• This study reviewed the sorption of sex hormones onto soils and sediment. • Hydrophobic and other specific interactions are the main sorption mechanisms. • The sorption of sex hormones is affected by pH, temperature, and ionic strength. • Future research should focus on the coupled leaching-sorption processes.
Sex hormones are a group of potent endocrine disruptors that can be released into agricultural soils and sediment via wastewater discharge and manure fertilization. Sorption represents a critical determinant for the transport potential and risks of sex hormones in the environment. Therefore, this study reviewed the sorption and desorption mechanisms of sex hormones in soil- and sediment-water systems, and summarized the effects of various factors on sorption and desorption processes. A total of 359 set of sorption data were collected from the literature. Sex hormones were mostly described by the linear model. The sorption magnitudes (logKoc) of estrogens, androgens, and progestins were in the range of 2.77–3.90, 2.55–4.18, and 2.61–4.39, respectively. The average logKoc values of the sex hormones were significantly correlated with their logKow values (R2= 0.13, p<0.05), while the R2 values were much lower than those when fewer sex hormones were included for analysis. In addition, the Kd values of most sex hormones were significantly correlated with the OC% of soils and sediment (R2= 0.16−0.99, p<0.05), but were insignificantly correlated with the particle size distribution and surface area. These results indicated that hydrophobic partitioning interaction and other specific interactions are responsible for sex hormone uptake in soil- and sediment-water systems. The sorption of sex hormones in soil- and sediment-water systems can also be affected by other environmental variables, including pH, temperature, and ionic strength. Future studies should focus on the coupled leaching-sorption processes in manure-water-soil systems under field-scale conditions.
• Bacterial diversity and community structure differed among agricultural practices. • Crop rotation enhanced bacterial community succession in rhizosphere. • Bacterial evenness in root zone was highest from no-tillage plot.
We are only beginning to understand the influence of agricultural practices, together with soil properties and geographic factors, affect bacterial communities and their influence on the soil processes. Here, we quantify how typical agro-practices, i.e., no-tillage, ridge tillage, continuous corn cropping, and crop rotation with corn and bean, and the corresponding soil physicochemical characteristics affect bacterial diversity and community compositions of the rhizosphere and root zone soils. Results show that species richness in the rhizosphere was significantly higher than that in the root zone soils (p<0.05), typically with more abundant Crenarchaeota and Firmicutes populations that are active members for C and N cycling. Specifically, crop rotation compared to other agro-practices was able to mediate soil pH value and the available P and thereby control the bacterial diversity pattern in the rhizosphere (p<0.05), while tillage practices regulated the relative abundance of bacterial populations in root zone soils by varying the soil available N (p<0.05). Analysis of biomarker patterns suggests that the observed differences in bacterial functional capabilities (e.g., nutrient cycling) are strongly related to the physicochemical properties of surrounding soils. Our results highlight the importance of soil-plant interaction in shaping soil bacterial community structure typically in the rhizosphere and root zone soils and also illustrates the challenges in linking soil ecosystem function to microbial processes.
• Polyester fibers increased aboveground biomass. • Under drought conditions the AM-fungal-only treatment had the highest biomass. • Colonization with AM fungi increased under microfiber addition. • The mean weight diameter of soil aggregates decreased under microplastic contamination and drought stress, respectively. • Under drought conditions AM fungi increased litter decomposition
Microplastics are increasingly recognized as a factor of global change. By altering soil inherent properties and processes, ripple-on effects on plants and their symbionts can be expected. Additionally, interactions with other factors of global change, such as drought, can influence the effect of microplastics. We designed a greenhouse study to examine effects of polyester microfibers, arbuscular mycorrhizal (AM) fungi and drought on plant, microbial and soil responses. We found that polyester microfibers increased the aboveground biomass of Allium cepa under well-watered and drought conditions, but under drought conditions the AM fungal-only treatment reached the highest biomass. Colonization with AM fungi increased under microfiber contamination, however, plant biomass did not increase when both AM fungi and fibers were present. The mean weight diameter of soil aggregates increased with AM fungal inoculation overall but decreased when the system was contaminated with microfibers or drought stressed. Our study adds additional support to the mounting evidence that microplastic fibers in soil can affect the plant–soil system by promoting plant growth, and favoring key root symbionts, AM fungi. Although soil aggregation is usually positively influenced by plant roots and AM fungi, and microplastic promotes both, our results show that plastic still had a negative effect on soil aggregates. Even though there are concerns that microplastic might interact with other factors of global change, our study revealed no such effect for drought.
