Table of contents

Due to the heterogeneity of PM_2.5 and population distribution, the representativeness of existing monitoring sites is questionable when the monitored data were used to assess the population exposure. By comparing the PM_2.5 concentration from a satellite-based dataset named the China High Air Pollutants (CHAP), population and exposure level in urban areas with monitoring stations (UWS) and without monitoring stations (UNS), we discussed the rationality of the current spatial coverage of monitoring stations in eastern China. Through an analysis of air pollution in all urban areas of 256 prefectural-level municipalities in eastern China, we found that the average PM_2.5 concentration in UNS in 2015 and 2018 were 52.26 μg m⁻³ and 41.32 μg m⁻³, respectively, which were slightly lower than that in UWS (52.98 μg m⁻³ and 41.48 μg m⁻³). About 12.1% of the prefectural-level municipalities had higher exposure levels in certain UNS than those in UWS. With the faster growth of UNS population, the gap between exposure levels of UNS and UWS were narrowing. Hence, currently prevalent administration-based principle of site location selection might have higher risk of missing the non-capital urban areas with relatively higher PM_2.5 exposure level in the future.

Microplastic particles (MPs, <5 mm) are found in marine ice in larger quantities than in seawater, however, the distribution pattern within the ice cores is not consistent. To get insights into the most general physical processes behind interactions of ice and plastic particles in cool natural environments, information from academic and applied research is integrated and verified against available field observations. Non-polar molecules of common-market plastics are hydrophobic, so MPs are weak ice nucleators, are repelled from water and ice, and concentrate within air bubbles and brine channels. A large difference in thermal properties of ice and plastics favours the concentration of MPs at the ice surface during freeze/thaw cycles. Under low environmental temperatures, falling in polar regions below the glass / brittle-ductile transition temperatures of the common-use plastics, they become brittle. This might partially explain the absence of floating macroplastics in polar waters. Freshwater freezes at a temperature well below that of its maximum density, so the water column is stably stratified, and MPs eventually concentrate at the ice surface and in air bubbles. In contrast, below growing sea ice, mechanisms of suspension freezing under conditions of (thermal plus haline) convection should permanently entangle MPs into ice. During further sea ice growth and aging, MPs are repelled from water and ice into air bubbles, brine channels, and to the upper/lower boundaries of the ice column. Sea ice permeability, especially while melting periods, can re-distribute sub-millimeter MPs through the brine channels, thus potentially introducing the variability of contamination with time. In accord with field observations, analysis reveals several competing factors that influence the distribution of MPs in sea ice. A thorough sampling of the upper ice surface, prevention of brine leakage while sampling and handling, considering the ice structure while segmenting the ice core—these steps may be advantageous for further understanding the pattern of plastic contamination in natural ice.

We present and estimate a dynamic stochastic general equilibrium model for an eco-environmental damage compensation system (EDCS) with multi-stakeholder engagements. Then we explore the dynamic effect under different shocks such as household and government supervision, environmental damage compensation ratio, pollution emission threshold, and pollution control efforts. The household and government supervision show the positive effect of environmental regulation on conserving energy, abating emission, reducing damage compensation, and increasing economic output. The environmental damage compensation ratio can also contribute to energy conservation and emission reduction, but there are no significant regulation effects of pollutant emission and damage compensation. The pollutant emission threshold and the pollution control efforts have significant environmental regulation effects, but the latter does not significantly restrain high energy consumption. All the shocks mentioned above can effectively improve the green development level.

A study was conducted in Thuma area in central Malawi to quantify contemporary land cover and to explore the degree of land use change in the Thuma forest reserve area of Malawi by analysing and comparing satellite-derived land cover maps from 1997, 2007 and 2017. The study was carried out using Remote Sensing and Geographic Information System (GIS), focusing on analysis of Landsat 5 ETM and Landsat 8 ORI/TIRS satellite images. The classification was conducted for the following distinct classes; closed forest, open forest, shrubland, savanna grassland, agriculture fields, and water. The analysis revealed that closed forest diminished from 19% in 1997 to 10% in 2007 to 6% in 2017. Open forest reduced from 30% to 21% from 1997 to 2007 but increased to 22% in 2017. Agriculture area almost doubled from 37% in 1997 to 64% in 2017. The actual area from 1997 to 2017, shows that closed forest has reduced from 7,000 ha to 3,000 ha while open forest from 12,900 ha to 7800 ha. Savanna grassland has doubled from 5,900 ha to 13,000 ha. However, future studies should use modern satellites such as Sentinel and Landsat 9 for improved quantification of changes. The findings show that even the protected forest reserve (previously dominated by closed forest) is not fully protected from deforestation by local communities. Government and other stakeholders should devise measures to meet the needs of the surrounding communities and the ecological/biophysical needs of the reserves. Based on this study, issues of re-demarcation of the forest reserve and the accessed area should also be explored. This study serves as a reference for the management of Thuma Forest Reserve as a refuge for natural tree species, rivers that harbour endemic fish species (Opsaridium microlepis and Opsaridium microcephalis) and the sustainable management of endangered elephants in the reserve.

