doi: 10.7185/geochemlet.1829 Millions of metric tons of plastics are produced annually and transported from land to the oceans. Finding the fate of the plastic debris will help define the impacts of plastic pollution in the ocean. Here, we report the abundances of microplastic in the deepest part of the world’s ocean. We found that microplastic abundances in hadal bottom waters range from 2.06 to 13.51 pieces per litre, several times higher than those in open ocean subsurface water. Moreover, microplastic abundances in hadal sediments of the Mariana Trench vary from 200 to 2200 pieces per litre, distinctly higher than those in most deep sea sediments. These results suggest that manmade plastics have contaminated the most remote and deepest places on the planet. The hadal zone is likely one of the largest sinks for microplastic debris on Earth, with unknown but potentially damaging impacts on this fragile ecosystem. Received 22 July 2018 | Accepted 29 October 2018 | Published 27 November 2018 1. Deep Sea Science Division, Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya, Hainan 572000, China 2. Institute of Marine Geology and Resources, Ocean College, Zhejiang University, Zhoushan 316021, China * Corresponding author (email: chans@idsse.ac.cn) Letter Plastics are worldwide marine pollutants, accumulating in seawater and sediments (Hammer et al., 2012; Cózar et al., 2014; Ivar do Sul and Costa, 2014). It was estimated that between 4.8 and 12.7 million metric tons of plastic waste entered the ocean in 2010 and this mass could increase by one order of magnitude by 2025 (Jambeck et al., 2015; Geyer et al., 2017). Besides the ocean surface (Thompson et al., 2004; Barnes et al., 2009; Van Sebille et al., 2015; Chae and An, 2017), potential sinks for plastics include deep sea biota (Oliveira et al., 2012), the water column (Courtene-Jones et al., 2017; Kanhai et al., 2018) and sediments (Bergmann et al., 2017), where broken plastics exist as microplastics (<5 mm in size) (Arthur et al., 2009; Hidalgo-Ruz et al., 2012). So far, however, microplastics in the deepest ocean remain largely unexplored. The hadal zone, which is the deepest region (6000-11000 m) of the oceans lying within trenches, represents 1-2 % of the global benthic area (Jamieson et al., 2010). Although it was reported that toxic anthropogenic pollutants (e.g., persistent organic pollutants) have reached the deepest ocean on Earth (Jamieson et al., 2017; Dasgupta et al., 2018), little is known about the nature of anthropogenic microplastics in this deep and remote environment. To evaluate the abundance, distribution, and fate of microplastics in the hadal zone, we collected bottom water samples and sediment samples at depths of 2500-11000 m and 5500-11000 m, respectively, from the southern Mariana Trench, where the Challenger Deep, the deepest point on Earth, is situated (Fujioka et al., 2002) (Fig. 1). Identification by optical microscope and Raman spectrometer confirmed that microplastics are abundant in hadal bottom water (Fig. S-1). The microplastics are fibrous, rod-like, and roundish in shape, and mostly blue, red, white, green, and purple in colour. Plastic microfibres dominate in all the microplastics and are commonly 1-3 mm in length in seawater samples and mostly 0.1-0.5 mm in sediment samples (Table S-4). The microplastic abundances in bottom waters range from 2.06 to 13.51 pieces per litre and become more concentrated with depth (Fig. 2) with one exception at depth of 6802 m, reaching 13.51 pieces per litre. At 10903 m, the microplastic abundance reaches 11.43 pieces per litre, which is four times higher than that reported in the subsurface water of open seas, including the NE Pacific Ocean (Desforges et al., 2014), South Pacific subtropical gyre (Eriksen et al., 2013), North Pacific Gyre (Goldstein, 2012), North Atlantic Ocean (Courtene-Jones et al., 2017), and the Arctic Ocean (Bergmann et al., 2017; Kanhai et al., 2018) (Table 1). The high abundance of microplastics in hadal bottom water is also comparable to that reported in coastal waters, for example, in the Yangtze River and the Strait of Georgia, which are regarded as heavily polluted by microplastics (Desforges et al., 2014; Zhao et al., 2014). Geochemical Perspectives Letters Letter Geochem. Persp. Let. (2018) 9, 1-5 | doi: 10.7185/geochemlet.1829 2 Figure 1 Sampling location map of Mariana Trench seawater (in red triangles) and sediments (in yellow circles). Please see Tables S-1 and S-2 for sampling details. Figure 2 Profile of microplastic abundances and compositions in water samples from Mariana Trench. Pie charts represent the microplastic compositions and numbers in the bracket are the microplastic abundances with units of pieces per litre. PVC-polyvinyl chloride, PA-polyamide, Ra-rayon, ABS-acrylonitrile butadiene styrene, PP-polypropylene, PE-polyethylene, PS-polystyrene, aPAaromatic polyamide, PET-polyethylene terephthalate, Pe-polyester, PU-polyurethane. The X-axis corresponds to the crossline from point A (12 oN, 142.5 oE) to point B (9.8 oN, 141.43 oE) in Figure 1.
