Environmental Science: Processes & Impacts最新文献

{"title":"A review on environmental contamination of petroleum hydrocarbons, its effects and remediation approaches","authors":"Bzhwen Khalid Majeed, Dler M.S Shwan and Khasraw Abdullah Rashid","doi":"10.1039/D4EM00548A","DOIUrl":"10.1039/D4EM00548A","url":null,"abstract":"<p >Oil leakage into soil is a major environmental concern, affecting its physical, chemical, biological, and geotechnical properties, which threatens soil fertility. Remediating contaminated sites helps mitigate risks to human health, the environment, and the economy, while also enabling land reuse for development or agriculture. Petroleum spills generally occur during production, processing, transportation, and storage. This review discusses the impact of hydrocarbon contamination on soil and its surrounding environment and examines various remediation techniques, including physical–chemical methods (soil excavation, soil washing, soil vapor extraction, thermal treatment, and chemical oxidation), biological methods (bioremediation and phytoremediation), nanotechnology-based approaches, and integrated methods. The effectiveness, limitations, and applicability of these techniques are critically analyzed, providing a comprehensive framework for managing soil contamination by petroleum hydrocarbons.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" 3","pages":" 526-548"},"PeriodicalIF":4.3,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143412444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal effect of PM_2.5 exposure in patients with COPD: a multicentre panel study.","authors":"Jin-Young Huh, Hajeong Kim, Shinhee Park, Seung Won Ra, Sung-Yoon Kang, Bock Hyun Jung, Mihye Kim, Sang Min Lee, Sang Pyo Lee, Dirga Kumar Lamichhane, Young-Jun Park, Seon-Jin Lee, Jae Seung Lee, Yeon-Mok Oh, Hwan-Cheol Kim, Sei Won Lee","doi":"10.1039/d4em00376d","DOIUrl":"https://doi.org/10.1039/d4em00376d","url":null,"abstract":"<p><p><i>Background</i>: Exposure to particulate matter <2.5 μm (PM_2.5) is linked to chronic obstructive pulmonary disease (COPD), but most studies lack individual PM_2.5 measurements. Seasonal variation and their impact on clinical outcomes remain understudied. <i>Objective</i>: This study investigated the impact of PM_2.5 concentrations on COPD-related clinical outcomes and their seasonal changes. <i>Methods</i>: A multicentre panel study enrolled 105 COPD patients (age range: 46-82) from July 2019 to August 2020. Their mean forced expiratory volume in 1 second after bronchodilation was 53.9%. Individual PM_2.5 levels were monitored continuously with indoor measurements at residences and outdoor data from the National Ambient Air Quality Monitoring Information System. Clinical parameters, including pulmonary function tests, symptom questionnaires (CAT and SGRQ-C), and impulse oscillometry (IOS), were assessed every three months over the course of one year. Statistical analysis was conducted using a linear mixed-effect model to account for repeated measurements and control for confounding variables, including age, sex, smoking status and socioeconomic status. <i>Results</i>: The mean indoor and outdoor PM_2.5 concentrations were 16.2 ± 8.4 μg m^-3 and 17.2 ± 5.0 μg m^-3, respectively. Winter had the highest PM_2.5 concentrations (indoor, 18.8 ± 11.7 μg m³; outdoor, 22.5 ± 5.0 μg m^-3). Higher PM_2.5 concentrations significantly correlated with poorer St. George's Respiratory Questionnaire for COPD (SGRQ-C) scores and increased acute exacerbations, particularly in winter. Patients of lower socioeconomic status were more vulnerable. Increased PM_2.5 concentrations were also associated with amplified small airway resistance (<i>R</i>5-<i>R</i>20). <i>Conclusions</i>: PM_2.5 concentration changes are positively correlated with poorer SGRQ-C scores and increased acute exacerbations in COPD patients with significant seasonal variations, especially in winter.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142913256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photodegradation of typical psychotropic drugs in the aquatic environment: a critical review","authors":"Chuanguang Wang, Ruonan Guo, Changsheng Guo, Hailong Yin and Jian Xu","doi":"10.1039/D4EM00669K","DOIUrl":"10.1039/D4EM00669K","url":null,"abstract":"<p >Continuous consumption combined with incomplete removal during wastewater treatment means residues of psychotropic drugs (PDs), including antidepressants, antipsychotics, antiepileptics and illicit drugs, are continuously entering the aquatic environment, where they have the potential to affect non-target organisms. Photochemical transformation is an important aspect to consider when evaluating the environmental persistence of PDs, particularly for those present in sunlit surface waters. This review summarizes the latest research on the photodegradation