Large-scale determinants of street tree growth rates across an urban environment.

Urban street trees offer cities critical environmental and social benefits. In New York City (NYC), a decadal census of every street tree is conducted to help understand and manage the urban forest. However, it has previously been impossible to analyze growth of an individual tree because of uncertainty in tree location.

Change of urban park usage as a response to the COVID-19 global pandemic.

Urban parks became critical for maintaining the well-being of urban residents during the COVID-19 global pandemic. To examine the impact of COVID-19 on urban park usage, we selected New York City (NYC) and used SafeGraph mobility data, which was collected from a large sample of mobile phone users, to assess the change in park visits and travel distance to a park based on 1) park type, 2) the income level of the visitor census block group (visitor CBG) and 3) that of the park census block group (park CBG). All analyses were adjusted for the impact of temperature on park visitation, and we focused primarily on visits made by NYC residents.

Comparing the hydrological performance of an irrigated native vegetation green roof with a conventional Sedum spp. green roof in New York City.

The objective of this study was to compare the hydrological performance of an irrigated, 127 mm deep green roof, planted with vegetation native to the New York City area, to a conventional, non-irrigated, 100 mm deep green roof, planted with drought-tolerant Sedum spp. Four years of climate and runoff data from both green roofs were analyzed to determine seasonal stormwater retention. Empirical relationships between rainfall and runoff were developed for both roofs, and applied to historical rainfall data in order to compare stormwater retention values for different rainfall depths.

Impacts of COVID-19 related stay-at-home restrictions on residential electricity use and implications for future grid stability.

"Stay-at-home" orders and other health precautions enacted during the COVID-19 pandemic have led to substantial changes in residential electricity usage. We conduct a case study to analyze data from 390 apartments in New York City (NYC) to examine the impacts of two key drivers of residential electricity usage: COVID-19 case-loads and the outdoor temperature. We develop a series of regression models to predict two characteristics of residential electricity usage on weekdays: The average occupied apartment's consumption (kWh) over a 9am-5pm window and the hourly peak demand (Watt) over a 12pm-5pm window.

MFRED, 10 second interval real and reactive power for groups of 390 US apartments of varying size and vintage.

Building electricity is a major component of global energy use and its environmental impacts. Detailed data on residential electricity use have many interrelated research applications, from energy conservation to non-intrusive load monitoring, energy storage, integration of renewables, and electric vs. fossil-based heating.

Observations of the seasonal buildup and washout of salts in urban bioswale soil.

The objective of this study was to quantify the seasonal risk of salt damage to bioswale plants, soil, microbes, and downstream waterbodies. To do so, we measured sodium, chloride, and electrical conductivity levels at seven bioswales located in the Bronx, New York City, over 42 storm events during a three-year monitoring period. The bioswale with the greatest salt contamination (median 206 mg/L chloride) had a unique inlet design without any possibility of inlet bypass.

Identifying linkages between urban green infrastructure and ecosystem services using an expert opinion methodology.

Stormwater green infrastructure (GI) has the potential to provide ecosystem services (ES) that are currently lacking in many urban environments. Nevertheless, while stormwater GI presents a major opportunity for cities to enhance urban ES, there is insufficient evidence to link the complex social and ecological benefits of ES to different GI types for holistic urban planning. This study used an expert opinion methodology to identify linkages between 22 ES and 14 GI types within a New York City context.

Studying the effect of bioswales on nutrient pollution in urban combined sewer systems.

The objective of this study was to evaluate the impact of bioswales on nutrient pollution in an urban combined sewershed. This evaluation was based on two criteria: the ability of bioswales to (1) remove nutrient pollution from stormwater runoff directly and (2) decrease sewer overflow volumes, which indirectly reduces total sewershed nutrient pollution during a storm event. Bioswales' direct nutrient removal was determined by analyzing nitrogen and phosphorus levels in water samples at seven bioswales located in the Bronx, New York City (NYC) over 42 storm events, while a bioswale's indirect nutrient removal through combined sewer overflow reduction was estimated by quantifying water retention at one of the bioswales.

