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1.
BMC Infect Dis ; 24(1): 697, 2024 Jul 14.
Article in English | MEDLINE | ID: mdl-39004725

ABSTRACT

BACKGROUND: This case report presents a unique instance of abscesses with an uncommon pathogen isolated from blood cultures. CASE PRESENTATION: We present the case of a perianal abscess in a 50-year-old man with a history of cocaine abuse and bilateral hip replacements. The rapid progression led to septic shock and multi-organ failure, requiring intensive care unit admission, surgery including protective transversostomy. Blood cultures showed growth of Butyricimonas spp. with resistance to penicillin and piperacillin-tazobactam. The immediate switch to meropenem led to a significant improvement in the patient's condition. The patient was discharged after 40 days of hospitalization in good general condition and the reversal of the transversostomy was performed six months later. CONCLUSION: The identification of Butyricimonas faecihominis, a rarely reported pathogen, emphasizes the challenges of diagnosing and treating unusual infections. This case emphasizes the importance of rapid microbiological diagnosis, interdisciplinary collaboration, and targeted antibiotic therapy in the treatment of abscesses and sepsis.


Subject(s)
Abscess , Anti-Bacterial Agents , Humans , Male , Middle Aged , Abscess/microbiology , Abscess/drug therapy , Anti-Bacterial Agents/therapeutic use , Anti-Bacterial Agents/pharmacology , Meropenem/therapeutic use
2.
Ecol Evol ; 14(7): e11663, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38994213

ABSTRACT

Several theoretical models have been proposed as the underlying mechanisms behind occupancy frequency distribution (OFD) patterns. For instance, the metapopulation dynamic model predicts bimodal OFD pattern indicating the dominance of dispersal processes in structuring the assemblages, while the niche-based model predicts unimodal right-skewed OFD pattern, and thus assemblages are driven mostly by niche processes. However, it is well known that the observed OFD pattern reflects the interplay of several other factors (e.g. habitat heterogeneity, species specificity and sampling protocol parameters). It follows that the individual contribution of each factor to the OFD pattern is rather complicated to explore. Our main objective was to examine the role of the spatial extent of the sampling and the dispersal strategies of species in shaping OFD pattern. For this, we collected samples of stream insect assemblages inhabiting near-natural streams in the Pannon Ecoregion. We formed groups of species representing contrasting dispersal strategies (referred to as dispersal groups). Applying a computer program algorithm, we produced samples with different spatial extent. We found that with increasing spatial extent, the OFD pattern changed from bimodal to unimodal for active dispersers. Insect groups with different dispersal strategies differed in the strength of support for OFD patterns within all spatial extent. Furthermore, the strength of support for OFD patterns varied across dispersal groups differently as the spatial extent increased. Our results reflected underlying changes in mechanisms structuring assemblages along an increasing spatial extent. We also assumed that the stream insect dispersal strategy influences the relative role of dispersal and niche processes particularly as spatial extent increases from stream reaches to the extent of adjacent valleys. We could define spatial extents and dispersal strategies within which unique metacommunity processes could underlie the organisation of assemblages.

3.
Article in English | MEDLINE | ID: mdl-38961610

ABSTRACT

BACKGROUND: Medicines are the cornerstone of healthcare. Lean methodology approach such as Value Stream Mapping (VSM) is being used in healthcare to manage resources wisely to ensure sustainability of medicines and resources. The aim of this quality improvement study was to evaluate and improve the medication management and hospital imprest supply processes in Australia's first dedicated cardiology hospital using VSM. METHOD: We conducted a review of our medicine supply processes at a 180-bed cardiology hospital in Australia. We followed a lean methodology approach over a 4-month period from February to May 2023 and evaluated the outcome of our improvements for another 4 months from July to October 2023. We used VSM to identify non-value adding activities. Cost of medicines holding was calculated, as well as time taken to complete supply processes, pre and post. RESULTS: Pharmacy department stockholdings reduced by 51%; p = 0.000121 (from $539,662 to $275,406). Time taken to manage the inventory system also reduced by 42%; p = 0.025762 (from 148 h/month to 62 h/month). Lean methodology such as VSM can facilitate cost-effective and sustainable system improvements for pharmacy procurement systems.