of typical PDs under environmentally relevant conditions. According to the analysis results, four classes of PDs discussed in this paper are influenced by direct and indirect photolysis. Indirect photodegradation has been more extensively studied for antidepressants and antiepileptics compared to antipsychotics and illicit drugs. Particularly, the photosensitization process of dissolved organic materials (DOM) in natural waters has received significant research attention due to its ubiquity and specificity. The direct photolysis pathway plays a less significant role, but it is still relevant for most PDs discussed in this paper. The photodegradation rates and pathways of PDs are influenced by various water constituents and parameters such as DOM, nitrate and pH value. The contradictory results reported in some studies can be attributed to differences in experimental conditions. Based on this analysis of the existing literature, the review also identifies several key aspects that warrant further research on PD photodegradation. These results and recommendations contribute to a better understanding of the environmental role of water matrixes and provide important new insights into the photochemical fate of PDs in aquatic environments.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" 2","pages":" 320-354"},"PeriodicalIF":4.3,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Environmental impact of an acid-forming alum shale waste rock legacy site in Norway†","authors":"Mila K. Pelkonen, Estela Reinoso-Maset, Gareth T. W. Law, Ole Christian Lind and Lindis Skipperud","doi":"10.1039/D4EM00298A","DOIUrl":"10.1039/D4EM00298A","url":null,"abstract":"<p >Alum shale formations in Scandinavia are generally enriched in uranium (U) and, when exposed to air and water, may produce acidic rock drainage (ARD), releasing potentially harmful elements into the environment. Taraldrud is a legacy site in southeast Norway where approx. 51 000 m<small>³</small> of alum shale was deposited in the 1980s–1990s. In 2006, ARD formation became obvious after high concentrations of leachable elements and low environmental pH were measured in a nearby stream. A manmade precipitation pond and liming treatments attempt to address the environmental pollution, but the site remains non-remediated. This study aimed to evaluate the extent of contamination caused by ARD and examine environmental and human health risks caused by mobilized trace elements and radionuclides. Surface water, sediment, soil, and biota samples were collected in the area and chemically and/or radiochemically analyzed to assess the prevailing concentrations within different environmental compartments. The elemental distribution and variation patterns were studied using principal component analysis. Most of the leachable elements were present in highly mobile and bioavailable forms in the pond water, out of which Cd, Mn, Ni, and U exceeded drinking water regulations. The highest enrichment in soil and sediment was for U, which was associated with the sulfide-bearing soil fraction, Fe, Cu, Mo, and As. No changes in water quality were observed between up- and downstream from the site, indicating that the Fe and S rich phases in the pond retain the leachable elements effectively under prevailing environmental conditions. This study provides valuable insights into the risks and challenges associated with ARD and where U is the main pollutant of concern.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" 1","pages":" 225-243"},"PeriodicalIF":4.3,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/em/d4em00298a?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142913253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical characterization of polymer and chloride content in waste plastic materials using pyrolysis – direct analysis in real time – high-resolution mass spectrometry†","authors":"Emily Halpern, Lauren Heirty, Christopher West, Yitao Li, Won M. Kim, Anthony S. Mennito and Alexander Laskin","doi":"10.1039/D4EM00501E","DOIUrl":"10.1039/D4EM00501E","url":null,"abstract":"<p >The increasing global demand for plastic has raised the need for effective waste plastic management due to its long lifetime and resistance to environmental degradation. There is a need for rapid plastic identification to improve the mechanical waste plastic sorting process. This study presents a novel application of Temperature-Programmed Desorption-Direct Analysis in Real Time-High Resolution Mass Spectrometry (TPD-DART-HRMS) that enables rapid characterization of various plastics. This technique was applied on four commercially available reference polymers (polyethylene, polypropylene, polystyrene, polyvinyl chloride) as well as three “waste” plastic samples of mixed origin. These waste plastic samples were obtained as discards from various industrial processes with