing transaction, lake visitation, and water quality data to quantify the impacts of HABs on property values and recreation activities in Iowa. This study will (1) advance the understanding of socio-economic impacts of HABs to Iowans; (2) support the evaluation and cost-benefit analysis of Iowa Nutrient Reduction Strategy and other conservation programs in Iowa; and (3) provide information for better designing water quality improvement policies in both regional and state scales.

Iowa’s agricultural lands are among the most productive in the world, but they are also a large source of nitrate (NO3-)pollution. Ideally, NO3-is incorporated into crop tissues which are removed through harvest. NO3-which is not utilized by crops, or is returned to the soil through mineralization, is primarily lost through leaching and denitrification (Libra et al., 2004). The highest rates of NO3-leaching in Iowa are found in the poorly drained Des Moines Lobe (DML), where extensive tile drainage is thought to promote leaching to streams (Jones et al., 2017). However, wet soil conditions also promote denitrification, where in the absence of oxygen, soil microbes reduce NO3-to gaseous forms, primarily nitrous oxide (N2O) and dinitrogen gas (N2) (Hall et al., in press). Soil water content in the DML is mediated by the presence of landscape depressions (former prairie pothole wetlands), where both infiltration and N2O production may exceed surrounding uplands (N. Lawrence, unpublished). Quantifying how much NO3-is removed through denitrification versus lost through leaching is critical to understanding the role of landscape depressions as a source and sink of NO3-at the landscape level and providing insight into how targeted management of depressions might address NO3-loads. Here, we propose to apply a cutting-edge method—analysis of the natural-abundance isotope composition of NO3-—to address the role of within-field denitrification in attenuating agricultural NO3-loads.

Wastewater effluent contains a complex mixture of biologically active chemicals, in-cludingpharmaceuticals. Many pharmaceuticals have demonstrated deleterious effects to aquatic organisms including endocrine disruption, causing intersex characteristics,and reduced fecundity. These biological impacts can be magnified under low-flow conditions where wastewater effluent substantially contributes to the streamflow. Effluent-dominated streamflow conditions are becom-ing more common in temperate regionssuch as Iowa and are expected to increase due to climate change and population shifts.Current understanding of pharmaceuticals in the aquatic environ-ment does not adequately account for how pharmaceutical mixtures evolve spatiotemporally, or how pharmaceutical mixture composition relates to biological effects. Natural attenuation pro-cesses can either reduce or increase the toxicity of pharmaceuticals towards the aquatic species. Thereisa critical needtounderstand the underlying attenuation mechanismsincluding sorption and biotransformation to better predict the fate, transformation,and associated biological impacts of pharmaceutical mixtures. This research will help protect ecosystem health in freshwater re-sources in Iowa and inform stakeholder decisions such as wastewater treatment plant design, op-eration,and upgrade.

Harmful algal blooms caused by cyanobacteria (cyanoHABs) are a serious water quality problem in Iowa’s lakes. The presence of cyanobacterial toxins in Iowa’s lakes can threaten human health and increase economic loss. The proposed study will investigate how co-nutrient limitations, such as nitrogen and iron, combine with factors such as temperature and dissolved oxygento fuelcyanoHAB growth and toxin release across different lake types in Iowa. In general, artificiallakes tend to havelowernutrients, but earlier studies found nutrient conditionsto be higher in those surrounded by agricultural land use. We hypothesize that cyanoHAB intensityis higher in Iowa’s artificial lakes (e.g. reservoirs, impoundments) due to greater surface runoff carrying agriculturally-derived nutrients (N, P). We will test this hypothesis by measuring nutrients, including iron (Fe), which is generally not measured. We willlook for correlates between individual nutrients or nutrient ratios and/or physical conditions with phytoplankton biomass and toxin presence. This approach will help reveal larger landscape-scale trends distinguishing the susceptibility of artificial vs. natural lakes to cyanoHAB formation and toxin release. Findings from this study will help facilitate environmental risk management and develop mitigation strategies to reduce human and animal health risk.