Epigenomic dissection of Alzheimer's disease pinpoints causal variants and reveals epigenome erosion.

Recent work has identified dozens of non-coding loci for Alzheimer's disease (AD) risk, but their mechanisms and AD transcriptional regulatory circuitry are poorly understood. Here, we profile epigenomic and transcriptomic landscapes of 850,000 nuclei from prefrontal cortexes of 92 individuals with and without AD to build a map of the brain regulome, including epigenomic profiles, transcriptional regulators, co-accessibility modules, and peak-to-gene links in a cell-type-specific manner. We develop methods for multimodal integration and detecting regulatory modules using peak-to-gene linking. We show AD risk loci are enriched in microglial enhancers and for specific TFs including SPI1, ELF2, and RUNX1. We detect 9,628 cell-type-specific ATAC-QTL loci, which we integrate alongside peak-to-gene links to prioritize AD variant regulatory circuits. We report differential accessibility of regulatory modules in late AD in glia and in early AD in neurons. Strikingly, late-stage AD brains show global epigenome dysregulation indicative of epigenome erosion and cell identity loss.

Yardangs sculpted by erosion of heterogeneous material.

The recognizable shapes of landforms arise from processes such as erosion by wind or water currents. However, explaining the physical origin of natural structures is challenging due to the coupled evolution of complex flow fields and three-dimensional (3D) topographies. We investigate these issues in a laboratory setting inspired by yardangs, which are raised, elongate formations whose characteristic shape suggests erosion of heterogeneous material by directional flows. We combine experiments and simulations to test an origin hypothesis involving a harder or less erodible inclusion embedded in an outcropping of softer material. Optical scans of clay objects fixed within flowing water reveal a transformation from a featureless mound to a yardang-like form resembling a lion in repose. Phase-field simulations reproduce similar shape dynamics and show their dependence on the erodibility contrast and flow strength. Through visualizations of the flow fields and analysis of the local erosion rate, we identify effects associated with flow funneling and the turbulent wake that are responsible for carving the unique geometrical features. This highly 3D scouring process produces complex shapes from simple and commonplace starting conditions and is thus a candidate explanation for natural yardangs. The methods introduced here should be generally useful for geomorphological problems and especially those for which material heterogeneity is a primary factor.

Lessons learnt on the impact of an unprecedented soil decontamination program in Fukushima on contaminant fluxes.

In the context of elevated concerns related to nuclear accidents and warfare, the lessons learnt from the Fukushima Daiichi Nuclear Power Plant accident in 2011 are important. In particular, Japanese authorities implemented an ambitious decontamination program to reduce the air dose rate in order to facilitate the return of the local inhabitants to previously evacuated areas. This approach contrasts the strategy adopted in Chernobyl, where the most contaminated areas remain off limits. Nonetheless, the effectiveness of the Japanese decontamination strategy on the dispersion of radioactive contaminant fluxes across mountainous landscapes exposed to typhoons has not been quantified. Based on the unique combination of river monitoring and modeling in a catchment representative of the most impacted area in Japan, we demonstrate that decontamination of 16% of the catchment area resulted in a decrease of 17% of sediment-bound radioactive fluxes in rivers. Decontamination operations were therefore relatively effective, although they could only be conducted in a small part of the area due to the dominance of steep forested slopes. In fact, 67% of the initial radiocesium contamination was calculated to remain stored in forested landscapes, which may contribute to future downstream radiocesium dispersion during erosive events. Given that only a limited proportion of the initial population had returned in 2019 (~30%), it raises the question as to whether decontaminating a small percentage of the contaminated area was worth the effort, the price, and the amount of waste generated?

Thermochronologic constraints on the origin of the Great Unconformity.

