Renbin Zhu

Introduction: Rapid urbanization and climate change drive widespread wetland degradation, yet it remains unclear whether wetland restoration improves ecological quality (EQ), a composite indicator reflecting vegetation, thermal, hydrological, environmental, and soil conditions at regional scales in highly urbanized landscapes. Objectives: This study aimed to quantify the spatiotemporal dynamics of wetland extent and EQ in the Beijing–Tianjin–Hebei region, assess the contribution of wetland restoration to EQ improvement, and disentangle its effects from climatic, edaphic, topographic, and anthropogenic influences. Methods: Using annual 30‐m Landsat‐based wetland maps and 500‐m EQ data (2001–2021), we quantified wetland dynamics and restoration effects using regression, spatial comparisons, and Partial Least Squares Structural Equation Model. Results: Areas with expanding wetland coverage showed improved EQ, with every 1% increase in wetland area corresponding to a 0.034 rise in EQ. Wetland restoration was especially effective in core areas, substantially enhancing local EQ. Although indirect effects of climate, soil, terrain, and human disturbance were detected, they did not weaken the positive relationship between wetland restoration and EQ improvement. Wetland loss was most pronounced in coastal and near‐coastal areas, and some regions lost wetlands completely. In contrast, inland areas exhibited a moderate increase in wetland coverage, with the average wetland fraction increasing by 2.18%. Notably, a shift in wetland dynamics was observed after 2015, with the previous declining trend reversing. Conclusions: These findings highlighted the pivotal role of wetland restoration in enhancing EQ.

Complete ammonia oxidizers (comammox), oxidizing ammonia to nitrate directly, have been found to exist widely in multiple environments, but their distribution patterns are still under-explored in Antarctic environments. For the first time, the sediments were collected from West Antarctic lakes to investigate distribution patterns and community structure for comammox, ammonia oxidizing archaea (AOA) and bacteria (AOB), and nitrite-oxidizing bacteria (NOB), as well as the associations between ammonia oxidizers and antibiotic resistance genes (ARGs). Comammox clade B and AOB were dominant ammonia oxidizers, with the abundances of (1.62 ± 0.10) × 10² – (5.21 ± 0.74) × 10⁶ and (0.17 ± 0.05) × 10⁵ – (4.79 ± 0.65) × 10⁵ copies g^− 1 sediment, respectively. Comammox clade B, instead of clade A, occurred in all sediments, exhibiting higher abundances than AOB and AOA in most of the sediments. The abundances for comammox clade B demonstrated significant positive correlation (p < 0.01) with NH₄⁺-N levels, but negative correlation (p < 0.05) with C: N ratios. The coexistence of ammonia oxidizers in lake sediments was jointly structured by niche differentiation and environmental variables, and pH, modulated by penguin guano input, was found to be the most crucial factor in shaping their community structure. Co-occurrence network analyses revealed strong synergistic interactions between comammox and AOB, AOA, NOB, which played a critical role in nitrification processes. Our results further confirmed that comammox could act as important hosts for ARGs, hence stimulated their transmission and proliferation in the sediments. This study presented novel insights into the distribution patterns for ammonia oxidizers, their niche differentiation and the associations with ARGs in natural lake sediments of West Antarctica.

Carbonyl sulfide (OCS) and carbon disulfide (CS2) are important sulfur carrier gases in the atmosphere. Higher plants have been identified as both their consumers and emitters, but relatively few studies focus on plants in high-latitude ecosystems. In this study, dominant plants (moss, lichen, and hair grass) and soils were collected across tundra ecotopes in maritime Antarctica and incubated under controlled conditions to explore the uptake and emission of OCS and CS2. Tundra vegetation (e.g., Sanionia georgicouncinata, Sanionia uncinata, Usnea antarctica) consistently consumed OCS (−2.66 to −11.36 pmol m–2 s–1) and CS2 (−0.08 to −0.48 pmol m–2 s–1) with a significant positive correlation between their uptake rates (r = 0.99, p < 0.001), likely driven by the activities of RuBisCO, an enzyme involved in photosynthesis. In comparison, tundra soils fluctuated between sources and sinks of OCS (−1.65 to 4.29 pmol m–2 s–1) but showed consistent CS2 emissions (4.70 to 7.65 pmol m–2 s–1). Particularly, penguin colony soils were uniform sources of OCS and CS2. Plants dominated the overall uptake of OCS and CS2 by Antarctic tundra (≥66%), and these biogenic sinks are expected to be conserved under climate warming, accompanying the enhancement in OCS uptake with light intensity. This study improved our understanding of sulfur biogeochemical interactions and their environmental implications in Antarctic tundra.

Numerous penguins can propagate pathogens with antibiotic resistance genes (ARGs) into Antarctica. However, the effects of penguin dissemination on the lake ARGs still have received little attention via guano deposition. Here, we have profiled ARGs in ornithogenic sediments subject to penguin guano (OLS) and nonornithogenic sediments (NOLS) from 16 lakes across Antarctica. A total of 191 ARGs were detected in all sediment samples, with a much higher abundance and diversity in OLS than in NOLS. Surprisingly, highly diverse and abundant ARGs were found in the OLS with a detection frequency of >40% and an absolute abundance of (2.34 × 10⁹)-(4.98 × 10⁹) copies g^-1, comparable to those in coastal estuarine sediments and pig farms. The strong correlations of identified resistance genes with penguin guano input amount, environmental factors, mobile genetic elements, and bacterial community, in conjunction with network and redundancy analyses, all indicated that penguins were responsible for the dissemination and high enrichment of ARGs in lake sediments via the guano deposition, which might greatly outweigh local human-activity effects. Our results revealed that ARGs could be carried into lakes across the Antarctica through penguin migration, food chains, and guano deposition, which were closely connected with the widespread pollution of ARGs at the global scale.