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Organic acids represent an important class of compounds in the atmosphere but there are many uncertainties in understanding their formation; in particular, few investigations have been carried out as to their sources in the Northeast U.S. Associated with a heat wave and pollution event on 1–2 July, 2018, unusually high concentrations of formic (HCOOH), acetic (CH3COOH), and oxalic (OxAc) acid in cloud water were measured at the summit of Whiteface Mountain (WFM) in upstate New York. To investigate the gas phase production of organic acids for this pollution event, this work uses a combination of the regional transport model WRF-Chem which gives information on transport and environmental factors affecting air parcels reaching WFM, the Lagrangian chemical box model BOXMOX, which allows analysis analysi of chemistry with different chemical mechanisms. Two chemical mechanisms are used in BOXMOX: 1) the Model for Ozone and Related chemical Tracers (MOZART T1), and 2) the Master Chemical Mechanism version 3.3.1 (MCM). The WRF-Chem results show that air parcels sampled during the pollution event at WFM originated in central Missouri, which has strong biogenic emissions of isoprene. Many air parcels were influenced by emissions of nitrogen oxides (NO x) from the Chicago Metropolitan Area. Ozonolysis of isoprene and related oxidation products were the major sources of HCOOH in both mechanisms. CH3COOH was produced from acetyl peroxy radical (CH3CO3) reacting with the hydroperoxy (HO2) radical, with MCM producing up to 40 % more CH3COOH under conditions of high isoprene and low NO x compared to MOZART T1. Both mechanisms underpredicted HCOOH and and CH3COOH by an order of magnitude compared to measurements at WFM. A simple gas+aqueous box model was used to determine if cloud water chemistry could have had an appreciable impact on organic acid formation. Aqueous chemistry exacerbated the discrepancies of HCOOH by leading to a net depletion within cloud water. There were large disagreements in the production of glyoxal (a key precursor of OxAc) between the two gas-phase mechanisms, with MOZART T1 showing stronger daytime production under high NO x conditions, while MCM showed strong nocturnal production via ozonolysis chemistry. The gas + aqueous model exhibited strong production of OxAc within cloud droplets, with glyoxal serving as an important precursor. The substantial differences between chemical mechanisms and between observations and models indicates that further studies are required to better constrain gas and aqueous production of low molecular weight organic acids. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between leaf area index (LAI) of loblolly pine plantations and the broadband simple ratio (SR) vegetation index calculated from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) data [...]

A study was conducted in loblolly pine (Pinus taeda L.) plantations on sandy and clayey upland sites, with and without the addition of 250 kg [ha.sup.-1] of diammonium phosphate (DAP) applied at planting, to estimate the effects of fertilization on ecosystem C storage. Soil C pools were inventoried before planting and in the 11th year of stand development. Tree inventory data were used to convert stand volume to accumulated biomass. During the 11 yr of stand development, total ecosystem C increased by 24.2 Mg [ha.sup.-1] on average across sites, averaging 2.2 Mg C [ha.sup.-1] [yr.sup.-1]. Fertilization increased accretion by 25.3 Mg [ha.sup.-1], or 2.3 Mg C [ha.sup.-1] [yr.sup.-1], with the majority of increase (65%) occurring in biomass. The clayey site averaged 64% more total ecosystem C than the sandy site. With the exception of a 12 Mg [ha.sup.-1] loss in mineral soil C for the 10- to 20-cm depth in nonfertilized (control) plots on the sandy site, soil C in the surface 20 cm did not change during the 11 yr of stand development, suggesting that the mineral soil C is a minor sink in these aggrading pine plantations. The loss in mineral soil C observed in control plots on the sandy site may be explained by the macroporosity of this coarse-textured sandy soil creating an environment conducive to oxidation and in turn optimal for respiration and C losses following site preparation, and a disadvantaged opportunity for C accumulation owing to higher soil temperatures. Fertilization may have improved the opportunity for C accumulation on the plots having been fertilized on the sandy site in early years by creating a cooler soil as a result of more rapid canopy closure and forest floor accumulation.