The origin of the phenomenon known as the Great Unconformity has been a fundamental yet unresolved problem in the geosciences for over a century. Recent hypotheses advocate either global continental exhumation averaging 3 to 5 km during Cryogenian (717 to 635 Ma) snowball Earth glaciations or, alternatively, diachronous episodic exhumation throughout the Neoproterozoic (1,000 to 540 Ma) due to plate tectonic reorganization from supercontinent assembly and breakup. To test these hypotheses, the temporal patterns of Neoproterozoic thermal histories were evaluated for four North American locations using previously published medium- to low-temperature thermochronology and geologic information. We present inverse time-temperature simulations within a Bayesian modeling framework that record a consistent signal of relatively rapid, high-magnitude cooling of ∼120 to 200 °C interpreted as erosional exhumation of upper crustal basement during the Cryogenian. These models imply widespread, synchronous cooling consistent with at least ∼3 to 5 km of unroofing during snowball Earth glaciations, but also demonstrate that plate tectonic drivers, with the potential to cause both exhumation and burial, may have significantly influenced the thermal history in regions that were undergoing deformation concomitant with glaciation. In the cratonic interior, however, glaciation remains the only plausible mechanism that satisfies the required timing, magnitude, and broad spatial pattern of continental erosion revealed by our thermochronological inversions. To obtain a full picture of the extent and synchroneity of such erosional exhumation, studies on stable cratonic crust below the Great Unconformity must be repeated on all continents.

Platelet biology and function: plaque erosion vs. rupture.

The leading cause of heart disease in developed countries is coronary atherosclerosis, which is not simply a result of ageing but a chronic inflammatory process that can lead to acute clinical events upon atherosclerotic plaque rupture or erosion and arterial thrombus formation. The composition and location of atherosclerotic plaques determine the phenotype of the lesion and whether it is more likely to rupture or to erode. Although plaque rupture and erosion both initiate platelet activation on the exposed vascular surface, the contribution of platelets to thrombus formation differs between the two phenotypes. In this review, plaque phenotype is discussed in relation to thrombus composition, and an overview of important mediators (haemodynamics, matrix components, and soluble factors) in plaque-induced platelet activation is given. As thrombus formation on disrupted plaques does not necessarily result in complete vessel occlusion, plaque healing can occur. Therefore, the latest findings on plaque healing and the potential role of platelets in this process are summarized. Finally, the clinical need for more effective antithrombotic agents is highlighted.

Deleterious and Adaptive Mutations in Plant Germplasm Conserved Ex Situ.

Conserving more than 7 million plant germplasm accessions in 1,750 genebanks worldwide raises the hope of securing the food supply for humanity for future generations. However, there is a genetic cost for such long-term germplasm conservation, which has been largely unaccounted for before. We investigated the extent and variation of deleterious and adaptive mutations in 490 individual plants representing barley, wheat, oat, soybean, maize, rapa, and sunflower collections in a seed genebank using RNA-Seq technology. These collections were found to have a range of deleterious mutations detected from 125 (maize) to 83,695 (oat) with a mean of 13,537 and of the averaged sample-wise mutation burden per deleterious locus from 0.069 to 0.357 with a mean of 0.200. Soybean and sunflower collections showed that accessions acquired earlier had increased mutation burdens. The germplasm with more years of storage in several collections carried more deleterious and fewer adaptive mutations. The samples with more cycles of germplasm regeneration revealed fewer deleterious and more adaptive mutations. These findings are significant for understanding mutational dynamics and genetic cost in conserved germplasm and have implications for long-term germplasm management and conservation.

TRF2 inhibition rather than telomerase disruption drives CD4T cell dysfunction during chronic viral infection.

We investigated the role of telomerase and telomere repeat-binding factor 2 (TRF2 or TERF2) in T-cell dysfunction in chronic viral infection. We found that the expression and activity of telomerase in CD4+ T (CD4T) cells from patients with hepatitis C virus (HCV) infections or people living with HIV (PLWH) were intact, but TRF2 expression was significantly inhibited at the post-transcriptional level, suggesting that TRF2 inhibition is responsible for the CD4T cell dysfunction observed during chronic viral infection. Silencing TRF2 expression in CD4T cells derived from healthy subjects induced telomeric DNA damage and CD4T cell dysfunction without affecting telomerase activity or translocation - similar to what we observed in CD4T cells from HCV patients and PLWH. These findings indicate that premature T-cell aging and dysfunction during chronic HCV or HIV infection are primarily caused by chronic immune stimulation and T-cell overactivation and/or proliferation that induce telomeric DNA damage due to TRF2 inhibition, rather than telomerase disruption. This study suggests that restoring TRF2 presents a novel approach to prevent telomeric DNA damage and premature T-cell aging, thus rejuvenating T-cell functions during chronic viral infection.

