Source, Distribution, and Risk Estimation of Hazardous Elements in Farmland Soils in a Typical Alluvial-Lacustrine Transition Basin, Hunan Province.

Increased concentrations of heavy metals in soil due to anthropogenic activities pose a considerable threat to human health and require constant attention. This study investigates the spatial distribution of heavy metals (Cd, Pb, Zn, Sb) and metalloids (As) in a typical alluvial-lacustrine transition basin and calculates the bioavailable forms of elements posing a direct threat. Qualitative and quantitative methods were used to identify the sources of contaminants, after which an ecological risk assessment was conducted. Total (T) As, Pb, and Zn decreased with the depth, whereas Cd and Sb increased in surface (0-20 cm) soil. Bioavailable (Bio) Cd and Pb in the topsoil were regulated by pH and organic matter, whereas Bio-Zn was regulated by soil pH. Within deeper soil layers, the combined effects of pH, organic matter, and clay contents regulated the bio-elements. The results of multiple methods and local investigation showed that TSb (65.3%) was mainly derived from mining activities, TCd (53.2%) and TZn (53.7%) were derived from direct pollution by industrial production and agricultural fertilizers, respectively, and TA (55.6%) was mainly derived from the soil parent material. TPb was related to vehicle exhaust emissions and atmospheric deposition from industrial activities. Although the potential ecological risk in the study area remains relatively low, there is a need for continuous monitoring of the potential ecological risks of Cd and Sb. This study can act as a reference for the prevention and mitigation of heavy metal contamination of alluvial-lacustrine transition basins.

Dynamic Metabolomics Study of the Bile Acid Pathway During Perioperative Primary Hepatic Carcinoma Following Liver Transplantation.

BACKGROUND There are many situations of abnormal metabolism influencing liver graft function. This study aims to provide data for the development of liver function recovery after liver transplantation by dynamically analyzing metabolites of bile acids pathway in serum. MATERIAL AND METHODS A comprehensive metabolomics profiling of serum of 9 liver transplantation patients before transplantation, on the 1st, 3rd, and 7th days after liver transplantation, and healthy individuals were performed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Multivariate data and dynamic analysis were used to search for biomarkers between the metabolomics profiles present in perioperative liver transplantation and normal controls. RESULTS Thirty-three differential endogenous metabolites were screened by the threshold of variable importance in the projection (VIP) from an orthogonal partial least square discriminant analysis (OPLS-DA) greater than 1.0, q-value <0.05, and fold change (FC) ≤0.8 or ≥1.2 between the preoperative group and the normal controls in negative mode. The metabolite intensities of taurocholic acid, taurochenodeoxycholic acid, chenodeoxycholic acid glycine conjugate, and glycocholic acid pre-transplantation were significantly higher than those of normal controls. The average metabolite intensities of taurocholic acid and taurochenodesoxycholic acid on the first day after liver transplantation were lower than those observed pre-transplantation. The average metabolite intensities on day 3 after liver transplantation showed a sudden increase and then decreased after 7 postoperative days. The average metabolite intensities of glycocholic acid and chenodeoxycholic acid glycine conjugate showed an increasing trend on the 1st, 3rd, and 7th days after liver transplantation. CONCLUSIONS Use of taurocholic acid and taurochenodeoxycholic acid-related bile secretion, liver regeneration, and de novo bile acid synthesis may help clinical evaluation and provide data for the development of liver function recovery after liver transplantation.

The two-phase flow IPTT method for measurement of nonwetting-wetting liquid interfacial areas at higher nonwetting saturations in natural porous media.

Interfacial areas between nonwetting-wetting (NW-W) liquids in natural porous media were measured using a modified version of the interfacial partitioning tracer test (IPTT) method that employed simultaneous two-phase flow conditions, which allowed measurement at NW saturations higher than trapped residual saturation. Measurements were conducted over a range of saturations for a well-sorted quartz sand under three wetting scenarios of primary drainage (PD), secondary imbibition (SI), and secondary drainage (SD). Limited sets of experiments were also conducted for a model glass-bead medium and for a soil. The measured interfacial areas were compared to interfacial areas measured using the standard IPTT method for liquid-liquid systems, which employs residual NW saturations. In addition, the theoretical maximum interfacial areas estimated from the measured data are compared to specific solid surface areas measured with the N2/BET method and estimated based on geometrical calculations for smooth spheres. Interfacial areas increase linearly with decreasing water saturation over the range of saturations employed. The maximum interfacial areas determined for the glass beads, which have no surface roughness, are 32±4 and 36±5 cm-1 for PD and SI cycles, respectively. The values are similar to the geometric specific solid surface area (31±2 cm-1) and the N2/BET solid surface area (28±2 cm-1). The maximum interfacial areas are 274±38, 235±27, and 581±160 cm-1 for the sand for PD, SI, and SD cycles, respectively, and ~7625 cm-1 for the soil for PD and SI. The maximum interfacial areas for the sand and soil are significantly larger than the estimated smooth-sphere specific solid surface areas (107±8 cm-1 and 152±8 cm-1, respectively), but much smaller than the N2/BET solid surface area (1387±92 cm-1 and 55224 cm-1, respectively). The NW-W interfacial areas measured with the two-phase flow method compare well to values measured using the standard IPTT method.

