In order to study the effect of cadmium ions on the mechanical properties and micro-structure characteristics of the red clay in Guilin, we have conducted triaxial test and the scanning electron microscope tests to analyze the effects of cadmium ion concentration and the number of dry and wet cycles on the mechanical properties and micro-structure changes of the red clay. The results showed the effects of cadmium ions and dry-wet cycles destroy the structure of red clay. The cohesive force of red clay decreases with the increase of cadmium ion concentration, and the internal friction angle first increases and then decreases. With the rise in the number of dry and wet cycles, the cohesive force of cadmium-contaminated red clay first increases and then decreases, and the angle of internal friction rises gradually. Under the action of different cadmium ion concentrations, the stress-strain curve is strain hardening. With the concentration of cadmium ions increases, the strain hardening becomes more apparent; the peak value reached faster. and the axial strain corresponding to the peak value of the line decreases. With the increase in the number of wet and dry cycles, the volume of cadmium-contaminated red clay shrinks and its compactness increases; it gets the peak shear strength faster during the shearing process, and its peak value becomes larger and larger. The main reason for the phenomenon is that cadmium ions destroy the cementation between the particles. The soil particles are mainly in point contact which loosens the structure of the soil; on the other hand, the thickness of the surface diffusion layer of the clay particles increases through chemical action, The exchange of cations increases the porosity of the soil and weakens its strength. The dry-wet cycle shrinks the volume of the red clay, and the soil particles are mainly in surface contact; as the number of dry-wet cycles increases, the soil particles connection is closer, the soil porosity decreases and the strength increases.

The influence of common textile finishes on cotton fabrics on the generation of microfibers during laundering was assessed. Microfiber release was determined to be in the range of 9000–14,000 particles per gram of cotton fabric. Cotton knitted fabrics treated with softener and durable press generate more microfibers (1.30–1.63 mg/g fabric) during laundering by mass and number than untreated fabric (0.73 mg/g fabric). The fabrics treated with softener generated the longest average microfiber length (0.86 mm), whereas durable press and water repellent treatments produced the shortest average microfiber length (0.62 and 0.63 mm, respectively). In general, the changes in the mechanical properties of the fibers and fabrics due to the finishing treatments are the main factor affecting the microfiber release. The abrasion resistance of the fabrics decreases for durable press treatments and water repellent treatments due to the brittleness in the structure originated by the crosslinking treatment. In the case of the softener treatment, the fabric surface is soft and smooth decreasing the friction coefficient between fibers favoring the fibers loosening from the textile and resulting in a high tendency for fuzz formation and microfiber release. These findings are useful for the textile industry in the design and selection of materials and treatments for the reduction of synthetic or natural microfiber shedding from textiles.

Produced water is a type of wastewater generated from hydraulic fracturing, which may pose a risk to the environment and humans due to its high ionic strength and the presence of elevated concentrations of metals/metalloids that exceed maximum contamination levels. The mobilization of As(V) and Se(VI) in produced water and selected soils from Qingshankou Formation in the Songliao Basin in China were investigated using column experiments and synthetic produced water whose quality was representative of waters arising at different times after well creation. Temporal effects of produced water on metal/metalloid transport and sorption/desorption were investigated by using HYDRUS-1D transport modelling. Rapid breakthrough and long tailings of As(V) and Se(VI) transport were observed in Day 1 and Day 14 solutions, but were reduced in Day 90 solution probably due to the elevated ionic strength. The influence of produced water on the hydrogeological conditions (i.e., change between equilibrium and non-equilibrium transport) was evidenced by the change of tracer breakthrough curves before and after the leaching of produced water. This possibly resulted from the sorption of polyacrylamide (PAM (-CH2CHCONH2-)n) onto soil surfaces, through its use as a friction reducer in fracturing solutions. The sorption was found to be reversible in this study. Minimal amounts of sorbed As(V) were desorbed whereas the majority of sorbed Se(VI) was readily leached out, to an extent which varied with the composition of the produced water. These results showed that the mobilization of As(V) and Se(VI) in soil largely depended on the solution pH and ionic strength. Understanding the differences in metal/metalloid transport in produced water is important for proper risk management.

Contamination of sea bottom sediments by microplastics is widely confirmed, but the reasons for its patchiness remain poorly understood. Laboratory experiments are reported where combined sets of various plastic particles, different by shape, size, density, and flexibility, were transported by the step-wise increasing open-channel flow over the bottom covered with natural sediment of increasing grain size. For every particular flow velocity, observations revealed the recurrent formation of relatively narrow retention areas, where plastic particles lingered for some time in their motion. These areas follow the line of change of the sediment type from finer to coarser grains. It is shown that contact friction drives the retention of a particle at finer sediments, while particle/sediment-grain interaction becomes of importance when particles and sediment grains are of similar sizes. The presence of this effect can be expected for a relatively wide range of natural conditions.

Wear and tear on fishing gear is a sparsely investigated source of microplastic pollution in the sea. In Norway, Danish seine ropes and trawls are the fishing gears that contribute most to this pollution. The main reason for this pollution is that the seine ropes are dragged along the seabed over a considerable distance, creating a friction force that results in high ropes wear. This note reports the findings after examining the wear of Danish seine ropes used in Norwegian fisheries. The results show that, in Norway alone, an average of 77 to 97 tons of plastic will be added to the sea annually due to this specific fishing gear. Aggregated to include all fly dragging, anchor seining, and pair seining globally, this number is estimated to be about 311 tons per year.

