Haizhou Bay National Ocean Park is the first national ocean park in China. Consequently, the investigation of the spatial distribution characteristics, source apportionment, and ecological risks ...associated with heavy metals in this area is of great significance. Twelve sediment samples were collected in October 2016, and the geoaccumulation index (Igeo) method and the potential ecological risk index (PERI) method were used to assess the ecological risk. The results showed that the concentrations of the heavy metals (except Cr and Cu) in the surface sediments of the study area met the primary standard of marine sediment quality (GB18668-2002). The spatial distribution pattern of heavy metals in the surface sediments of Haizhou Bay National Ocean Park featured high concentrations in the southwestern region and low concentrations in the northeastern region, with a gradual decrease with increasing distance offshore, indicating that anthropogenic activities were the main source of heavy metal pollution. The evaluation results of the Igeo and PERI methods showed that Cd was the element posing the greatest ecological risk and that the ecological risk level in Haizhou Bay National Ocean Park corresponded to moderately contaminated. These findings indicate that effective management strategies should be developed to protect the marine environmental quality.
•The contents of heavy metals, except Cr and Cu, meet the primary standard of marine sediment quality.•Spatially, the concentrations were high in the southwest and low in the northeast.•Anthropogenic activities were the main source of heavy metal pollution.•Cd was the main ecological risk element in Haizhou Bay National Ocean Park.•The ecological risk level in Haizhou Bay National Ocean Park corresponded to moderately contaminated.
The concentrations of seven heavy metals in the surface water and sediments from the Sheyang Estuary were investigated to determine their spatial distribution, source apportionment and the potential ...ecological risks. The relative concentrations of heavy metals in the sediments were ranked as follows: Zn > Cr > Cu > Pb > As > Cd > Hg. The majority of the average concentrations of heavy metals in the sediment were higher than their background values, except for Cr and Hg, whereas the surface water heavy metals concentrations were lower. All of the elements apart from Cd indicated that there was no contamination and a low degree of pollution overall. Moreover, the heavy metal levels generally indicated low ecological risks, except for Cd. The results showed that Cu, Pb, Cr and Cd are influenced significantly by anthropogenic activities. Therefore, it is necessary to control heavy metal contamination caused by anthropogenic activities in the study area.
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•The contamination of heavy metals in water and sediment were analyzed.•Heavy metal elements are uncontaminated and low risks, except for Cd.•Heavy metal pollution was significantly related with anthropogenic activities.
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•Not all invasive plants are unusable, Spartina alterniflora (SA) has multiple exploitable benefits.•When utilized in controlled conditions SA’s benefits significantly outweigh the ...implications.•SA is an excellent biomass resource, CO2 sequestrator, and pollution remover.•SA’s soil restoration and resilience improvement potentials are effective in polluted or degraded soils.•SA is an underrated plant species with multiple application potential.
Invasive species have become a major threat to ecosystem stability, diversity and sustainability in recent times. Invasive plants such as Spartina alterniflora (SA), outgrow resident flora by rapidly utilizing essential soil nutrients depriving the native plant species, impacting the ecosystem diversity and stability. SA is also notorious for its effect on local biodiversity as it grows and spreads faster, ultimately dominating local biodiversity. This dominance and the negative effect of invasive SA is due to features such as allochemical’s secretion, positive feedback between plant and soil, and rapid absorption of soil nutrients, exerting a competitive advantage over native plants. Therefore, in this review, we aim to contemplate the implications and potential applications of SA under control conditions or special circumstances as a source of biomass, soil restorer, CO2 capture agent, soil resilience enhancer and pollution remover as most of the studies on SA have focused on controlling its impact on the local ecosystem. On the other hand, SA's ability to grow quickly in poor alkaline soils is useful but very little is explored to exploit SA for biomass production in controlled cultivation in different environmental conditions. In addition to these aspects, the CO2 sequestration capability requires greater focus, especially in sensitive salt marshes and wetlands along the coastal areas.
