Litter Composition Research Articles

Study of pollution status in urban environment caused by attitude and waste littering behavior of citizens

Littering behavior is one of the main challenges in waste management, especially in big cities. In this study, density and composition of litter in Tehran was investigated and the urban pollution status was calculated by using the clean environment index. The results showed that the average density of litter in the studied locations was 0.182 number/m2. Spatial variation in the litter density showed that the average density in commercial and residential land-uses was 0.22 and 0.14 number/m2, respectively. Cigarette butts (29%), bottle caps (18%), and paper receipts (10%) consisted the largest ratio of the litter composition in the studied locations. Clean environment index for the studied locations was calculated in the range of 2.34 to 10.42. Based on this, 30% of the studied locations were in a clean status and 70% were in a polluted and worse status. The litter density in the city, interviews with citizens, and the results of previous studies showed insufficient awareness of citizens about the consequences of littering in the urban environment, which led to the prevalence of littering behavior. So, the littering behavior by citizens has caused the urban environment pollution and increased health risk. Educating citizens and modifying their behavior to avoid littering is necessary to improve the observed status.

Assessment of transboundary macro-litter on the remote island of Andaman and Nicobar: Unveiling the governing factors and risk assessment

The increasing occurrence of mismanaged plastic litter along India's coastline and the ominous challenges it poses to biodiversity and ecosystem health is a growing environmental concern. To address this issue, we comprehensively investigated the abundance, composition, and probable sources of marine litter on North Cinque Island, a remote uninhabited island in the Andaman and Nicobar archipelago, Bay of Bengal. This island is a designated wildlife sanctuary and serves as an important nesting site for Green, Hawksbill and Leatherback turtles. A total of 6227 litter items were enumerated, with an average concentration of 0.12 items/m2, representing 20 diverse litter types, with plastic dominating the litter composition (86 %). The cleanliness and environmental hazards of the coast due to the litter were assessed using different indices such as the Clean Coast Index (CCI), Plastic Accumulation Index (PAI), Hazardous Item Index (HII), and Clean Environment Index (CEI). CCI indicates the moderately clean-to-clean status of the surveyed sites. PAI points to low to moderate accumulation of plastic litter. HII of all five coasts fell in category II, suggesting a moderate abundance of hazardous items that can inflict injuries to the foraging turtle and their hatchlings. The CEI articulates the moderately clean to very clean status of the sites. Litter brand audit suggests a considerable amount of stranded litter on the coasts was transboundary and originated from six Indian Ocean Rim Countries (IORC), namely Thailand, Myanmar, Malaysia, Indonesia, Sri Lanka, and UAE. Joint solid waste management by the IORC is the need of the hour to avert litter accumulation on the pristine, remote islands.

Macrophyte litter mixtures mediate decomposition processes in coastal sediments

Understanding litter decomposition processes in coastal macrophyte habitats is critically important for predicting ecosystem functioning. However, decomposition processes of litter mixtures in coastal habitats remain largely unexplored. Here, we evaluated the litter mixture effects on the decomposition of six marine macrophytes (two seagrasses and four macroalgae) through in situ litter-mixing experiments with five levels of litter species richness and 36 different litter compositions. We found that the litter species identity and composition, rather than species richness, were crucial in structuring benthic faunal communities. Macroalgal litter, particularly Sargassum sp., hosted higher numbers of polychaetes and crustaceans than seagrass litter. More macroalgal presence induced faster decomposition rates of seagrass litter in the late stage, but not in the early stage. These findings suggest that changes in macrophyte diversity and composition can alter decomposition processes and, consequently, the sediment organic carbon stock through the transition of litter sources and benthic faunas.

Litter in French urban areas-part 1: composition, sources, and spatio-temporal variations on urban surfaces.