The growing number of artificial structures in estuarine, coastal and marine environments is causing “ocean sprawl”. Artificial structures do not only modify marine and coastal ecosystems at the sites of their placement, but may also produce larger-scale impacts through their alteration of ecological connectivity - the movement of organisms, materials and energy between habitat units within seascapes. Despite the growing awareness of the capacity of ocean sprawl to influence ecological connectivity, we lack a comprehensive understanding of how artificial structures modify ecological connectivity in near- and off-shore environments, and when and where their effects on connectivity are greatest. We review the mechanisms by which ocean sprawl may modify ecological connectivity, including trophic connectivity associated with the flow of nutrients and resources. We also review demonstrated, inferred and likely ecological impacts of such changes to connectivity, at scales from genes to ecosystems, and potential strategies of management for mitigating these effects. Ocean sprawl may alter connectivity by: (1) creating barriers to the movement of some organisms and resources - by adding physical barriers or by modifying and fragmenting habitats; (2) introducing new structural material that acts as a conduit for the movement of other organisms or resources across the landscape; and (3) altering trophic connectivity. Changes to connectivity may, in turn, influence the genetic structure and size of populations, the distribution of species, and community structure and ecological functioning. Two main approaches to the assessment of ecological connectivity have been taken: (1) measurement of structural connectivity - the configuration of the landscape and habitat patches and their dynamics; and (2) measurement of functional connectivity - the response of organisms or particles to the landscape. Our review reveals the paucity of studies directly addressing the effects of artificial structures on ecological connectivity in the marine environment, particularly at large spatial and temporal scales. With the ongoing development of estuarine and marine environments, there is a pressing need for additional studies that quantify the effects of ocean sprawl on ecological connectivity. Understanding the mechanisms by which structures modify connectivity is essential if marine spatial planning and eco-engineering are to be effectively utilised to minimise impacts.