4.
J Lesbian Stud ; : 1-16, 2024 Jul 03.
Article in English | MEDLINE | ID: mdl-38961676

ABSTRACT

This essay looks at, and compares, Hotel World by Ali Smith and Mrs. Dalloway by Virginia Woolf and attempts to understand the differences within both the formal and philosophical/political outlook of the two works. Presuming stream-of-consciousness as both a set of formal prosaic styles and a genre, the essay argues that the way the novels utilize formal style is indicative of their individual politics in counterintuitive ways. Furthermore, it argues that by looking at these two novels we can begin to map a lineage of queer stream-of-consciousness works and explore how those perspectives have changed over time.

5.
Biol Lett ; 20(7): 20230394, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38982850

ABSTRACT

Urban stream syndrome alters stream habitat complexity. We define habitat complexity as the degree of variation in physical habitat structure, with increasing variation equating to higher complexity. Habitat complexity affects species composition and shapes animal ecology, physiology, behaviour and cognition. We used a delayed detour test to measure whether cognitive processes (motor self-regulation) and behaviour (risk-taking) of female Western mosquitofish, Gambusia affinis, varied with habitat structural complexity (low, moderate and high) that was quantified visually for nine populations. We predicted that motor self-regulation and risk-taking behaviour would increase with increasing habitat complexity, yet we found support for the opposite. Lower complexity habitats offer less refuge potentially leading to higher predation pressure and selecting for greater risk-taking by fish with higher motor self-regulation. Our findings provide insight into how habitat complexity can shape cognitive processes and behaviour and offers a broader understanding of why some species may tolerate conditions of urbanized environments.


Subject(s)
Behavior, Animal , Cognition , Cyprinodontiformes , Ecosystem , Animals , Cyprinodontiformes/physiology , Female , Risk-Taking , Rivers
6.
Infection ; 2024 Jul 12.
Article in English | MEDLINE | ID: mdl-38995551

ABSTRACT

OBJECTIVES: Advancements in Artificial Intelligence(AI) have made platforms like ChatGPT increasingly relevant in medicine. This study assesses ChatGPT's utility in addressing bacterial infection-related questions and antibiogram-based clinical cases. METHODS: This study involved a collaborative effort involving infectious disease (ID) specialists and residents. A group of experts formulated six true/false, six open-ended questions, and six clinical cases with antibiograms for four types of infections (endocarditis, pneumonia, intra-abdominal infections, and bloodstream infection) for a total of 96 questions. The questions were submitted to four senior residents and four specialists in ID and inputted into ChatGPT-4 and a trained version of ChatGPT-4. A total of 720 responses were obtained and reviewed by a blinded panel of experts in antibiotic treatments. They evaluated the responses for accuracy and completeness, the ability to identify correct resistance mechanisms from antibiograms, and the appropriateness of antibiotics prescriptions. RESULTS: No significant difference was noted among the four groups for true/false questions, with approximately 70% correct answers. The trained ChatGPT-4 and ChatGPT-4 offered more accurate and complete answers to the open-ended questions than both the residents and specialists. Regarding the clinical case, we observed a lower accuracy from ChatGPT-4 to recognize the correct resistance mechanism. ChatGPT-4 tended not to prescribe newer antibiotics like cefiderocol or imipenem/cilastatin/relebactam, favoring less recommended options like colistin. Both trained- ChatGPT-4 and ChatGPT-4 recommended longer than necessary treatment periods (p-value = 0.022). CONCLUSIONS: This study highlights ChatGPT's capabilities and limitations in medical decision-making, specifically regarding bacterial infections and antibiogram analysis. While ChatGPT demonstrated proficiency in answering theoretical questions, it did not consistently align with expert decisions in clinical case management. Despite these limitations, the potential of ChatGPT as a supportive tool in ID education and preliminary analysis is evident. However, it should not replace expert consultation, especially in complex clinical decision-making.

