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LINKING NUTRIENT CYCLING AND ECOLOGICAL DYNAMICS: A CASE STUDY OF INTERNAL PHOSPHORUS LOADING IN THE LAKE KANASATKA WATERSHED
No full textEven with extensive implementation of best management practices to mitigate external nutrient loading, numerous New Hampshire lakes are experiencing diminished water quality due to internal phosphorus loading (IPL). Remobilization of legacy nutrients like phosphorus can lead to more frequent and prolonged cyanobacteria blooms and exacerbate the process of eutrophication. This is the case for Lake Kanasatka, located in Moultonborough, New Hampshire, where IPL contributes to nearly 25% of its total phosphorus budget, with that percentage increasing towards 50% by the end of summer, as the hypolimnion becomes anoxic. After years of monitoring and watershed management, Lake Kanasatka received an aluminum sulfate treatment in May of 2024. Residing in the same watershed as Lake Kanasatka and recently exhibiting similar seasonal patterns in water quality and cyanobacteria diversity, Wakondah Pond was established as a reference site to compare to Lake Kanasatka, before and after treatment, to understand the effectiveness of treatment as well as the trends in water quality within the watershed as a whole.In this study, both lakes were monitored monthly from April to October 2024 to understand changes in phosphorus loading and ecological dynamics following this chemical treatment. Full water column profiles were collected for phosphorus fractionation, photosynthetic pigments, and plankton identification to establish seasonal trends and elucidate the relationship between IPL and cyanobacteria in this watershed. After treatment, Lake Kanasatka had a significantly smaller fraction of soluble reactive phosphorus (SRP), the crucial bioavailable form of phosphorus utilized by cyanobacteria and other phytoplankton. Towards the end of the season in October, over 60% of the total phosphorus concentration was SRP in Wakondah Pond, compared to Lake Kanasatka that was estimated to be only 6%. Wakondah Pond was dominated by diverse populations of cyanobacteria and frequently experienced blooms, whereas Lake Kanasatka shifted to a dominance in diatoms and golden-brown algae. With IPL effectively suppressed in Lake Kanasatka, there was much less SRP available to promote the growth of cyanobacteria to the extent it had in previous years. With only two other lakes in New Hampshire receiving an aluminum sulfate treatment since 1984, it is important to analyze seasonal trends in nutrient loading along with consistent monitoring to better understand the longevity of treatment and its impact on water quality in New Hampshire lakes. Understanding the role of Wakondah Pond in the Lake Kanasatka watershed will allow us to determine future management and monitoring techniques. Long-term monitoring can determine the geochemical and biological effects of lake treatment, especially when compared to a reference site, to better manage freshwater resources and assist in future preservation
PHASE EQUILIBRIA MODELING OF BLUESCHIST- AND ECLOGITE-FACIES METAMORPHISM: TILLOTSON PEAK COMPLEX, NORTHERN VERMONT
No full textPreservation of high- and ultra-high pressure Taconic metamorphic terranes is enigmatic in the northern Appalachians due to persistent metamorphic overprinting from subsequent orogenies. The Tillotson Peak Complex (TPC) in northern Vermont preserves the highest pressure conditions in the northern Appalachians. Previously, pressure-temperature (P-T) estimates were carried out using albite = jadeite + quartz thermobarometry, which yielded peak conditions of 1.2–1.4 GPa at 520–620ºC. Since these estimates, phase equilibria modeling software has improved, allowing for more accurate estimates of P-T. This study aims to provide new P-T estimates for the TPC by using the phase equilibria modeling software PERPLEX. SEM-EDS obtained mineral chemistry of mafic schist is utilized for phase equilibria (pseudosection) and isopleth calculations to constrain P-T conditions for the Taconic and Acadian orogenies. This thesis integrates results from Laird and Albee (1981) with new data collected in this study. The data are interpreted to reflect prograde conditions of metamorphism as high as 2.10 ± 0.20 GPa and 485 ± 10ºC during the Taconic, and conditions of 0.65 ± 0.25 GPa and 490 ± 20 ºC during the Acadian. Results suggest that the TPC was subducted to ~70 km during the Taconic, then exhumed to depths no greater than ~27 km before the Acadian. These results provide new insight into the variation of pressure and temperature conditions within the TPC, and suggest that the complex may have been multiple, separate slices that were imbricated during exhumation
A Random Forest Regression Approach for Prediction of Specific Flux for Ultrafiltration Membranes