Urban areas concentrate on human activities that generate large amounts of waste. A small fraction is mismanaged and ends up on urban surfaces and eventually in waterways. The fraction reaching waterways is usually estimated using poorly constrained data, while litter density on urban surfaces and its subsequent transfer dynamics are also poorly documented. This study provides new insights into litter composition, sources, and spatio-temporal variations in the urban catchments of Pin Sec and Jules Verne (Nantes, France), which are dominated by industrial/commercial, collective, and individual housing areas. Regular litter collection on selected street sections was combined with visual counting of street litter (> 1 cm). In total, 50.8 kg (dry weight) of litter were collected and 232,217 items were counted, mainly smoking and food consumption-related items. Litter densities ranged between 40,000 and 452,000 items/km2 depending on local activities, item mobility, and land use as a driver of road and foot traffic. A median litter accumulation rate of 7 g/inhabitant/day was estimated, suggesting that 0.6% of the total amount of waste generated in public places is mismanaged. Results over space show that litter is strongly correlated with land use and that litter accumulation is promoted in green spaces. Results over time show that litter stock is quickly renewed and that items may have long residence time on urban surfaces.

Benthic litter in fishing grounds of the Northern Adriatic: Role of the trawling fleet as cleaners of the seafloor

This study represents the baseline of estimation of the potential service provided by fishermen as “cleaners of the sea”. The amount, composition and depth distribution of marine litter in fishing grounds of the Northern Adriatic seafloor has been investigated through the fishing for litter (FFL) scheme. Passive FFL campaigns were carried out by trawlers from two of the most important fishing ports in the northern Adriatic, Chioggia and Goro, from May 2020 to May 2021. Over the course of 256 days of fishing, over 6 tons of litter were removed from 265 km2 of seafloor. Abandoned, lost and derelict fishing gears (ALDFG) were the most represented litter category (48 % of the total litter), and of these 67 % were plastic ALDFG (mostly mussel socks and fishing nets). Fouling on plastic waste was analyzed to determine the fraction of collected litter items that could be destinated to recycling. Only a small percentage of the plastic litter analyzed was “clean” from adherent and/or encrusting organisms. Approximately 2.4 tons of plastic were recovered, but, due to the biological colonization of surfaces, they cannot be recycled by using the technologies present in the area.

Prescribed fire regimes influence responses of fungal and bacterial communities on new litter substrates in a brackish tidal marsh.

Processes modifying newly deposited litter substrates should affect fine fuels in fire-managed tidal marsh ecosystems. Differences in chemical composition and dynamics of litter should arise from fire histories that generate pyrodiverse plant communities, tropical cyclones that deposit wrack as litter, tidal inundation that introduces and alters sediments and microbes, and interactions among these different processes. The resulting diversity and dynamics of available litter compounds should affect microbial (fungal and bacterial) communities and their roles in litter substrate dynamics and ecosystem responses over time. We experimentally examined effects of differences in litter types produced by different fire regimes and litter loads (simulating wrack deposition) on microbial community composition and changes over time. We established replicated plots at similar elevations within frequent tidal-inundation zones of a coastal brackish Louisiana marsh. Plots were located within blocks with different prescribed fire regimes. We deployed different measured loads of new sterilized litter collected from zones in which plots were established, then re-measured litter masses at subsequent collection times. We used DNA sequencing to characterize microbial communities, indicator families, and inferred ecosystem functions in litter subsamples. Differences in fire regimes had large, similar effects on fungal and bacterial indicator families and community compositions and were associated with alternate trajectories of community development over time. Both microbial and plant community compositional patterns were associated with fire regimes, but in dissimilar ways. Differences in litter loads introduced differences in sediment accumulation associated with tidal inundation that may have affected microbial communities. Our study further suggests that fire regimes and tropical cyclones, in the context of frequent tidal inundation, may interactively generate substrate heterogeneities and alter microbial community composition, potentially modifying fine fuels and hence subsequent fires. Understanding microbial community compositional and functional responses to fire regimes and tropical cyclones should be useful in management of coastal marsh ecosystems.

