Assessment of the stabilization effect of ferrous sulfate for arsenic-contaminated soils based on chemical extraction methods and in vitro methods: Methodological differences and linkages.

Stabilization of arsenic-contaminated soils with ferrous sulfate has been reported in many studies, but there are few stabilization effects assessments simultaneously combined chemical extraction methods and in vitro methods, and further explored the corresponding alternative relationships. In this study, ferrous sulfate was added at FeAs molar ratio of 0, 5, 10 and 20 to stabilize As in 10 As spiked soils. Stabilization effects were assessed by 6 chemical extraction methods (toxicity characteristic leaching procedures (TCLP), HCl, diethylenetriamine pentaacetic acid (DTPA), CaCl2, CH3COONH4, (NH4)2SO4), and 4 in vitro methods (physiologically based extraction test (PBET), in vitro gastrointestinal method (IVG), Solubility Bioaccessibility Research Consortium (SBRC) method, and the Unified Bioaccessibility Research Group of Europe method (UBM)). The results showed that the HCl method provides the most conservative assessment results in non-calcareous soils, and in alkaline calcareous soils, (NH4)2SO4 method provides a more conservative assessment. In vitro methods provided significantly higher As concentrations than chemical extraction methods. The components of the simulated digestion solution as well as the parameters may have contributed to this result. The small intestinal phase of PBET and SBRC method produced the highest and lowest ranges of As concentrations, and in the range of 127-462 mg/kg and 68-222 mg/kg when the FeAs molar ratio was 5. So the small intestinal phase of PBET method may provide the most conservative assessment results, while the same phase of SBRC may underestimate the human health risks of As in stabilized soil by 51 %(at a FeAs molar ratio of 5). Spearman correlation analysis indicated that the small intestinal phase of PBET method correlated best with HCl method (correlation coefficient: 0.71). This study provides ideas for the assessment of stabilization efforts to ensure that stabilization meets ecological needs while also being less harmful to humans.

Bioaccessibility assessment of arsenic and cadmium in polished and unpolished rice: Comparison of three in vitro methods.

INFOGEST is a standardized in vitro digestion method suitable for foods, but rarely used to study the bioaccessibility of heavy metals in food. This study aimed to explore the differences between INFOGEST and the extensively used Physiologically Based Extraction Test (PBET) and Unified Bioaccessibility Research Group of Europe Method (UBM) methods for determining the bioaccessibility of As and Cd in rice. Intestinal As (79.3 ± 8.5 %, 75.8 ± 12.7 %, and 72.3 ± 12.2 % for INFOGEST, PBET, and UBM, respectively) and Cd (47.0 ± 6.4 %, 40.7 ± 13.8 %, and 38.1 ± 15.7 % for INFOGEST, PBET, and UBM, respectively) bioaccessibilities in the rice samples determined by the three methods were generally similar (p > 0.1, except for As bioaccessibility between INFOGEST and UBM). Furthermore, PBET was significantly correlated with INFOGEST for As bioaccessibility (R2 = 0.416) and with UBM for Cd bioaccessibility (R2 = 0.879). Additionally, PBET indicated that the bioaccessibilities of As and Cd in the polished rice were 17.0 % and 19.8 % higher, respectively, than that in the unpolished rice. This study highlights the influence of in vitro methods and rice matrices on heavy metal bioaccessibility values, necessitating a more accurate assessment of health risks associated with rice consumption.

Effect of vitamin C supplement on lead bioaccessibility in contaminated soils using multiple in vitro gastrointestinal assays: Mechanisms and health risks.

Effects of vitamin C supplementation on the oral bioaccessibility of lead (Pb) present in contaminated soils were examined using a number of in vitro assays (PBET, SBRC, UBM and IVG). In the presence of vitamin C, an increase in Pb bioaccessibility was observed in the gastric phase by 1.3-fold (30.5%-85.5%) and in the intestinal phase by 3.1-fold (0.9%-58.9%). Lead mobilization was regulated by reductive dissolution of Fe(III) and sequestration of Pb on secondary Fe minerals. Sequential extraction by the Bureau Community of Reference (BCR) provided more evidence that reducible fraction and residual fraction were major contributor of gastric Pb bioaccessibility, as well as reduced fractions in intestinal Pb bioaccessibility. In addition, higher non-carcinogenic risks may occur based on target hazard quotient (THQ ≥ 1). For people exposed to Pb present in soil, the management of vitamin C supplements is of serious concern.

Stabilization of fluorine-contaminated soil in aluminum smelting site with biochar loaded iron-lanthanide and aluminum-lanthanide bimetallic materials.

