Insight into the humification and carbon balance of biogas residual biochar amended co-composting of hog slurry and wheat straw.

The impact of biogas residual biochar (BRB) on the humification and carbon balance process of co-composting of hog slurry (HGS) and wheat straw (WTS) was examined. The 50-day humification process was significantly enhanced by the addition of BRB, particular of 5% BRB, as indicated by the relatively higher humic acid content (67.28 g/kg) and humification ratio (2.31) than other treatments. The carbon balance calculation indicated that although BRB addition increased 22.16-46.77% of C lost in form of CO2-C, but the 5% BRB treatment showed relatively higher C fixation and lower C loss than other treatments. In addition, the BRB addition reshaped the bacterial community structure during composting, resulting in increased abundances of Proteobacteria (25.50%) during the thermophilic phase and Bacteroidetes (33.55%) during the maturation phase. Combined these results with biological mechanism analysis, 5% of BRB was likely an optimal addition for promoting compost humification and carbon fixation in practice.

Potential and benefits of biochar production: crop straw management and carbon emission mitigation in Shaanxi Province, China.

Shaanxi Province is an important agricultural province in western China. Its profit-oriented management of crop residues remains a concern in the agriculture sector. Aiming to accelerate the valorization of agricultural straw and offer potential solutions for profit-oriented use of crop residues in Shaanxi, this study estimated the quantity of resources and collectable amount of crop straw by using the grain-to-straw ratio, analyzed the carbon emission reduction potential considering biochar energy and soil uses with the help of a life cycle assessment (LCA) model, and calculated the economic benefits of biochar production using waste and abandoned straw in Weinan (a city of Shaanxi). The theoretical resources and collectible amount of crop straw in Shaanxi showed an overall growth trend from 1949 to 2021, reaching 1.47 × 107 and 1.26 × 107 t in 2021 respectively. In 2021, straw from corn, wheat, and other grains accounted for 94.32% of the total straw. Among the 11 cities in Shaanxi, Weinan had the largest straw resources of 2.82 × 106 t, Yulin had the largest per capita straw resources of 0.72 t/person, and Yangling had the highest resource density of 7.60 t/hm2. The total carbon emission reduction was 3.11 × 104 t under scenario A with crop straw used for power generation. The emission reduction ranged from 1.25 × 107 to 1.27 × 107 CO2e t under scenario B with biochar production for energy and soil use. By using waste and abandoned straw in Weinan for biochar production, carbon emissions could be reduced by up to 2.07 × 105 t CO2e. In terms of the economic benefit from straw pyrolysis, the actual income was estimated to range from 0.67 × 108 to 1.33 × 108 ¥/a with different carbon prices. This study sheds light on the economic and environmental benefits of agricultural straw valorization through pyrolysis in Shaanxi, and provided an important basis for promoting the agricultural straw utilization in view of its potential for carbon emission reduction.

Microplastics in agricultural soils in China: Sources, impacts and solutions.

The detection of microplastics (MPs) in agricultural soils has raised alarms on their potential impacts on agricultural production, particularly in China where agriculture has great importance for domestic consumption and export. This review aims to present the abundance, sources and impacts of MPs in the agricultural soils of China. It has the novelty of synthesizing sustainable agronomic practices to reduce MPs pollution of agricultural soils based on the sources identified. According to the extant study, the abundance of MPs in the agricultural soils in China ranged from 4.94 items/kg in the lower reaches of Yangtze River to 40,800 items/kg in Yunnan Province. The MPs were predominantly ≤1 mm and were mainly composed of fragments, films and fibers. Polyethylene and polypropylene MPs were most reported. Plastic mulching films were the most significant source of MPs in agricultural soils, followed by abandoned greenhouses and the use of organic fertilizers containing fugitive MPs or whose sources were often MPs-polluted. MPs were found to alter soil physicochemical properties for instance, water flow, water-stable aggregates, soil aggregation, soil pH, bulk density and nutrient contents. MPs also affect soil biota through changing the richness and diversity of soil microbial community while retarding growth and disrupting physiological functions of soil macrofauna. The effects of MPs on crops vary and range from alteration of biomass, metabolism and nutrient demands to impacted photosynthesis. Sustainable solutions include the use of grass clippings - straw mix as organic mulches, the use of compost as soil amendment in conjunction with grass-straw mix and incorporation of weed-suppressing biomass into compost, the use of jute and biodegradable plastics for greenhouses, proper decommissioning of abandoned greenhouses as well as setting standards for allowable MPs contents in organic fertilizers and irrigation water.

