A comparison of watershed nitrogen loading and watershed nitrogen exports from on-site wastewater treatment systems and centralized sewer systems in the North Carolina Coastal Plain

Elevated nitrogen (N) concentrations in groundwater may cause adverse effects to adjacent surface water bodies. In North Carolina, half of the residences use on-site wastewater treatment systems (OWTS), yet they are typically not regulated beyond the permitting process. The overall goal of this study was to determine if OWTS affect groundwater N loading and surface water N export at the watershed scale. Eight sub-watersheds were monitored monthly for physical and chemical parameters in Greenville, NC. Four watersheds used OWTS and four watersheds used a centralized sewer system (CSS) that transported wastewater from these watersheds and discharged the treated wastewater to the Tar River. To evaluate the effects of wastewater management on groundwater quality, groundwater was monitored at 10 residential sites, five in an OWTS watershed and five in a CSS watershed. Groundwater samples were collected quarterly for a year (August 2011 to August 2012) and analyzed for dissolved N species (ammonium, nitrate + nitrite, and dissolved organic N) and chloride. Surface water samples were collected monthly and analyzed for the same physical and chemical parameters, including turbidity and particulate N. Groundwater and surface water samples were collected and sent to the Stable Isotope Facility at UC Davis for [delta]¹�N and [delta]¹�O of nitrate analysis. Groundwater TDN concentrations and loads at OWTS sites were significantly greater than at CSS sites, with mean TDN concentrations in OWTS groundwater up to two times greater and loads up to five times greater than CSS TDN concentrations and loads. Groundwater and surface water stable isotopes, ¹�N and ¹�O in nitrate, suggested that N sources in OWTS watersheds were wastewater derived, while CSS sources were fertilizer derived. Mean total nitrogen (TN) concentrations in surface water at OWTS watersheds were approximately two times greater than for CSS watersheds during baseflow and storm conditions. Streams draining OWTS watersheds exported significantly greater TN masses than CSS watersheds. Assuming average measured OWTS loads to the soil were representative of each residence in OWTS watersheds, on average OWTS watersheds were found to attenuate 81% (± 14%) of OWTS TN loads to the soil prior to TN export from the watershed. The results from this study illustrate a need for inclusion among nutrient management strategies by North Carolina Department Environment and Natural Resources and other state, federal, and international agencies.M.S

Nitrogen Treatment by a Dry Detention Basin with Stormwater Wetland Characteristics

Dry detention basins (DB) are commonly used to reduce the rate of runoff in urban areas and may provide open space for recreation between storms. However, most are not effective at nitrogen removal in comparison to other measures, such as constructed wetlands. The study goal was to assess the nitrogen treatment efficiency of a DB that exhibited some wetland characteristics, including saturated soil near the inlet and wetland vegetation that covered 40% of the surface area. Influent and effluent samples were collected during multiple stages of eight storm events for nitrogen concentration analyses. High-frequency water stage, pH, dissolved oxygen (DO), and temperature loggers were deployed at the inlet and outlet prior to anticipated rain. As stormwater passed through the DB, the event mean concentrations (EMCs) and masses of TN declined by 20.7% and 52.3%, respectively, while the DO and pH dropped by 62% and 20.5%, respectively. Load reductions of TN exceeding 93% were observed during two small storms with rain depths of less than 0.16 cm and when the outflow volumes were reduced by greater than 82%. Temperature was significantly correlated (p < 0.001; r = 0.964) with volume reductions (via infiltration and evapotranspiration), and, thus, the treatment was better during warmer periods. The DB was effective at removing inorganic nitrogen, likely via nitrification, denitrification, and immobilization, but frequently exported higher EMCs of organic nitrogen. Overall, the DB exceeded the 10% TN removal expectation for dry basins. The findings from this study suggest that the TN treatment efficiency of DBs may be improved by incorporating wetland characteristics

Activation loop dynamics are controlled by conformation-selective inhibitors of ERK2