Citizen science-based water quality monitoring: Constructing a large database to characterize the impacts of combined sewer overflow in New York City.

To protect recreational water users from waterborne pathogen exposure, it is crucial that waterways are monitored for the presence of harmful bacteria. In NYC, a citizen science campaign is monitoring waterways impacted by inputs of storm water and untreated sewage during periods of rainfall. However, the spatial and temporal scales over which the monitoring program can sample are constrained by cost and time, thus hindering the construction of databases that benefit both scientists and citizens.

Meta-principles for developing smart, sustainable, and healthy cities.

Policy directives in several nations are focusing on the development of smart cities, linking innovations in the data sciences with the goal of advancing human well-being and sustainability on a highly urbanized planet. To achieve this goal, smart initiatives must move beyond city-level data to a higher-order understanding of cities as transboundary, multisectoral, multiscalar, social-ecological-infrastructural systems with diverse actors, priorities, and solutions. We identify five key dimensions of cities and present eight principles to focus attention on the systems-level decisions that society faces to transition toward a smart, sustainable, and healthy urban future.

Quantifying evapotranspiration from urban green roofs: a comparison of chamber measurements with commonly used predictive methods.

Quantifying green roof evapotranspiration (ET) in urban climates is important for assessing environmental benefits, including stormwater runoff attenuation and urban heat island mitigation. In this study, a dynamic chamber method was developed to quantify ET on two extensive green roofs located in New York City, NY. Hourly chamber measurements taken from July 2009 to December 2009 and April 2012 to October 2013 illustrate both diurnal and seasonal variations in ET.

Transport of in Aquifer Sediments of Bangladesh: Implications for Widespread Microbial Contamination of Groundwater.

Fecal bacteria are frequently found at much greater distances than would be predicted by laboratory studies, indicating that improved models that incorporate more complexity are might be needed to explain the widespread contamination of many shallow aquifers. In this study, laboratory measurements of breakthrough and retained bacteria in columns of intact and repacked sediment cores from Bangladesh were fit using a two-population model with separate reversible and irreversible attachment sites that also incorporated bacterial decay rates. Separate microcosms indicated an average first order decay rate of 0.

Unsealed tubewells lead to increased fecal contamination of drinking water.

Bangladesh is underlain by shallow aquifers in which millions of drinking water wells are emplaced without annular seals. Fecal contamination has been widely detected in private tubewells. To evaluate the impact of well construction on microbial water quality 35 private tubewells (11 with intact cement platforms, 19 without) and 17 monitoring wells (11 with the annulus sealed with cement, six unsealed) were monitored for culturable Escherichia coli over 18 months.

Comparison of fecal indicators with pathogenic bacteria and rotavirus in groundwater.

Groundwater is routinely analyzed for fecal indicators but direct comparisons of fecal indicators to the presence of bacterial and viral pathogens are rare. This study was conducted in rural Bangladesh where the human population density is high, sanitation is poor, and groundwater pumped from shallow tubewells is often contaminated with fecal bacteria. Five indicator microorganisms (E.

Increase in diarrheal disease associated with arsenic mitigation in Bangladesh.

Background: Millions of households throughout Bangladesh have been exposed to high levels of arsenic (As) causing various deadly diseases by drinking groundwater from shallow tubewells for the past 30 years. Well testing has been the most effective form of mitigation because it has induced massive switching from tubewells that are high (>50 µg/L) in As to neighboring wells that are low in As. A recent study has shown, however, that shallow low-As wells are more likely to be contaminated with the fecal indicator E.

Implications of fecal bacteria input from latrine-polluted ponds for wells in sandy aquifers.

Ponds receiving latrine effluents may serve as sources of fecal contamination to shallow aquifers tapped by millions of tube-wells in Bangladesh. To test this hypothesis, transects of monitoring wells radiating away from four ponds were installed in a shallow sandy aquifer underlying a densely populated village and monitored for 14 months. Two of the ponds extended to medium sand.

Hand-pumps as reservoirs for microbial contamination of well water.