7.
Front Neurosci ; 18: 1373232, 2024.
Article in English | MEDLINE | ID: mdl-38952924

ABSTRACT

Timbre is a central aspect of music that allows listeners to identify musical sounds and conveys musical emotion, but also allows for the recognition of actions and is an important structuring property of music. The former functions are known to be implemented in a ventral auditory stream in processing musical timbre. While the latter functions are commonly attributed to areas in a dorsal auditory processing stream in other musical domains, its involvement in musical timbre processing is so far unknown. To investigate if musical timbre processing involves both dorsal and ventral auditory pathways, we carried out an activation likelihood estimation (ALE) meta-analysis of 18 experiments from 17 published neuroimaging studies on musical timbre perception. We identified consistent activations in Brodmann areas (BA) 41, 42, and 22 in the bilateral transverse temporal gyri, the posterior superior temporal gyri and planum temporale, in BA 40 of the bilateral inferior parietal lobe, in BA 13 in the bilateral posterior Insula, and in BA 13 and 22 in the right anterior insula and superior temporal gyrus. The vast majority of the identified regions are associated with the dorsal and ventral auditory processing streams. We therefore propose to frame the processing of musical timbre in a dual-stream model. Moreover, the regions activated in processing timbre show similarities to the brain regions involved in processing several other fundamental aspects of music, indicating possible shared neural bases of musical timbre and other musical domains.

8.
Pediatr Hematol Oncol ; : 1-17, 2024 Jul 08.
Article in English | MEDLINE | ID: mdl-38975680

ABSTRACT

Bloodstream infections (BSI) are one of the leading causes of morbidity and mortality in children and young adults receiving chemotherapy for malignancy or undergoing hematopoietic stem cell transplantation (HSCT). Antibiotic prophylaxis is commonly used to decrease the risk of BSI; however, antibiotics carry an inherent risk of complications. The aim of this manuscript is to review levofloxacin prophylaxis in pediatric oncology patients and HSCT recipients. We reviewed published literature on levofloxacin prophylaxis to prevent BSI in pediatric oncology patients and HSCT recipients. Nine manuscripts were identified. The use of levofloxacin is indicated in neutropenic children and young adults receiving intensive chemotherapy for leukemia or undergoing HSCT. These results support the efficacy of levofloxacin in pediatric patients with leukemia receiving intensive chemotherapy and should be considered in pediatric patients undergoing HSCT prior to engraftment.

9.
Comput Med Imaging Graph ; 116: 102414, 2024 Jul 03.
Article in English | MEDLINE | ID: mdl-38981250

ABSTRACT

The use of multi-modality non-contrast images (i.e., T1FS, T2FS and DWI) for segmenting liver tumors provides a solution by eliminating the use of contrast agents and is crucial for clinical diagnosis. However, this remains a challenging task to discover the most useful information to fuse multi-modality images for accurate segmentation due to inter-modal interference. In this paper, we propose a dual-stream multi-level fusion framework (DM-FF) to, for the first time, accurately segment liver tumors from non-contrast multi-modality images directly. Our DM-FF first designs an attention-based encoder-decoder to effectively extract multi-level feature maps corresponding to a specified representation of each modality. Then, DM-FF creates two types of fusion modules, in which a module fuses learned features to obtain a shared representation across multi-modality images to exploit commonalities and improve the performance, and a module fuses the decision evidence of segment to discover differences between modalities to prevent interference caused by modality's conflict. By integrating these three components, DM-FF enables multi-modality non-contrast images to cooperate with each other and enables an accurate segmentation. Evaluation on 250 patients including different types of tumors from two MRI scanners, DM-FF achieves a Dice of 81.20%, and improves performance (Dice by at least 11%) when comparing the eight state-of-the-art segmentation architectures. The results indicate that our DM-FF significantly promotes the development and deployment of non-contrast liver tumor technology.

