RESUMEN
The Early Triassic Nanzhang-Yuan'an Lagerstätte of Hubei Province, South China, preserves abundant marine reptiles in the uppermost part of the Jialingjiang Formation and provides detailed insights into marine organisms, including newly discovered and well preserved conodont clusters of the Family Ellisonidae. These conodont elements allow us to assess the bias introduced during the acquisition process. We examined conodont elements preserved on the bedding planes and those acquired after the acid-dissolving method to analyze their attributes and length distributions. We identified a biased preservation of different conodont elements related to their morphologies. After the acid-dissolving procedures, the bias increased, and all different elements were affected, with larger individuals being particularly prone to destruction. Among them, the P elements of Ellisonidae were the least affected, while the S elements were the most affected. This study further indicates that paleobiological interpretations based on fossil size or morphology could be obscured if the influence of post-mortem effect is ignored.
Asunto(s)
Fósiles , Animales , China , Paleontología/métodos , ReptilesRESUMEN
It is unclear whether the United States Environmental Protection Agency (US EPA) method can accurately assess heavy metal risks in high-Se areas. Herein, a black shale outcropping in Enshi County, China, was taken as the study area, and a carbonate outcropping in Lichuan County was the control area. Selenium and associated heavy metal concentrations in rock, soil, rice, human blood and urine samples and human sensitive hepatic and renal biomarkers were measured. The results showed that the contents of selenium, cadmium, molybdenum and copper in the study area were 3.68 ± 2.72 µg/g, 2.65 ± 1.42 µg/g, 16.3 ± 15.5 µg/g, and 57.3 ± 17.6 µg/g, respectively, in soil (n = 47) and 1.072 ± 0.924 µg/g, 0.252 ± 0.310 µg/g, 2.800 ± 2.167 µg/g, and 10.91 ± 27.42 µg/g, respectively, in rice (n = 47). The daily adult intake levels of selenium, cadmium and molybdenum from rice consumption in the study area (exposure group) exceed the recommended tolerance values in China. According to the US EPA method, these environmental media pose a significant risk to human health. However, in the exposure group (n = 111), the median levels of the sensitive hepatic biomarkers alanine aminotransferase (18 U/L), aspartate aminotransferase (28 U/L) and total bilirubin (10.9 µmol/L) and the sensitive renal biomarkers serum creatinine (70.1 µmol/L), urinary nitrogen (5.73 mmol/L) and uric acid (303.80 µmol/L) were within reference ranges and had values equivalent to those of the control group (P > 0.05). The elements tended to differentiate during migration from one medium to another. Due to the complex interaction between selenium and heavy metals, a survey of human health indicators is indispensable when the US EPA method is used to assess the heavy metal risks in high-Se areas. The recommended molybdenum tolerable intake in the U.S. (2000 µg/d) is reasonable based on a comparison.