Double Advantages of Nutrients and Biostimulants Derived from Sewage Sludge by Alkaline Thermal Hydrolysis Process for Agricultural Use: Quality Promotion of Soil and Crop

Low-carbon alkaline thermal hydrolysis of sewage sludge for the production of high-quality plant-growth-promoting nutrients and biostimulants is a growing concern for sludge resource utilization in agriculture. Thus, this study aims to investigate functional characteristics and soil biochemical effects of sewage sludge-derived nutrients and biostimulants (SS-NB). The content of heavy metals in SS-NB decreased by 47.39-100%, and an increase in soil protease, invertase, and soil nutrient utilization rates are observed in SS-NB groups. SS-NB substituted for chemical fertilizer increased the diversity and evenness of microbial community and reduced the abundance of the soil-borne bacterial genus Arthrobacter. The dominant community of SS-NB100 group is mainly enriched in Microvirga, Ensifer, Novosphingobium, Bosea and Ellin6055, which are principally beneficial symbiotic bacteria of plants and participated in C and N cycles. Moreover, SS-NB reduced the accumulation of Ktedonobacteria and Nitrosospira, which are involved in the production of CO2 and N2O, and also enhanced the coordination of soil microorganisms with enzyme activities and nutrient utilization rate. In conclusion, the results suggest that SS-NB exerts a positive effect on reducing greenhouse gas emissions and preventing soil-borne diseases, and can further enhance collaboration with soil enzyme activity and soil nutrient utilization by stimulating soil microorganisms.

The effects of co-invasion by three Asteraceae invasive alien species on plant taxonomic and functional diversity in herbaceous ruderal communities in southern Jiangsu, China

Invasive alien species can affect plant taxonomic and functional diversity. Multiple invasive alien species can co-invade the same plant community. However, the effects of such co-invasion on plant taxonomic and functional diversity are currently unclear. Our study aimed to estimate the effects of co-invasion by three Asteraceae invasive alien species (i.e., Conyza canadensis (L.) Cronquist, Conyza sumatrensis (S.F. Blake) Pruski and G. Sancho, and Solidago canadensis L.) on plant taxonomic and functional diversity in herbaceous ruderal communities in southern Jiangsu, China. The effects of these three invasive alien species under seven invasion combinations (including invasion by one invasive alien species, co-invasion by two invasive alien species, and co-invasion by these three invasive alien species) on plant taxonomic and functional diversity were investigated in a comparative field study of herbaceous ruderal communities. Niche differentiation mediated the functional divergence between these three invasive alien species and natives under all invasion combinations. These three invasive alien species significantly increased plant taxonomic diversity (especially plant diversity and richness) and plant functional diversity (especially Rao's quadratic entropies) under all invasion combinations. The relative abundance of invasive alien species was significantly positively associated with plant functional diversity (especially community-weighted mean trait values and Rao's quadratic entropy). The number of invasive alien species was significantly positively associated with plant taxonomic diversity (especially plant diversity and richness) and plant functional diversity (especially Rao's quadratic entropies). Thus, co-invasion by these three invasive alien species may synergistically increase plant taxonomic diversity (especially plant diversity and richness) and functional diversity (especially Rao's quadratic entropies).

Enhanced Competitive Immunomagnetic Beads Assay Assisted with PAMAM-Gold Nanoparticles Multi-Enzyme Probes for Detection of Deoxynivalenol

Contamination of deoxynivalenol (DON) in grains has attracted widespread concern. It is urgently needed to develop a highly sensitive and robust assay for DON high-throughput screening. Antibody against DON was assembled on the surface of immunomagnetic beads orientationally by the aid of Protein G. AuNPs were obtained under the scaffolding of poly(amidoamine) dendrimer (PAMAM). DON-horseradish peroxidase (HRP) was combined on the periphery of AuNPs/PAMAM by a covalent link to develop DON-HRP/AuNPs/PAMAM. Magnetic immunoassay based on DON-HRP/AuNPs/PAMAM was optimized and that based on DON-HRP/AuNPs and DON-HRP was adopted as comparison. The limits of detection (LODs) were 0.447 ng/mL, 0.127 ng/mL and 0.035 ng/mL for magnetic immunoassays based on DON-HRP, DON-HRP/Au and DON-HRP/Au/PAMAM, respectively. Magnetic immunoassay based on DON-HRP/AuNPs/PAMAM displayed higher specificity towards DON and was utilized to analyze grain samples. The recovery for the spiked DON in grain samples was 90.8-116.2% and the method presented a good correlation with UPLC/MS. It was found that the concentration of DON was in the range of ND-3.76 ng/mL. This method allows the integration of dendrimer-inorganic NPs with signal amplification properties for applications in food safety analysis.