limited analytical characterization data. Through the application of CH<small>₂</small> Kendrick mass defect (KMD) grouping, characteristic trends in the mass spectra of each sample were identified, allowing for a simplified numerical comparison. This approach utilized a robust statistical approach using the Tanimoto coefficient, allowing for the quantitative measures of similarity between standards and unknown samples. The application of this mathematical evaluation methodology was used to identify plastic types and to distinguish structurally similar polymers. Additionally, we report that a chloride ion clustering effect with copper substrate can identify chlorinated polymer PVC (polyvinyl chloride) utilizing pyro-(−)DART-HRMS mode. PVC polymer is of particular interest in recycling due to its high chloride content, which can present technical challenges for some types of recycling. We found that chloride ion clusters are a good screening marker for the presence of chlorinated polymers in mixed waste plastic samples. This study can possibly help advance rapid and accurate analytical techniques for identifying the composition of waste plastics to advance the effectiveness of the waste plastic sorting process.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" 1","pages":" 104-118"},"PeriodicalIF":4.3,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/em/d4em00501e?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142941677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A mechanistic model for determining factors that influence inorganic nitrogen fate in corn cultivation†","authors":"Patrick J. Dunn and Leanne M. Gilbertson","doi":"10.1039/D4EM00566J","DOIUrl":"10.1039/D4EM00566J","url":null,"abstract":"<p >Conventional practices for inorganic nitrogen fertilizer are highly inefficient leading to excess nitrogen in the environment. Excess environmental nitrogen induces ecological (<em>e.g.</em>, hypoxia, eutrophication) and public health (<em>e.g.</em>, nitrate contaminated drinking water) consequences, motivating adoption of management strategies to improve fertilizer use efficiency. Yet, how to limit the environmental impacts from inorganic nitrogen fertilizer while maintaining crop yields is a persistent challenge. The lack of empirical data on the fate and transport of nitrogen in an agriculture soil-crop system and how transport changes under varying conditions limits our ability to address this challenge. To this end, we developed a mechanistic model to assess how various parameters within a soil-crop system affect where nitrogen goes and inform how we can perturb the system to improve crop nitrogen content while reducing nitrogen emissions to the environment. The model evaluates nitrogen transport and distribution in the soil-corn plant system on a conventional Iowa corn farm. Simulations determine the amount of applied nitrogen fertilizer acquired by the crop root system, leached to groundwater, lost to tile drainage, and denitrified. Through scenario modeling, it was found that reducing application rates from 200 kg ha<small>⁻¹</small> to 160 kg ha<small>⁻¹</small> had limited impact on plant nitrogen content, while decreasing wasted nitrogen fertilizer by 25%. Delayed application until June significantly increased the f-NUE and denitrification while reducing the amount of fertilizer leached and exported through tile drainage. The value in a model like the one presented herein, is the ability to perturb the system through manipulation of variables representative of a specific scenario of interest to inform how one can improve crop-based nitrogen management.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" 3","pages":" 549-562"},"PeriodicalIF":4.3,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/em/d4em00566j?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142941659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitigating matrix effects in oil and gas wastewater analysis: LC-MS/MS method for ethanolamines†","authors":"Glen Andrew D. de Vera, Loredana Caldiero, Giovanni Conte and Desirée L. Plata","doi":"10.1039/D4EM00716F","DOIUrl":"10.1039/D4EM00716F","url":null,"abstract":"<p >The high salinity and organic content in oil and gas wastewaters can cause ion suppression during liquid chromatography mass spectrometry (LC/MS) analysis, diminishing the sensitivity and accuracy of measurements in available methods. This suppression is severe for low molecular weight organic compounds such as ethanolamines (<em>e.g.</em>, monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), <em>N</em>-methyldiethanolamine (MDEA), and <em>N</em>,<em>N</em>-ethyldiethanolamine (EDEA)). Here, we deployed solid phase extraction (SPE), mixed-mode LC, triple quadrupole MS with positive electrospray ionization (ESI), and a suite of stable isotope standards (<em>i.e.