The increasing prevalence of marine debris is a global problem, and urgent action for amelioration is needed. Identifying hotspots where marine debris accumulates will enable effective control; however, knowledge on the location of accumulation hotspots remains incomplete. In particular, marine debris accumulation on beaches is a concern. Surveys of beaches require intensive human effort, and survey methods are not standardized. If marine debris monitoring is conducted using a standardized method, data from different regions can be compared. With an unmanned aerial vehicle (UAV) and deep learning computational methods, monitoring a wide area at a low cost in a standardized way may be possible. In this study, we aimed to identify marine debris on beaches through deep learning using high-resolution UAV images by conducting a survey on Narugashima Island in the Seto Inland Sea of Japan. The flight altitude relative to the ground was set to 5 m, and images of a 0.81-ha area were obtained. Flight was conducted twice: before and after the beach cleaning. The combination of UAVs equipped with a zoom lens and operation at a low altitude allows for the acquisition of high resolution images of 1.1 mm/pixel. The training dataset (2970 images) was annotated by using VoTT, categorizing them into two classes: 'anthropogenic marine debris' and 'natural objects.' Using RetinaNet, marine debris was identified with an average sensitivity of 51% and a precision of 76%. In addition, the abundance and area of marine debris coverage were estimated. In this study, it was revealed that the combination of UAVs and deep learning enables the effective identification of marine debris. The effects of cleanup activities by citizens were able to be quantified. This method can widely be used to evaluate the effectiveness of citizen efforts toward beach cleaning and low-cost long-term monitoring.

Nitrogen Use Efficiency (NUE) is one of the established metrics for benchmarking management of Nitrogen (N) in various systems. Numerous approaches to calculate NUE exist, making it difficult to compare the performances of systems depending on the methodology used. This study adopted the conceptualized framework by European Union Nitrogen Expert Panel (EUNEP) to calculate NUE values for cereal crops to determine future trends for the first time in the Lake Victoria region. Data were collected through in-person interviews among maize and rice smallholder farmers within the Lake Victoria region. A total of 293 observations were recorded. Collected data on yield and N fertilizer were used to make projections on the changes of NUE based on scientific and policy recommendations for Sub-Saharan Africa for 2020 (base year), 2025, 2030, and 2050. Significant differences in maize grain yield for both fertilized and unfertilized farms were observed with very low yields of 2.4 t ha⁻¹ (fertilized) and 1.4 t ha⁻¹ (unfertilized). The graphical representation of NUE of both maize and rice showed that most farmers were in the zone of soil N mining. Projected results showed that most maize farmers within Lake Victoria region will continue to experience NUE values >90%, low N inputs <50 kg N ha⁻¹) and less than 5 t ha⁻¹ maize crop yield over the years. For rice farmers, Nyando and Nzoia catchments had surpassed the set target of both yield (6 t ha⁻¹) and N input (50 kg N ha⁻¹). However, NUE values remain higher than the optimal ranges of 50%–90% (127.14%−267.57%), indicating risks of depleting soil N status. The unbalanced N fertilization also showed a trend below the linear neutrality option and the average N output for good N management for both crops. Therefore, farmers need to explore various crop management options that could increase N use efficiencies. This should be coupled with policies that promote farmers to access more N input and advocate for optimal management of N and improved quality of the cereals.

