Kendallhoppe4481

Boreal forests are adapted to cold climates and are thus especially sensitive and vulnerable to climate change. In this study, we chose 10 plots covering different topographies at the southern edge of a boreal forest. The annual ring widths of the 249 Dahurican larch (Larix gmelinii) tree cores from these plots were measured and used to calculate the basal area increment (BAI) and the interannual sensitivity (Sx). We found that forests in 10 plots showed a significant change in Sx consistently around 1980. The growth of slope forest was significantly correlated with increases in temperature and precipitation, while the wetland forests, including bogs and peatland plateaus, responded negatively to temperature. In terms of precipitation, there was no effect in the peatland plateaus, but a negative effect occurred in bogs. Our results imply that the depth of the frost table could lead to different soil waterlogging from surplus water from thawing permafrost, resulting in different responses of tree growth to climate change.Dicarboxylic acids are a group of highly oxidized components, which can provide insights into the formation mechanism and aging process of secondary organic aerosols (SOA). Based on the 12-h day and night PM2.5 samples collected in downtown Beijing in January, April, July and October of 2017, dicarboxylic acids and relevant components were measured to investigate their seasonal variation pattern and sources. High concentrations of the identified organic acids were observed, following the decreasing order of July > January > October > April. The high fractions of phthalic acid and maleic acid in January indicated severe aromatic SOA pollution during the sampling period in winter, and the high malonic acid to succinic acid and malic acid to succinic acid ratios in July suggested strong photochemical formation over the sampling period in summer. Based on the calculation of principle component analysis and multiple linear regression, water-soluble organic acids were mainly formed from the aerosol aging process during the sampling periods except for January, while water-soluble organic carbon (WSOC) mostly originated from combustion sources. Correlation analysis was conducted between the CO-normalized concentrations of organic acids and PM2.5, O3, as well as the meteorological parameters. The results suggested that gas-phase photooxidation contributed significantly to the formation of these organic acids during the entire sampling period, and the aqueous-phase process played an important role over the severe haze event in January. Our results also suggested that the intensity of photooxidation and the aging degree of SOA were enhanced along with the reduction of PM2.5 in Beijing in recent years.This work investigates the effectiveness of the electro-Fenton reaction for the treatment of wastewaters contaminated with petroleum hydrocarbons. More specific attention was given to field deployment applications in remote regions, such as the sub-Antarctic, where there is a need for low-cost technologies that can aid in remediation efforts. Naphthalene, a high priority pollutant for removal within these regions, was chosen as a model contaminant and treated with inexpensive graphite electrodes to promote the electro-Fenton pathway. Results show that naphthalene can be fully removed from a near-saturated solution, 20 mg/L, in less than 3 h of treatment. The underlying removal mechanisms were identified, and a kinetic model is presented that can accurately predict treatment outcomes at varying operating conditions of applied electric currents, 0-5 mA, and iron(II) concentrations, 0-2.0 mM. Optimal operating conditions for the electro-Fenton pathway were found to be at an applied current of 5 mA and an iron(II) concentration of 0.06 mM; this resulted in a specific energy consumption of 5.6 kWhr/kg of naphthalene removed, low enough to be operated in remote regions via sustainable energy sources.A series of ordered mesoporous FeMn bimetal oxides (OMFMs) were fabricated by using a novel inverse micelle method, and the texture, nanostructure and interface chemistry properties of OMFMs were closely correlated to the calcination temperature. Due to the amorphous regular inner-connected nanostructure and bimetallic synergistic effect, the obtained OMFMs exhibited superior arsenic sequestration performance than pure mesoporous Fe oxides (PMF) and Mn oxides (PMM). The optimum ratio of Fe/Mn and calcination temperature for arsenic removal was 3/1 and 350 °C (OMFM-3), and the maximum As(III) and As(V) adsorption capacities of OMFM-3 were 174.59 and 134.58 mg/g, respectively. Solution pH value negligibly affected the uptake of arsenic (ranged from 3.0 to 7.0), while SiO32-/PO43- ions and humic acid (HA) displayed significant inhibitory effect on arsenic removal by OMFM-3. According to the mechanism of arsenic removal, which simultaneously analyzed the arsenic redox transformation in aqueous phase and on solid phase interface, it was concluded that manganese oxides in OMFM-3 mainly played the role as a remarkable As(III) oxidant in water, whereas iron oxides dominantly acted as an excellent arsenic species adsorbent. Finally, the prominent arsenic sequestration behavior and performance in surface water suggested that OMFM-3 could be a promising and hopeful candidate for arsenic-contaminated (especially As(III)) surface water and groundwater remediation and treatment.We studied the relationships between the trace element concentration in sediments from a saline lake at a tropical latitude (Sochagota Lake, Colombia) containing hydrothermal and anthropic inputs with the organic matter content, the mineral assemblage composition and the activity of the bacterial communities of the sediments. Organic matter-poor sediments (TOC less then 0.7%) with quartz and kaolinite near the southern entrance of the lake were enriched in Zr (up to 603 mg/kg) and some major detrital elements (Na, Ti, Al and Si). Fine-sized clay-rich sediments deposited in the deep zones of the lake (central and northern segments) were characterized by substantial organic matter (up to 11.10%) and the crystallization of S-bearing minerals, clay mineral mixed layers and illite. These sediments were enriched in S, Fe, Zn, Mo, Rb, Co, K, Cr, Sb, Ni, As, Ba, Cu, Mn, Pb, P, Mg, and Sr. Selleck A2ti-2 The presence of Fe sulfide nanoparticles enriched in heavy metals encrusting microbial cells and a dominant sulfate-reducing bacteria (SRB) community (Desulfatiglans, Desulfobacterales and Sva0485) suggested that the precipitation of the hydrothermal S and the accumulation of trace elements in the sediments was regulated by SRB activity.