Which contributes more to the relict flora distribution pattern in East Asia, geographical processes or climate change? New evidence from the phylogeography of Rehderodendron kwangtungense.

BACKGROUND: Relict species are important for enhancing the understanding of modern biogeographic distribution patterns. Although both geological and climatic changes since the Cenozoic have affected the relict flora in East Asia, the contributions of geographical processes remain unclear. In this study, we employed restriction-site associated DNA sequencing (RAD-seq) and shallow genome sequencing data, in conjunction with ecological niche modeling (ENM), to investigate the spatial genetic patterns and population differentiation history of the relict species Rehderodendron kwangtungense Chun. RESULTS: A total of 138 individuals from 16 populations were collected, largely covering the natural distribution of R. kwangtungense. The genetic diversity within the R. kwangtungense populations was extremely low (HO = 0.048 ± 0.019; HE = 0.033 ± 0.011). Mantel tests revealed isolation-by-distance pattern (R2 = 0.38, P < 0.001), and AMOVA analysis showed that the genetic variation of R. kwangtungense occurs mainly between populations (86.88%, K = 7). Between 23 and 21 Ma, R. kwangtungense underwent a period of rapid differentiation that coincided with the rise of the Himalayas and the establishment of the East Asian monsoon. According to ENM and population demographic history, the suitable area and effective population size of R. kwangtungense decreased sharply during the glacial period and expanded after the last glacial maximum (LGM). CONCLUSION: Our study shows that the distribution pattern of southern China mountain relict flora may have developed during the panplain stage between the middle Oligocene and the early Miocene. Then, the flora later fragmented under the force of orogenesis, including intermittent uplift during the Cenozoic Himalayan orogeny and the formation of abundant rainfall associated with the East Asian monsoon. The findings emphasized the predominant role of geographical processes in shaping relict plant distribution patterns.

Ingenious Synergy of a Pathology-Specific Biomimetic Multifunctional Nanoplatform for Targeted Therapy in Rheumatoid Arthritis.

Based on the pathological characteristics of rheumatoid arthritis, including the overproduction of reactive oxygen species (ROS), inflammatory responses, and osteoclast differentiation, a biomimetic multifunctional nanomedicine (M-M@I) is designed. Iguratimod (IGU) is loaded, which inhibits inflammatory responses and osteoclast differentiation, into mesoporous polydopamine (MPDA), which scavenges ROS. Subsequently, the nanoparticles are coated with a cell membrane of macrophages to achieve actively targeted delivery of the nanoparticles to inflamed joints. It is shown that the M-M@I nanoparticles are taken up well by lipopolysaccharide-induced RAW 264.7 macrophages or bone marrow-derived macrophages (BMDMs). In vitro, the M-M@I nanoparticles effectively scavenge ROS, downregulate genes related to inflammation promotion and osteoclast differentiation, and reduce the proinflammatory cytokines and osteoclast-related enzymes. They also reduce the polarization of macrophages to a pro-inflammatory M1 phenotype and inhibit differentiation into osteoclasts. In mice with collagen-induced arthritis, the M-M@I nanoparticles accumulate at arthritic sites and circulate longer, significantly mitigating arthritis symptoms and bone destruction. These results suggest that the pathology-specific biomimetic multifunctional nanoparticles are effective against rheumatoid arthritis, and they validate the approach of developing multifunctional therapies that target various pathological processes simultaneously.

An approach of separating the overlapped cells or nuclei based on the outer Canny edges and morphological erosion.