10.
Food Chem ; 458: 139838, 2024 May 25.
Article in English | MEDLINE | ID: mdl-38959792

ABSTRACT

Side streams from milling result in significant food wastage. While highly nutritious, their harmful elements raise concerns. To repurpose these side streams safely, this study designed a dry fractionation technique for anthocyanin-rich purple bread wheat. Four fractions - from inner to outer layers: flour, middlings, shorts and bran - alongside whole-wheat flour were obtained and examined by microstructure, antioxidant activity, anthocyanin profiles, and essential and harmful minerals. Across the four investigated cultivars, both anthocyanin content and antioxidant capacity increased from inner to outer layers. In comparison to flour, cyanidin-3-glucoside concentrations in middlings, shorts and bran were 2-5 times, 3-9 times, and 6-19 times, respectively. Concentrations of Cr, Ni, Sr and Ba progressively increased from inner to outer layers, Pb and Se exhibited uniform distribution, while Al was more concentrated in inner layers. These findings indicate that the fractionation technique is effective in deriving valuable ingredients from underexploited side streams, especially bran.

11.
J Gen Fam Med ; 25(4): 206-213, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38966654

ABSTRACT

Background: We aimed to aid the appropriate use of antimicrobial agents by determining the timing of secondary bacteremia and validating and updating clinical prediction models for bacteremia in patients with COVID-19. Methods: We performed a retrospective cohort study on all hospitalized patients diagnosed with COVID-19 who underwent blood culture tests from January 1, 2020, and September 30, 2021, at an urban teaching hospital in Japan. The primary outcome measure was secondary bacteremia in patients with COVID-19. Results: Of the 507 patients hospitalized with COVID-19, 169 underwent blood culture tests. Eleven of them had secondary bacteremia. The majority of secondary bacteremia occurred on or later than the 9th day after symptom onset. Positive blood culture samples collected on day 9 or later after disease onset had an odds ratio of 22.4 (95% CI 2.76-181.2, p < 0.001) compared with those collected less than 9 days after onset. The area under the receiver operating characteristic curve of the modified Shapiro rule combined with blood culture collection on or after the 9th day from onset was 0.919 (95% CI, 0.843-0.995), and the net benefit was high according to the decision curve analysis. Conclusions: The timings of symptom onset and hospital admission may be valuable indicators for making a clinical decision to perform blood cultures in patients hospitalized with COVID-19.

12.
Cortex ; 178: 91-103, 2024 Jul 01.
Article in English | MEDLINE | ID: mdl-38986277

ABSTRACT

In a sentence reading ERP study in Swedish we investigated the roles of the N400 and P600 components. By manipulating ease of lexical retrieval and discourse integration of the critical words in four conditions (contextually primed/non-primed and degree of contextual fit), we explored these components from a sentence processing perspective. The results indicate that the N400 indexes lexical retrieval and access of stored conceptual knowledge, whereas the P600 component indexes pragmatic processes, such as integration of a word into the discourse context, or the information structural status of the word. The results support single-stream models of sentence processing where lexical retrieval and integration do not take place in parallel, as in multi-stream models.