Airborne microplastics: Occurrence, sources, fate, risks and mitigation.

This paper serves to enhance the current knowledge base of airborne microplastics which is significantly smaller than that of microplastics in marine, freshwater and terrestrial environments. It systematically presents the prevalence, sources, fate, risks and mitigations of airborne microplastics through the review of >140 scientific papers published mainly in the last 10 years. Unlike the extant review, it places an emphasis on the indoor microplastics, the risks of airborne microplastics on animals and plants and their mitigations. The outdoor microplastics are mostly generated by the wear and tear of tires, brake pads, waste incineration and industrial activities. They have been detected in many regions worldwide at concentrations ranging from 0.3 particles/m3 to 154,000 particles/L of air even in the Pyrenees Mountains and the Arctic. As for indoor microplastics, the reported concentrations range from 1 piece/m3 to 9900 pieces/m2/day, and are frequently higher than those of the outdoor microplastics. They come from the wear and tear of walls and ceilings, synthetic textiles and furniture finishings. Airborne microplastics could be suspended and resuspended, entrapped, settle under gravity as well as interact with chemicals, microorganisms and other microplastic particles. In the outdoors, they could also interact with sunlight and be carried by the wind over long distance. Airborne microplastics could adversely affect plants, animals and humans, leading to reduced photosynthetic rate, retarded growth, oxidative stress, inflammatory responses and increased cancer risks in humans. They could be mitigated indirectly through filters attached to air-conditioning system and directly through source reduction, regulation and biodegradable substitutes.

Impacts of COVID-19 on primary, secondary and tertiary education: a comprehensive review and recommendations for educational practices.

COVID-19 lockdown has caused disruption to education of all levels with far-reaching implications and unveiled the shortfalls of the current education model. Cycles of tightening and relaxation of COVID-19 lockdown confer uncertainty to the continuity of education. This article aims to comprehensively present the impacts of COVID-19 on primary, secondary and tertiary education and propose sound educational practices in the COVID-19 era. Papers related to educational impacts and implications of COVID-19 were selected for this review through a PRISMA model. The review shows that a shift of learning remotely or online has affected educators and learners, especially in relation to learning loss among learners, limitations in instructions, assessment and experiential learning in virtual environment, technology-related constraints, connectivity, learning resources and materials, besides psychosocial well-being. These impacts are exacerbated by inequalities in the distribution of resources as well as inequities attributed to socioeconomic status, gender, ethnicity, learning ability and physical conditions. The recommendations for future educational practices comprise adaptability of curricula to embed independent and online learning options, concurrence of diverse learning modalities for seamless learning transitions and flexibility, flexible staffing and learning model, enhanced support, technological and curricular innovation with simplification and standardization, as well as interactive, responsive and authentic virtual environment. This review contributes significantly to enhance preparedness of education to crisis while ensuring continuity and quality of education in the era of COVID-19 uncertainty.

The application of bioremediation in wastewater treatment plants for microplastics removal: a practical perspective.