In biomedicine, the automatic processing of medical microscope images plays a key role in the subsequent analysis and diagnosis. Cell or nucleus segmentation is one of the most challenging tasks for microscope image processing. Due to the frequently occurred overlapping, few segmentation methods can achieve satisfactory segmentation accuracy yet. In this paper, we propose an approach to separate the overlapped cells or nuclei based on the outer Canny edges and morphological erosion. The threshold selection is first used to segment the foreground and background of cell or nucleus images. For each binary connected domain in the segmentation image, an intersection based edge selection method is proposed to choose the outer Canny edges of the overlapped cells or nuclei. The outer Canny edges are used to generate a binary cell or nucleus image that is then used to compute the cell or nucleus seeds by the proposed morphological erosion method. The nuclei of the Human U2OS cells, the mouse NIH3T3 cells and the synthetic cells are used for evaluating our proposed approach. The quantitative quantification accuracy is computed by the Dice score and 95.53% is achieved by the proposed approach. Both the quantitative and the qualitative comparisons show that the accuracy of the proposed approach is better than those of the area constrained morphological erosion (ACME) method, the iterative erosion (IE) method, the morphology and watershed (MW) method, the Generalized Laplacian of Gaussian filters (GLGF) method and ellipse fitting (EF) method in separating the cells or nuclei in three publicly available datasets.

Effect of using the Simple Erosion Narrowing Score or Sharp/van der Heijde score on power of rheumatoid arthritis clinical trials to detect differences in radiographic progression.

OBJECTIVES: The Simple Erosion Narrowing Score (SENS) is a simplification of the Sharp/van der Heijde score (SHS). Previous studies found SENS and SHS to have very similar measurement properties, but suggest that SENS has a lower discriminative ability that may result in reduced power. Therefore, we aimed to quantify the effect of using SENS rather than SHS on the power to show between-group differences in radiographic progression. METHODS: Using data from two clinical trials in rheumatoid arthritis (DRESS and BeSt), SENS was derived from the SHS. Criterion validity of the SENS in relation to the SHS was assessed by calculating the Spearman correlation. The power of both scores to show a difference between groups was compared using bootstrapping to generate 10.000 replications of each study. Then, the number of replications with a significant difference in progression (using ANCOVA adjusted for baseline scores) were compared. RESULTS: Correlations between SENS and SHS were all >0.9, indicating high criterion validity of SENS compared with SHS as a reference standard. There was one exception, the DRESS study showed a somewhat lower correlation for the change score at 18 months (0.787). The loss in power of SENS over SHS was limited to at most 19% (BeSt year 5). In addition, the difference in power between SENS and SHS is smaller at higher levels of power. CONCLUSION: SENS appears to be a reasonable alternative to SHS, with only a limited loss of power to show between-group differences in radiographic progression.

A palaeogenomic investigation of overharvest implications in an endemic wild reindeer subspecies.

Overharvest can severely reduce the abundance and distribution of a species and thereby impact its genetic diversity and threaten its future viability. Overharvest remains an ongoing issue for Arctic mammals, which due to climate change now also confront one of the fastest changing environments on Earth. The high-arctic Svalbard reindeer (Rangifer tarandus platyrhynchus), endemic to Svalbard, experienced a harvest-induced demographic bottleneck that occurred during the 17-20th centuries. Here, we investigate changes in genetic diversity, population structure, and gene-specific differentiation during and after this overharvesting event. Using whole-genome shotgun sequencing, we generated the first ancient and historical nuclear (n = 11) and mitochondrial (n = 18) genomes from Svalbard reindeer (up to 4000 BP) and integrated these data with a large collection of modern genome sequences (n = 90) to infer temporal changes. We show that hunting resulted in major genetic changes and restructuring in reindeer populations. Near-extirpation followed by pronounced genetic drift has altered the allele frequencies of important genes contributing to diverse biological functions. Median heterozygosity was reduced by 26%, while the mitochondrial genetic diversity was reduced only to a limited extent, likely due to already low pre-harvest diversity and a complex post-harvest recolonization process. Such genomic erosion and genetic isolation of populations due to past anthropogenic disturbance will likely play a major role in metapopulation dynamics (i.e., extirpation, recolonization) under further climate change. Our results from a high-arctic case study therefore emphasize the need to understand the long-term interplay of past, current, and future stressors in wildlife conservation.