[Fluorine speciation and its distribution characteristics in selected agricultural soils of North China Plain].

The objectives of this study were to study fluorine speciation and its distribution characteristics in the cultivated soils of wheat-corn fields at the typical areas, the North China Plain. The fluorine contents in cultivated soils and profile soils were measured by consecutive extraction. The results showed that the soil total fluorine (T-F) content at typical areas in the North China Plain ranged from 338.31 mg x kg(-1) to 781.67 mg x kg(-1), with a mean of 430.46 mg x kg(-1). The soil fluorine speciation with the highest content was Residual-Fluorine (Res-F), with a mean of 402.73 mg x kg(-1). The average content of Water soluble Fluorine (Ws-F) was 14.39 mg x kg(-1). The result indicated that the cultivated soil in the study area was at a relatively high fluoride pollution level, which may be harmful to human health and the ecological environment. The contents of Organic Fluorine (Or-F) and Fe/Mn Oxide-Fluorine (Fe/ Mn-F) were also quite high, with a mean of 8.90 mg x kg(-1) and 4.10 mg x kg(-1), respectively. The exchangeable fluorine (Ex-F) only had a very small amount of 0.33 mg x kg(-1). Soil Ws-F was positively correlated with soil pH and CEC, while it was negatively correlated with the percentage of soil clay. The content of soil Fe/Mn-F was positively correlated with soil pH, CEC and the sand grain content percentage, while it was negatively correlated with the clay grain content percentage. The soil pH value had the most significant influence on the water soluble fluorine (Ws-F) and Fe/Mn Oxide-Fluorine (Fe/Mn-F), and the soil CEC had the most significant influence on the soil total fluorine (T-F) and residual-Fluorine (Res-F) by stepwise regression analysis. In the soil profiles, the T-F content appeared as peaks and valleys representing the change of the soil lithology in the vadose zone. The Ws-F in the soil profiles mainly changed in the depth of 0-100 cm near the surface soil and was little influenced by the soil lithology. But it was strongly influenced by the soil pH, and was positively correlated with the soil pH. This study can provide a scientific evidence for soil fluorine pollution, prevention and a theoretical basis for soil fluorine mobility and its influence on ecology and environment.

Groundwater recharge at five representative sites in the Hebei Plain, China.

Accurate estimates of groundwater recharge are essential for effective management of groundwater, especially when supplies are limited such as in many arid and semiarid areas. In the Hebei Plain, China, water shortage is increasingly restricting socioeconomic development, especially for agriculture, which heavily relies on groundwater. Human activities have greatly changed groundwater recharge there during the past several decades. To obtain better estimates of recharge in the plain, five representative sites were selected to investigate the effects of irrigation and water table depth on groundwater recharge. At each site, a one-dimensional unsaturated flow model (Hydrus-1D) was calibrated using field data of climate, soil moisture, and groundwater levels. A sensitivity analysis of evapotranspirative fluxes and various soil hydraulic parameters confirmed that fine-textured surface soils generally generate less recharge. Model calculations showed that recharge on average is about 175 mm/year in the piedmont plain to the west, and 133 mm/year in both the central alluvial and lacustrine plains and the coastal plain to the east. Temporal and spatial variations in the recharge processes were significant in response to rainfall and irrigation. Peak time-lags between infiltration (rainfall plus irrigation) and recharge were 18 to 35 days in the piedmont plain and 3 to 5 days in the central alluvial and lacustrine plains, but only 1 or 2 days in the coastal plain. This implies that different time-lags corresponding to different water table depths must be considered when estimating or modeling groundwater recharge.