Species‐specific effects of leaf litter leachate on the aquatic microbial community and the ratio of heterotrophic to autotrophic biomass

Abstract Dissolved organic carbon (DOC) released from submerged leaf litter is an important allochthonous carbon source for heterotrophic bacteria that enhances the detrital food chain in freshwater ecosystems. In contrast, nitrogen (N), phosphorus (P) and micronutrients released during the leaching process support primary production and enhance the grazing food chain in these ecosystems. This study investigated how DOC and dissolved N and P from the leaf litter of two temperate broadleaf and two coniferous tree species affect heterotrophic and autotrophic biomass by incubating the freshwater microbial community in the culture media prepared from the leaf litter leachate. The results showed that heterotrophic biomass, including bacteria, heterotrophic‐flagellated protists and fungal zoospores, was the highest in the leaf litter leachate, which contained the highest DOC concentration relative to dissolved N and P (Japanese hemlock). In contrast, autotrophic biomass, including small algae, autotrophic flagellated protists and cyanobacteria, was associated with concentrations of dissolved N and P in the leaf litter leachates. Amendment of basal nutrients other than N and P, including micronutrients, trace elements and vitamins, increased autotrophic biomass in two leaf litter leachates (oak, Siebold's beech), suggesting that some elements other than N and P were deficient relative to the requirements of autotrophic organisms. These results indicated that the elemental composition of leaf litter leachates influences microbial community structure and heterotrophic versus autotrophic biomass in freshwater ecosystems. More importantly, the present results suggest that changes in forest vegetation surrounding freshwater ecosystems alter detritus‐based heterotrophic production relative to autotrophic production through the changes in the elemental composition (i.e. stoichiometry) of leaf litter inputs.

Litter mixture effects on nitrogen dynamics during decomposition predominantly vary among biomes but little with litter identity, diversity and soil fauna

Nitrogen (N) is essential for net primary production, with much of the required N in terrestrial ecosystems derived from recycling via litter decomposition. The diversity and identity of plant species and decomposer organisms affect N cycling during litter decomposition, yet the generality and magnitude of these effects remain uncertain. To fill this gap, a decomposition experiment with four leaf litter species that differed widely in initial litter quality was conducted including single species and all possible multispecies mixtures, with and without microarthropods access across a broad latitudinal gradient covering four major forest biomes of the Northern Hemisphere. The results showed that leaf litter N dynamics (both N loss and N immobilization) in single species treatments depended primarily on litter species identity and the local environmental context. We found strong mixture effects, that overall tended to increase N loss and to reduce 15N transfer. The relative mixture effects on N dynamics differed among forest biomes, but were little affected by the other factors we manipulated. The N loss of individual litter species in mixtures not only depended on litter identity and soil microarthropod access, but also on forest biomes; while 15N transfer depended strongly on litter mixing, independently of litter species richness or composition of the mixtures. Litter N dynamics were mainly driven by a small subset of litter traits, regardless of species richness and microarthropod access. Overall, our results highlight that litter mixture strongly affects N dynamics during decomposition, with the mixture effects predominantly varying among forest biomes but little with litter identity, diversity and microarthropod access. To improve predictions on how changes in tree species composition and diversity may impact nutrient dynamics in forest ecosystems in face of increasing N deposition, interactions between litter and soil but also within litter mixtures need closer attention.

Impact of naphthalene on soil fauna diversity: Consequences for ecosystem functioning and carbon cycling in grasslands