•More specific functional bacteria were enriched in the rhizosphere of Suaeda glauca.•The metabolic network of rhizosphere dominant bacteria of S. glauca was established.•Sulfate-reducing bacteria ...played a hub function for the growth of salt-tolerant plants.•Functionally complete bacterial community is an indicator of soil benign development.
Coastal silt soil (CSS), hydraulically transported and filled by dredger and mud pump from the bottom of beach in coastal zone in the process of reclamation project, has a high salinity which poses difficulties for coastal development. The use of salt-tolerant plants to improve CSS is a green and efficient method. In this process, the rhizosphere of predominate salt-tolerant plants should enrich more functional microorganisms, which will exert an indispensable ecological influence on plant growth and benign soil transformation. Therefore, comparing the characteristics of plant rhizosphere bacterial communities with different growth capacities on the same CSS can help to find the key rhizosphere hub microorganisms, which will lay a theoretical foundation for the precise improvement of CSS. High-throughput sequencing technology was used to study rhizosphere bacterial diversity of wild salt-tolerant plants (Suaeda glauca, Tripolium vulgare, and Phragmites australis) in the CSS of Lianyun New-town, Lianyungang City, China, through α-diversity, β-diversity, community composition diversity and environmental correlation analysis, and the rhizosphere bacterial functions were predicted. The results showed that the sulfur-oxidizing bacteria (Sulfurovum, Woeseia, and Thioalkalispira) which were dominant in all samples, might impart important salt-stress resistance. Bacteroidetes and sulfate-reducing bacteria Desulfuromonas were enriched in the rhizosphere of S. glauca and P. australis. Bacteroidetes can increase the degradation of organic matter, provide electrons for sulfate-reducing bacteria, and thus promote efficient sulfur-cycling. Sulfate-reducing bacteria can serve as hub bacteria for the growth of salt-tolerant plants by connecting sulfur cycles and organic matter decomposition. In addition, S. glauca, as the dominant plant in CSS, can enrich more functional dominant bacteria, and its rhizosphere bacterial community composition was significantly positively correlated with TN and TOC. These rhizosphere bacteria include phototrophic bacteria Altererythrobacter and methane-oxidizing bacteria Methylophaga related to C cycling, Geothermobacter and Pelobacter related to Fe cycling, and nitrogen-cycle-related bacteria Marinobacterium, Halomonas, and Motiliproteus involved in nitrification/denitrification. This indicates that S. glauca growth can promote the turnover of soil C, N, S, and Fe by enriching these functional bacteria. The analysis of bacterial diversity, as an important ecological indicator, can help to understand the growth of dominant plants in CSS, and the mechanism of benign soil development. The results show that the rhizosphere of S. glauca can enrich a functionally complete bacterial community, which is beneficial to the positive evolution of CSS.
Jiangsu Province of China has a large area of coastal silt soil (CSS) with poor permeability, high salinity, and poor nutrients, which brings great difficulties to the development and utilization of ...coastal zones, so that needs to be improved as a matter of urgency. In this study, river-sand, serpentine, and organic fertilizer were used as additives in CSS, and
, a salt-tolerant cash crop, was planted in these differently treated soils. Through high-throughput sequencing, analysis of soil physico-chemical properties, and detection of plant growth status, the rhizosphere bacterial diversity of
growing in CSS under different treatments and their environmental impact factors were studied, while exploring the effect and mechanism of organic fertilizer combined with gravel as a CSS modifier. The results implied that single application of organic fertilizer could significantly increase the fertility levels of total nitrogen (TN), total organic carbon (TOC) and Avail. P in CSS; then, the application of organic fertilizer with river-sand significantly reduced salt content and alkalinity of soil; meanwhile, in the treatment of single application of organic fertilizer and application of organic fertilizer combined with river-sand, the rhizosphere of
enriched the bacterial communities of organic matter degradation and utilization to varying degrees. The soil moisture content and indicators related to saline-alkali soil (including total salt, electrical conductivity (EC), exchangeable sodium percentage (ESP), Avail. Na and Avail. K,
.) were further reduced significantly by the application of organic fertilizer combined with river-sand and serpentine. The method has greatly improved the growth conditions of
and promoted the positive development of its rhizosphere bacterial community. Among them, in the treatment of organic fertilizer combined with river-sand and serpentine, a variety of plant growth-promoting rhizobacteria (PGPR, such as
,
, and
) and nitrogen-cycle-related bacteria (such as nitrate-reduction-related bacteria, nitrogen-fixing bacteria like
, and purple non-sulfur photosynthetic bacteria like
) were enriched in the rhizosphere of
; moreover, the mutual association and robustness of bacterial co-occurrence networks have been significantly enhanced. The results provide a theoretical basis and reference model for the improvement of coastal saline-alkali silt soil.
