Spatial Distribution Characteristics of Heavy Metals Cu and Zn in Coastal Wetland Sediments

The content of Cu, Zn in the sediments from coastal wetlands of the Yellow River Delta was determined. The results showed that: (i) The content of Cu, Zn range was 16.70—50.40 mg/kg, 18.15—48.80 mg/kg, respectively. The mean content of Cu, Zn was 31.12 mg/kg, 36.74 mg/kg, respectively. Compared with the soil environmental background values of Shandong Province, the content of Cu was excessive, while the content of Zn was below the background. (ii) The concentrations of Cu, Zn in sediment in the coast of the Yellow River Delta were higher than in the other two areas. (iii) Vertical distribution characteristics of the concentrations of Cu, Zn were increasing with depth. The maximum content of Cu, Zn was 80—100 cm, in general, the content of Cu, Zn in the bottom sediments was higher than that in the surface sediments. The growth and decline trends of Zn in Tamarix and Suaeda areas were much the same and all higher than in the Phragmites communis area. (iv) The distribution characteristics of Cu concentration in different vegetation cover in sediment is Suaeda> Phragmites communis> Tamarix, which reflected different effects on retention of Cu in the sediments because of the different vegetation types. The highest content of Zn in the 0—20 cm sediments in Tamarix area was 44.07 mg/kg

Spatial Distribution of Heavy Metals in Sediments of Tamarix chinensis Wetland on the South Bank of Bohai Bay

In order to understand the spatial distribution of heavy metals in coastal wetlands, Tamarix chinensis wetlands on the south bank of Bohai Bay were selected as the research object. The content of Cr, Mn, Ni, Zn and Cu in soil was determined by sampling method in April 2018. The spatial distribution characteristics of heavy metals and causes were studied. The results showed that except for Cr, Ni and Zn, the content of other heavy metals in this area did not exceed the background value of soil environment in Shandong Province. The study area was slightly polluted by these three heavy metals. In the vertical direction, the content of Cr, Mn, Cu and Ni followed the law of surface layer>middle layer>bottom layer, while the content of Zn was higher in the bottom layer, which needed to be further studied. In the horizontal direction, the content of the five heavy metals was not significantly different according to the distance from the coastline. There was no significant difference in the content of heavy metals between rhizosphere soil and non-rhizosphere soil. There was a significant correlation between the content of heavy metal elements, except Mn, the content of heavy metals was significantly correlated with the content of soil organic matter. The content of some heavy metals was significantly correlated with the content of available phosphorus and ammonium nitrogen

Effect of Batch Annealing Temperature on Microstructure and Resistance to Fish Scaling of Ultra-Low Carbon Enamel Steel

In the present work, an ultra-low carbon enamel steel was batch annealed at different temperatures, and the effect of the batch annealing temperature on the microstructure and resistance to fish scaling was investigated by optical microscopy, transmission electron microscopy, and a hydrogen permeation test. The results show that the main precipitates in experimental steel are fine TiC and coarse Ti4C2S2 particles. The average sizes of both TiC and Ti4C2S2 increase with increasing the batch annealing temperature. The resistance to fish scaling decreases with increasing the annealing temperature, which is caused by the growth of ferrite grain and the coarsening of the TiC and Ti4C2S2 particle

Impact of Parthenium hysterophorus L. invasion on soil fungal communities in the Yellow River Delta

Abstract Purpose As an invasive plant, Parthenium hysterophorus severely impacts the ecological environment of the Yellow River Delta and reduces biodiversity in the invaded areas. The effects of P. hysterophorus invasion on the local environment became increasingly critical, while few information was available for the effects of P. hysterophorus invasion on soil bacteria. The present study aimed to reveal the impacts of hysterophorus on the fungal communities in the Yellow River Delta. Methods Sixteen soil samples including four groups (ROOT group, YRR group, YNR group, and GBS group) were collected. High-throughput methods were used to explore the fungal composition of the P. hysterophorus-invaded surrounding environment and native plant-growed environment. Results Our results showed that the ACE (351.97) and Chao1 (351.95) values of the rhizosphere soils of P. hysterophorus (YRR group) were the highest among the four groups, whereas the non-rhizosphere soil samples of P. hysterophorus (YNR group) had the highest Shannon (7.188) and Simpson (0.984) values. The total number of operational taxonomic units (OTUs) obtained from the four groups was 1965, with 161 common OTUs among different groups. At the phylum level, both Ascomycota and Basidiomycota were the dominant fungi, with Ascomycota having the highest abundance. At the genus level, except for the endophytic fungi of P. hysterophorus roots (ROOT group), Fusarium, Mortierella, Comoclathris, and Cladosporium were the dominant fungi in three groups. The fungal communities within the roots of P. hysterophorus were distant from other groups, indicating that the composition of the fungal communities within the roots had a low degree of similarity to the other three groups. LEfSe analysis showed that Ascomycota at the phylum level and Cladosporium, Curvularia, and Alternaria at the genus level play essential roles in the ROOT group, and Comoclathris plays a vital role in the YNR group. Conclusions This study explored the effects of P. hysterophorus invasion on the local soil fungal communities by analyzing the fungal communities in P. hysterophorus roots, rhizosphere soil, non-rhizosphere soil, and rhizosphere soil of native plants. Generally, P. hysterophorus rhizosphere fungi specifically affect the surrounding environment