13.
Sci Total Environ ; : 174597, 2024 Jul 08.
Article in English | MEDLINE | ID: mdl-38986691

ABSTRACT

The spatial pattern of toxic metals plays a major role in watershed diffuse metal non-point source pollution, particularly during stream sediment transportation at hills mines. This study investigated a typical hilly mine area to quantitatively analyze the characteristics, sensitivities, and influencing factors of toxic elements transported in stream sediments through field research and Geodetector models. The results showed that the spatial patterns of toxic elements in stream sediment transportation at the hills mine area were significantly influenced by water erosion and sulfate. Water erosion and sulfate promoted the transport differences of stream sediment metals from upstream to downstream at the hills mine area. Arsenic, cadmium, mercury, and antimony in the stream sediments at the hills mine exhibited higher coefficients of variation (101 % to 397 %) than those in plain and basin topographies. Potential ecological risks of arsenic and cadmium were assessed as high-risk levels, at 19 % and 64 %, respectively. Metal import in the midstream sediments of the hills mine area was accelerated by strong water erosion. Sulfate and dissolved organic matter (DOM) were highly enriched in stream sediments, with sulfate showing a strong correlation with toxic metals (24 %). Positive responses were observed between arsenic, mercury, antimony, and sulfate in sediments, with sensitivities of 41 %, 25 %, and 16 %, respectively, while cadmium was associated with DOM, with a sensitivity of 46 %. Importantly, water erosion interactions with functional type of mine significantly influenced on the spatial transportation patterns of toxic metals in stream sediments. The interactive influences of sulfate combined with bicarbonate on arsenic, mercury, and antimony and bicarbonate combined with DOM on cadmium were enhanced compared to individual factors (>20 %). This study elucidates the spatial patterns of metals during stream sediment transportation in hills mine and offers the novel insights for developing effective watershed metal management strategies in hilly mine environments.

14.
Microbiol Resour Announc ; : e0113023, 2024 Jul 11.
Article in English | MEDLINE | ID: mdl-38990023

ABSTRACT

Sediments in cryoconite holes and meltwater streams in the McMurdo Dry Valleys, Antarctica, provide both substrates and conditions that support life in an arid polar desert. Here, we report the genomic sequences of eight environmental, bacterial isolates from Canada Glacier cryoconite holes and stream. These isolates span three major phyla.

15.
Environ Pollut ; : 124362, 2024 Jun 20.
Article in English | MEDLINE | ID: mdl-38908675

ABSTRACT

Streams and tributaries can play a significant role in the transport of inland microplastics to rivers and oceans; however, research on microplastics in these water bodies is limited compared to riverine and marine environments. Analyzing microplastic abundance at higher spatial and temporal resolutions is crucial to comprehend the dynamics of microplastics in these water bodies. Therefore, this study investigated year-round spatiotemporal variations of microplastics monthly in surface waters and sediments along the Jungnang Stream, one of the main tributaries to the Han River in South Korea. The mean concentration of microplastics in the stream was 9.8 ± 7.9 particles L-1 in water and 3640 ± 1620 particles kg-1 in sediment. Microplastic concentrations in surface waters during summer were significantly higher than in other seasons, positively linked to increased precipitation and river discharges. Polymer compositions mainly consisted of polyethylene, polypropylene, and polyethylene terephthalate, with the majority of microplastics detected smaller than 200 µm. Fragment-shaped microplastics were predominant over fibrous ones. The estimated annual input and output of microplastics through surface waters were 1.2 to 207 kg (2.7 - 150 billion particles) and 11.3 - 272 kg (17 - 769 billion particles), with the summer months contributing more than 70% of the total output. The greater microplastics output in the Jungnang Stream's waters compared to its receiving waters (Han River) indicates microplastics transport from water to other environmental compartments, such as sediments. These findings highlight the importance of investigating microplastic abundances in surface waters and sediments with temporal resolution, at least across different seasons. Such investigations offer valuable insights into the spatiotemporal occurrence and dynamic transport of microplastics, providing essential information for water management and the development of policies in freshwater ecosystems.