Vegetation control (VC) and fertilization (FR) can change N availability in southern pine plantations, but the magnitude, duration, and reasons for change are not fully understood. The effects of a factorial combination of vegetation control (none vs. complete) and fertilization (none vs. 224 kg N [ha.sup.-1] and 56 kg P [ha.sup.-1]) on net N mineralization and soil temperature and moisture were investigated in a 14-yr-old loblolly pine (Pinus taeda L.) plantation located on the Piedmont of North Carolina. Net N mineralization and sod temperature and moisture were measured monthly for 2 yr beginning in July 1998, four months after the treatments were applied. A companion aerobic laboratory incubation study of field-moist soil was conducted at 28[degree]C during the second year. Vegetation control increased soil temperature by 1.8[degree]C during the growing season. Both vegetation control and fertilization increased field net N mineralization, and there was a strong positive interaction between the treatments. Net nitrification constituted 72% of net N mineralization for the combined treatment, and only 8% of net N mineralization for the other treatments. Seasonal patterns in net N mineralization were poorly correlated with soil temperature and moisture. The field and laboratory studies showed the same seasonal dynamics and magnitude of annual treatment effects on net N mineralization, suggesting other factors (e.g., labile C inputs) may be important in controlling net N mineralization.

Atmospheric aqueous chemistry can have profound effects on our environment. The importance of chemistry within the atmospheric aqueous phase was first realized in the 1970s as there was growing concern over the negative impacts on ecosystem health from acid deposition. Research at mountaintop observatories including Whiteface Mountain (WFM) showed that gas phase sulfur dioxide emissions react in cloud droplets to form sulfuric acid, which also impacted aerosol mass loadings. Cloud chemistry research has experienced a major resurgence in scientific interest due to the potential for aqueous chemical processes to fill the gap between modeled and observed organic aerosol mass. The current study updates the long-term trends in cloud water composition at WFM for the past 28 years (1994–2021). Substantial decreases in sulfate (SO2-4) and nitrate (NO-3) concentrations have not been matched by an equivalent decrease in ammonium (NH+4) concentrations, leading to significantly higher cloud droplet pH. Meanwhile, Total Organic Carbon (TOC) concentrations may be increasing (both in relative and absolute terms). In the past, samples were excluded from trend analysis if they did not meet an approximate ion balance, which resulted in approximately half of samples being excluded in recent years. We show that, when including the entire available dataset, decreasing trends in SO2-4, NO-3 and NH+4 become more modest, TOC concentrations increase at a faster rate, and increasing trends in Ca2+ and Mg2+ emerge. A growing trend in cation / anion ratios is also observed, implying that a significant fraction of anions are not being measured with the current suite of measurements, and these missing anions are growing in importance. Organic acids are identified as the most likely candidates for the missing anions, since the measured ion imbalance correlates strongly with measured TOC concentrations. The TOC trend becomes statistically insignificant when evaluating cloud water loadings (or air equivalent mass loadings), possibly due to the complex role that LWC may play in TOC concentrations. We highlight the emergence of a new chemical regime characterized by low acidity and relatively high conductivity, and increasing TOC and base cation concentrations. With the increasing impact from Ca2+ and Mg2+ on the bulk cloud water pH, which are largely thought to reside within coarse mode aerosol that only represent a small fraction of cloud droplets, an "inferred cloud droplet pH" is introduced, to better represent the pH of the vast majority of cloud droplets as they reside in the atmosphere. While measured pH has increased during the history of the monitoring site, the cloud droplet pH has remained relatively flat since 2009. We also show that there is a missing source of acidity in the system that correlates with TOC. The chemical system at WFM has shifted away from a system dominated by SO2-4 to a system controlled by base cation, nitrogen containing species and TOC. Further research is required to understand the effects on air quality, climate, and ecosystem health. [ABSTRACT FROM AUTHOR]

A study was established to investigate soil and site variables associated with early growth of eastern white pine (Pinus strobus L.) on reclaimed strip mines in southern West Virginia and Virginia. A total of 78 plantations were studied on 14 different mines, 5 to 9 yr following planting. Two-year terminal height growth at ages 4 and 5 was selected as the growth variable in a multiple linear regression equation developed to show the relationship between tree growth and soil andsite variables. Many soil/site variables were tested, but rooting depth, electrical conductivity, surface soil P and Mn, and slope were the dominant independent variables, accounting for 48% of the variability in growth. Soil depth had a standardized regression coefficient of 0.35, and was the most significant variable. Through proper reclamation, it is possible to establish a site that will not only provide for adequate early height growth to facilitate bond release, but also provide for future long-term productivity of surface-mined lands. [ABSTRACT FROM AUTHOR]