Conformational selection by small molecules expands inhibitory possibilities for protein kinases. Nuclear magnetic resonance (NMR) measurements of the mitogen-activated protein (MAP) kinase ERK2 have shown that activation by dual phosphorylation induces global motions involving exchange between two states, L and R. We show that ERK inhibitors Vertex-11e and SCH772984 exploit the small energetic difference between L and R to shift the equilibrium in opposing directions. An X-ray structure of active 2P-ERK2 complexed with AMP-PNP reveals a shift in the Gly-rich loop along with domain closure to position the nucleotide in a more catalytically productive conformation relative to inactive 0P-ERK2:ATP. X-ray structures of 2P-ERK2 complexed with Vertex-11e or GDC-0994 recapitulate this closure, which is blocked in a complex with a SCH772984 analog. Thus, the L→R shift in 2P-ERK2 is associated with movements needed to form a competent active site. Solution measurements by hydrogen-exchange mass spectrometry (HX-MS) reveal distinct binding interactions for Vertex-11e, GDC-0994, and AMP-PNP with active vs. inactive ERK2, where the extent of HX protection correlates with R state formation. Furthermore, Vertex-11e and SCH772984 show opposite effects on HX near the activation loop. Consequently, these inhibitors differentially affect MAP kinase phosphatase activity toward 2P-ERK2. We conclude that global motions in ERK2 reflect conformational changes at the active site that promote productive nucleotide binding and couple with changes at the activation loop to allow control of dephosphorylation by conformationally selective inhibitors

Quantifying Total Phosphorus and Heavy Metals in Residential Septage

Septic systems are used for wastewater treatment in rural areas. Septic tanks promote stratification of wastewater into solid (sludge and scum) and liquid layers. Pollutant concentrations in the layers of residential septic tanks may be highly variable, and thus septage pumped from tanks with different layer thicknesses may also be variable. The goal of this study was to quantify the total phosphorus (TP) and heavy metal concentrations and masses of residential septage. The solid and liquid layer thicknesses were measured in 37 septic tanks. Samples were collected from each layer for pollutant concentration analysis. The median TP concentration (10.6 mg L−1) was greatest in the sludge layer, followed by the scum (5.3 mg L−1) and liquid (1.8 mg L−1) layers. Concentrations of heavy metals were highly variable for each layer type. The masses of the TP, cadmium, copper, lead, nickel, and zinc contained median (range) values of 19.4 g (0.9–1041 g), <0.01 g (<0.01–1.99 g), 1.3 g (0.1–520 g), 1.8 g (<0.01–44.2 g), 1.3 g (<0.01–4.3 g), and 13.8 g (0.3–788 g), respectively. Since septage is typically applied on land as a soil amendment for crop growth, it is important that representative composite samples are collected to prevent excess buildup of TP and metals, which may harm yields or environmental health

Activation loop dynamics are controlled by conformation-selective inhibitors of ERK2

Conformational selection by small molecules expands inhibitory possibilities for protein kinases. Nuclear magnetic resonance (NMR) measurements of the mitogen-activated protein (MAP) kinase ERK2 have shown that activation by dual phosphorylation induces global motions involving exchange between two states, L and R. We show that ERK inhibitors Vertex-11e and SCH772984 exploit the small energetic difference between L and R to shift the equilibrium in opposing directions. An X-ray structure of active 2P-ERK2 complexed with AMP-PNP reveals a shift in the Gly-rich loop along with domain closure to position the nucleotide in a more catalytically productive conformation relative to inactive 0P-ERK2:ATP. X-ray structures of 2P-ERK2 complexed with Vertex-11e or GDC-0994 recapitulate this closure, which is blocked in a complex with a SCH772984 analog. Thus, the L→R shift in 2P-ERK2 is associated with movements needed to form a competent active site. Solution measurements by hydrogen-exchange mass spectrometry (HX-MS) reveal distinct binding interactions for Vertex-11e, GDC-0994, and AMP-PNP with active vs. inactive ERK2, where the extent of HX protection correlates with R state formation. Furthermore, Vertex-11e and SCH772984 show opposite effects on HX near the activation loop. Consequently, these inhibitors differentially affect MAP kinase phosphatase activity toward 2P-ERK2. We conclude that global motions in ERK2 reflect conformational changes at the active site that promote productive nucleotide binding and couple with changes at the activation loop to allow control of dephosphorylation by conformationally selective inhibitors

Adaptation, migration or extirpation: climate change outcomes for tree populations