Trivalent metals-modified-biochar (BC) has been widely used for the removal of fluorine (F) in water, but little is known about its effects on the stability and mobility of F-contaminated soil. Two types of modified-BC materials (BC-loaded iron-lanthanide (BC/Fe-La) and BC-loaded aluminum-lanthanide (BC/Al-La)) were synthesized and used for the remediation of F-contaminated soil. The forms of BC/LaxFe3x(OH)y in BC/Fe-La and BC/LaxAl3x(OH)y in BC/Al-La were identified by spectroscopy, X-ray dispersion, thermogravimetric, and pore diameter/volume analyses. Following application (4-12%, w/w) to F-contaminated soil for 30 d, water soluble fluoride (WSF) decreased significantly. The modified-BC with a 1:1:1 molar ratio (BC: Al3+ or Fe3+: La3+) were more effective than those at 1:0.5:0.5. The BC/Al-La were the most effective to stabilize F. In particular, the highest decrease in WSF (by 91.75%) was obtained with the application of 12% BC/Al-La-2, while 8% BC/Al-La-2% and 12% BC/Al-La-1 reduced the WSF by 87.58% and 90.17%, respectively; all values obtained were lower than the national standard of China (< 1.5 mg/L). In addition, the sequential extraction results showed that modified-BC promoted the transformation of the other chemical speciation to the Fe/Mn-F.

The Effect of Replacing Wildrye Hay with Mulberry Leaves on the Growth Performance, Blood Metabolites, and Carcass Characteristics of Sheep.

The objective of this study was to evaluate the effects of partially substituting for conventional forage, Chinese wildrye (CW), with mulberry leaves (ML) on the growth, digestion, ruminal fermentation, blood metabolites, and meat quality of sheep in a 65-day feedlot study. Thirty-two four-month-old male small-tailed Han sheep (25.15 ± 1.03 kg) were randomly assigned to one of four treatments. The dietary treatments consisted of four proportions of ML (0, 8, 24, and 32%) as a substitute for CW (designated as ML0, ML8, ML24, and ML32, respectively). Rumen digesta and blood samples were collected at day 63 of the trial. Carcass traits were assessed after slaughter at the end of performance period. The results from this study revealed no differences in average daily bodyweight gain (ADG), feed conversion ratio (FCR), and final body weight (FBW) among treatments. The apparent digestibility of dry matter (DM), organic matter (OM), and acid detergent fiber (ADF) was higher in the sheep fed with ML than in those fed CW. The ML24 treatment had a higher digestibility of crude protein (CP) and ether extract (EE). There were no differences (p = 0.13) in ruminal pH values among the treatments. However, there was more microbial protein (p < 0.01) in ML24 and ML32 treatments than the ML0 treatment. Ruminal concentrations of acetate and butyrate were significantly different among treatments, although no difference in concentrations of total volatile fatty acid were found. Additionally, no differences were detected for serum parameters except blood urea nitrogen (BUN). No differences were observed for carcass weight (p = 0.62), dressing percentage (p = 0.31) or longissimus dorsi muscle (LM) area (p = 0.94) among treatments. However, intramuscular fat was higher in the ML24 treatment than in the ML0 treatment. (p < 0.01). There were higher pH values of the 24-h longissimus dorsi in the ML24 treatment than in the ML0 treatment. In addition, the saturated fatty acid (SFA) content was lower (p < 0.01) and the monounsaturated fatty acid (MUFA) content higher (p < 0.01) in the ML24 treatment than in the ML0 treatment. In conclusion, the partially substitution of mulberry leaves for Chinese wildrye in the diet of sheep had a beneficial influence on the growth performance, blood metabolites and carcass characteristics. The inclusion of 24% (air dry basis) mulberry leaf hay in the ration of sheep is recommended based on these findings.

Mitochondrial genomes of blister beetles (Coleoptera, Meloidae) and two large intergenic spacers in Hycleus genera.

BACKGROUND: Insect mitochondrial genomes (mitogenomes) exhibit high diversity in some lineages. The gene rearrangement and large intergenic spacer (IGS) have been reported in several Coleopteran species, although very little is known about mitogenomes of Meloidae. RESULTS: We determined complete or nearly complete mitogenomes of seven meloid species. The circular genomes encode 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs) and two ribosomal RNAs (rRNAs), and contain a control region, with gene arrangement identical to the ancestral type for insects. The evolutionary rates of all PCGs indicate that their evolution is based on purifying selection. The comparison of tRNA secondary structures indicates diverse substitution patterns in Meloidae. Remarkably, all mitogenomes of the three studied Hycleus species contain two large intergenic spacers (IGSs). IGS1 is located between trnW and trnC, including a 9 bp consensus motif. IGS2 is located between trnS2 (UCN) and nad1, containing discontinuous repeats of a pentanucleotide motif and two 18-bp repeat units in both ends. To date, IGS2 is found only in genera Hycleus across all published Coleopteran mitogenomes. The duplication/random loss model and slipped-strand mispairing are proposed as evolutionary mechanisms for the two IGSs (IGS1, IGS2). The phylogenetic analyses using MrBayes, RAxML, and PhyloBayes methods based on nucleotide and amino acid datasets of 13 PCGs from all published mitogenomes of Tenebrionoids, consistently recover the monophylies of Meloidae and Tenebrionidae. Within Meloidae, the genus Lytta clusters with Epicauta rather than with Mylabris. Although data collected thus far could not resolve the phylogenetic relationships within Meloidae, this study will assist in future mapping of the Meloidae phylogeny. CONCLUSIONS: This study presents mitogenomes of seven meloid beetles. New mitogenomes retain the genomic architecture of the Coleopteran ancestor, but contain two IGSs in the three studied Hycleus species. Comparative analyses of two IGSs suggest that their evolutionary mechanisms are duplication/random loss model and slipped-strand mispairing.