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{"Abstract":["This data product contains physical, chemical, and biological data ranging from the minute to daily to weekly scale in six artificial ponds (400 square meter surface area, 2m depth) in central Iowa (USA) 2020. Ponds were paired into three sets of treatment and reference with treatment ponds receiving two nutrient pulses designed to increase ambient phosphorus concentrations ~ 3 - 5%. Nitrogen and phosphorus were added as NH4NO3 and H3PO4, respectively, at a 24:1 molar ratio. The first nutrient pulse occurred on Julian day of year (DOY) 176 corresponding to a 3% increase and the second nutrient pulse occurred on DOY 211 to a 5% increase. Each treatment-reference set had a different food web structure established ranging between low, intermediate, and high complexity based on trophic connectivity and food chain length. \n \n Added to this data package is a document titled "2020 Iowa State University Horticultural Farm Experimental Ponds Nutrient Addition Experiment". For experimental set up, context, and a summary table of the data tables archived herein with available variables please review this document. It is added to aid in successful interpretation and to increase ease-of-use. Please email Tyler Butts (tyler.james.butts@gmail.com) for any and all questions regarding context or use of this dataset!"]} 

We constructed a conceptual biogeochemical model for microcystin through a comprehensive literature synthesis, identifying four major pools and nine major fluxes in lakes that also connect to the terrestrial environment. We also performed a literature synthesis, collating measurements of various pools and fluxes of microcystin in inland waters from the literature. A subset of those values were used in an analysis of microcystin detection for field surveys of waterbodies and a random effects model to estimate the mean and 95% confidence interval for various microcystin pools and fluxes in lakes. 

Abstract Microcystin poses a serious threat to aquatic ecosystems and human health. There is a pressing need to understand the production, movement, and storage of microcystin in lakes. We constructed a conceptual biogeochemical model for microcystin through a comprehensive literature synthesis, identifying four major pools and nine major fluxes in lakes that also connect to the terrestrial environment. This conceptual model can be used as the framework for developing ecosystem mass balances of microcystin. We propose that the concentration of microcystin in the water column is the balance between the import, sediment translocation, production and degradation, uptake, burial, and export. However, substantial unknowns remain pertaining to the magnitude and movement of microcystin. Future investigations should focus on sediment fluxes, drivers of biodegradation, and seasonal dynamics. Adopting the framework of a “microcystin cycle” improves our understanding of processes driving toxin prevalence and helps to prioritize strategies for minimizing exposure risks. 

{"Abstract":["These data sets summarize the results of a project to quantify and explain spatial variation in sediment phosphorus (P) pools in seven shallow lakes in NW Iowa, USA.1. "Cores_ALLDATA_2018.csv" is the primary data set. It contains sediment core data for all study lakes. Variables include sediment physical characteristics (moisture content, organic matter content, bulk density), sediment total P concentrations, and sediment P speciation (concentrations of loosely-bound, redox-sensitive, aluminum-bound, calcium-bound, and labile organic P). The file "Cores_ALLDATA_2018_README.csv" provides detailed meta-data.2. "Chla_MobileP_Regression.csv" provides additional data on the long-term concentrations of the algal pigment chlorophyll a in the study lakes. We used these data to analyze the relationship between long term lake productivity and mobile sediment P fractions in the sediments. The file "Chla_MobileP_Regression_README.csv" provides detailed meta-data.3. "Swan_macrophytes_2018.csv" summarizes the distribution of aquatic plants (macrophytes) in one study lake (Swan Lake), and "Swan_SedP_2018.csv" summarizes sediment P data for that lake. We used these datasets to analyze spatial relationships between macrophyte beds and sediment P pools. Detailed meta-data can be found in "Swan_macrophytes_2018_README.csv" and "Swan_SedP_2018_README.csv""]}