Soil fauna, key indicators of grassland ecosystem health, face significant threats from the vast amounts of chemical pollutants released by human activities. These organisms are crucial for fundamental processes such as litter decomposition and carbon cycling. However, the response of soil animal communities and their functional dynamics to environmental chemical stress remains poorly understood. To investigate this, we conducted a naphthalene addition and litterbag experiment in the Bashang Grassland, located on the southern Inner Mongolia Plateau, to analyze its effects on soil fauna and litter decomposition. The investigated soil fauna groups included Arachnida (Arachnids), Insecta (Insects), Collembola (Springtails), Enoplea (enopleans), and Chromadorea (chromadoreans). The litter composition included Leymus chinensis, Stipa krylovii, Artemisia, Saussurea amara, and Artemisia giraldii. The findings indicated that a high diversity of soil fauna enhanced the decomposition of litter and the release of organic carbon from the litter. While the addition of naphthalene decreased both the abundance of soil fauna and the rate of litter decomposition, it specifically increased the relative proportion of Collembola (Springtails). Microfauna and mesofauna (0.1–2.0 mm) contributed more to the loss of litter mass and the release of organic carbon from the litter than macrofauna (2.0–4.0 mm). The effects of diverse soil fauna on litter decomposition and soil organic carbon accumulation were diminished by naphthalene exposure. This study further reveals the relationship between composite soil fauna diversity, litter decomposition, and soil organic carbon under chemical stress, highlighting the threat of environmental pollution to ecosystem health. It also enriches our understanding of the complexity of grassland ecosystems, especially in response mechanisms under chemical pollution stress.

Microbial diversity and cellulase activity of forest soils and litters

The quantity, composition and cellulase activity of forest soils and litters with deciduous and coniferous tree vegetation on the territory of Natural Park "Vitosha" were investigated. Biogenicity, the rate of decomposition of organic matter and specifically of cellulose decomposition were higher in Fagus sylvatica litters than in Pinus sylvestris. In most soil profiles, the total microflora has higher values in the mixed fermentative and humic layer of the litter compared to the fresh litter. The quantity of microorganisms and cellulase activity decrease in the depth of the soil profiles. In general, non-spore-forming bacteria, followed by mold fungi and bacilli, occupy a major share in the composition of the total microflora in litters and soils, and actinomycetes are less represented. The cellulase activity depends to the highest degree on the non-sporulating bacteria, and the values of the mineralization coefficient on the bacteria assimilating mineral nitrogen. The humidity of the litters and soils has a stronger influence on the development, composition, mineralization and cellulase activity of microorganisms, compared to the altitude.

Commercial fishing vessels as marine-based sources of plastic pollution: The Namibian perspective

Plastic pollution in the marine ecosystem and their sources have been widely investigated, however some parts of the world remain under studied. Herein, we report on plastic pollution in the Namibian marine ecosystem, based on data collected by fisheries observers between 2003 and 2020 during commercial fishing activities. A total of 79 plastic pollution incidents were reported between 2003 and 2020, which consisted of unspecified non-biodegradable objects (55.7%), unspecified plastic items (25.3%), fishing gear (8.9%), plastic bottles (5.0%), plastic gloves (1.3%) and single-use plastic bags (3.8%). We found no significant Pearson correlation between the number of disposal incidents and the fisheries observer coverage (r = 0.3254, df = 14, p = 0.2187). The spatial analysis in the disposal of non-biodegradable objects show a fair distribution along the Namibian coast with more concentrations around latitude 18⁰S, 22⁰S, and 26⁰S. We conclude that fishing vessels are important marine-based sources of plastic pollution, highlighting a continuous need to raise awareness over the fishing industry, in particular seafarers, on plastic use and management. The study expands the plastic pollution knowledge by quantifying incidents of plastic pollution, plastic litter composition, and identifying spatial distribution in the Namibian waters, thus, to the best of our knowledge, represents a baseline for studies on marine plastic pollution in this oceanic region. Identifying sources of marine plastic litter and providing a spatial picture is a step closer to develop and implement specific regulatory tools to combat marine pollution.

Revealing the role of land-use features on macrolitter distribution in Swiss freshwaters

