Land use and COVID-19 lockdowns influence debris composition and abundance in stormwater drains

Litter in French urban areas - Part 2: transport dynamic and fluxes in stormwater

Urban areas constitute a major hotspot of litter, including plastic litter, that stormwater can wash off towards waterways. However, few studies quantified and characterized litter densities in urban areas and fluxes transported by stormwater networks. Moreover, little information is available on litter transport dynamics in stormwater, and on the factors driving this transport. This study aims at characterizing and quantifying litter amounts transported by stormwater of two nested French urban catchments (total surface area of 105 ha). Litter densities relative to land uses and rain events were investigated in the same catchments as in a compagnon paper (Ledieu et al., 2024). The present study explores the impact of rain events on the transport of urban litter in stormwater. Litter collection and characterization combined with a capture/recapture experiment using tagged litter placed in stormwater inlets show total litter fluxes of 29 kg/year, in which 14 kg/year are plastics, exported at the stormwater outlet. These fluxes confirm that stormwater runoff is a considerable pathway from urban surfaces to waterways, especially regarding small plastic litter (< 2.5 cm). Item transport dynamic is however not linear and only 0.3% of the urban litter appear remobilized. Litter transport dynamics depends on several factors (urban litter densities, hydrometeorological parameters, item composition and morphologies, and stormwater management systems) that should be considered in global models.

Pavement wear generates microplastics in stormwater runoff

Tire and road wear particles are a major source of microplastics to urban stormwater. They are composed of hetero-aggregates of abraded tire and pavement particles that are difficult to distinguish. While tire wear is a known source of microplastics, little is known on the contribution of pavement wear. This two-year field study with complementary lab testing evaluates the effects of pavement degradation on microplastic generation in stormwater from different pavement types: asphalt, concrete, and recycled rubber pavers. Pavement specimens from each site were collected and underwent degradation testing. We directly demonstrated that pavement wear is a source of microplastics in stormwater separate from tire wear. We showed that the rubber pavement released the most microplastics in lab testing, suggesting that the formulation of such novel recycled-tire pavers must undergo thorough testing before wide application. The asphalt pavement was the most susceptible to rutting and released the most microplastics in the field, including a large proportion of tire wear particles. Both land-use and pavement surface characteristics influenced microplastic generation. These results demonstrate the need to consider microplastic generation during pavement material selection and mitigate the spread of microplastics from pavement wear to nearby environments.

Microplastic characteristics in rain/snow sampled from two northern Chinese cities

Atmospheric precipitation is recognized as a significant source of environmental microplastics, especially in inland waters and remote areas. However, due to the limited availability of existing data, further information on microplastics in precipitation is essential. Therefore, this study aims to elucidate the contamination of microplastics in both snowfall and rainfall while identifying potential factors that may influence their presence during atmospheric deposition. Samples of snowfall and rainfall were collected from two representative cities in Northern China across winter and summer seasons. Subsequently, microplastics were identified and quantified automatically using laser-assisted direct infrared imaging techniques. The findings indicate that microplastic concentrations are higher in snowfall (City A: 182.30 ± 190.25 items/L; City B: 301.74 ± 325.81 items/L) compared to rainfall (City A: 58.90 ± 51.00 items/L; City B: 39.20 ± 30.31 items/L), revealing significant variations in the polymer composition of microplastics. Moreover, a greater diversity of polymers was identified in snowfall relative to rainfall, despite some commonalities among polymers; fragments measuring between 20 μm to 100 μm comprised the majority of detected microplastic particles across both types of precipitation. Crucially, the frequency of precipitation events (rainfall versus snowfall) appears to affect the concentration of atmospheric microplastics, resulting in notably higher levels within snowfalls. These findings offer valuable insights into wet deposition processes by underscoring the atmospheric origins contributing to environmental microplastic pollution.

Assessing rural land use in contemporary China: Data compilation and methodology

In rural areas, land use decisions are not only shaped by economic considerations but also deeply influenced by cultural and social factors. The objective of this research is to examine the complex and diverse aspects of making decisions about how land is used in rural communities, specifically by investigating the influence of cultural and social elements. Using empirical data and rigorous analysis, this research examine how traditional practices, social norms, and community dynamics influence land use patterns. The research topic focuses on the need to have a thorough understanding of the fundamental elements that affect land use choices in rural regions, going beyond only economic incentives. This research objective is to address a significant vacuum in the current literature by examining the cultural and social aspects of land usage. This research provides vital insights for policymakers and stakeholders engaged in land management and rural development projects. This research utilizes a mixed-methods approach, using qualitative interviews, participatory observations, and quantitative surveys to collect comprehensive data on the cultural and socioeconomic elements that impact land use choices. The research sample includes a wide range of rural areas, guaranteeing a thorough representation of various cultural settings and socioeconomic backgrounds. Our study reveals that cultural traditions, social networks, and power structures have a substantial impact on land use practices in rural regions. Traditional land tenure systems, community ownership arrangements, and customary land-use practices play a vital role in influencing land-use choices and resource distribution within communities. The significance of these results is substantial for policymakers, land managers, and rural development practitioners. Policymakers may create land use policies and actions that are more appropriate to the specific cultural and socioeconomic environment by understanding the complex relationship between these aspects. Furthermore, promoting community involvement and allowing local actors to participate in decision-making may result in land management results that are both more sustainable and fair.

Mapping COVID-19's potential infection risk based on land use characteristics: A case study of commercial activities in two Egyptian cities

The contagious COVID-19 has recently emerged and evolved into a world-threatening pandemic outbreak. After pursuing rigorous prophylactic measures two years ago, most activities globally reopened despite the emergence of lethal genetic strains. In this context, assessing and mapping activity characteristics-based hot spot regions facilitating infectious transmission is essential. Hence, our research question is: How can the potential hotspots of COVID-19 risk be defined intra-cities based on the spatial planning of commercial activity in particular? In our research, Zayed and October cities, Egypt, characterized by various commercial activities, were selected as testbeds. First, we analyzed each activity's spatial and morphological characteristics and potential infection risk based on the Centre for Disease Control and Prevention (CDCP) criteria and the Kriging Interpolation method. Then, using Google Mobility, previous reports, and semi-structured interviews, points of interest and population flow were defined and combined with the last step as interrelated horizontal layers for determining hotspots. A validation study compared the generated activity risk map, spatial COVID-19 cases, and land use distribution using logistic regression (LR) and Pearson coefficients (rxy). Through visual analytics, our findings indicate the central areas of both cities, including incompatible and concentrated commercial activities, have high-risk peaks (LR = 0.903, rxy = 0.78) despite the medium urban density of districts, indicating that urban density alone is insufficient for public health risk reduction. Health perspective-based spatial configuration of activities is advised as a risk assessment tool along with urban density for appropriate decision-making in shaping pandemic-resilient cities.

Legacy community science data suggest reduced beached litter in response to a container deposit scheme at a local scale

Marine debris is causing significant environmental harm. Legislation is being implemented to reduce litter, including schemes like container deposit legislation that incentivize the return of commonly littered items for recycling. While there is a suggestion that these schemes reduce litter, no study has examined the long-term impact on the local environment before and after implementation. This study analyses community science data from 8 years prior to the implementation of a container deposit scheme, paired with 3 years of data afterwards, to assess the scheme's effectiveness at a local scale. Although using legacy datasets limits the generalizability of the conclusions compared to dedicated studies, the findings strongly indicate that container deposit schemes effectively manage targeted containers but have little impact on overall waste abundances. Long-term datasets like these are invaluable for assessing the impact of management efforts.