Based on historical materials about the technology of the 15th and 16th century Portuguese maritime expansion, the author shows that in order to understand the emergence, functioning, and collapse of technological systems we need to develop an approach that will be centred on the notion of heterogeneous engineering. Heterogeneous engineering presupposes that the building of technological systems involves associating and channelling diverse entities and forces, both human and nonhuman. This permits an analysis of how the existence of particular systems is shaped equally by different factors: natural, social, economic, and technical. In the case of Portuguese maritime expansion, the success of system-building was determined by the association between shipbuilding; the navigational skills of the navigators; navigational equipment and guns; features of the capes, oceanic currents, and winds; and the system of state support, training, and regulation—all of which made possible the establishment of a stable and powerful network that allowed the Portuguese to dominate the Atlantic and Indian Oceans. Therefore, the construction of a technological system is a process of resolving conflicts between heterogeneous elements, and the associated elements must be able to withstand encounters with hostile forces and entities, both physical (e.g. oceans) and social (e.g. the Muslims). The systems approach proposed by the author shows, first, that technology can be analysed using the principle of generalized symmetry, which states that the same type of analysis should be made for all components in a system whether these components are human or not; and, second, that actors should be understood as entities that exert detectable influence on other entities
Mariculture wastewater contains a diverse array of pollutants, such as antibiotics, heavy metals, and ammonia nitrogen (NH4+-N). The concurrent removal of multiple pollutants has emerged as an urgent problem that demands immediate attention. In this research, photovoltaic powered ocean-based electrochemical system (POECs) was employed to treat mariculture wastewater. POECs exhibited outstanding performance in the treatment of mariculture wastewater, attaining high removal rates for various pollutants: 98 % for TC, 97.4 % for Cu(II), and 95.5 % for NH4+-N. The integration of the bioelectrochemical system (BES) and the electrolytic cell (EC) augmented the overall treatment capacity of the system. This integration led to the generation of a variety of highly oxidizing active species, including hydroxyl radicals and reactive chlorine species (RCS). In the anode chamber, the ocean - sourced sludge served as a source of bioelectricity. At the class level, functional microorganisms like Gammaproteobacteria and Campylobacteria were the dominant species. The study offers technical optimization for the environmentally-friendly treatment of mariculture wastewater and holds promising prospects for engineering applications.
Study region: The Pearl River Estuary in southern China has strong monsoonal wet-dry discharge contrasts and extensive cascade reservoir regulation in its basin. Study focus: This study quantifies how reservoir-driven discharge re-partitioning affects the seasonality and multi-decadal evolution of tidal duration asymmetry (TDA; the difference between flood and ebb durations). To reveal the linkage between TDA and regulated discharge, we analyze 51 years (1966–2016) of water levels from 21 tide gauges and daily discharge from three upstream stations using a tidal skewness metric, non-stationary harmonic diagnostics, and trend analysis. New hydrological insights for the region: TDA shows significant seasonality, with higher skewness in the wet season (April–September) and lower skewness in the dry season (October–March), and a basin-wide trough in late June–early July when discharge peaks. The discharge-TDA relation is threshold-dependent: normalized skewness increases with normalized discharge up to ∼0.62 (∼12,550 m³/s) and decreases thereafter. Reservoir regulation reduced wet-season peak flows (−76.3 m³/s/yr) and increased dry-season baseflows (+16.5 m³/s/yr), attenuating seasonal TDA amplitude most strongly in river–tide transition reaches (−0.0036 /yr). Spatial differences indicate phase-controlled TDA seasonality upstream but amplitude-controlled seasonality downstream, consistent with shifts in dominant tidal interactions from K₁–O₁–M₂ to M₂–M₄. The threshold rule links managed discharge to seasonal TDA and supports basin-to-estuary flow management in regulated coastal rivers.
Assessing and forecasting the long-term behavior of glass fiber-reinforced polymer (GFRP) rebars continue to pose significant challenges. To address this, the present study introduces a predictive framework aimed at estimating the retained tensile strength of GFRP rebars when exposed to alkaline environments. A total of 350 experimental data points were collected through keyword-based literature retrieval and subsequently augmented using a Gaussian Copula-based generative model. Six machine learning algorithms, combined with grid search and five-fold cross-validation, were employed to develop predictive models for residual tensile strength in alkaline environments. SHAP (SHapley Additive exPlanations) was used to conduct parameter importance and sensitivity analyses. Unlike prior ML-based durability studies that often suffer from data scarcity and limited generalization, this work uniquely integrates a statistical generative approach to rigorously expand small-scale experimental datasets while preserving their underlying physical correlations, thereby significantly enhancing model robustness. The results show that the Gaussian Copula model effectively captures the primary distributional characteristics of the experimental data, and that XGB (eXtreme Gradient Boosting) is the most suitable model for predicting residual tensile strength. Among the input parameters, environmental temperature has the greatest influence on residual tensile strength, while pH exhibits the least impact. Fiber content and rebar diameter positively affect residual tensile strength—higher values lead to greater strength. Conversely, higher pH, elevated temperature, and longer exposure duration negatively influence residual tensile strength. These findings on parameter importance and sensitivity provide valuable insights for durability studies of GFRP rebars.