Macrolitter, especially macroplastics, (> 0.5 cm) negatively impact freshwater ecosystems, where they can be retained along lake shores, riverbanks, floodplains or bed sediments. Long-term and large-scale assessments of macrolitter on riverbanks and lake shores provide an understanding of litter abundance, composition, and origin in freshwater systems. Combining macrolitter quantification with hydrometeorological variables allows further study of leakage, transport, and accumulation characteristics. Several studies have explored the role of hydrometeorological factors in influencing macrolitter distribution and found that river discharge, runoff, and wind only partially explains its distribution. Other factors, such as land-use features, have not yet been thoroughly investigated. In this study, we provide a country-scale assessment of land-use influence on macrolitter abundance in freshwater systems. We analyzed the composition of the most commonly found macrolitter items (referred to as ‘top items’, n = 42,565) sampled across lake shores and riverbanks in Switzerland between April 2020 and May 2021. We explored the relationship between eleven land-use features and macrolitter abundance at survey locations (n = 143). The land-use features included buildings, city centers, public infrastructure, recreational areas, forests, marshlands, vineyards, orchards, other land, and rivers and canals. The majority of top items are significantly and positively correlated with land-use features related to urban coverage, notably roads and buildings. Over 60% of top items were found to be correlated with either roads or buildings. Notably, tobacco, food and beverage-related products, as well as packaging and sanitary products, showed strong associations with these urban land-use features. Other types of items, however, did not exhibit a relationship with land-use features, such as industry and construction-related items. Ultimately, this highlights the need to combine measures at the local and regional/national scales for effective litter reduction.

Quantification of litter in cities using a smartphone application and citizen science in conjunction with deep learning-based image processing

Cities are a major source of litter pollution. Determination of the abundance and composition of plastic litter in cities is imperative for effective pollution management, environmental protection, and sustainable urban development. Therefore, here, a multidisciplinary approach to quantify and classify the abundance of litter in urban environments is proposed. In the present study, litter data collection was integrated via the Pirika smartphone application and conducted image analysis based on deep learning. Pirika was launched in May 2018 and, to date, has collected approximately one million images. Visual classification revealed that the most common types of litter were cans, plastic bags, plastic bottles, cigarette butts, cigarette boxes, and sanitary masks, in that order. The top six categories accounted for approximately 80 % of the total, whereas the top three categories accounted for more than 60 % of the total imaged litter. A deep-learning image processing algorithm was developed to automatically identify the top six litter categories. Both precision and recall derived from the model were higher than 75 %, enabling proper litter categorization. The quantity of litter derived from automated image processing was also plotted on a map using location data acquired concurrently with the images by the smartphone application. Conclusively, this study demonstrates that citizen science supported by smartphone applications and deep learning-based image processing can enable the visualization, quantification, and characterization of street litter in cities.

Chemical composition, energy content, and nutrient digestibility of rye grain in broiler chickens

The development of livestock farming is always associated with the search for new dietary components that increase feed efficiency or reduce feed costs. The maximum use of regional, conventional feed in the feeding of farm animals is quite relevant today. Furthermore, certain feeds, the production of which is accompanied by low greenhouse gas emissions, help reduce the carbon footprint of the diet as a whole. The purpose of this study was to determine the nutritional value of rye grain of the modern hybrid KWS Tayo and the digestibility of nutrients in poultry. The chemical composition of grain, digestibility of nutrients in broiler chickens, and total energy content were investigated. The chemical composition of feed, compound feed, and litter was determined according to the Wende method. Nutrient digestibility studies were conducted on broiler chickens of the ROSS-308 cross. For the physiological experiment, 5 chickens aged 22 days were selected. The experiment was carried out using a complex method, by replacing part of the basic diet. The experiment consisted of 2 parts. In the first experiment, the nutrient digestibility of the main diet was determined – compound feed containing 5% rye grain; in the second, the main diet with an additional 5% rye grain was used. The calculation was made on the assumption that the digestibility of nutrients in the main diet was the same in both experiments. The compound feed was balanced according to the recommendations of the cross developer. The energy content of rye grain was calculated in J of metabolisable energy by the regression equation, based on the data on the content of digestible protein, fat, fibre, and NFES determined in the physiological experiment. The average dry matter content of the rye samples was 87.4%. The content of the main nutrients in the grain of natural moisture was as follows: crude protein – 8.87±0.484%; crude fat – 1.63±0.105%; NFES – 73.95±0.494%, and crude ash – 0.53±0.109%. The nutrient digestibility of rye grain was as follows: crude protein – 76%; crude fat – 82%, crude fibre – 8%; NFES – 81% and organic matter – 78%. The total energy value of rye grain was 12.420±0.2573 MJ/kg of metabolic energy for poultry. Nutritionists can use the nutritional and nutrient digestibility data of rye grain to develop practical recipes for poultry compound feed