No full textUltrafiltration (UF) membrane operation is strongly affected by fouling, where dissolved and suspended water quality constituents interact with each other and the membrane surface, leading to pore blockage. As a result, a fouled membrane loses filtration efficiency, reducing the volume of treated water produced and increasing operation and maintenance costs associated with membrane cleaning. At a Dutch full-scale facility in North Holland, fouling is indicated by both an increase in the amount of pressure required across the membrane, known as transmembrane pressure (TMP), and a decrease in permeability, represented by specific flux (SF). The facility performs hydraulic backwashing - both with and without chemical addition- occurs on a fixed frequency to scour readily removable foulants from the membrane surface. However, more persistent fouling that remains after backwashing can accumulate throughout filtration and must be removed with a more aggressive cleaning method. This is done through a cleaning in place (CIP) procedure, during which the membrane is soaked in two stages of chemicals for several hours to attack the fouling that remains after backwashing. The UF system consists of eight membrane blocks (i.e., groups of membranes), with six of them having viable data for modeling, resulting in six models tailored to each of the membrane blocks.The CIP is typically performed once TMP reaches 100 kPa. Currently, there is no early warning system to alert operators when this threshold has been reached, requiring frequent manual monitoring of TMP to determine an appropriate time to conduct a CIP. A previous intern of the utility investigated machine learning approaches to forecast TMP and found that a random forest (RF) model yielded the lowest prediction error. Building on that work, this study applies a regression-based RF approach to predict how SF will change in the next week, providing operators with an estimate of future SF with ample time (seven days) for CIP scheduling. The model uses current SF and SF from the previous week as inputs to predict the change in SF that will occur in the next week. Operational input data was collected from online UF data collectors, while water quality data was collected from both UF influent data collectors and from laboratory measurements. The resulting ‘Block Model’ for each of the six membrane blocks achieved R2 values exceeding 60% and mean square error (MSE) values below 3.20E-8. A combined ‘Universal Model’ achieved an R2 of 66%. Operators may consult this Universal Model to anticipate changes in SF and proactively plan CIP procedures
Portrait of a man in Tajikistan, Central Asia, ca. 1932-1933
No full textPhotograph of a man in Tajikistan, taken by Lotte Jacobi in Central Asia, ca. 1932-1933. Candid portrait of a man sitting outside, wearing a light coat and turban. He is looking at the camera and people are visible in a busy scene behind him.https://scholars.unh.edu/jacobi_ussr_central_asia/2235/thumbnail.jp
Nustratullo Maksum (Lutfullayev), a Tajikistani Soviet politician, at a silk factory in Stalinabad, Central Asia, ca. 1932
No full textPhotograph of Nustratullo Maksum (Lutfullayev), a Tajikistani Soviet politician, at a silk factory in Stalinabad, taken by Lotte Jacobi in Central Asia, ca. November or December 1932. Maksum is standing in a crowd of people, holding a hank of silk, wearing a coat and embroidered hat.https://scholars.unh.edu/jacobi_ussr_central_asia/3226/thumbnail.jp
Worker in a silk factory in Central Asia, ca. 1932
No full textPhotograph of a silk factory in Central Asia, taken by Lotte Jacobi, December 9, 1932. Close shot of a woman in a headscarf working at a machine in a silk factory, with more women working in the background.https://scholars.unh.edu/jacobi_ussr_central_asia/2536/thumbnail.jp
Woman carrying a bucket at a bazaar in Stalinabad (Dushanbe), Tajikistan, Central Asia, ca. 1932-1933
No full textPhotograph of a woman at a bazaar in Stalinabad (Dushanbe), taken by Lotte Jacobi in Tajikistan, Central Asia, ca. 1932-1933. A woman in a headscarf is carrying a bucket in one hand and something else over her shoulder. Behind her, a man in a coat is carrying a basket of flatbreads through a busy street at a bazaar.https://scholars.unh.edu/jacobi_ussr_central_asia/1934/thumbnail.jp
Woman working in a factory in the USSR, ca. 1932-1933
No full textPhotograph of a woman working in a factory in the USSR, taken by Lotte Jacobi, ca. 1932-1933. A woman wearing a collared shirt and headscarf is looking up, adjusting something on a machine in a large rom in a factory.https://scholars.unh.edu/jacobi_ussr_central_asia/3691/thumbnail.jp
Group of women and young men in Central Asia, ca. 1932-1933
No full textPhotograph of a group of women and young men in Central Asia, possibly Stalinabad, taken by Lotte Jacobi, ca. 1932-1933. Twenty-four women, two young men, and a boy are sitting on chairs or standing posed for a group portrait outside by a tree and weathered building. The women are wearing coats, embroidered hats, and headscarves, and the young men are wearing suits, ties, and embroidered hats. The boy is wearing a coat and wool-brimmed hat.https://scholars.unh.edu/jacobi_ussr_central_asia/3467/thumbnail.jp