Micro-Doppler (m-D) signatures serve as an indispensable component of modern space situational awareness, which provides additional feature dimension for target detection and recognition. However, the existing microwave radar systems exhibit a limited sensitivity to micromotion detection capabilities, especially in component-level motion of space targets. To address this issue, a geometry-guided time-frequency-based method is proposed to estimate micromotion parameters of space targets under terahertz (THz) band, leveraging the high frequency and inherent sensitivity of the THz band to m-D effects. First, the orbital dynamics and observation geometry tailored for spaceborne THz radar are analyzed. Subsequently, the m-D parameter estimation suitable for space targets is developed based on the geometry-guided time-frequency feature, which is different for the traditional assumption of point targets and accommodates the geometric symmetry of space targets. Finally, we compare three representative satellite attitudes with solar panels being different, i.e., nadir-pointing orientation, tilted orientation, and different direction tilted orientation, and the coat material being smooth and nonsmooth. Both numerical simulation and measured experiments are carried out to validate the effectiveness and superiority of the proposed method in terms of the reliable retrieval of m-D parameters.
True leaf area index (LAIt) is a more crucial and efficient structural parameter to characterize the photosynthetic capacity of broadleaf forests than the concept of effective leaf area index, which is the predominant form retrieved by remote sensing. Conventional LAIt retrieval methods rely on the accurate terrestrial laser scanning (TLS), regarded as an essential means for capturing the size and distribution of leaves within the tree crown. However, results of current TLS-based LAIt retrieval algorithms are highly sensitive to physical parameters such as voxel configuration and gap size. In this study, we proposed a point cloud multi-inclined-planes (MIP) method to address the above issue. The MIP begins by extracting leaf point clouds from individual tree point clouds and clustering these leaf points. Independent leaf clusters are identified through clustering, and each cluster is treated as a complex surface composed of multiple inclined planes. The area of this complex surface is then calculated to derive the LAIt. Through validating on both simulated and measured data with comparison to other methods, MIP achieved a root mean square error of 1.197 m<sup>2</sup>/m<sup>2</sup> and demonstrated robustness. By eliminating the factors that may affect retrieval of LAIt while ensuring insensitivity to parameter variations, it holds great promise in forest monitoring and application.
Ulfah Maria, Cindy Safitri Arsa, Andianto Dika
et al.
The health and sustainability of coral reefs are influenced by the complex interactions of various organisms, and one indicator of their health is the presence of herbivorous reef fish. This study aims to analyze the health of coral reefs based on the abundance of herbivorous reef fish in the waters of Krueng Raya, Aceh Besar. The research was conducted in October 2023 at three stations. Data collection was carried out using the Point Intercept Transect (PIT) method for coral monitoring, while the herbivorous fish were assessed using the Underwater Visual Census (UVC) Belt Transect method. The results showed that the abundance of herbivorous reef fish ranged from 1597.92 ind/ha to 5918.18 ind/ha, with a total of families, 12 genera, and 25 species of herbivorous reef fish identified. The percentage of algae cover ranged from 4.65% to 35.55%. This study indicates an inverse relationship between the abundance of herbivorous reef fish and algae cover. As the abundance of herbivorous reef fish increases, the percentage of algae cover decreases.