16.
Sensors (Basel) ; 24(11)2024 Jun 04.
Article in English | MEDLINE | ID: mdl-38894423

ABSTRACT

Gesture recognition using electromyography (EMG) signals has prevailed recently in the field of human-computer interactions for controlling intelligent prosthetics. Currently, machine learning and deep learning are the two most commonly employed methods for classifying hand gestures. Despite traditional machine learning methods already achieving impressive performance, it is still a huge amount of work to carry out feature extraction manually. The existing deep learning methods utilize complex neural network architectures to achieve higher accuracy, which will suffer from overfitting, insufficient adaptability, and low recognition accuracy. To improve the existing phenomenon, a novel lightweight model named dual stream LSTM feature fusion classifier is proposed based on the concatenation of five time-domain features of EMG signals and raw data, which are both processed with one-dimensional convolutional neural networks and LSTM layers to carry out the classification. The proposed method can effectively capture global features of EMG signals using a simple architecture, which means less computational cost. An experiment is conducted on a public DB1 dataset with 52 gestures, and each of the 27 subjects repeats every gesture 10 times. The accuracy rate achieved by the model is 89.66%, which is comparable to that achieved by more complex deep learning neural networks, and the inference time for each gesture is 87.6 ms, which can also be implied in a real-time control system. The proposed model is validated using a subject-wise experiment on 10 out of the 40 subjects in the DB2 dataset, achieving a mean accuracy of 91.74%. This is illustrated by its ability to fuse time-domain features and raw data to extract more effective information from the sEMG signal and select an appropriate, efficient, lightweight network to enhance the recognition results.


Subject(s)
Deep Learning , Electromyography , Gestures , Neural Networks, Computer , Electromyography/methods , Humans , Signal Processing, Computer-Assisted , Pattern Recognition, Automated/methods , Algorithms , Machine Learning , Hand/physiology , Memory, Short-Term/physiology
17.
Ecol Evol ; 14(6): e11539, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38895578

ABSTRACT

While macroinvertebrate dispersal operates at the individual level, predictions of their dispersal capabilities often rely on indirect proxies rather than direct measurements. To gain insight into the dispersal of individual specimens, it is crucial to mark (label) and capture individuals. Isotopic enrichment with 15N is a non-invasive method with the potential of labelling large quantities of macroinvertebrates. While the analysis of 15N is widely utilised in food web studies, knowledge on the specific utility of isotopic enrichment with 15N for mass labelling of macroinvertebrate individuals across different taxa and feeding types is limited. Previous studies have focused on single species and feeding types, leaving gaps in our understanding of the broader applicability of this method. Therefore, this study aimed to test and compare isotopic mass enrichment across several macroinvertebrate taxa and feeding types. We released 15NH4Cl at five stream reaches in North-Rhine Westphalia, Germany, and successfully enriched 12 distinct macroinvertebrate taxa (Crustacea and Insecta). Significant enrichment was achieved in active and passive filter feeders, grazers, shredders and predators, and predominantly showed positive correlations with the enrichment of the taxa's main food sources phytobenthos and particulate organic matter. Enrichment levels rose rapidly and peaked at distances between 50 m and 300 m downstream of the isotopic inlet; significant enrichment occurred up to 2000 m downstream of the isotopic inlet in all feeding types. Macroinvertebrate density estimates on the stream bottom averaged to a total of approximately 3.4 million labelled individuals of the 12 investigated taxa, thus showing the high potential of isotopic (15N) enrichment as a non-invasive method applicable for mass labelling across different macroinvertebrate feeding types. Hence, isotopic enrichment can greatly assist the analysis of macroinvertebrate dispersal through mark-and-recapture experiments, as it allows to measure the movement at the level of individual specimens.

18.
Sci Total Environ ; 943: 173807, 2024 Sep 15.
Article in English | MEDLINE | ID: mdl-38852873

ABSTRACT

There is growing concern about the rising levels of dissolved organic matter (DOM) in surface waters across the Northern hemisphere. However, only limited research has been conducted to unveil its precise origin. Compositional changes along terrestrial-aquatic pathways can help determine the terrestrial sources of DOM in streams. Stream water, soil water and soil horizons were sampled at four sites representing typical settings within a forested catchment in the Ore Mountains (Erzgebirge, Germany) from winter 2020 to spring 2022. The samples were analyzed using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The resulting data were successfully subjected to semi-automatic processing of the molecular composition of DOM, reaching a percentage of identified peaks up to 98 %. Principal component analysis (PCA) and cluster analyses were carried out to identify distinct differences between DOM from the potential sources and in the streams. According to the PCA, organic soil horizons, soil water, and stream water samples could be clearly distinguished. Cluster analysis revealed that soil water DOM at all depths of Peats and deeper horizons of the Peaty Gleysols contributed the most to DOM in the stream section dominated by organic soils. In areas dominated by mineral soils, stream DOM resembled the DOM from the deeper mineral horizons of Cambisols and Podzols. Overall, our results suggested that most of the DOM exported from the catchment was derived from deeper mineral soil horizons, with little contribution of DOM derived from organic soils. Therefore, DOM fingerprint analysis of in-situ soil water proved to be a promising approach for tracing back the main sources of stream water DOM.