Wastewater treatment plants (WWTPs) play the role of intercepting microplastics in the environment and provide a platform for bioremediation to remove microplastics. Despite, this opportunity has not been adequately studied. This paper shows the potential ways microplastics-targeted bioremediation could be incorporated into wastewater treatment through the review of relevant literature on bioaugmentation of water treatment processes for pollutants removal. Having reviewed more than 90 papers in this area, it highlights that bioremediation in WWTPs can be employed through bioaugmentation of secondary biological treatment systems, particularly the aerobic conventional activated sludge, sequencing batch reactor, membrane bioreactor and rotating biological contactor. The efficiency of microplastics removal, however, is influenced by the types and forms of microorganisms used, the polymer types and the incubation time (100% for polycaprolactone with Streptomyces thermoviolaceus and 0.76% for low-density polyethylene with Acinetobacter iwoffii). Bioaugmentation of anaerobic system, though possible, is constrained by comparatively less anaerobic microplastics-degrading microorganisms identified. In tertiary system, bioremediation through biological activated carbon and biological aerated filter can be accomplished and enzymatic membrane reactor can be added to the system for deployment of biocatalysts. During sludge treatment, bioaugmentation and addition of enzymes to composting and anaerobic digestion are potential ways to enhance microplastics breakdown. Limitations of bioremediation in wastewater treatment include longer degradation time of microplastics, incomplete biodegradation, variable efficiency, specific microbial activities and uncertainty in colonization. This paper provides important insight into the practical applications of bioremediation in wastewater treatment for microplastics removal.

Immobilized enzyme/microorganism complexes for degradation of microplastics: A review of recent advances, feasibility and future prospects.

Environmental prevalence of microplastics has prompted the development of novel methods for their removal, one of which involves immobilization of microplastics-degrading enzymes. Various materials including nanomaterials have been studied for this purpose but there is currently a lack of review to present these studies in an organized manner to highlight the advances and feasibility. This article reviewed more than 100 peer-reviewed scholarly papers to elucidate the latest advances in the novel application of immobilized enzyme/microorganism complexes for microplastics degradation, its feasibility and future prospects. This review shows that metal nanoparticle-enzyme complexes improve biodegradation of microplastics in most studies through creating photogenerated radicals to facilitate polymer oxidation, accelerating growth of bacterial consortia for biodegradation, anchoring enzymes and improving their stability, and absorbing water for hydrolysis. In a study, the antimicrobial property of nanoparticles retarded the growth of microorganisms, hence biodegradation. Carbon particle-enzyme complexes enable enzymes to be immobilized on carbon-based support or matrix through covalent bonding, adsorption, entrapment, encapsulation, and a combination of the mechanisms, facilitated by formation of cross-links between enzymes. These complexes were shown to improve microplastics-degrading efficiency and recyclability of enzymes. Other emerging nanoparticles and/or enzymatic technologies are fusion of enzymes with hydrophobins, polymer binding module, peptide and novel nanoparticles. Nonetheless, the enzymes in the complexes present a limiting factor due to limited understanding of the degradation mechanisms. Besides, there is a lack of studies on the degradation of polypropylene and polyvinyl chloride. Genetic bioengineering and metagenomics could provide breakthrough in this area. This review highlights the optimism of using immobilized enzymes/microorganisms to increase the efficiency of microplastics degradation but optimization of enzymatic or microbial activities and synthesis of immobilized enzymes/microorganisms are crucial to overcome the barriers to their wide application.

Bioremediation of perfluorochemicals: current state and the way forward.

Perfluorochemicals are widely found in the environment due to their versatile uses and persistent nature. Perfluorochemicals have also been detected in human and animals due to direct or indirect exposures, giving rise to health concerns. This review aims to examine the bioremediation of perfluorochemicals with plants, bacteria and fungi, including their efficiency and limitations. It also aims to propose the future prospects of bioremediation of perfluorochemicals. This review retrieved peer-reviewed journal articles published between 2010 and 2021 from journal databases consisting of Web of Science, Scopus and ScienceDirect. This review shows that multiple Pseudomonas species could degrade perfluorochemicals particularly perfluoroalkyl acids under aerobic condition. Acidimicrobium sp. degraded perfluoroalkyl acids anaerobically in the presence of electron donors. A mixed Pseudomonas culture was more effective than pure cultures. Multiple plants were found to bioconcentrate perfluorochemicals and many demonstrated the ability to hyperaccumulate perfluoroalkyl acids, particularly Festuca rubra, Salix nigra and Betula nigra. Fungal species, particularly Pseudeurotium sp. and Geomyces sp., have the potential to degrade perfluorooctanoic acid or perfluorooctane sulphonic acid. Perfluorochemicals bioremediation could be advanced with identification of more candidate species for bioremediation, optimization of bioremediation conditions, mixed culturing, experiments with environmental media and studies on the biochemical pathways of biotransformation. This review provides comprehensive insight into the efficiency of different bacterial, plant and fungal species in perfluorochemicals bioremediation under different conditions, their limitations and improvement.

