Periphyton responses to nutrient and atrazine mixtures introduced through agricultural runoff

Agricultural runoff often contains pollutants with antagonistic impacts. The individual influence of nutrients and atrazine on periphyton has been extensively studied, but their impact when introduced together and with multiple agricultural pollutants is less clear. We simulated a field-scale runoff pulse into a riverine wetland that mimicked pollutant composition typical of field runoff of the Mississippi River Alluvial Plain. Periphyton biomass and functional responses were measured for 2 weeks along a 500 m section. Additionally, laboratory chamber assays were used to identify potential periphyton changes due to nutrients, atrazine, and their interactions. Generally, nutrients stimulated, and atrazine reduced chlorophyll a (Chl a) in chambers. In the wetland, nutrient and atrazine relationships with periphyton were weaker, and when found, were often opposite of trends in chambers. Total nitrogen (TN) was inversely related to Chl a, and total phosphorus was inversely related to respiration (R) rates. Atrazine (10–20 lg L-1 in the wetland) had a positive relationship with ash-free dry mass (AFDM), and weakened the relationship between TN and AFDM. Wetland periphyton biomass was better correlated to total suspended solids than nutrients or atrazine. Periphyton function was resilient as periphyton gross primary production (GPP)/R ratios were not strongly impacted by runoff. However, whole-system GPP and R decreased over the 2-week period, suggesting that although periphyton metabolism recovered quickly, whole-system metabolism took longer to recover. The individual and combined impacts of nutrients and atrazine in complex pollutant mixtures can vary substantially from their influence when introduced separately, and non-linear impacts can occur with distance downstream of the pollutant introduction point

Anatomy of a Community-Level Fiscal Impact Model: FIT-4-NH.

Abstract: This paper describes the development of a fiscal impact tool for New Hampshire communities (HT -4-NH). FIT -4-NH belongs to a family of computergenerated fiscal impact assessment models designed to estimate the impacts to local government revenues and expenditures that result from economic changes. In the past, work in this area has centered on the completion of countylevel models for the midwestern states. FIT-4-NH is unique in that it was designed for rural community-level use in the northern New England region of the country

Simulation of Surface Runoff and Channel Flows Using a 2D Numerical Model

Numerical simulation of surface runoff is used to understand and predict watershed sediment transport and water quality and improve management of agricultural watersheds. However, models currently available are either simplified or parameterized for efficiency. In this chapter, CCHE2D, a physically based hydrodynamic model for general free surface flow hydrodynamics, was applied to study watershed surface runoff and channel flows. Multiple analytical solutions and experimental data were used to verify and validate this finite element model systematically with good results. A numerical scheme for correcting the bilinear interpolation of the water surface elevation solutions from the cell centers to the computational nodes was developed to improve the model. The correction was found necessary and effective for the sheet runoff simulations over the irregular bed topography. The modified numerical model was then used to simulate storms in a low-relief agricultural watershed in the Mississippi River alluvial plain. This physically based model identified the channel networks, watershed boundary automatically, and helped to develop rating curves at the gage station of this complex watershed. The numerical simulations resolved detailed runoff and turbulent channel flows, which can be used for soil erosion and gully development analyses

Numerical simulation of sediment related processes in water quality model

Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732Sediment is a major nonpoint-source pollutant, and the exchange of materials between water and sediment is an important component of the lake eutrophication process. Suspended sediment increases water surface reflectivity and light attenuation in the water column. Nutrients can be absorbed to sediment particles and desorb from sediment to the water. In addition, nutrients can also be released from bed sediment. In this study, a water quality model, CCHE3D_WQ, was applied to simulate the concentrations of phytoplankton and nutrients in a shallow, natural lake with special emphasis on sediment-related processes. A formula was generated from field measurements to calculate the light attenuation coefficient using the concentration of chlorophyll and suspended sediment. The concentrations of adsorbed and dissolved nutrients due to adsorption-desorption were calculated using two formulas derived based on the Langmuir Equation. The release rates of nutrients from the lake bed were calculated by considering the effects of the concentration gradient across the water-sediment interface, pH, temperature, dissolved oxygen concentration, and flow conditions. Model algorithms describing the adsorption and desorption of nutrients from sediment particles as well as their release from bed sediment were tested using laboratory experimental data. Model simulation results show that there are strong interactions between sediment-related processes and nutrient concentrations

