Distribution characteristics of microplastics in the soil of mangrove restoration wetland and the effects of microplastics on soil characteristics

Microplastics that enter the soil environment are transformed by migration and can affect soil properties, which in turn have an impact on soil function and biodiversity. In this study, we investigated the distribution of soil microplastics at different planting densities and their effects on soil properties in a mangrove restoration wetland. The results showed that the average abundance of soil microplastics in the study area was 2177.5 n/500g, with the largest proportion of 0.038-0.05 mm diameter microplastics accounting for 70.9% and the rest of the diameter microplastics accounting for less than 20%, indicating that the smaller the diameter microplastics are easy to accumulate in the wetland soil. The abundance of microplastics in the restored area by planting density was ranked as 0.5×0.5m > 1.0×0.5m > 1.0×1.0m > control area. Three microplastics, polyethylene terephthalate (PET, accounted for 52%), polyethylene (PE, accounted for 24%), and polypropylene (PP, accounted for 15%), were the most prevalent and dominant microplastics in the soils of the area. SEM images showed that fractures, tears, EDS spectroscopy showed that a large number of metals were detected on the surface of microplastics. PET can influence the distribution of soil particle size due to its adsorptive viscosity, which may affect soil structure. Apart from soil pH, all other physicochemical factors changed significantly in response to PET. Besides, the results of the CV analysis reflect that soils in vegetated areas are more susceptible to the effects of PET than bare ground soils resulting in greater variability in the properties.

Urbanization-induced environmental changes strongly affect wetland soil bacterial community composition and diversity

Soil microbial communities potentially serve as indicators for their responses to changes in various ecosystems at scales from a region to the globe. However, changes in wetland soil bacterial communities and how they are related to urbanization intensities remains poorly understood. Here, we collected sixty soil samples along urbanization intensity gradients from twenty wetlands. We measured a range of environmental factors and characterized bacterial communities structure using 16S rRNA gene amplicon sequencing that targeted the V4-V5 region. Our results revealed the dominant soil microbial phyla included Proteobacteria (39.3%), Acidobacteria (21.4%) and Chloroflexi (12.3%) in the wetlands, and showed a significant divergence of composition in intensive urbanization area (UI_4) than other places. A critical "threshold" exists in the soil bacterial diversity, demonstrating different patterns: a gradual increase in the areas of low-to-intermediate disturbances but a significant decrease in highly urbanized areas where metabolic functions were significantly strong. Additionally, soil pH, total phosphorus (TP), available phosphorus (AP ) and ammonia nitrogen (NH4+-N) made a significant contribution to variations in bacterial communities, explaining 49.6%, 35.1%, 26.2% and 30.7% of the total variance, respectively. pH and NH4+-N were identified as the main environmental drivers to determine bacterial community structure and diversity in the urban wetlands. Our results highlight collective changes in multiple environmental variables induced by urbanization rather than by the proportion of impervious surface area (ISA), which were potentially attributed to the spatial heterogeneity along different urbanization gradients.

Molecular Characterisation and Plasmid Profiling of Hydrocarbon Utilizing Bacteria Isolates from Wetlands in Rivers State, Southern Nigeria

Wetlands can intercept runoff from surfaces prior to reaching open water and remove pollutants through physical, chemical, and biological processes thereby protecting and preserving the environment. Because of unsustainable oil exploration activities, most wetlands in Rivers State, Southern Nigeria have suffered severe petroleum-damaged ecosystems. This research was carried out to characterize and identify the hydrocarbon utilizing bacteria associated with crude oil polluted wetlands and to screen for the presence of plasmids that could confer resistance to antibiotics using both cultural and molecular methods. Soil samples were collected from three different wetlands across the state with hand auger at two depths of 0-15cm and 15-30cm twice monthly for three months. The presence of microbial activity was determined by the enumeration and isolation of total heterotrophic and hydrocarbon utilizing bacteria. Eight (8) most occuring hydrocarbon utilizing bacterial isolates were isolated and identified culturally and phenotypically from the 54 wetland soil samples. These bacteria isolates were confirmed to be Bacillus flexus, Bacillus subtilis, Lysinibacillus macroides, Staphylococcus aureus, Chryseobacterium aquifrigidense, Pseudomonas aeruginosa and Salmonella enterica molecularly via sequencing of the 16S rRNA gene. The most common bacteria isolated were Bacillus species, followed by Pseudomonas at a dilution of 106. Seven (7) out of the eight (8) isolates (except Salmoella enterica) showed the presence of the 25kb plasmids at various intensities.