Movement control as an effective measure against Covid-19 spread in Malaysia: an overview.

Aim: The first Covid-19 cases were reported in Malaysia on 25 January 2019 followed by a quiescent period before an upward swing of the cases at the end of February 2020, partly attributed to mass gathering during a religious event. This short communication aims to provide an overview of the measures taken by the Malaysian Government in response to Covid-19, and of the effectiveness of the Movement Control Order. Subjects and methods: This short communication reviews articles and government announcements related to containment measures and the Movement Control Order of Malaysia, and graphically presents data pertinent to Covid-19 in Malaysia in order to show the relationship between fluctuations in Covid-19 cases and movement control. Results: At the onset of the Covid-19 outbreak, Malaysia had initiated travel restrictions and quarantine; but with a persistent increase in new Covid-19 cases, the Movement Control Order was finally rolled out on 18 March 2020, requiring closure of all businesses except those providing essential services and items. Enforcement of the order was tightened progressively, resulting in significant improvement of compliance, while other interventions such as tracking of potential contacts and medical screening were underway, and the media continued to provide updates and general advices. The numbers of new and active Covid-19 cases started showing evident downtrends from mid-April, thus indicating the effectiveness of movement control and its compliance. Conclusion: The article provides insight into crucial factors contributing to the success of movement control to effectively contain Covid-19, and highlights the need to prevent future upsurge through continuous monitoring and enforcement.

Recent advances, current issues and future prospects of bioenergy production: A review.

With the immense potential of bioenergy to drive carbon neutrality and achieve the climate targets of the Paris Agreement, this paper aims to present the recent advances in bioenergy production as well as their limitations. The novelty of this review is that it covers a comprehensive range of strategies in bioenergy production and it provides the future prospects for improvement. This paper reviewed more than 200 peer-reviewed scholarly papers mainly published between 2010 and 2021. Bioenergy is derived from biomass, which, through thermochemical and biochemical processes, is converted into various forms of biofuels. This paper reveals that bioenergy production is temperature-dependent and thermochemical processes currently have the advantage of higher efficiency over biochemical processes in terms of lower response time and higher conversion. However, biochemical processes produce more volatile organic compounds and have lower energy and temperature requirements. The combination of the two processes could fill the shortcomings of a single process. The choices of feedstock are diverse as well. In the future, it can be anticipated that continuous technological development to enhance the commercial viability of different processes, as well as approaches of ensuring their sustainability, will be among the main aspects to be studied in greater detail.

Implications of COVID-19 on global environmental pollution and carbon emissions with strategies for sustainability in the COVID-19 era.

The impacts of COVID-19 on global environmental pollution since its onset in December 2019 require special attention. The rapid spread of COVID-19 globally has led countries to lock down cities, restrict traffic travel and impose strict safety measures, all of which have implications on the environment. This review aims to systematically and comprehensively present and analyze the positive and negative impacts of COVID-19 on global environmental pollution and carbon emissions. It also aims to propose strategies to prolong the beneficial, while minimize the adverse environmental impacts of COVID-19. It systematically and comprehensively reviewed more than 100 peer-reviewed papers and publications related to the impacts of COVID-19 on air, water and soil pollution, carbon emissions as well as the sustainable strategies forward. It revealed that PM2.5, PM10, NO2, and CO levels reduced in most regions globally but SO2 and O3 levels increased or did not show significant changes. Surface water, coastal water and groundwater quality improved globally during COVID-19 lockdown except few reservoirs and coastal areas. Soil contamination worsened mainly due to waste from the use of personal protective equipment particularly masks and the packaging, besides household waste. Carbon emissions were reduced primarily due to travel restrictions and less usage of utilities though emissions from certain ships did not change significantly to maintain supply of the essentials. Sustainable strategies post-COVID-19 include the development and adoption of nanomaterial adsorption and microbial remediation technologies, integrated waste management measures, "sterilization wave" technology and energy-efficient technologies. This review provides important insight and novel coverage of the environmental implications of COVID-19 in more than 25 countries across different global regions to permit formulation of specific pollution control and sustainability strategies in the COVID-19 and post-COVID-19 eras for better environmental quality and human health.