19.
J Environ Health Sci Eng ; 22(1): 271-279, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38887755

ABSTRACT

Adsorption of heavy metals on stream sediments has important implications for the fate and transport of contaminants in subsurface ecosystems. Lead (Pb) is a potentially hazardous heavy metal that is found in high amounts in anthropogenic environments, especially aquatic ecosystems. The key mechanisms for distributing this metal in the environment are adsorption and desorption in stream to sediment, and vice versa. Therefore, this work is mainly focused on the study of the influence of amorphous Fe/Al-oxyhydroxides and soil organic matter (SOM) on the adsorption of Pb onto natural stream sediment. Spiking adsorption experiments were carried out with four types of samples namely, untreated dried sediment, Fe/Al-oxyhydroxides depleted sediment, SOM depleted sediment and both Fe/Al as well as SOM depleted sediment in the pH range of 3.0 to 8.0. The results showed that Pb adsorption was reduced by up to 45% in amorphous Fe/Al-oxyhydroxide depleted sediment at pH 4.0 to 6.0, whereas a similar adsorption reduction was observed in SOM depleted sediment at pH 6.5 to 7.5. Maximum Pb adsorption was reduced by up to 75% in both amorphous Fe/Al-oxyhydroxides and SOM depleted sediment samples at pH ranges ranging from 3.0 to 7.0. Furthermore, it was shown that SOM was most significant at pH 6.5, while Fe/Al-oxyhydroxides were more important when pH was > 6.5 for the Pb adsorption in natural stream sediment.

20.
Sci Total Environ ; 943: 173669, 2024 Sep 15.
Article in English | MEDLINE | ID: mdl-38839005

ABSTRACT

A multitude of anthropogenic stressors impact biological communities and ecosystem processes in urban streams. Prominent among them are salinization, increased temperature, and altered flow regimes, all of which can affect microbial decomposer communities and litter decomposition, a fundamental ecosystem process in streams. Impairments caused by these stressors individually or in combination and recovery of communities and ecosystem processes after release from these stressors are not well understood. To improve our understanding of multiple stressors impacts we performed an outdoor stream mesocosm experiment with 64 experimental units to assess the response of microbial litter decomposers and decomposition. The three stressors we applied in a full-factorial design were increased salinity (NaCl addition, 0.53 mS cm-1 above ambient), elevated temperature (3.5 °C above ambient), and reduced flow velocity (3.5 vs 14.2 cm s-1). After two weeks of stressor exposure (first sampling) and two subsequent weeks of recovery (second sampling), we determined leaf-associated microbial respiration, fungal biomass, and the sporulation activity and community composition of aquatic hyphomycetes in addition to decomposition rates of black alder (Alnus glutinosa) leaves confined in fine-mesh litter bags. Microbial colonization of the litter was accompanied by significant mass loss in all mesocosms. However, there was little indication that mass loss, microbial respiration, fungal biomass, sporulation rate or community composition of aquatic hyphomycetes was strongly affected by either single stressors or their interactions. Two exceptions were temperature effects on sporulation and decomposition rate. Similarly, no notable differences among mesocosms were observed after the recovery phase. These results suggest that microbial decomposers and leaf litter decomposition are either barely impaired by exposure to the tested stressors at the levels applied in our experiment, or that communities in restored urban streams are well adapted to cope with these stressor levels.


Subject(s)
Rivers , Salinity , Rivers/chemistry , Rivers/microbiology , Biodegradation, Environmental , Ecosystem , Plant Leaves , Alnus , Temperature , Environmental Monitoring
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