Contents of Heavy Metals in Typical Aquatic Products from a Market in Binzhou

To evaluate the levels of heavy metal pollution and risks in consumption of aquatic products from a market in Binzhou, the contents of Cu, Zn, Cd, Cr and Pb in the edible part of eight aquatic species such as Ctenopharyngodon idellus were determined by inductively coupled plasma mass spectrometry. The results show that the levels of the five elements differed among different species of aquatic products. The ability of bivalves to accumulate heavy metals was significantly higher than that of fish. Compared with relevant food hygiene standards, there was a certain excess of Cr in Ruditapes philippinarum and Penaeus vannamei. The results of human exposure risk assessment show that the THQ values of the heavy metals in the eight aquatic species were all less than 1, indicating that the consumption of these aquatic products had no potential non-carcinogenic risks

Isolating, identifying and evaluating of oil degradation strains for the air-assisted microbial enhanced oil recovery process.

Due to the inefficient reproduction of microorganisms in oxygen-deprived environments of the reservoir, the applications of microbial enhanced oil recovery (MEOR) are restricted. To overcome this problem, a new type of air-assisted MEOR process was investigated. Three compounding oil degradation strains were screened using biochemical experiments. Their performances in bacterial suspensions with different amounts of dissolved oxygen were evaluated. Water flooding, microbial flooding and air-assisted microbial flooding core flow experiments were carried out. Carbon distribution curve of biodegraded oil with different oxygen concentration was determined by chromatographic analysis. The long-chain alkanes are degraded by microorganisms. A simulation model was established to take into account the change in oxygen concentration in the reservoir. The results showed that the optimal dissolved oxygen concentration for microbial growth was 4.5~5.5mg/L. The main oxygen consumption in the reservoir happened in the stationary and declining phases of the microbial growth systems. In order to reduce the oxygen concentration to a safe level, the minimum radius of oxygen consumption was found to be about 145m. These results demonstrate that the air-assisted MEOR process can overcome the shortcomings of traditional microbial flooding techniques. The findings of this study can help for better understanding of microbial enhanced oil recovery and improving the efficiency of microbial oil displacement

Robust Lidar-Inertial Odometry with Ground Condition Perception and Optimization Algorithm for UGV

Unmanned ground vehicles (UGVs) are making more and more progress in many application scenarios in recent years, such as exploring unknown wild terrain, working in precision agriculture and serving in emergency rescue. Due to the complex ground conditions and changeable surroundings of these unstructured environments, it is challenging for these UGVs to obtain robust and accurate state estimations by using sensor fusion odometry without prior perception and optimization for specific scenarios. In this paper, based on an error-state Kalman filter (ESKF) fusion model, we propose a robust lidar-inertial odometry with a novel ground condition perception and optimization algorithm specifically designed for UGVs. The probability distribution gained from the raw inertial measurement unit (IMU) measurements during a certain time period and the state estimation of ESKF were both utilized to evaluate the flatness of ground conditions in real-time; then, by analyzing the relationship between the current ground condition and the accuracy of the state estimation, the tightly coupled lidar-inertial odometry was dynamically optimized further by adjusting the related parameters of the processing algorithm of the lidar points to obtain robust and accurate ego-motion state estimations of UGVs. The method was validated in various types of environments with changeable ground conditions, and the robustness and accuracy are shown through the consistent accurate state estimation in different ground conditions compared with the state-of-art lidar-inertial odometry systems