</em>, one per target compound) to correct for ion suppression by salts and organic matter, SPE losses, and instrument variability. The method was evaluated in produced water samples from Italy (NaCl salinity from 8110–18 100 mg L<small>⁻¹</small>; diesel range organic compounds ranging from 5.1–7.9 mg L<small>⁻¹</small>). After correcting for matrix effects, ethanolamines in produced water samples were quantified. The first batch of samples (March 2019) had 37–646 μg L<small>⁻¹</small> total ethanolamines. The second batch of samples (September 2019) had greater ethanolamine content of 77–3976 μg L<small>⁻¹</small> which was attributed to a reduced water cut during oil production, enhancing the proportionate abundance of these compounds in the aqueous phase. In all samples, DEA and MEA were the dominant ethanolamine species. Possible sources (<em>e.g.</em>, corrosion inhibitor and biotransformation) and natural attenuation potential during storage (<em>e.g.</em>, at different temperatures, acidification, and addition of sodium azide) were investigated. The developed analytical method enables further investigation of the fate of low molecular weight organic additives in oil and gas development and provides an enhanced ability to evaluate risks associated with chemical release to the environment.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" 2","pages":" 412-422"},"PeriodicalIF":4.3,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2025/em/d4em00716f?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142976926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reversible and irreversible retention of heavy metals in saturated porous media: association with kaolin","authors":"Yan Liang, Erxiao Jiang, Hui Tang, Qiuyu Luo, Pengcheng Dong and Tian Xie","doi":"10.1039/D4EM00372A","DOIUrl":"10.1039/D4EM00372A","url":null,"abstract":"<p >Contamination of heavy metals (HMs) has caused increasing concern due to their ecological toxicities and difficulties in degradation. The transport, retention, and release of HMs in porous media are highly related to their environmental fate and risk to groundwater. Column transport experiments and numerical simulations were conducted to investigate the retention and release behaviors of Cu<small>²⁺</small>, Pb<small>²⁺</small>, Cd<small>²⁺</small>, and Zn<small>²⁺</small> in the presence and absence of kaolin under varying ionic strengths and cation types. The interaction between HMs and soil colloids is critical to these processes, yet it remains poorly understood. In both single and multi-metal systems, the mobility of HMs ranked as Cd<small>²⁺</small> &gt; Zn<small>²⁺</small> &gt; Cu<small>²⁺</small> &gt; Pb<small>²⁺</small>, is influenced by their hydrolysis ability. Multi-metal systems showed higher mobility due to competition for retention sites, and Ca<small>²⁺</small> enhanced transport more than Na<small>⁺</small> due to greater affinity to the sand surface. Kaolin reduced HM transport by adsorption and led to irreversible retention. Cation exchange (Na<small>⁺</small> replacing Ca<small>²⁺</small>) followed by reduced ionic strength promoted HM release due to the remobilization of kaolin associated with HMs. Uniform, nonmonotonic, and exponential retention profiles indicated variations in the spatial distribution of HMs. The Pb<small>²⁺</small> and Cu<small>²⁺</small> were more retained near the column inlet than Cd<small>²⁺</small> and Zn<small>²⁺</small>, indicating limited mobility in the deep subsurface. Numerical simulations well described HM transport, considering the adsorption and desorption of HMs and the solid–water interface. These results enhance understanding of HM fate in terrestrial environments.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" 3","pages":" 586-596"},"PeriodicalIF":4.3,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142880738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Speciating volatile organic compounds in indoor air: using <i>in situ</i> GC to interpret real-time PTR-MS signals.","authors":"Jenna C Ditto, Han N Huynh, Jie Yu, Michael F Link, Dustin Poppendieck, Megan S Claflin, Marina E Vance, Delphine K Farmer, Arthur W H Chan, Jonathan P D Abbatt","doi":"10.1039/d4em00602j","DOIUrl":"https://doi.org/10.1039/d4em00602j","url":null,"abstract":"<p><p>Proton transfer reaction mass spectrometry (PTR-MS) is often employed to characterize gas-phase compounds in both indoor and outdoor environments. PTR-MS measurements are usually made without upstream chromatographic separation, so it can be challenging to differentiate between an ion of interest, its isomers, and fragmentation products from other species all detected at the same mass-to-charge ratio. These isomeric contributions and fragmentation interferences can confound the determination of accurate compound mixing ratios, the assignment of accurate chemical properties, and corresponding analyses of chemical fate. In this study, we deployed a gas chromatograph upstream of a PTR-MS to investigate contributions of isomers and fragmentation products for select indoor air-relevant chemicals. Measurements were made in a test house across a variety of indoor chemical sources, oxidants, and environmental conditions during the Chemical Assessment of Surfaces and Air (CASA) study. Observed confounding signals at each extracted ion chromatogram ranged from 0% (C₂H₆OH⁺, C₈H₂₄O₄Si₄H⁺, and C₁₀H₃₀O₅Si₅H⁺) to 98% (at C₅H₉⁺). For many ions, confounding signals varied between indoor conditions, and there were also differences between confounding signals across indoor <i>vs.