• Topsoil diversity was greater in phenosoils than genosoils, but the trend was reversed in subsoils. • Bacterial community in topsoils was influenced by both soil orders and soil forms, however, in subsoils it was more impacted by soil orders. • Cropping increased the similarity of bacteria structures among different soil orders.
Human disturbances to soils can lead to dramatic changes in soil physical, chemical, and biological properties. The influence of agricultural activities on the bacterial community over different orders of soil and at depth is still not well understood. We used the concept of genoform and phenoform to investigate the vertical (down to 1 m depth) soil bacterial community structure in paired genosoils (undisturbed forests) and phenosoils (cultivated vineyards) in different soil orders. The study was conducted in the Hunter Valley area, New South Wales, Australia, where samples were collected from 3 different soil orders (Calcarosol, Chromosol, and Kurosol), and each soil order consists of a pair of genosoil and phenosoil. The bacterial community structure was analyzed using high-throughput sequencing of 16S rRNA. Results showed that bacterial-diversity decreased with depth in phenosoils, however, the trend is less obvious in genoform profiles. Topsoil diversity was greater in phenosoils than genosoils, but the trend was reversed in subsoils. Thus, cropping not only affected topsoil bacteria community but also decreased its diversity in the subsoil. Bacterial community in topsoils was influenced by both soil orders and soil forms, however, in subsoils it was more impacted by soil orders. Constrained Analysis of Principal Coordinates revealed that cropping increased the similarity of bacterial structures of different soil orders. This study highlighted the strong influence of agricultural activities on soil microbial distribution with depth, which is controlled by soil orde
Leshan Giant Buddha is damaged seriously because of weathering and plant settlement Amounts of soil organic C, N and P was accumulated in the surface of the Buddha Soil organic C, N and P stocks under herbs are the most abundant Soil organic C, N and P mainly stocks in the shoulder, arm and the platform
The accumulation of soil organic matter and nutrients are important pathways in effectively understanding the mechanisms of plant settlement and rock weathering, while the characteristics of soil organic carbon (C), nitrogen (N) and phosphorus (P) under different vegetation remains unclear. In this study, the stocks and stoichiometry of soil organic C, N and P were determined in different positions and types of vegetation on the surface of the Leshan Giant Buddha. We found that the total stocks of soil organic C, N and P were 1689.77, 134.6 and 29.48 kg, respectively, for the Buddha. The stocks of soil organic C, N and P under vascular plants were higher than those under other vegetation, with highest values observed under herb. Higher stocks per unit area (m2) of soil organic C, N and P were found on the left and right arms, shoulders, and two platforms. These results provide a full primary picture in understanding soil organic C, N and P accumulation and distribution on the surface of the Buddha, which could supply the fundamental data on weathering management of the Buddha and other similar open-air stone carvings.
• Elevated CO2 increased the amounts of rhizodeposits. • The turnover of rhizodeposits derived from N soil was faster than no N soil. • Rhizodeposits derived from elevated CO2 decomposed slower than from ambient air. • Microaggregates and silt-clay were the most and least affected fractions separately.
Rhizodeposits in rice paddy soil are important in global C sequestration and cycling. This study explored the effects of elevated CO2 and N fertilization during the rice growing season on the subsequent mineralization and retention of rhizodeposit-C in soil aggregates after harvest. Rice (Oryza sativa L.) was labeled with 13CO2 under ambient (400 ppm) and elevated (800 ppm) CO2 concentrations with and without N fertilization. After harvest, soil with labeled rhizodeposits was collected, separated into three aggregate size fractions, and flood-incubated for 100 d. The initial rhizodeposit-13C content of N-fertilized microaggregates was less than 65% of that of non-fertilized microaggregates. During the incubation of microaggregates separated from N-fertilized soils, 3%–9% and 9%–16% more proportion of rhizodeposit-13C was mineralized to 13CO2, and incorporated into the microbial biomass, respectively,, while less was allocated to soil organic carbon than in the non-fertilized soils. Elevated CO2 increased the rhizodeposit-13C content of all aggregate fractions by 10%–80%, while it reduced cumulative 13CO2 emission and the bioavailable C pool size of rhizodeposit-C, especially in N-fertilized soil, except for the silt-clay fraction. It also resulted in up to 23% less rhizodeposit-C incorporated into the microbial biomass of the three soil aggregates, and up to 23% more incorporated into soil organic carbon. These results were relatively weak in the silt-clay fraction. Elevated CO2 and N fertilizer applied in rice growing season had a legacy effect on subsequent mineralization and retention of rhizodeposits in paddy soils after harvest, the extent of which varied among the soil aggregates.