Mitigating agrichemicals from an artificial runoff event using a managed riverine wetland

We examined the mitigation efficiency of a managed riverine wetland amended with a mixture of suspended sediment, two nutrients (nitrogen and phosphorus), and three pesticides (atrazine, metolachlor, and permethrin) during a simulated agricultural runoff event. Hydrologic management of the 500 m-long, 25 mwide riverine wetland was done by adding weirs at both ends. The agrichemical mixture was amended to the wetland at the upstream weir simulating a four-hour, ~1 cm rainfall event from a 16 ha agricultural field. Water samples (1 L) were collected every 30 min within the first 4 h, then every 4 h until 48 h, and again on days 5, 7, 14, 21, and 28 post-amendment at distances of 0 m, 10 m, 40 m, 300 m and 500 m from the amendment point within the wetland for suspended solids, nutrient, and pesticide analyses. Peak sediment, nutrient, and pesticide concentrations occurred within 3 h of amendment at 0 m, 10 m, 40 m, and 300 m downstream and showed rapid attenuation of agrichemicals from the water column with 79–98%, 42–98%, and 63–98% decrease in concentrations of sediments, nutrients, and pesticides, respectively, within 48 h. By day 28, all amendments were near or below pre-amendment concentrations. Water samples at 500 m showed no changes in sediment or nutrient concentrations; pesticide concentrations peaked within 48 h but at ≤11% of upstream peak concentrations and had dissipated by day 28. Managed riverine wetlands≥1 ha and with hydraulic residence times of days to weeks can efficiently trap agricultural runoff during moderate (1 cm) late-spring and early-summer rainfall events, mitigating impacts to receiving rivers

Nanoparticle Networks Reduce the Flammability of Polymer Nanocomposites

Synthetic polymer materials are rapidly replacing more traditional inorganic materials such as metals and natural polymeric materials such as wood. Since these novel materials are flammable, they require modifications to decrease their flammability through the addition of flame-retardant (FR) compounds. Recently, environmental regulation has restricted the use of some halogenated FR additives, initiating a search for alternative FR additives. Nanoparticle fillers are highly attractive for this purpose since they can simultaneously improve both the physical and flammability properties of the polymer nanocomposite. We show that carbon nanotubes can surpass nano-clays as effective FR additives if they form a jammed network structure within the polymer matrix, such that the material as a whole behaves rheologically like a gel. We find this kind of network formation for a variety of highly extended carbon-based nanoparticles: single and multi-walled nanotubes, as well as carbon nanofibers

Angular analysis of D0→π+π−μ+μ−D^0 \to \pi^+\pi^-\mu^+\mu^- and D0→K+K−μ+μ−D^0 \to K^+K^-\mu^+\mu^- decays and search for CPCP violation

The first full angular analysis and an updated measurement of the decay-rate $CP$ asymmetry of the $D^0 \to \pi^+\pi^-\mu^+\mu^-$ and $D^0 \to K^+K^-\mu^+\mu^-$ decays are reported. The analysis uses proton-proton collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV. The data set corresponds to an integrated luminosity of 9 fb$^{-1}$. The full set of $CP$-averaged angular observables and their $CP$ asymmetries are measured as a function of the dimuon invariant mass. The results are consistent with expectations from the standard model and with $CP$ symmetry.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2021-035.html (LHCb public pages

Study of the psi(2)(3823) and chi(c1)(3872) states in B+->(J/psi pi(+)pi(-))K(+)decays