Characterization of microplastics in the water and sediment of Baram River estuary, Borneo Island.

The Baram River is one of the largest rivers in Sarawak, where many large industries, such as plywood, sawmills, shipyards, interisland ports, and other wood-based industries are located along the river. Microplastic contamination has become a widespread and growing concern worldwide because of the small sizes of microplastics and their presence in seafood such as fish, squid, scallop, crabs, shrimp, and mussels. In this study, microplastics were found in all sampling stations. Out of the 4017 microplastics found in the water and sediment, microplastics fragment accounted for 67.8% of total microplastics, followed by fiber, film, pellet, and foam. Five microplastic polymer types were detected by ATR-FTIR, including polyethylene (PE), polyester (PET) fibers, silicon polymer, nitrile, and polystyrene (PS). The most common microplastics size range in Baram River was 0.3-1 mm, with blue as the highly abundant color.

Microplastics in the freshwater and terrestrial environments: Prevalence, fates, impacts and sustainable solutions.

The ubiquitous occurrences of microplastics in the environment have raised much concern and resulted in voluminous studies related to microplastics. Studies on microplastics pollution of the marine environment have received significantly higher attention compared to those of the freshwater and terrestrial environments. With the impetus to better understand microplastics in the freshwater and terrestrial environments, this review elucidates the findings of >100 articles related to the prevalence, fates and impacts of microplastics therein and the sustainable solutions, mostly in the past 10 years. This review shows the interconnection between terrestrial and freshwater microplastics with wastewater and sewage treatment plants as the most significant contributors of environmental microplastics via sludge and effluent discharges. Microplastics in both ecosystems comprise the primary and secondary forms with the latter resulted from weathering of the former. Besides retaining in soil and infiltrating with rainwater underground, terrestrial microplastics also enter the freshwater environment. The environmental microplastics interact with the biotic and abiotic components resulting in entrainment, settlement, biofouling, degradation, fragmentation and entry into the food chain, with subsequent transfer across the food chain. The abundance of environmental microplastics is attributed to population density and urbanization though tidal cycle, storms, floods and human activities can affect their distribution. The leaching of additives from microplastics poses major health concern and sustainable solutions target at reduction of plastics use and disposal, substitution with bioplastics and wastewater treatment innovations. Further studies on classification, detection, characterization and toxicity of microplastics are necessary to permit more effective formulation of solutions.

Climate change in Malaysia: Trends, contributors, impacts, mitigation and adaptations.

PURPOSE: This paper reviews the past and future trends of climate change in Malaysia, the major contributors of greenhouse gases and the impacts of climate change to Malaysia. It also reviews the mitigation and adaptations undertaken, and future strategies to manage the impacts of regional climate change. METHODOLOGY: The review encompasses historical climate data comprising mean daily temperature, precipitation, mean sea level and occurrences of extreme weather events. Future climate projections have also been reviewed in addition to scholarly papers and news articles related to impacts, contributors, mitigation and adaptations in relation to climate change. FINDINGS: The review shows that annual mean temperature, occurrences of extreme weather events and mean sea level are rising while rainfall shows variability. Future projections point to continuous rise of temperature and mean sea level till the end of the 21st century, highly variable rainfall and increased frequency of extreme weather events. Climate change impacts particularly on agriculture, forestry, biodiversity, water resources, coastal and marine resources, public health and energy. The energy and waste management sectors are the major contributors to climate change. Mitigation of and adaptations to climate change in Malaysia revolve around policy setting, enactment of laws, formulation and implementation of plans and programmes, as well as global and regional collaborations, particularly for energy, water resources, agriculture and biodiversity. There are apparent shortcomings in continuous improvement and monitoring of the programmes as well as enforcement of the relevant laws. ORIGINALITY/VALUE: This paper presents a comprehensive review of the major themes of climate change in Malaysia and recommends pertinent ways forward to fill the gaps of mitigation and adaptations already implemented.