Serious complications and recurrences after retropubic vs transobturator midurethral sling procedures for 2682 patients in the VIGI-MESH register.

BACKGROUND: Midurethral slings are the gold standard for treating stress urinary incontinence, but their complications may raise concerns. Complications may differ by the approach used to place them. OBJECTIVE: This study aimed to compare serious complications and reoperations for recurrence after midurethral sling procedures when using the retropubic vs the transobturator route for female stress urinary incontinence. STUDY DESIGN: This analysis was of patients included in the French, multicenter VIGI-MESH register since February 2017 who received a midurethral sling for female stress urinary incontinence either by the retropubic or the transobturator route and excluded patients with single-incision slings. Follow-up continued until October 2021. Serious complications (Clavien-Dindo classification ≥ grade III) attributable to the midurethral sling and reoperations for recurrence were compared using Cox proportional hazard models including any associated surgery (hysterectomy or prolapse) and a frailty term to consider the center effect. Baseline differences were balanced by propensity score weighting. Analyses using the propensity score and Cox models were adjusted for baseline differences, center effect, and associated surgery. RESULTS: A total of 1830 participants received a retropubic sling and 852 received a transobturator sling in 27 French centers that were placed by 167 surgeons. The cumulative 2-year estimate of serious complications was 5.8% (95% confidence interval, 4.8-7.0) in the retropubic group and 2.9% (95% confidence interval, 1.9-4.3) in the transobturator group, that is, after adjustment, half of the retropubic group was affected (adjusted hazard ratio, 0.41; 95% confidence interval, 0.3-0.6). The cumulative 2-year estimate of reoperation for recurrence of stress urinary incontinence was 2.7% (95% confidence interval, 2.0-3.6) in the retropubic group and 2.8% (95% confidence interval, 1.7-4.2) in the transobturator group with risk for revision for recurrence being higher in the transobturator group after adjustment (adjusted hazard ratio, 1.9; 95% confidence interval, 1.2-2.9); this surplus risk disappeared after exclusion of the patients with a previous surgery for stress urinary incontinence. CONCLUSION: The transobturator route for midurethral sling placement is associated with a lower risk for serious complications but a higher risk for surgical reoperation for recurrence than the retropubic route. Despite the large number of surgeons involved, these risks were low. The data are therefore reassuring.

Laser excision of urethral mesh erosion: a 10-year experience.

PURPOSE: To review our 10-year experience with laser excision for urethral mesh erosion (UME) of mid-urethral slings (MUS). METHODS: Following Institutional Review Board approval, the charts of female patients with endoscopic laser excision of UME were retrospectively reviewed. Demographics, clinical presentation, surgical history, pre- and post-operative Urinary Distress Inventory-6 scores and quality of life ratings, operative reports, and outcomes were obtained from electronic medical records. UME cure was defined as no residual mesh on office cystourethroscopy 5-6 months after the final laser excision procedure. RESULTS: From 2011 to 2021, 23 patients met study criteria; median age was 56 (range 44-79) years. Twenty (87%) had multiple prior urogynecologic procedures. Median time from MUS placement to presentation with UME-related complaints was 5.3 [interquartile range (IQR) 2.3-7.6] years. The most common presenting symptom was recurrent urinary tract infection (rUTI) (n = 10). Median operating time was 49 (IQR 37-80) minutes. Median duration of follow-up was 24 (IQR 12-84) months. Fourteen (61%) required more than 1 laser excision procedure for UME. Although 5 were asymptomatic (22%), new (n = 5) or persistent (n = 8) urinary incontinence was the most common symptom on follow-up (57%). CONCLUSION: UME presenting symptoms are highly variable, necessitating a high index of suspicion in patients with a history of MUS, especially in the case of rUTI. Endoscopic laser excision is a minimally invasive, brief, safe, outpatient procedure with a high UME cure rate.

Victim of changes? Marine macroalgae in a changing world.