Difference in the production and elemental composition of litter in Kandelia obovata mangrove forests due to site elevation

Site elevation is a crucial driver for mangrove restoration, and litter production restoration is a significantly important target of mangrove restoration, but little attention has been paid to impact of site elevation on the production and elemental composition of litter in the restored mangrove forests. This study compared the production and elemental composition of mangrove litter at the three intertidal elevations, to explore impacts of site elevation on the production and elemental composition of mangrove litter. Compared with the upper elevation site, significantly lower annual litter production was found at the lower elevation site. Leaf litter was the main component of litter, up to 60.49% of total litter production at the upper elevation site, while reproductive materials (flower and fruit) were the key part of litter and accounted for 50.80% (the lower elevation site) and 57.02% (the middle elevation site) of total litter production. As site elevation decreased, element stocks within total litter decreased by approximately 65.39% (organic carbon), 65.17% (total nitrogen) and 63.66% (total phosphorus), respectively, which was attributed more to element stocks within leaf litter instead of element stocks within the other litter. Results showed that site elevation decreases resulted in decreased litter production, altered composition percentages of litter production, and reduced element stocks within total litter. In the future mangrove restoration projects, it is advisable to prioritize upper elevation (above local mean level) for promoting litter production.

Emerging Technologies for Remote Sensing of Floating and Submerged Plastic Litter

Most advances in the remote sensing of floating marine plastic litter have been made using passive remote-sensing techniques in the visible (VIS) to short-wave-infrared (SWIR) parts of the electromagnetic spectrum based on the spectral absorption features of plastic surfaces. In this paper, we present developments of new and emerging remote-sensing technologies of marine plastic litter such as passive techniques: fluid lensing, multi-angle polarimetry, and thermal infrared sensing (TIS); and active techniques: light detection and ranging (LiDAR), multispectral imaging detection and active reflectance (MiDAR), and radio detection and ranging (RADAR). Our review of the detection capabilities and limitations of the different sensing technologies shows that each has their own weaknesses and strengths, and that there is not one single sensing technique that applies to all kinds of marine litter under every different condition in the aquatic environment. Rather, we should focus on the synergy between different technologies to detect marine plastic litter and potentially the use of proxies to estimate its presence. Therefore, in addition to further developing remote-sensing techniques, more research is needed in the composition of marine litter and the relationships between marine plastic litter and their proxies. In this paper, we propose a common vocabulary to help the community to translate concepts among different disciplines and techniques.

Study on the Influence of Canopy Density on Cycling of Soil Available N in Different Landform of Loess Plateau in China

In this paper, a total of 330 soil samples with 0-100cm soil depth of 66 planted square forest (10*10m) with different canopy density in the Loess Plateau were selected for the determination and analysis of soil N content in different soil layers, and the effects of different canopy density on soil N cycle under different topographic factors of planted forest were studied. The results showed as follows: (1) the migration mechanism of different N forms to the root surface was different, the migration of nitrate nitrogen to the root surface mainly depended on mass flow, there was enrichment phenomenon near the root, ammonium nitrogen mainly through diffusion, resulting in deficiency and loss in the near rhizosphere, and the leaching loss of nitrate nitrogen was affected by soil water and root growth. (2) The thickness, composition and decomposition rate of litter were different due to different canopy density, which affected the content of ammonium nitrogen and nitrate nitrogen in forest soil. (3) Although the change of different regions in this region was spatially different, keeping the stand cover in the middle and high range of 0.75-0.8 can be conducive to maintaining the balance between the consumption of soil nutrients by the stand and the supplement of nutrient consumption, which can also be conducive to the sustainable recovery and growth of the stand in this region.

