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.

The ability of fragile ecosystems of alpine regions to adapt and thrive under warming and nitrogen deposition is a pressing conservation concern. The lack of information on how these ecosystems respond to the combined impacts of elevated levels of nitrogen and a warming climate limits the sustainable management approaches of alpine grasslands. In this study, we experimented using a completely random blocked design to examine the effects of warming and nitrogen deposition on the aboveground biomass and diversity of alpine grassland plant communities. The experiment was carried out from 2015 to 2018 in four vegetation types, e.g., alpine desert, alpine desert steppe, alpine marsh, and alpine salinised meadow, in the Aerjin Mountain Nature Reserve (AMNR) on the Qinghai–Tibetan Plateau (QTP). We found that W (warming) and WN (warming plus N deposition) treatment significantly increased the aboveground biomass of all the vegetation types (p < 0.05) in 2018. However, W and WN treatment only significantly increased the Shannon diversity of salinised meadows in 2018 and had no significant effect on the Shannon diversity of other vegetation types. Such results suggested that long-term nitrogen deposition and warming can consistently stimulate biomass accumulation of the alpine plant communities. Compared with other vegetation types, the diversity of alpine salinised meadows are generally more susceptible to long-term warming and warming combined with N deposition. Warming accounts many of such variabilities, while short-term N deposition alone may not significantly have an evident effect on the productivity and diversity of alpine grasslands. Our findings suggested that the effects of short-term (≤4 years) N deposition on alpine vegetation productivity and diversity were minimal, while long-term warming (>4 years) will be much more favourable for alpine vegetation.

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.