BACKGROUND: Marine macroalgae ('seaweeds') are a diverse and globally distributed group of photosynthetic organisms that together generate considerable primary productivity, provide an array of different habitats for other organisms, and contribute many important ecosystem functions and services. As a result of continued anthropogenic stress on marine systems, many macroalgal species and habitats face an uncertain future, risking their vital contribution to global productivity and ecosystem service provision. SCOPE: After briefly considering the remarkable taxonomy and ecological distribution of marine macroalgae, we review how the threats posed by a combination of anthropogenically induced stressors affect seaweed species and communities. From there we highlight five critical avenues for further research to explore (long-term monitoring, use of functional traits, focus on early ontogeny, biotic interactions and impact of marine litter on coastal vegetation). CONCLUSIONS: Although there are considerable parallels with terrestrial vascular plant responses to the many threats posed by anthropogenic stressors, we note that the impacts of some (e.g. habitat loss) are much less keenly felt in the oceans than on land. Nevertheless, and in common with terrestrial plant communities, the impact of climate change will inevitably be the most pernicious threat to the future persistence of seaweed species, communities and service provision. While understanding macroalgal responses to simultaneous environmental stressors is inevitably a complex exercise, our attempt to highlight synergies with terrestrial systems, and provide five future research priorities to elucidate some of the important trends and mechanisms of response, may yet offer some small contribution to this goal.

Mollisol Erosion-Driven Efflux of Energetic Organic Carbon and Microflora Increases Greenhouse Gas Emissions from Cold-Region Rivers.

Massive soil erosion occurs in the world's Mollisol regions due to land use change and climate warming. The migration of Mollisol organic matter to river systems and subsequent changes in carbon biogeochemical flow and greenhouse gas fluxes are of global importance but little understood. By employing comparative mesocosm experiments simulating varying erosion intensity in Mollisol regions of northeastern China, this research highlights that erosion-driven export and biomineralization of terrestrial organic matter facilitates CO2 and CH4 emission from receiving rivers. Stronger Mollisol erosion, as represented by a higher soil-to-water ratio in suspensions, increased CO2 efflux, particularly for the paddy Mollisols. This is mechanistically attributable to increased bioavailability of soluble organic carbon in river water that is sourced back to destabilized organic matter, especially from the cultivated Mollisols. Concurrent changes in microbial community structure have enhanced both aerobic and anaerobic processes as reflected by the coemission of CO2 and CH4. Higher greenhouse gas effluxes from paddy Mollisol suspensions suggest that agricultural land use by supplying more nitrogen-containing, higher-free-energy organic components may have enhanced microbial respiration. These new findings highlight that Mollisol erosion is a hidden significant contributor to greenhouse gas emissions from river water, given that the world's four major Mollisol belts are all experiencing intensive cultivation.

Where, When, and How Much Should We Pay for Wind Erosion Prevention Services of the Largest Chinese Grassland Reserve?

The large-scale and cross-regional payment for ecosystem services (PES) contributes positively to ecology-economy balance and thus helps prevent environmental challenges such as "sand storm". However, existing PES programs often overlook the connection between service-providing areas (SPAs) and service-benefiting areas (SBAs). Here, we developed an interregional PES framework based on the theory of ecosystem services flow and applied it to the largest Chinese grassland nature reserve, Xilingol Prairie, to quantitatively identify SPAs, SBAs, and flow paths of the ecosystem wind erosion prevention service (WEPS). We showed that, from 2000 to 2020, the grassland ecosystem of Xilingol Prairie had brought an annual WEPS benefit of 1.21 × 108 t/a and economic value of 12.44 × 108 CNY/a, accounting for approximately 107.71% of the GDP in the same area and year and with a slightly increasing trend in most areas. We reveal obvious seasonal (over half in the spring) and interannual variations in the benefit and that Inner Mongolia, Hebei, and Northeast China are the most important beneficiaries of WEPS, rather than Beijing and Tianjin as traditionally thought. Our results warn that the WEPS supply capacity will not last long and call for finer spatial (e.g., among cities) and temporal (e.g., focus on the spring) resolution for PES policy design.

Could robotic-assisted surgery reduce mesh-related complications after ventral mesh rectopexy? Experience of a tertiary centre and systematic review of the literature.

