Enhancing machine learning models for total organic carbon prediction by integrating geospatial parameters in river watersheds.

This study utilizes machine learning (ML) algorithms to develop a robust total organic carbon (TOC) prediction model for river waters in the Geumho River sub-basins, South Korea, considering both non-rain and rain events. The model incorporates geospatial parameters such as land use, slope, flow rate, and basic water quality metrics including biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and suspended solids (SS). A key aspect of this research is examining how land use information enhances the model's predictive accuracy. We compared two ML algorithms-extreme gradient boosting (XGBoost) and deep neural networks (DNN)-with a traditional multiple linear regression (MLR) approach. XGBoost outperformed the others, achieving an R2 value between 0.61 and 0.68 in the test dataset and demonstrating significant improvement during rain events with an R2 of 0.77 when including land use data. In contrast, this enhancement was not observed with the MLR model. Feature importance analysis using Shapley values highlighted COD as the primary predictor for non-rain events, while during rain events, COD, TP, TN, SS and agricultural land collectively influenced TOC levels. This study significantly advances understanding of TOC variability across different land use scenarios in river systems and underscores the importance of integrating geospatial and water quality parameters to enhance TOC prediction, particularly during rain events. This methodology provides a valuable framework for developing river management strategies and monitoring long-term TOC trends, especially in scenarios with gaps in essential monitoring data.

Quantitative source tracking for organic foulants in ultrafiltration membrane using stable isotope probing approach.

Quantitatively identifying the primary sources of organic membrane fouling is essential for the effective implementation of membrane technology and optimal water resource management prior to the treatment. This study leveraged carbon stable isotope tracers to estimate the quantitative contributions of various organic sources to membrane fouling in an ultrafiltration system. Effluent organic matter (EfOM) and aquatic natural organic matter (NOM), two common sources, were combined in five different proportions to evaluate their mixed effects on flux decline and the consequent fouling behaviors. Generally, biopolymer (BP) and low molecular weight neutral (LMWN) size fractions - abundantly present in EfOM - were identified as significant contributors to reversible and irreversible fouling, respectively. Fluorescence spectroscopy disclosed that a protein-like component notably influenced overall membrane fouling, whereas humic-like components were predominantly responsible for irreversible fouling rather than reversible fouling. Fluorescence index (FI) and biological index (BIX), common fluorescence source tracers, showed promise in determining the source contribution for reversible foulants. However, these optical indices were insufficient in accurately determining individual source contributions to irreversible fouling, resulting in inconsistencies with the observed hydraulic analysis. Conversely, applying a carbon stable isotope-based mixing model yielded reasonable estimates for all membrane fouling. The contribution of EfOM surpassed 60 % for reversible fouling and increased with its content in DOM source mixtures. In contrast, aquatic NOM dominated irreversible fouling, contributing over 85 %, regardless of the source mixing ratios. This study emphasizes the potential of stable isotope techniques in accurately estimating the contributions of different organic matter sources to both reversible and irreversible membrane fouling.

Separately tracking the sources of hydrophobic and hydrophilic dissolved organic matter during a storm event in an agricultural watershed.

The hydrophobicity of dissolved organic matter (DOM) affects various aspects of its environmental impacts in terms of water quality, sorption behaviors, interactions with other pollutants, and water treatment efficiency. In this study, source tracking of river DOM was conducted separately for hydrophobic acid (HoA-DOM) and hydrophilic (Hi-DOM) fractions using end-member mixing analysis (EMMA) in an agricultural watershed during a storm event. EMMA with optical indices of bulk DOM revealed larger contributions of soil (24 %), compost (28 %), and wastewater effluent (23 %) to riverine DOM under high versus low flow conditions. Molecular level analysis of bulk DOM revealed more dynamic features, showing an abundance of CHO and CHOS formulae in riverine DOM under high- and low flow conditions. CHO formulae originated from soil (78 %) and leaves (75 %) and contributed to the increasing CHO abundance during the storm event, whereas CHOS formulae likely originated from compost (48 %) and wastewater effluent (41 %). The characterization of bulk DOM at the molecular level demonstrated that soil and leaves are the dominant contributors for the high-flow samples. However, in contrast to the results of bulk DOM analysis, EMMA with HoA-DOM and Hi-DOM revealed major contributions from manure (37 %) and leaf DOM (48 %) during storm events, respectively. The results of this study highlight the importance of individual source tracking of HoA-DOM and Hi-DOM for the proper evaluation of the ultimate roles of DOM in affecting river water quality and for a better understanding of DOM dynamics and transformation in natural and engineered systems.