Abstract The current research of master cylinder pressure estimation mainly relies on hydraulic characteristic or vehicle dynamics. But they are not independently applicable to any environment and have their own scope of application. In addition, about the master cylinder pressure control, there are few studies that can simultaneously balance pressure building accuracy, speed, and prevent pressure overshoot and jitter. In this paper, an adaptative fusion method based on electro-hydraulic characteristic and vehicle mode is proposed to estimate the master cylinder pressure. The fusion strategy is mainly based on the prediction performance of two algorithms under different vehicle speeds, pressures, and ABS states. Apart from this, this article also includes real-time prediction of the friction model based on RLS to improve the accuracy of the electro-hydraulic mode. In order to simultaneously balance pressure control accuracy, response speed, and prevent overshoot and jitter, this article proposes an adaptative LQR controller for MC pressure control which uses fuzzy-logic controller to adjust the weights of LQR controller based on target pressure and difference compared with actual pressure. Through mode-in-loop and hardware-in-loop tests in ramp, step and sinusoidal response, the whole estimation and control system is verified based on real hydraulic system and the performance is satisfactory under these scenes. This research proposes an adaptative pressure estimation and control architecture for integrated electro-hydraulic brake system which could eliminate pressure sensors in typical scenarios and ensure the comprehensive performance of pressure control.
Ocean engineering, Mechanical engineering and machinery
Andrew S. Medeiros, Michael Bakaic, Julia A. Guimond
et al.
Climate change is likely to be an important factor affecting the ability of Arctic communities to continue supplying freshwater from single-source reservoirs; yet, infrastructure planning and assessment processes rarely take climate change into consideration for needs-based improvements. Here, we identify potential threats to the provisioning of freshwater by examining local water sources in the community of Coral Harbour, Arctic Canada. While we did not identify any concerns over water quality through the analysis of samples collected in 2021–2022, we did find that the current reservoir for the community is insufficient to continue provisioning water over a typical 20-year planning horizon. We also note that if anomalous climate conditions occur (e.g., extreme temperatures), the exhaustion of the annual water supply could occur faster than projected, causing a local water shortage until ice-off when replenishment is possible. Hydrometric data collected from Post River, the source used to replenish the reservoir, also highlight the response of river levels to both rainfall and dry periods, and thus qualitatively demonstrates the potential impacts of future episodic late-summer droughts on river water availability, which could affect resupply. These results highlight the need to include climate-based assessment in freshwater infrastructure assessment and planning processes in remote Arctic communities.
The abundance of waste plastic is a major issue for the sustainability of the environment as plastic pollutes rivers, land, and oceans. However, the versatile behavior of plastic (it is lightweight, flexible, strong, moisture-resistant, and cheap) can make it a replacement for or alternative to many existing composite materials like concrete. Over the past few decades, many researchers have used waste plastic as a replacement for aggregates in concrete. This paper presents a comprehensive review of the engineering properties of waste recycled plastic. It is divided into three sections, along with an introduction and conclusion. The influence of recycled waste plastics on the fresh properties of concrete is discussed first, followed by its influence on the mechanical and durability properties of concrete. Current experimental results have shown that the mechanical and durability properties of concrete are altered due to the inclusion of plastic. However, such concrete still fulfills the requirements of many engineering applications. This review also advocates further study of possible pre-treatment of waste plastic properties for the modification of its surface, shape, and size in order to improve the quality of the composite product and make its use more widespread.
The world faces escalating crises: record-breaking temperatures, widespread fires, severe flooding, increased oceanic microplastics, and unequal resource distribution. Academia introduces courses around sustainability to meet the new demand, but software engineering education lags behind. While software systems contribute to environmental issues through high energy consumption, they also hold the potential for solutions, such as more efficient and equitable resource management. Yet, sustainability remains a low priority for many businesses, including those in the digital sector. Business as usual is no longer viable. A transformational change in software engineering education is urgently needed. We must move beyond traditional curriculum models and fully integrate sustainability into every aspect of software development. By embedding sustainability as a core competency, we can equip future engineers not only to minimise harm but also to innovate solutions that drive positive, sustainable change. Only with such a shift can software engineering education meet the demands of a world in crisis and prepare students to lead the next generation of sustainable technology. This article discusses a set of challenges and proposes a customisable education roadmap for integrating sustainability into the software engineering curricula. These challenges reflect our perspective on key considerations, stemming from regular, intensive discussions in regular workshops among the authors and the community, as well as our extensive research and teaching experience in the field.