Improved Wetland Soil Organic Carbon Stocks of the Conterminous U.S. Through Data Harmonization

Wetland soil stocks are important global repositories of carbon (C) but are difficult to quantify and model due to varying sampling protocols, and geomorphic/spatio-temporal discontinuity. Merging scales of soil-survey spatial extents with wetland-specific point-based data offers an explicit, empirical and updatable improvement for regional and continental scale soil C stock assessments. Agency-collected and community-contributed soil datasets were compared for representativeness and bias, with the goal of producing a harmonized national map of wetland soil C stocks with error quantification for wetland areas of the conterminous United States (CONUS) identified by the USGS National Landcover Change Dataset. This allowed an empirical predictive model of SOC density to be applied across the entire CONUS using relational %OC distribution alone. A broken-stick quantile-regression model identified %OC with its relatively high analytical confidence as a key predictor of SOC density in soil segments; soils <6% OC (hereafter, mineral wetland soils, 85% of the dataset) had a strong linear relationship of %OC to SOC density (RMSE = 0.0059, ~4% mean RMSE) and soils >6% OC (organic wetland soils, 15% of the dataset) had virtually no predictive relationship of %OC to SOC density (RMSE = 0.0348 g C cm−3, ~56% mean RMSE). Disaggregation by vegetation type or region did not alter the breakpoint significantly (6% OC) and did not improve model accuracies for inland and tidal wetlands. Similarly, SOC stocks in tidal wetlands were related to %OC, but without a mappable product for disaggregation to improve accuracy by soil class, region or depth. Our layered harmonized CONUS wetland soil maps revised wetland SOC stock estimates downward by 24% (9.5 vs. 12.5Pg C) with the overestimation being entirely an issue of inland organic wetland soils (35% lower than SSURGO-derived SOC stocks). Further, SSURGO underestimated soil carbon stocks at depth, as modeled wetland SOC stocks for organic-rich soils showed significant preservation downcore in the NWCA dataset (<3% loss between 0 and 30 cm and 30 and 100 cm depths) in contrast to mineral-rich soils (37% downcore stock loss). Future CONUS wetland soil C assessments will benefit from focused attention on improved organic wetland soil measurements, land history, and spatial representativeness.

Severe lung infection and septicemia caused by Paludibacterium purpuratum---a case report and evaluation of bacterial traits

Paludibacterium species are gram-stain negative rods, facultatively anaerobic, and have been isolated from wetland soil. Clinical infection caused by this genus is rarely reported. We reported an 84-year-old woman with chronic renal disease and hypertension acquired P. purpuratum lung infection and septicemia in southern Taiwan.

Halorubrum Salipaludis Sp. Nov., Isolated From the Saline–Alkaline Soil

Strain WN019T, an aerobic, motile, and pleomorphic rods bacterium, was isolated from the natural saline-alkali wetland soil of Binhai new district, Tianjin, China. Cells of strain WN019T were 0.5-0.8 µm in width and 2.0-2.5 µm in length, and the growth occurred optimally at 33-37 ℃, pH 7.5-8.0, and in the presence of 15.0-20.0 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences showed that the isolate belonged to the genus Halorubrum and exhibited high sequence similarity of 97.8 % to Halorubrum saccharovorum JCM 8865T. The major respiratory quinone of strain WN019T were MK-8 and MK-8 (H2), and the major polar lipids were Glycolipid (GL), Phospholipid (PL), Phosphatidylglycerol-Sulfate (PGS), Phosphatidylglycerol (PG) and Phosphatidylglycerol-Phosphate-Methyl Ester (Me-PGP). The DNA G+C content of the strain was 67.3 mol%. The average nucleotide identity (ANI) based on whole genome sequences of strain WN019T and Halorubrum saccharovorum JCM 8865T was 87.5 %, and the digital DNA-DNA hybridization (dDDH) value between them was determined to be 35.4 %. Phenotypic, chemotaxonomic, phylogenetic, and genomic analyses suggested that strain WN019T represent a novel species of the genus Halorubrum, for which the name Halorubrum salipaludis sp. nov. is proposed. The type strain is WN019T (= KCTC 4269T = ACCC 19977T).

Removal behaviour of residual pollutants from biologically treated palm oil mill effluent by Pennisetum purpureum in constructed wetland

The reason for such enormous efforts in palm oil mill effluent research would be what has been singled out as one of the major sources of pollution in Malaysia, and perhaps the most costly and complex waste to manage. Palm oil mill final discharge, which is the treated effluent, will usually be discharged to nearby land or river since it has been the least costly way to dispose of. Irrefutably, the quality level of the treated effluent does not always satisfy the surface water quality in conformity to physicochemical characteristics. To work on improving the treated effluent quality, a vertical surface-flow constructed wetland system was designed with Pennisetum purpureum (Napier grass) planted on the wetland floor. The system effectively reduced the level of chemical oxygen demand by 62.2 ± 14.3%, total suspended solid by 88.1 ± 13.3%, ammonia by 62.3 ± 24.8%, colour by 66.6 ± 13.19%, and tannin and lignin by 57.5 ± 22.3%. Heat map depicted bacterial diversity and relative abundance in life stages from the wetland soil, whereby bacterial community associated with the pollutant removal was found to be from the families Anaerolineaceae and Nitrosomonadaceae, and phyla Cyanobacteria and Acidobacteria.