Middletonkaya8621

Inorganic soil solution constituents can alter the charge, size, and conformation of dissolved organic molecules, thus affecting their environmental behavior. Here, we investigated how pH, cation valence and activities induce conformational changes and aggregation-sedimentation reactions of organic polyelectrolytes. For that we determined the hydrodynamic diameter of the model compound tannic acid by laser light scattering at concentrations of 1-30 g L-1 in the pH range from 3 to 10 and with electrolyte additions of CaCl2 and hydroxyl-Al cations. Charge properties were quantified by polyelectrolyte titration and zeta potential measurements. After dispersion by sonication, aggregation was determined in time sequences up to 60 min and suspension stability was traced in sedimentation experiments. Tannic acid was present in ultrapure water in a self-aggregated state. At pH 7.5, its hydrodynamic diameter increased. Whereas at high pH this behavior could be assigned to unfolding of molecular conformations, at low pH it is likely that charge neutralization decreased repulsive forces and facilitated aggregation. At pH 5 and ionic strengths of up to 5 mM, CaCl2 did not affect aggregation state of tannic acid and results resembled those obtained in ultrapure water. Addition of hydroxyl-Al cations broke-up the self-aggregated tannic acid structures under formation of Al-organic coprecipitates. Strong aggregation only occurred at mixing ratios where opposite surface charges were completely balanced. Under natural conditions, self-aggregation of tannic acid can be expected only at higher solution concentrations. However, at acidic pH, hydroxyl-Al cations and tannic acid may form discrete colloidal particles already at low tannic acid concentrations, resulting in the destabilization of suspensions. Our data emphasize that the soil solution composition strongly modifies the physical state of tannic acid, and likely also of other biopolymers, and thus their interactions within environmental matrices.In soil, ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are regarded as key factors mediating nitrous oxide (N2O) production and emission. However, there are scarce reports about the effect of film mulching on ammonia oxidizers, and the biological nitrification process of N2O emission is unclear. This study was based on potato field experiments under different mulching films, including polyethylene mulching film (PM), transparent degradable mulching film (TDM), black degradable mulching film (BDM), and bare land (CK). AOB and AOA abundances were estimated using real-time PCR, and their diversity and community structure were measured using high-throughput sequencing. Result revealed that the total N2O emission from CK was 12.32%-41.03% higher than that from film mulching soil. Under film mulching, according to total N2O emission from soil and N2O concentration in soil treatments were ordered as PM > BDM > TDM, and N2O production was closely correlated with copy numbers of the amoA gene. BDM significantly increased the number of amoA-AOB gene copies (P less then 0.01), and PM significantly increased the those of amoA-AOA (P less then 0.01). GSK583 solubility dmso BDM and TDM increased AOB operational taxonomic units (OTUs), Chao1, Simpson, and Shannon indices, while PM increased the AOA OTUs and Chao1 index. Variations in AOA abundance and diversity were closely related to soil mineral N and temperature changes induced by polyethylene film mulching (P less then 0.05), whereas AOB showed no significant association with soil properties. Meanwhile, we did not find a distinct treatment effect on AOB community structure. Our findings indicate that (i) degradable film mulching increased AOB abundance and diversity and N2O concentration, but obviously reduced N2O emissions, and (ii) AOA were more sensitive than AOB to polyethylene mulching film.Ambient ozone (O3) has emerged as an important public health issue worldwide. Previous studies found an association between O3 and cardiorespiratory mortality. However, evidence was limited regarding the risk of O3 on mortality from other diseases. In this study, we aimed to estimate the association between O3 and mortality from a broad spectrum of diseases in Guangzhou, China, which has experienced a rapid increase in O3 concentration over the past decades. Daily data were obtained on cause-specific mortality, air pollutant concentrations and weather conditions during 2013-2018. A generalized additive model with quasi-Poisson regression was applied to examine the association between O3 and mortality from 10 broad causes and 26 refined subcategories, with adjustment of long-term and seasonal trends, weather conditions, public holidays and days of the week. We found that the threshold concentrations of O3 were 40 μg/m3 for all-cause, non-accidental, cardiovascular and respiratory mortality. Mortality risk increased monotonically with O3 concentrations above the threshold. Per 10 μg/m3 increase of O3 at lag 0-3 days was associated with 0.54% (95%CI 0.34-0.74%), 0.56% (95%CI 0.36-0.76%), 0.59% (95%CI 0.30-0.88%), 0.78% (95%CI 0.33-1.24%) and 0.52% (95%CI 0.21-0.83%) elevated risk of death from all causes, non-accidental causes, cardiovascular diseases, respiratory diseases and neoplasms, respectively. Among the subcategories, the largest effect estimate was observed in people with chronic obstructive pulmonary disease. The elderly suffered from a higher mortality risk from O3. Stringent emission control strategies and multi-sectoral collaborations are needed to reduce the detrimental impact of O3 on vulnerable populations.Treatment technologies such as ion exchange (IX) process exhibit promising potentials for the removal of toxic per- and poly-fluoroalkyl substances (PFAS) from natural waters. In recent years, industries have started manufacturing PFAS-specific resins which are typically operated in a single use-and-dispose mode until exhaustion. However, this increases the resin demand and the consequent operational cost and environmental burden of the IX process. In this study, the performance of a PFAS-specific resin (A592) was compared with that of a regenerative organic scavenger resin (A860) which is traditionally employed for dissolved organic matter (DOM) and micorpollutant removal. Comparative studies were performed to examine the removal of multiple long- and short-chain carboxylic, sulfonic, precursor and emerging PFAS (including GenX) from synthetic and natural waters. The A592 resin exhibited faster uptake kinetics for PFAS while simultaneously removing 10-15% of DOM. The A860 resin removed ~60-70% of DOM; however, it required approximately 3-fold higher contact times for achieving the same degree of PFAS removal when compared to the PFAS-specific resin.