Species distribution models predict a wholesale redistribution of trees in the next century, yet migratory responses necessary to spatially track climates far exceed maximum post-glacial rates. The extent to which populations will adapt will depend upon phenotypic variation, strength of selection, fecundity, interspecific competition, and biotic interactions. Populations of temperate and boreal trees show moderate to strong clines in phenology and growth along temperature gradients, indicating substantial local adaptation. Traits involved in local adaptation appear to be the product of small effects of many genes, and the resulting genotypic redundancy combined with high fecundity may facilitate rapid local adaptation despite high gene flow. Gene flow with preadapted alleles from warmer climates may promote adaptation and migration at the leading edge, while populations at the rear will likely face extirpation. Widespread species with large populations and high fecundity are likely to persist and adapt, but will likely suffer adaptational lag for a few generations. As all tree species will be suffering lags, interspecific competition may weaken, facilitating persistence under suboptimal conditions. Species with small populations, fragmented ranges, low fecundity, or suffering declines due to introduced insects or diseases should be candidates for facilitated migration

Animal-borne telemetry: An integral component of the ocean observing toolkit

Animal telemetry is a powerful tool for observing marine animals and the physical environments that they inhabit, from coastal and continental shelf ecosystems to polar seas and open oceans. Satellite-linked biologgers and networks of acoustic receivers allow animals to be reliably monitored over scales of tens of meters to thousands of kilometers, giving insight into their habitat use, home range size, the phenology of migratory patterns and the biotic and abiotic factors that drive their distributions. Furthermore, physical environmental variables can be collected using animals as autonomous sampling platforms, increasing spatial and temporal coverage of global oceanographic observation systems. The use of animal telemetry, therefore, has the capacity to provide measures from a suite of essential ocean variables (EOVs) for improved monitoring of Earth's oceans. Here we outline the design features of animal telemetry systems, describe current applications and their benefits and challenges, and discuss future directions. We describe new analytical techniques that improve our ability to not only quantify animal movements but to also provide a powerful framework for comparative studies across taxa. We discuss the application of animal telemetry and its capacity to collect biotic and abiotic data, how the data collected can be incorporated into ocean observing systems, and the role these data can play in improved ocean management

Nutrient contributions from septic systems in nutrient-sensitive watersheds: Quantifying nutrient inputs, reduction methods, and economic feasibility

Eutrophication of surface waters is a global issue threatening aquatic ecosystems and recreational opportunities. Nutrient management strategies exist to reduce nutrient inputs from various sources; however, septic systems are typically not listed in these strategies. The goal of this research was to: 1) quantify mass export of nitrogen and phosphorus from septic-dominated watersheds relative to control watersheds (those without significant septic system usage); 2) implement retrofit best management practices (BMPs) in septic-dominated watersheds to quantify nutrient mass attenuation; and 3) perform cost-benefit analysis (CBA) to compare economic feasibility of using retrofit BMPs to conversion of septic to sewer. Results showed that nutrient exports were significantly elevated from watersheds with a high-density (HD) of septic systems (approximately 1.8 systems ha-1). Mass exports of total dissolved nitrogen (TDN) and phosphate from HD watersheds (median: 4.9 kg-N yr-1 ha-1; 0.2 kg-P yr-1 ha-1) were approximately 5 and 10 times greater, respectively, than control watershed and low-density septic watersheds. An in-stream bioreactor (IBR) was installed upstream from a natural wetland (NW) to improve watershed attenuation of nutrients. Mass inputs of TDN and phosphate to the IBR were approximately 177.1 g-N day-1 (14.8 g-N day-1 ha-1) and 24.6 g-P day-1 (2.1 g-P day-1 ha-1), respectively. Mass exports of TDN and phosphate from the NW were 31.9 g-N day-1 (0.3 g-N day-1 ha-1) and 2.1 g-P day-1 (0.02 g-P day-1 ha-1), respectively, which was a load reduction of 82% (98% area normalized) and 91% (99% area normalized) for TDN and phosphate, respectively. CBAs implied that constructing and maintaining septic systems along with an IBR and NW was economically feasible based on nutrient attenuation benefits alone. Costs associated with converting from septic to municipal sewer along with utility fees outweighed potential nutrient removal benefits. This research suggests that including septic systems among nutrient management strategies may help North Carolina and other regions achieve nutrient reduction goals

Special Issue on Applied Research on Water Treatment by Onsite Wastewater Management and Agricultural and Stormwater Control Measures at Varying Spatial Scales

Human population growth has led to increased wastewater generation and discharges, land clearing and fertilization for food production, and impervious surfaces associated with housing and road construction [...