The retention and release of total coliforms and Escherichia coli was investigated in hand-pumps removed from tubewells tapping a faecally contaminated aquifer in Matlab, Bangladesh, and from a new hand-pump deliberately spiked with E. coli. All hand-pumps were connected to reservoirs of sterile water and flushed.

Electrolyte solution transport in electropolar nanotubes.

Electrolyte transport in nanochannels plays an important role in a number of emerging areas. Using non-equilibrium molecular dynamics (NEMD) simulations, the fundamental transport behavior of an electrolyte/water solution in a confined model nanoenvironment is systematically investigated by varying the nanochannel dimension, solid phase, electrolyte phase, ion concentration and transport rate. It is found that the shear resistance encountered by the nanofluid strongly depends on these material/system parameters; furthermore, several effects are coupled.

Fecal contamination of shallow tubewells in Bangladesh inversely related to arsenic.

The health risks of As exposure due to the installation of millions of shallow tubewells in the Bengal Basin are known, but fecal contamination of shallow aquifers has not systematically been examined. This could be a source of concern in densely populated areas with poor sanitation because the hydraulic travel time from surface water bodies to shallow wells that are low in As was previously shown to be considerably shorter than for shallow wells that are high in As. In this study, 125 tubewells 6-36 m deep were sampled in duplicate for 18 months to quantify the presence of the fecal indicator Escherichia coli.

Thermal effect on the dynamic infiltration of water into single-walled carbon nanotubes.

Thermally induced variation in wetting ability in a confined nanoenvironment, indicated by the change in infiltration pressure as water molecules enter a model single-walled carbon nanotube submerged in aqueous environment, is investigated using molecular dynamics simulations. The temperature-dependent infiltration behavior is impacted in part by the thermally excited radial oscillation of the carbon nanotube, and in part by the variations of fundamental physical properties at the molecular level, including the hydrogen bonding interaction. The thermal effect is also closely coupled with the nanotube size effect and loading rate effect.

Mechanisms of water infiltration into conical hydrophobic nanopores.

Fluid channels with inclined solid walls (e.g. cone- and slit-shaped pores) have wide and promising applications in micro- and nano-engineering and science.

Experimental study on energy dissipation of electrolytes in nanopores.

When a nonwetting fluid is forced to infiltrate a hydrophobic nanoporous solid, the external mechanical work is partially dissipated into thermal energy and partially converted to the liquid-solid interface energy to increase its enthalpy, resulting in a system with a superior energy absorption performance. To clarify the energy dissipation and conversion mechanisms, experimental infiltration and defiltration tests of liquid/ion solutions into nanopores of a hydrophobic ZSM-5 zeolite were conducted. The characteristics of energy dissipation were quantified by measuring the temperature variation of the immersed liquid environment and compared against that estimated from pressure-infiltration volume isotherms during infiltration and defiltration stages of the test.

Thermally responsive fluid behaviors in hydrophobic nanopores.

A fundamental understanding of the thermal effects on nanofluid behaviors is critical for developing and designing innovative thermally responsive nanodevices. Using molecular dynamics (MD) simulation and experiment, we investigate the temperature-dependent intrusion/adsorption of water molecules into hydrophobic nanopores (carbon nanotubes and nanoporous carbon) and the underlying mechanisms. The critical infiltration pressure is reduced for elevated temperature or increased pore size.

Nanoscale fluid transport: size and rate effects.

The transport behavior of water molecules inside a model carbon nanotube is investigated by using nonequilibrium molecular dynamcis (NMED) simulations. The shearing stress between the nanotube wall and the water molecules is identified as a key factor in determining the nanofluidic properties. Due to the effect of nanoscale confinement, the effective shearing stress is not only size sensitive but also strongly dependent on the fluid flow rate.

Spinning Drop Tensiometry Using a Square Section Sample Tube.

When measuring interfacial tensions, conventional spinning drop tensiometry requires knowledge of the index of refraction of the denser, outer fluid phase, in order to correct for the magnification of the inner, spinning drop. We have modified a spinning drop tensiometer to accommodate a square section sample tube, which does not require this correction. Tests performed using calibration rods are used to demonstrate this fact.