Butyl Benzyl Phthalate in Urban Sewage by Magnetic-Based Immunoassay: Environmental Levels and Risk Assessment

A magnetic-based immunoassay (MBI) combined with biotin-streptavidin amplification was proposed for butyl benzyl phthalate (BBP) investigation and risk assessment. The values of LOD (limit of detection, IC10) and IC50 were 0.57 ng/mL and 119.61 ng/mL, with a detection range of 0.57-24,977.71 ng/mL for MBI. The specificity, accuracy and precision are well demonstrated. A total of 36 environmental water samples of urban sewage from Zhenjiang, China, were collected and assessed for BBP contamination. The results show that BBP-positive levels ranged from 2.47 to 89.21 ng/mL, with a positive rate of 77.8%. The health effects of BBP in the urban sewage were within a controllable range, and the ambient severity for health (ASI) was below 1.49. The highest value of AS for ecology (ASII) was 7.43, which indicates a potential harm to ecology. The entropy value of risk quotient was below 100, the highest being 59.47, which poses a low risk to the environment and ecology, indicating that there is a need to strengthen BBP controls. The non-carcinogenic risk of BBP exposure from drinking water was higher for females than that for males, and the non-carcinogenic risk from drinking-water and bathing pathways was negligible. This study could provide an alternative method for detecting BBP and essential information for controlling BBP contamination.

Heavy metal pollution improves allelopathic effects of Canada goldenrod on lettuce germination

Large amounts of heavy metals have been released into the environment. Thus, the allelopathic effects of invasive alien species on the germination performance of co-occurring indigenous species may be altered or even heightened with the rapid growth in heavy metal pollution. This study evaluated the impacts of Canada goldenrod (Solidago canadensis L.) leaf extracts at concentrations of 0, 10 or 20 gl 1 on the germination of lettuce under different forms of heavy metal pollution (Cu2+ , Pb2+ or a combination of Cu2+ and Pb2+ ; 35 mgl 1) during incubation in Petri dishes for 10 days. Goldenrod leaf extracts (high concentration) reduced growth of aboveground and belowground parts of lettuce as well as competition for light and soil nutrients. However, low concentrations of goldenrod leaf extracts dramatically improved growth of lettuce roots, competition for light, soil nutrient availability, leaf photosynthetic area and growth competitiveness. The combination of goldenrod leaf extracts and heavy metal pollution was synergistic on most lettuce germination parameters, probably because high concentrations of goldenrod leaf extracts together with heavy metal pollution had a synergistic negative impact on lettuce germination. Consequently, increased levels of heavy metal pollution may favour invasion of invasive alien species while largely suppressing germination of indigenous species.

Allelopathic effects of Canada goldenrod leaf extracts on the seed germination and seedling growth of lettuce reinforced under salt stress

Allelopathic effects on the seed germination and seedling growth of the natives play a crucial role in the successful invasion of numerous invaders. Meanwhile, soil salinity is an emerging driver of the spread of many invaders, especially in the colonization of saline habitats. Thus, the allelopathic effects of the invaders on the seed germination and seedling growth of the natives may be altered or even reinforced under salt stress. This study aims to address the allelopathic effects of the notorious invader Canada goldenrod (Solidago canadensis L.; goldenrod hereafter) on the seed germination and seedling growth of the native lettuce (Lactuca sativa L.; lettuce hereafter) under a gradient of salt stress. Goldenrod leaf extracts with high concentration significantly decreased root length, leaf shape index, germination percentage, germination potential, germination index, germination vigor index, and germination rate index of lettuce. However, goldenrod leaf extracts with low concentration significantly increased root length and leaf width of lettuce. Goldenrod leaf extracts with high concentration display more serious allelopathic effects on the seed germination and seedling growth of lettuce than those with low concentration. Salt stress regardless of concentration significantly decreased seedling height, root length, leaf shape index, and seedling biomass (fresh weight) of lettuce. The combined goldenrod leaf extracts and salt stress have a synergistic effect on seedling height, root length, leaf shape index, germination percentage, germination potential, germination index, and germination rate index of lettuce. Thus, the allelopathic effects of the invaders on the seed germination and seedling growth of the natives may be reinforced under salt stress. Accordingly, salt stress may be beneficial to the further invasion of the invaders mainly via the reduced growth performance of the natives.

Silver nanoparticles with different particle sizes enhance the allelopathic effects of Canada goldenrod on the seed germination and seedling development of lettuce

Allelopathic effects on the seed germination and seedling development of co-occurring native plant species (natives hereafter) are regarded as an important driver facilitating invasion of many invasive plant species (invaders hereafter). The release of silver nanoparticles (AgNPs) into the environment may affect the allelopathic effects of the invaders on the seed germination and seedling development of natives. This study aims to assess the allelopathic effects (using leaf extracts) of Canada goldenrod (Solidago canadensis L.) on the seed germination and seedling development of native lettuce (Lactuca sativa L.) treated with AgNPs with different particle sizes. Canada goldenrod leaf extracts with high concentration exhibit stronger allelopathic effects on the seedling height and root length of lettuce than those treated with low concentration. AgNPs of all particle sizes significantly decreased seed germination and seedling development indices of lettuce. AgNPs with larger particle sizes exerted stronger toxicity on leaf length and width of lettuce than those with smaller particle sizes. Thus, nanoparticles with larger particle sizes might mediate the production of increased sizes of cell wall pore size and large absorption of such substances by plant roots can be harmful. AgNPs significantly enhanced the allelopathic effects of Canada goldenrod on the seed germination and seedling development of lettuce. Small particle size AgNPs may play a more essential role in the enhanced allelopathic effects of low concentrations of Canada goldenrod leaf extracts; however, large particle size AgNPs may play a more important role in the enhanced allelopathic effects of high concentrations of Canada goldenrod leaf extracts.