groundwater system by means

of hydrochemical facies distribution in a regiona

Processes Governing Alkaline Groundwater Chemistry within a Fractured Rock (Ophiolitic Mélange) Aquifer Underlying a Seasonally Inhabited Headwater Area in the Aladağlar Range (Adana, Turkey)

The aim of this study was to investigate natural and anthropogenic processes governing the chemical composition of alkaline groundwater within a fractured rock (ophiolitic mélange) aquifer underlying a seasonally inhabited headwater area in the Aladağlar Range (Adana, Turkey). In this aquifer, spatiotemporal patterns of groundwater flow and chemistry were investigated during dry (October 2011) and wet (May 2012) seasons utilizing 25 shallow hand-dug wells. In addition, representative samples of snow, rock, and soil were collected and analyzed to constrain the PHREEQC inverse geochemical models used for simulating water-rock interaction (WRI) processes. Hydrochemistry of the aquifer shows a strong interseasonal variability where Mg–HCO3 and Mg–Ca–HCO3 water types are prevalent, reflecting the influence of ophiolitic and carbonate rocks on local groundwater chemistry. R-mode factor analysis of hydrochemical data hints at geochemical processes taking place in the groundwater system, that is, WRI involving Ca- and Si-bearing phases; WRI involving amorphous oxyhydroxides and clay minerals; WRI involving Mg-bearing phases; and atmospheric/anthropogenic inputs. Results from the PHREEQC modeling suggested that hydrogeochemical evolution is governed by weathering of primary minerals (calcite, chrysotile, forsterite, and chromite), precipitation of secondary minerals (dolomite, quartz, clinochlore, and Fe/Cr oxides), atmospheric/anthropogenic inputs (halite), and seasonal dilution from recharge

Conceptual model for landfill hydrologic transport developed using chloride tracer data and dual-domain modeling

Waste-derived chloride present in a landfill cell was used as a hydrologic tracer in conjunction with a mathematical model to better elucidate landfill hydrologic dynamics for a municipal solid-waste landfill in which the cover material is significantly more permeable than the waste material. Long-term temporal chloride data from a lined landfill cell in Florida were used to calibrate a variably saturated dual-domain model (originally developed for soil-science research) to landfill hydrology and solute transport. The model successfully simulated the chloride temporal trend. The dual-domain processes were needed to simulate the long-term decline in conservative chloride concentrations. However, the temporal variations about the general trend could only be simulated accurately by considering the variations in landfill recharge. The fitted value of Darcy flux (0.274 cm/day) was less than literature values, and the dispersion coefficient (900 cm2/day) was higher than simple estimates based on heterogeneous aquifers. The other fitted parameters, first-order mass transfer coefficient (0.0018/day) and fraction of mobile water (0.22), were within the range of values reported in the literature. Model sensitivity studies were conducted to assess the relative importance of each parameter. The most sensitive parameter was recharge rate to the landfill, a factor that can be measured with the proper instrumentation. Although the model performance was not as sensitive to the values of the dual-domain parameters, inclusion of these parameters was required to accurately simulate the long-term temporal trend

Conceptual model for landfill hydrologic transport developed using chloride tracer data and dual-domain modeling

Waste-derived chloride present in a landfill cell was used as a hydrologic tracer in conjunction with a mathematical model to better elucidate landfill hydrologic dynamics for a municipal solid-waste landfill in which the cover material is significantly more permeable than the waste material. Long-term temporal chloride data from a lined landfill cell in Florida were used to calibrate a variably saturated dual-domain model (originally developed for soil-science research) to landfill hydrology and solute transport. The model successfully simulated the chloride temporal trend. The dual-domain processes were needed to simulate the long-term decline in conservative chloride concentrations. However, the temporal variations about the general trend could only be simulated accurately by considering the variations in landfill recharge. The fitted value of Darcy flux (0.274 cm/day) was less than literature values, and the dispersion coefficient (900 cm2/day) was higher than simple estimates based on heterogeneous aquifers. The other fitted parameters, first-order mass transfer coefficient (0.0018/day) and fraction of mobile water (0.22), were within the range of values reported in the literature. Model sensitivity studies were conducted to assess the relative importance of each parameter. The most sensitive parameter was recharge rate to the landfill, a factor that can be measured with the proper instrumentation. Although the model performance was not as sensitive to the values of the dual-domain parameters, inclusion of these parameters was required to accurately simulate the long-term temporal trend

Differential Enzymatic Activity of Common Haplotypic Versions of the Human Acidic Mammalian Chitinase Protein*

Mouse models have shown the importance of acidic mammalian chitinase activity in settings of chitin exposure and allergic inflammation. However, little is known regarding genetic regulation of AMCase enzymatic activity in human allergic diseases. Resequencing the AMCase gene exons we identified 8 non-synonymous single nucleotide polymorphisms including three novel variants (A290G, G296A, G339T) near the gene area coding for the enzyme active site, all in linkage disequilibrium. AMCase protein isoforms, encoded by two gene-wide haplotypes, and differentiated by these three single nucleotide polymorphisms, were recombinantly expressed and purified. Biochemical analysis revealed the isoform encoded by the variant haplotype displayed a distinct pH profile exhibiting greater retention of chitinase activity at acidic and basic pH values. Determination of absolute kinetic activity found the variant isoform encoded by the variant haplotype was 4-, 2.5-, and 10-fold more active than the wild type AMCase isoform at pH 2.2, 4.6, and 7.0, respectively. Modeling of the AMCase isoforms revealed positional changes in amino acids critical for both pH specificity and substrate binding. Genetic association analyses of AMCase haplotypes for asthma revealed significant protective associations between the variant haplotype in several asthma cohorts. The structural, kinetic, and genetic data regarding the AMCase isoforms are consistent with the Th2-priming effects of environmental chitin and a role for AMCase in negatively regulating this stimulus