Shrub effects on the decomposition microenvironment and changes in litter quality have opposing effects on litter decomposition

Increasing abundance of tall deciduous shrubs has been shown to affect tundra soil properties, which may further affect carbon and nitrogen cycling in these soils, including through effects on litter decomposition. These tall deciduous shrubs produce a higher quantity of litter, and also a different quality of litter, than tundra species in non-shrub dominated tundra, both of which may affect community-wide decomposition rates. We examined how presence of tall deciduous shrubs, including resulting increases in litter quantity, affects litter decomposition through effects on both the decomposition environment and on litter composition. In a factorial experiment, we modified the decomposition environment by manipulating both the abundance of tall deciduous shrubs (present/absent) and their litter (absent, natural, and doubled). In each environment we decomposed litter of the tall deciduous shrub, Betula glandulosa and two other dominant species in our study area; Salix reticulata, a dwarf deciduous shrub, and Carex consimilis, a graminoid. We report that while tall Betula shrub presence reduced decomposition rates, decomposition was not affected by manipulations of litter quantity. Although litter decomposed slower under deciduous shrubs, B. glandulosa litter decomposed faster than the litter of the other dominant tundra plant species. However, the reduction in decomposition rates due to tall deciduous shrub presence and higher decomposition rates of B. glandulosa litter in comparison to other plant species were of the same magnitude and these opposing effects may result in little to no change of shrub encroachment on litter decomposition rate overall.

Plastic litter assessment of the riverbanks of Pulot River and its tributary in Sofronio Española, Palawan Island, Philippines

Rivers are essential sources of plastic litter in the marine environment. Recently, the Philippines was reported as the biggest polluter of plastic litter from riverine sources. However, the riverine plastic litter's origin has been less established. In this study, we determined the density, composition, and accumulation of plastic litter on the riversides of Pulot River and its tributary in Palawan Island, Philippines. We also identified the possible sources of plastic litter. Results showed that the plastic litter density was highest at the river edge during the first sampling period. Litter densities for the predefined zones and sampling periods all showed no significant differences. The most dominant plastic litter types were food packaging and plastic bags, followed by toiletries. ‘Others’ consisted of multilayers, mixed, and plastics accounted for the most abundant polymer types. We identified the residents in the vicinity illegally dumping litter, for there were small illegal dumping sites along the river. These results suggest the urgent need for better waste policy implementation measures to protect the riparian environments and reduce the input of riverine plastic litter into the marine environment to ensure river resource sustainability.

Vertical distribution of edaphic oribatid mites (Acari: Oribatida) in two artificial forests planted on temperate grasslands

Context Oribatid mites are the most abundant taxon in forest soils that rely on porosity and organic matter availability. Exotic forests of Pinus radiata and Eucalyptus globulus planted over native grasslands in the Pampas region of Argentina have produced modification in soil properties, which can affect the composition and structure of native oribatids communities. Aims To compare oribatid communities in soils under artificial woodlands of pine and eucalyptus and to assess the vertical distribution of oribatids in relation to edaphic variables. Methods In each forest, oribatids were collected from three levels of the A horizon: (1) litter layer; (2) 0–5 cm; and (3) 5–10 cm. Edaphic variables measured were penetration resistance, bulk density, total porosity, pH and water content and luminosity at soil level. Density, species richness, diversity and evenness of oribatids were calculated in each level of each forest. Comparisons were made through multivariate analyses. Key results Edaphic variables showed no significant differences between plots but litters were structurally different. Richness and diversity showed no differences between plots whereas evenness was significantly higher in plot P. Density had higher values in the litter layer of both forests. Canonical Analysis of Principal Coordinates (CAP) showed that Pine plots had a more defined vertical distribution. Conclusions The structure and composition of litters promoted differences in the vertical distribution of oribatids. In Pinus, thick unaltered litter showed a marked vertical gradient of mites along levels while in Eucalyptus, thin and easily decomposing litter, showed no vertical patterns. Implications Assessment and management of soil biodiversity in artificial woodlands.