The decays $B^+\rightarrow J/\psi \pi^+ \pi^- K^+$ are studied using a data set corresponding to an integrated luminosity of 9fb$^{-1}$ collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate $\psi_2(3823)$, $\chi_{c1}(3872)$ and $\psi(2S)$ states are reported. The decay of $B^+\rightarrow \psi_2(3872)K^+$ with $\psi_2(3823)\rightarrow J\psi\pi^+\pi^-$ is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the $\psi_2(3823)$, $\chi_{c1}(3872)$ and $\psi(2S)$ states are measured to be $$\begin{array}{rcl} m_{\chi_{c1(3872)}} - m_{\psi_2(3823)} &= & 47.50 \pm 0.53 \pm 0.13\,\mathrm{MeV/}c^2\,, \\ m_{\psi_2(3823)} - m_{\psi(2S)} &= & 137.98 \pm 0.53 \pm 0.14\,\mathrm{MeV/}c^2\,, \\ m_{\chi_{c1}(3872)} - m_{\psi(2S)} &= & 185.49 \pm 0.06 \pm 0.03\,\mathrm{MeV/}c^2\,, \end{array}$$ resulting in the most precise determination of the $\chi_{c1}(3782)$ mass. The width of the $\psi_2(3823)$ state is found to be below 5.2MeV at 90\% confidence level. The Breit-Wigner width of the $\chi_{c1}(3872)$ state is measured to be $$\Gamma^{\mathrm{BW}}_{\chi_{c1}(3872)} = 0.96^{+0.19}_{-0.18}\pm0.21 \mathrm{MeV},$$ which is inconsistent with zero by 5.5 standard deviations.Comment: 26 pages, 3 figures. All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2020-009.html (LHCb public pages

Observation of Two New Excited Ξb0 States Decaying to Λb0 K-π+

Two narrow resonant states are observed in the Λb0K-π+ mass spectrum using a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 6 fb-1. The minimal quark content of the Λb0K-π+ system indicates that these are excited Ξb0 baryons. The masses of the Ξb(6327)0 and Ξb(6333)0 states are m[Ξb(6327)0]=6327.28-0.21+0.23±0.12±0.24 and m[Ξb(6333)0]=6332.69-0.18+0.17±0.03±0.22 MeV, respectively, with a mass splitting of Δm=5.41-0.27+0.26±0.12 MeV, where the uncertainties are statistical, systematic, and due to the Λb0 mass measurement. The measured natural widths of these states are consistent with zero, with upper limits of Γ[Ξb(6327)0]<2.20(2.56) and Γ[Ξb(6333)0]<1.60(1.92) MeV at a 90% (95%) credibility level. The significance of the two-peak hypothesis is larger than nine (five) Gaussian standard deviations compared to the no-peak (one-peak) hypothesis. The masses, widths, and resonant structure of the new states are in good agreement with the expectations for a doublet of 1D Ξb0 resonances

Study of the ψ 2 (3823) and χ c1 (3872) states in B + → (J /ψπ + π − )K + decays

Abstract: The decays B+→ J/ψπ+π−K+ are studied using a data set corresponding to an integrated luminosity of 9 fb−1 collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate ψ2(3823), χc1(3872) and ψ(2S) states are reported. The values areBB+→ψ23823K+×Bψ23823→J/ψπ+π−BB+→χc13872K+×Bχc13872→J/ψπ+π−=3.56±0.67±0.11×10−2, BB+→ψ23823K+×Bψ23823→J/ψπ+π−BB+→ψ2SK+×Bψ2S→J/ψπ+π−=1.31±0.25±0.04×10−3, BB+→χc13872K+×Bχc13872→J/ψπ+π−BB+→ψ2SK+×Bψ2S→J/ψπ+π−=3.69±0.07±0.06×10−2, where the first uncertainty is statistical and the second is systematic. The decay of B+→ ψ2(3823)K+ with ψ2(3823) → J/ψπ+π− is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ2(3823), χc1(3872) and ψ(2S) states are measured to be mχc13872−mψ23823=47.50±0.53±0.13MeV/c2, mψ23823−mψ22S=137.98±0.53±0.14MeV/c2, mχc13872−mψ22S=185.49±0.06±0.03MeV/c2, resulting in the most precise determination of the χc1(3872) mass. The width of the ψ2(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χc1(3872) state is measured to be Γχc13872BW=0.96−0.18+0.19±0.21MeV which is inconsistent with zero by 5.5 standard deviations