In the exploitation and development of the muddy coastal zone in Lianyun New Town, Jiangsu Province, much coastal silt soil (CSS) has been formed through reclamation projects, which is difficult to ...use. The proportion of wild
Suaeda glauca
increased significantly and became a dominant species in CSS modified by sea-sand mulching (Treated CSS, TCSS), but it was still affected by saline-alkali stress. To use
S. glauca
efficiently to improve TCSS, high-throughput sequencing technology and conventional soil analysis methods were adopted to investigate the rhizosphere microbial community structure of
S. glauca
and the physico-chemical properties of TCSS as well as its internal correlation. The results showed that TCSS had low organic matter content, poor nutrients such as N and P, and poor fertility retention. TCSS was still affected by mild or moderate saline-alkali stress, and the total Ca was greater than 1%, so the soil properties indicated a calcareous saline-alkali soil. The growth of
S. glauca
can reduce soil salinity and increase soil TN content, and its rhizosphere bacterial community was significantly different from that of bulk soil without
S. glauca
: the rhizosphere was significantly enriched with C-cycle-related bacterium such as organic matter degrading bacteria
mariniflexile
, photobacterium Sphingomonadaceae, and N-cycle-related bacterium such as nitrogen-fixing bacteria
Azoarcus
, denitrifying bacteria Pseudomonadaceae; the symbiotic relationship of rhizosphere bacterial community in
S. glauca
tended to be more complicated, and the functions of nitrogen-respiration, photo-nutrition, and methyl-nutrition were enhanced. Based on the above results, it is reasonable to predict that the interaction between
S. glauca
and its rhizosphere bacteria in TCSS could promote the process of soil carbon and nitrogen cycles, as to accelerate soil substance transformation and increase soil fertility, thus driving the benign development of TCSS. The results lay a theoretical basis for developing muddy coasts and promoting the precise improvement of TCSS by large-scale cultivation of
S. glauca
in the local area.
In order to assess the characteristics of polybrominated diphenyl ether (PBDEs) in the atmosphere of urban Jinan, eastern China, gas phase and PM2.5 were hereby sampled in July 2020. The ...concentration and composition characteristics of 11 PBDEs were obtained. The Human exposure was evaluated by the daily exposure calculation method. During the observation period, the average concentration of ∑
11
PBDEs in PM
2.5
and gas phase was 214.8±31.3 pg/m
3
, that of low-PBDEs was 119.1±2.1 pg/m
3
, and that of BDE209 was 95.8±15.4 pg/m
3
. Among the 10 low-PBDEs, the highest single content was BDE99, followed by BDE47, accounting for 43%. PCA showed the main sources of PBDEs in the atmosphere of urban Jinan were Penta-BDEs and Deca-BDEs. The daily respiratory exposure of children were higher than that of adults, and the potential risk should be taken seriously.
In the present paper, an offshore platform model dealing with sacrificial anode protection was simulated using boundary element method. The potential and current density were calculated, and the ...distribution trend of the data was analyzed. To evaluate the computation results, proper physical model was built in a given dimension. The physical platform model was placed in a marine environment modeling tank that was designed to simulate the real marine environment with seawater, and the calculation data were compared with those from laboratory experimental work. This study showed that the boundary element method is a powerful tool for the sacrificial anode protection of marine structures.
► Boundary element method (BEM) is powerful for sacrificial anode protection modeling. ► Potential and current density are simulated using BEASY software based on BEM. ► The experimental validation proved the computation results to be valid.
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