</i> outdoor measurements. The relative contribution of sets of key structural isomers (<i>e.g.</i>, C₆-C₈ carbonyls, xylenes, trimethylbenzenes, and monoterpenes) remained consistent throughout the measurement period despite changing indoor conditions. These relatively stable isomer distributions yielded stable chemical property assignments for these isomer sets. Taken together, these observations can inform future interpretations of PTR-MS signals measured in different indoor conditions without upstream chromatography.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142880740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An in-depth analysis of the impact of environmental drivers on the variability of phytoplankton community in the Arabian Sea during 2010–2021†","authors":"Syed Moosa Ali, Jayanarayanan Kuttippurath, Aswathy Vijaya Krishna, Anurag Gupta, Debojyoti Ganguly, Anjaneyan P, Mini Raman, Arvind Sahay and K. N. Babu","doi":"10.1039/D4EM00385C","DOIUrl":"10.1039/D4EM00385C","url":null,"abstract":"<p >This study examines the long-term changes in phytoplankton size classes (PSCs) in the Arabian Sea (AS) using the remote sensing reflectance (<em>R</em><small>_rs</small>) data collected over 12 years (2010–2021) from the Moderate Resolution Imaging Spectroradiometer (MODIS). The <em>R</em><small>_rs</small> spectra were inverted to chlorophyll-a (Chl-a) concentrations using a non-linear optimisation method, which were then used to estimate the PSC using a region specific three-component model. The analysis is carried out for all four seasons, <em>i.e.</em>, winter (December–February), pre-monsoon (March–May), monsoon (June–September) and post-monsoon (October–November). A machine learning random forest (RF) model is employed to predict the seasonal and long-term variability in PSCs and to quantify the influence of environmental drivers. The seasonal climatology of three size classes – micro (larger), nano (medium-sized), and pico (smaller) – reveals that micro-phytoplankton predominantly occupy the northern AS during winter and pre-monsoon seasons, contributing over 50% to the total Chl-a. During the monsoon season, a significant rise in micro-phytoplankton contribution (60–80%) is noted off the coasts of Somalia, Oman and Kerala due to strong upwelling. In contrast, nano-phytoplankton contributions are minimal during the pre-monsoon season but remain fairly consistent in other seasons, and pico-phytoplankton dominates the oligotrophic waters of the central and southern AS during pre- and post-monsoon. The analysis of PSCs from 2010 to 2021 shows a strong decreasing trend in micro-phytoplankton concentration (−0.13 ± 0.19 mg m<small>⁻³</small> year<small>⁻¹</small>), accompanied by a steady increase in pico-phytoplankton (0.0009 ± 0.0005 mg m<small>⁻³</small> year<small>⁻¹</small>) and nano-phytoplankton (0.001 ± 0.0009 mg m<small>⁻³</small> year<small>⁻¹</small>). To elucidate these long-term trends, RF model was instrumental in identifying key environmental drivers, with sea surface temperature (SST) emerging as the most influential factor affecting pico- and micro-phytoplankton. The feature importance scores for SST are highest during winter and pre-monsoon for both pico-phytoplankton and micro-phytoplankton, underscoring the sensitivity of these classes to temperature changes. RF model also highlights the role of mixed layer depth (MLD) and wind speed (WS) in driving the seasonal shifts in PSCs, particularly during the monsoon and post-monsoon periods. These findings suggest that the rise in SST, coupled with changes in vertical mixing and stratification, drives the shift towards smaller cells, mainly pico-phytoplankton in the AS. This shift towards smaller cells indicates a possible decline in marine food chain efficiency, reduced carbon export rates and declining primary productivity—a real concern for food security in the region.</p>","PeriodicalId":74,"journal":{"name":"Environmental Science: Processes & Impacts","volume":" 2","pages":" 498-512"},"PeriodicalIF":4.3,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143187869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}