Change detection in remote sensing images is a challenging task due to object appearance diversity and the interference of complex backgrounds. Self-attention- and spatial-attention-based solutions face limitations, such as high memory consumption and an inadequate ability to capture long-range relations, leading to imprecise contextual information and restricted performance. To address these challenges, this article introduces a novel mask-guided local–global attentive network (MLA-Net). The MLA-Net incorporates a memory-efficient local–global attention module that leverages the benefits of both self-attention and spatial attention to accurately capture the local–global context. Through simultaneous exploitation of context within inter- and intrapatches and information refinement, the feature representation capability is significantly enhanced. In addition, we introduce a change mask to refine feature differences and eliminate interference from irrelevant changes caused by complex backgrounds. Accordingly, a mask loss is defined to guide the generation of the mask. Extensive experiments on the LEVIR-CD, WHU-CD, and CLCD datasets show that our MLA-Net performs better than state-of-the-art methods.
The model-based polarimetric interferometric synthetic aperture radar forest height inversion is inherently affected by nonideal system parameters, including channel imbalance, crosstalk, and noise. To investigate the impact of nonideal system parameters on the estimated forest height, this article introduces an analytical forest height inversion error model based on the two-layer randomly oriented volume over ground model. First, the error transfer function is derived to present the forest height error caused by the disturbance of the volume coherence. Then, the coupled effects of the nonideal system parameters on the volume coherence are established and demonstrated to reduce the amplitude of the volume coherence. The effects of channel imbalance and crosstalk are explicitly derived and found to be coupled together to amplify the noise. Finally, the error model is established by combining the error transfer function and the disturbance of the volume coherence caused by the nonideal system parameters. The proposed error model is verified by simulation analyses on real airborne repeat-pass BioSAR 2008 datasets. The results demonstrate that the proposed model can accurately capture the relationship between the height estimation errors and the system parameters.
Abstract Solving nonlinear equation systems (NESs) requires locating different roots in one run. To effectively deal with NESs, a multi-population cooperative teaching–learning-based optimization, named MCTLBO, is presented. The innovations of MCTLBO are as follows: (i) two niching technique (crowding and improved speciation) are integrated into the algorithm to enhance population diversity; (ii) an adaptive selection scheme is proposed to select the learning rules in the teaching phase; (iii) the new learning rules based on experience learning are developed to promote the search efficiency in the teaching and learning phases. MCTLBO was tested on 30 classical problems and the experimental results show that MCTLBO has better root finding performance than other algorithms. In addition, MCTLBO achieves competitive results in eighteen new test sets.
Electronic computers. Computer science, Information technology
Nano-water-based drilling fluids (NWBDFs) are prepared using nano-copper oxide (CuO) and multiwalled carbon nanotubes (MWCNTs) as modification materials. The effects of the temperature and concentration of the nanoparticles (NPs) on the rheological properties are studied using a rotational rheometer and viscometer. Also, the influence of two NPs on the filtration properties is studied using a low-pressure and low-temperature filtration apparatus, as well as a scanning electron microscope (SEM). It is found that MWCNTs with a concentration of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.05</mn><mo> </mo><mi>w</mi><mo>/</mo><mi>v</mi><mo>%</mo></mrow></semantics></math></inline-formula> have the most obvious influence on the NWBDFs, which improve the stability of the gel structure against temperature and also decrease the filtration rate. Finally, a theoretical model predicating the yield point (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>YP</mi></mrow></semantics></math></inline-formula>) and the plastic viscosity (PV) as a function of the temperature considering the influence of the NPs is developed based on DLVO theory.