In-water cleaning can clear-off foulants from ship hulls to prevent transportation of non-indigenous species and reduce hull friction and consequent fuel use. However, during cleaning, antifouling paint residues containing toxic substances can be released into the environment. To understand the potential risks of in-water hull cleaning, cleaning effluents were collected and analyzed for total suspended solid (TSS), particle size distribution, and metal concentrations. TSS concentrations were 97.3–249 mg/L, corresponding to release rates of 12.9–37.5 g/m² from the hull surface. Particles with sizes of ≥8 μm contributed 75–94% of the TSS. Average Cu and Zn concentrations in the effluents were 209 μg/L and 1510 μg/L, respectively, which were used for risk assessment in two port scenarios. Although the risks vary with the scale of the hull cleaning and the ports, in-water cleaning poses clear risks to marine environments, unless the effluents are recovered or treated before being released.

The European Water Framework Directive requires a good ecological potential for heavily modified water bodies. This standard has not been reached for most large estuaries by 2015. Management plans for estuaries fall short in linking implementations between restoration measures and underlying spatial analyses. The distribution of emergent macrophytes – as an indicator of habitat quality – is here used to assess the ecological potential. Emergent macrophytes are capable of settling on gentle tidal flats where hydrodynamic stress is comparatively low. Analyzing their habitats based on spatial data, we set up species distribution models with ‘elevation relative to mean high water’, ‘mean bank slope’, and ‘length of bottom friction’ from shallow water up to the vegetation belt as key predictors representing hydrodynamic stress. Effects of restoration scenarios on habitats were assessed applying these models. Our findings endorse species distribution models as crucial spatial planning tools for implementing restoration measures in modified estuaries.

A multi-nested prediction system for the Yellow Sea using drifter trajectory simulations was developed to predict the movements of an oil spill after the MV Hebei Spirit accident. The speeds of the oil spill trajectories predicted by the model without tidal forcing were substantially faster than the observations; however, predictions taking into account the tides, including both tidal cycle and subtidal periods, were satisfactorily improved. Subtidal flow in the simulation without tides was stronger than in that with tides because of reduced frictional effects. Friction induced by tidal stress decelerated the southward subtidal flows driven by northwesterly winter winds along the Korean coast of the Yellow Sea. These results strongly suggest that in order to produce accurate predictions of oil spill trajectories, simulations must include tidal effects, such as variations within a tidal cycle and advections over longer time scales in tide-dominated areas.

Soil polluted by oil and its derivatives is a critical environmental issue worldwide that jeopardizes ecological systems and causes geotechnical problems. This review paper focuses on the previous studies concerning the impacts of oil pollution on soil geotechnical properties. To this end, related academic literature on this topic was investigated and discussed. The findings of this study demonstrated that the addition of oil pollution in coarse-grained soils significantly reduces particle surface roughness. On the other hand, in fine-grained soils, it results in flocculation and secondary aggregation of clay particles, less aggregated and loose packing in the soil matrix, the formation of isometric pores, the formation of fissure-like pores, and an increase in mesoporosity. In general, it was found that the geotechnical properties of oil-polluted soils are mostly determined by the physicochemical and/or physical interactions between the soil and contaminant. Additionally, previous research has demonstrated that oil pollutants alter the geotechnical properties of cohesive and non-cohesive soils significantly, including the Atterberg limits, particle-size distribution, compaction behavior, unconfined compressive strength, friction angle, cohesion, hydraulic conductivity, and consolidation characteristics. However, no general pattern could be established for the majority of them. Besides, it was found that the degree of geotechnical property alteration of oil-polluted soil is strongly influenced by the soil type and features, as well as the quantity, type, and chemical composition of oil pollutants.

This paper presents the characterization of municipal solid waste (MSW) randomly collected from two material recovery facilities in São Paulo city, before (input — recyclables) and after (output — rejects) the sorting processes. Geo-environmental and geotechnical tests were performed on shredded samples and a digestion method was applied to detect the metals As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn concentrations using an ICP OES. The objective was to assist future activities of integrated solid waste management and soil pollution. Results showed different particle sizes comparing the input (44.6%) and the output MSW (75.1%) passing through the 100-mm sieve. Organic matter and ash contents indicated the influence of inorganic carbon due to the plastics’ presence, with values varying between 6 and 13%. The pH values obtained were neutral and the electrical conductivity of the MSW rejects suggested a higher amount of ions, with values above 1000 µS/cm. Metals analyses show that Cd, Cu, Ni, Pb, and Zn are present in high concentrations, depending on the types of the materials. Standard Proctor compaction curves yielded maximum dry unit weight varying from 6.6 to 10.0 kN/m³ and optimum moisture contents from 20 to 42%. Cohesion ranged from 1.3 to 31.3 kPa and friction angle from 3.2 to 42.9°. The results are comparable with those obtained for other countries using different MSW treatments and contribute to the data basis for MSW from the selective collection, aiming the integrated solid waste management, serving for other countries that adopt MSW sorting and recycling.