AIM: The development of robotic assistance has made dissection and suturing in the deep pelvis much easier. The augmented quality of the images and the articulation of the robotic arms have also enabled a more precise dissection. The aim of this study is to present the data on robotic-assisted ventral mesh rectopexy procedures in a university hospital and examine the literature in terms of mesh erosion. METHOD: The electronic databases Pubmed, Embase and Cochrane were searched. Studies from January 2004 until January 2023 in the English language were included. Studies which included fewer than 10 patients were excluded. Laparoscopic or robotic-assisted ventral mesh rectopexies were included. Mesh erosion rates following laparoscopic or robotic-assisted ventral mesh rectopexies were measured. RESULTS: Overall, the systematic review presents 5911 patients from 43 studies who underwent laparoscopic ventral mesh rectopexy compared with 746 patients treated with robotic-assisted ventral mesh rectopexy from six studies and our centre. Mesh erosion was rare in both groups; however, the prevalence was greater in the laparoscopy group (0.90% vs. 0.27%). CONCLUSION: The mesh erosion rates are very low with robotic-assisted ventral mesh rectopexy. For precise results, more studies and experience in robotic surgery are required.

Primary production of the kelp Lessonia corrugata varies with season and water motion: Implications for coastal carbon cycling.

Kelp forests provide vital ecosystem services such as carbon storage and cycling, and understanding primary production dynamics regarding seasonal and spatial variations is essential. We conducted surveys at three sites in southeast Tasmania, Australia, that had different levels of water motion, across four seasons to determine seasonal primary production and carbon storage as living biomass for kelp beds of Lessonia corrugata (Order Laminariales). We quantified blade growth, erosion rates, and the variation in population density and estimated both the net biomass accumulation (NBA) per square meter and the carbon standing stock. We observed a significant difference in blade growth and erosion rates between seasons and sites. Spring had the highest growth rate (0.02 g C · blade-1 · d-1 ) and NBA (1.62 g C · m-2 · d-1 ), while summer had the highest blade erosion (0.01 g C · blade-1 · d-1 ), with a negative NBA (-1.18 g C · m-2 · d-1 ). Sites exhibiting lower blade erosion rates demonstrated notably greater NBA than sites with elevated erosion rates. The sites with the highest water motion had the slowest erosion rates. Moreover, the most wave-exposed site had the densest populations, resulting in the highest NBA and a greater standing stock. Our results reveal a strong seasonal and water motion influence on carbon dynamics in L. corrugata populations. This knowledge is important for understanding the dynamics of the carbon cycle in coastal regions.

Enhancement of sewer sediment control and disruption of adhesive gelatinous sediment structure using low-dose calcium peroxide.

Large quantities of sediments in urban sewer systems pose significant risk of pipe clogging and corrosion. Owing to their gel-like structure, sewer sediments have strong resistance to hydraulic shear stress. This study proposed a novel approach to weaken the erosion resistance of sewer sediments by destroying viscous gel-like biopolymers in sediments with low doses of calcium peroxide (CaO2). After treatment with 10-50 mg g-1 TS of CaO2, the critical erosion shear stress was significantly reduced by 25.7%-59.9%. The sediment aggregates gradually disintegrated into small diameter particles with increasing CaO2 dosage. Further analysis showed that the strong oxidizing and alkaline environment induced by CaO2 treatment led to cell lysis and changes in the composition and property of extracellular polymeric substances (EPS). After CaO2 treatment, aromatic proteins and humic acid-like substances associated with adhesion translocated from the inner EPS layers to outer layers while being disintegrated into small organic molecules. Concomitantly, CaO2 treatment disrupted the main functional groups (-OH, COO-, C-N, CO, and CN) in inner EPS layers, thus weakening EPS adhesion. Analysis of protein secondary structure and zeta potential reflected the reduced aggregation capacity of sediment microorganisms and loosening of sediment structure after CaO2 treatment. Thus, CaO2 treatment facilitated fragmentation and disaggregation of the gelatinous structure of sewer sediments. Such green strategy decreased the cost of sewer sediment disposal by 42.10-68.95% when compared to water flushing, and it would improve the self-cleaning capacity of sewer system and efficiency of dredging equipment.