Nowadays, plant invasion has become a global ecological threat to local biodiversity and ecosystem stability. Spartina alterniflora encroaches on the ecological niches of local species and changes the soil’s nutrient cycle. However, few comprehensive assessments focus on the effects of S. alterniflora invasion. Here, we investigated how soil sulfur changed with spatiotemporal variation and life forms of native species after S. alterniflora invasion and speculated the possible mechanism of the sulfur increase based on the references. The invasion of S. alterniflora increased soil total sulfur by 57.29% and phytotoxic sulfide by 193.29%. In general, the invasion of S. alterniflora enhanced the total plant biomass and soil nutrients, e.g., soil organic carbon, total nitrogen, and soil microbial biomass carbon, further increasing soil sulfur content. The sulfur accumulation caused by S. alterniflora might result in the poisoning of native species. Thus, we hypothesized that the success of S. alterniflora invasion was closely connected with soil sulfur, especially toxic sulfide. Our study suggests that researchers should give more attention to the correlation between S. alterniflora invasion and the soil sulfur increase. More research is needed to investigate the mechanisms of the successful invasion by accumulating phytotoxic sulfide.

Purpose The Spartina alterniflora invasion across the southeast coast in China significantly reduced vegetation diversity and generated associated ecological problems. Sulfur (S) is a vital nutrient, while sulfide is phytotoxic and the impact of S. alterniflora invasion on soil S cycle remains unclear. Therefore, this study aims to investigate the impacts of S. alterniflora invasion on the S cycle and associated soil microbial communities. Methods Both field investigation and lab-scale experiments were conducted, analyzing soil sulfide and sulfate contents, soil properties over four seasons in the Jiuduansha Wetland of Shanghai, China, the high-throughput sequencing of soil microbial communities, S cycle-related functional genes and seed germination experiments. Results The contents of sulfide, soil organic carbon (SOC), and total nitrogen (TN) in the bulk soil of S. alterniflora invaded area were higher than those in the native species S. mariqueter habitat and bare mudflat soils. Spartina alterniflora invasion increased the abundance of the Nitrospiraceae and Desulfarculaceae families and reduced that of Hydrogenophilaceae. The relative abundance of the SO₄²⁻ reduction functional genes (dsrA + dsrB) in the soil was increased after S. alterniflora invasion, while that of the S oxidation functional genes (yedZ + soxY) in the soil was reduced. Seed germination experiments with different sodium sulfide concentrations (Na₂S) revealed that the phytotoxicity of sulfide caused more lethal damage to S. mariqueter than to S. alterniflora. Conclusion The S. alterniflora invasion significantly increased SOC and TN contents and reduced the abundance of sulfur-oxidizing functional genes, which led to the accumulation of soil sulfide.

Advanced oxidation processes (AOPs) have become a favored approach in wastewater treatment due to the high efficiency and diverse catalyzed ways. Iron-based materials were the commonly used catalyst due to their environmental friendliness and sustainability in the environment. We collected the published papers relative to the application of the modified iron-based materials in AOPs between 1999 and 2020 to comprehensively understand the related mechanism of modified materials to improve the catalytic performance of iron-based materials in AOPs. Related data of iron-based materials, modification types, target pollutants, final removal efficiencies, and rate constants were extracted to reveal the critical process of improving the catalytic efficiency of iron-based materials in AOPs. Our results indicated that the modified materials through various mechanisms to enhance the catalytic performance of iron-based materials. The principal aim of iron-based materials modification in AOPs is to increase the content of available Fe²⁺ and enhance the stability of Fe²⁺ in the system. The available Fe²⁺ is elevated by the following mechanisms: (1) modified materials accelerate the electron transfer to promote the Fe³⁺/Fe²⁺ reaction cycle in the system; (2) modified materials form chelates with iron ions and bond with iron ions to avoid Fe³⁺ precipitation. We further analyzed the effect of different modifying materials in improving these two mechanisms. Combining the advantages of different modified materials to develop iron-based materials with composite modification methods can enhance the catalytic performance of iron-based materials in AOPs for further application in wastewater treatment.

Subsoil carbon (C) stocks are a prime target for efforts to increase soil C storage for climate change mitigation. However, subsoil C dynamics are not well understood, especially in soils under long-term intensive agricultural management. We compared subsoil C storage and soil organic matter (SOM) composition in tomato–corn rotations after 25 years of differing C and nutrient management in the California Central Valley: CONV (mineral fertilizer), CONV+WCC (mineral fertilizer and cover crops), and ORG (composted poultry manure and cover crops). The cover crop mix used in these systems is a mix of oat (Avena sativa L.), faba bean (Vicia faba L.), and hairy vetch (Vicia villosa Roth). Our results showed a ∼19 Mg ha⁻¹ increase in soil organic C (SOC) stocks down to 1 m under ORG systems, no significant SOC increases under CONV+WCC or CONV systems, and an increased abundance of carboxyl-rich C in the subsoil (60–100 cm) horizons of ORG and CONV+WCC systems. Our results show the potential for increased subsoil C storage with compost and cover crop amendments in tilled agricultural systems and identify potential pathways for increasing C transport and storage in subsoil layers.