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Water planning and governance strategies must adapt to challenges associated with population growth, climate change, and projected water shortages. In the Western United States, agriculture is the dominant water use, and agricultural water users are being asked to conserve or share their water with other uses. Managing scarce water supplies at the local level often involves creative solutions, many of which are not well documented, especially in the agricultural sector. It is therefore critical to understand ideas to manage scarce water resources from the perspective of agricultural water users and those who work with them. In our research, we used interviews to explore how agricultural water users are managing increasing water scarcity in the Middle Rio Grande basin of central New Mexico and what enables or prevents them from taking innovative action to manage water scarcity. We hypothesized that we would find undocumented water use innovations born out of water users’ responses to lower and more variable water availability in recent years. We primarily recruited interviewees through snowball sampling, with a total of 42 (47%) agricultural water users, decision makers, and non-profit leaders influencing agricultural water governance in the basin accepting our invitation to participate. Our approximately one-hour, semi-structured and open-ended interviews explored agricultural water users’ lived experiences with water governance and opportunities to manage water scarcity. The interviews were recorded, transcribed, coded, and analyzed using HyperRESEARCH software (version 4.5.4). Our results did not support our hypothesis. Instead, we found that agricultural water users struggled to implement well-known innovations amid the pressures of water scarcity, supply uncertainty, administrative complexity, and constraints on their time, labor, and money. Water users and decision makers were mutually interested in implementing innovations in crop choice, flexibility in water storage, use, and management, stricter enforcement of water use efficiency, and access to more efficient irrigation equipment. However, high costs, a lack of knowledge, education, and training, and challenges related to water distribution and scheduling prevented agricultural water users from accessing these and other innovations. Recommendations include incentive-based policies to promote agricultural water use innovations that require high initial costs, improved water accounting at the basin and regional levels to promote flexible and reliable access to agricultural water, targeted education and outreach programming on alternative irrigation methods and cropping patterns, and improved access to irrigation scheduling information to support agricultural water users in planning for water scarcity. 

Home dust samples were collected from the surface of heating, ventilation, and air conditioning (HVAC) filters from eleven homes at different locations in Columbia, South Carolina, USA. Bulk metal concentrations in the dusts were measured using inductively coupled plasma-mass spectrometry (ICP-MS). Size-based elemental distributions in the <450 nm particles were determined by asymmetrical flow-field flow fractionation (AF4) coupled to ICP-MS. The bulk Ti/Nb ratios are generally higher (up to 5609) than the natural background ratios ( e.g. , 320), indicating contamination of home dusts with TiO 2 -engineered particles. Size-based Ti/Nb ratios in the <450 nm fraction are similar to the natural background ratio, indicating a natural origin of Ti-bearing particles in this size fraction, and subsequently that anthropogenic Ti-bearing particles (TiO 2 ) are associated with particles >450 nm either due to aggregation or to their release as large particles. The concentrations of TiO 2 -engineered particles were estimated by mass balance calculations using total Ti concentrations and increases in Ti/Nb ratios above the natural background ratio. They vary between 0 and 13 300 mg TiO 2 kg −1 . The upper crustal-normalized rare earth element pattern indicates a positive La and Ce anomaly. The size of the cerium and lanthanum anomalies varies from 0.8 to 1.6 and 0.7 to 3.95, respectively, indicating contamination of several home dusts with Ce and La. The concentrations of bulk anthropogenic Ce and La were estimated based on mass balance calculations and anomaly size and varied between 0 and 5.7 ± 2.2 mg Ce kg −1 and 0 and 21.1 ± 7.4 mg La kg −1 , respectively. Size-based Ce/La ratios in the <450 nm fraction are lower than the natural background ratio, indicating contamination of this size fraction with nanosized La-bearing particles. Anthropogenic Ti and La concentrations in home dust are attributed to releases from paint during home renovation. This implies that exposure of construction workers to Ti- and La-bearing particles during home renovation may potentially pose human health risks. 

Urban runoff is a significant source of pollutants, including incidental and engineered nanoparticles, to receiving surface waters. The aim of this study is to investigate the impact of urbanization on the concentrations of TiO 2 engineered particles in urban surface waters. The study area boundaries are limited to the Lower Saluda and Nicholas Creek-Broad River from upstream, and outlet of upper Congaree River in Columbia, South Carolina, United States from downstream. This sampling area captures a significant footprint of the urban area of the city of Columbia. Water samples were collected daily from four sites during two rain events. All samples were analyzed for total metal concentrations following acid digestion and for particle number concentration and elemental composition using single particle-inductively coupled plasma-time of flight-mass spectrometry (SP-ICP-TOF-MS). The Ti/Nb ratios in the Broad and Congaree River samples are generally higher than those of natural background ratios, indicating contamination of these two rivers with anthropogenic Ti-bearing particles. Clustering of multi-metal nanoparticles (mmNPs) demonstrated that Ti-bearing particles are distributed mainly among three clusters, FeTiMn, AlSiFe, and TiMnFe, which are typical of naturally occurring iron oxide, clay, and titanium oxide particles, indicating the absence of significant number of anthropogenic multi-element Ti-bearing particles. Thus, anthropogenic Ti-bearing particles are attributed to single-metal particles; that is pure TiO 2 particles. The total concentration of anthropogenic TiO 2 in the rivers was determined by mass balance calculation using bulk titanium concentration and increases in Ti/Nb above the natural background ratio. The concentration of anthropogenic TiO 2 increases following the order 0 to 24 μg L −1 in the Lower Saluda River <0 to 663 μg L −1 in the Broad River <43 to 1051 μg L −1 in Congaree River at Cayce <58 to 5050 μg L −1 in the Congaree River at Columbia. The concentration of anthropogenic TiO 2 increases with increases in urban runoff. The source of anthropogenic TiO 2 is attributed to diffuse urban runoff. This study demonstrates that diffuse urban runoff results in high concentrations of TiO 2 particles in urban surface waters during and following rainfall events which may pose increased risks to aquatic organisms during these episodic events.