Importance of detection of capitellar cartilage injuries concomitant with isolated radial head fractures: A retrospective clinical study.

OBJECTIVE: This study aimed to analyze the injury pattern and clinical importance of concomitant capitellar cartilage defects (CCDs) among patients treated surgically for radial head fracture (RHF). METHODS: A total of 74 patients who were treated surgically for isolated RHFs were retrospectively reviewed. Of these, 12 patients with CCDs (16.2%) were classified as Group I (10 men; mean age, 41.3±12.8 years) and the remaining 62 patients without CCD as Group II (control group) (48 men; mean age, 50.8±13 years). The mean follow-up was 21.3±3.2 months in Group I and 18.7±6.4 in Group II. In Group I, 11 patients underwent open reduction and internal fixation, whereas 1 patient was treated by radial head resection. The preoperative range of motion (ROM) was recorded; the severity of RHF was assessed using the Mason classification. The location, size, and thickness of CCD injuries at the time of surgery were also documented. At the final follow-up, radiological assessment was performed to determine the bone union, and clinical measurements, including ROM and the Mayo elbow performance score (MEPS), were performed. The clinical features of the 2 groups were statistically analyzed. RESULTS: In Group I, 10 patients showed limited forearm rotation. CCD was located posterolaterally in 11 patients and anterolaterally in 1 patient. At the final follow-up, 11 patients from Group I who underwent open reduction and internal fixation showed complete union of RHF and full recovery of pronation and supination. According to the MEPS, 9 patients exhibited excellent results, and 3 patients exhibited good results. In Group I, RHFs were classified as Mason type II in 7 patients (58.3%) and type III in 4 patients (58.3%). In Group II, RHFs were type II in 45 patients (72.6%) and type III in 17 patients (27.4%). In comparative analyses, there was a significant difference in age (41.3±12.8 versus 50.8±13.0, p=0.041) between the 2 groups. Preoperative pronation/supination was higher in Group II (131.7±36.2) than in Group I (106.3±31.6) (p=0.021). There were no significant differences in sex (p=0.097), follow-up period (p=0.326), Mason type (p=0.482), preoperative extension/flexion (102.3±43.3 [Group I] versus 107.6±44.9 [Group II]) (p=0.584), final follow-up extension/flexion (133.3±10.7 [Group I] versus 126.9±21.2 [Group II]) (p=0.384), pronation/supination (151.2±9.1 [Group I] versus 151.2±13.3 [Group II]) (p=0.558), and the MEPSs (92.9±6.6 [Group I] versus 93.3±7.5 [Group II]) (p=0.701). CONCLUSION: If a thorough physical examination of a patient with RHF reveals limited forearm rotation, effort must be made to identify the cause, and the possibility of CCD must be considered. Moreover, there is a need for careful observation during RHF surgery for not only fracture reduction or fixation but also possible CCD. LEVEL OF EVIDENCE: Level III, Therapeutic Study.

Treatment of unusual locked posterior fracture-dislocation of the shoulder: a case series.

BACKGROUND: Locked posterior fracture-dislocation of the shoulder (LPFDS) is a very rare injury that occurs predominantly in young patients following high-energy trauma. The long-term outcome of the treatment of this injury is often poor. This study sought to present the characteristics of injury, discuss the pathological anatomy, and to report the treatment outcomes of our case series. METHODS: Between January 2012 and May 2018, a total of 234 patients who underwent surgical treatment for proximal humerus fractures were reviewed. Among them, six patients (mean age, 54.7 years; range, 35-76 years) with LPFDS were included in this study. Four patients were treated with open reduction and internal fixation (ORIF) with locking plates, one with hemiarthroplasty, and one with reverse total shoulder arthroplasty. Clinical results were evaluated by Constant, American Shoulder and Elbow Surgeons (ASES), and visual analog scale (VAS) scores and radiologic evaluation was conducted using follow-up radiographs. RESULTS: The mean length of follow-up was 26.2 months (range, 12-54). The mean Constant, ASES, and VAS scores were 66.7, 65.5, and 2.2, respectively. Four patients who underwent ORIF achieved bony union, but avascular necrosis (AVN) of the humeral head was observed in two patients. No complications were observed in the patients who underwent arthroplasty surgery until final follow-up. CONCLUSIONS: In the treatment of LPFDS, replacement arthroplasty can produce predictable results. The approach of ORIF may be considered as a first choice of treatment in young patients but is sometimes correlated with postoperative complications such as AVN and the functional outcomes may be unpredictable. Therefore, patients should undergo careful diagnosis and treatment of this type of injury.