The economic development of rural economies across the global south is often related to access to water and the development of water infrastructure. It has been argued that the construction of new dams would unleash the agricultural potential of African nations that are exposed to seasonal water scarcity, strong interannual rainfall variability, and associated uncertainties in water availability. While water security is often presented as the pathway to poverty alleviation and invoked to justify large dam projects for irrigation, it is still unclear to what extent small holders will benefit from them. Are large dams built to the benefit of subsistence farmers or of large-scale commercial agriculture? Here we use remote sensing imagery in conjunction with advanced machine learning algorithms to map the irrigated areas (or 'command areas') that have appeared in the surroundings of 18 major dams built across the African continent between 2000 and 2015. We quantify the expansion of irrigation afforded by those dams, the associated changes in population density, forest cover, and farm size. We find that, while in the case of nine dams in the year 2000 there were no detectable farming patterns, in 2015 a substantial fraction of the command area (ranging between 8.5% and 96.7%) was taken by large-scale farms (i.e., parcels >200 ha). Seven of the remaining 9 dams showed a significant increase in average farm size and number of farms between 2000 and 2015, with large-scale farming accounting for anywhere between 5.2% and 76.7% of the command area. Collectively, these results indicate that many recent dam projects in Africa are associated either with the establishment of large-scale farming or a transition from small-scale to mid-to-large scale agriculture.

To develop a climatic suitability index and conduct the cultivation division of loquat in Lishui, Zhejiang province of China, we introduced the multi-indicator comprehensive risk assessment method to combine with the hazard factor model, necessary climatic elements during the growing season of loquat and geographic information elements. Results show that the annual active accumulated temperature (rainfall) over most Lishui is more than 4500 °C (1600mm). The two climatic factors above can well meet the needs of loquat growth. The frozen injury days over most Lishui during the young fruit period of loquat are more than 10.0 days, which are higher than those during the flowering period. The annual mean number of continuous overcast rain occurrences is less than 4.5. The climatic mean annual occurrence of persistent abnormal high temperature weather is less than 1. Overall, the most suitable area for the cultivation of loquat mainly located over the relatively flat areas such as river valleys and basins, especially the banks of the Oujiang River in Qingtian and Xiaoxi River valley in Jingning. The excellent combinations of light, heat and water with relatively few meteorological disasters just like frozen injury, continuous rain and high temperature provide a good climatic conditions of the high-quality of loquat planting.

Environmental problems such as global warming, ozone depletion and climate change remain universal subjects of concern, with baneful effects on both the environment and human health. The consumption and venting of ozone depleting substances (ODS) into the atmosphere are the chief anthropogenic cause of ozone depletion. One such manmade ODS with high global warming potential Chlorodifluoromethane (HCFC-22). The MP targeted to phase-out HCFC-22 with obligatory cut-off timelines for its use by 2040 for developing nations. To comply with the HCFC-22 phase-out timelines, meant at embarking on national communications to disseminate information on HCFC-22 phase-out through key stakeholders' involvement. The achievement of HCFC-22 phase-out strategy depends on participation of key stakeholders in the implementation process. the level of awareness and product knowledge of service stakeholders in the importation and distribution of HCFC-22 in Botswana. customs officers, officers and industrial consumers. Questionnaires and interviews were used to solicit key stakeholders' views, opinions and perceptions on HCFC-22 phase-out awareness and product knowledge. Results revealed that 87% of the stakeholders are learned and knowledgeable in ODS related service provision. The level of HCFC-22 knowledge and awareness among stakeholders is moderate with distinguished inter-group differences. In particular, industrial consumers had the highest median level of HCFC-22 awareness than other stakeholders, indicating gaps in HCFC-22 phase-out awareness raising and training. About 67% of respondents had low levels of awareness of the HPMP and alternative technologies to HCFC-22. This proposes gaps in information dissemination to key stakeholders and this remains a crucial disparity between the country's HPMP success lead and lag indicators. There is need to carefully select communication media used in line with the media consumption habits of target markets. Use of popular and commonly accessed social-media platforms would ensure that the HCFC-22 phase-out messages have high chance of reaching targeted stakeholders and the general population.

The increasing frequency and severity of Natech accidents warn us to investigate the occurrence mechanism of these events. Cascading disasters chain magnifies the impact of natural hazards due to its propagation through critical infrastructures and socio-economic networks. In order to manipulate imprecise probabilities of cascading events in Natech scenarios, this work proposes an improved Bayesian network (BN) combining with evidence theory to better deal with epistemic uncertainty in Natech accidents than traditional BNs. Effective inference algorithms have been developed to propagate system faulty in a socio-economic system. The conditional probability table (CPT) of BN in the traditional probability approach is modified by utilizing an OR/AND gate to obtain the belief mass propagation in the framework of evidence theory. Our improved Bayesian network methodology makes it possible to assess the impact and damage of Natech accidents under the environment of complex interdependence among accidents with insufficient data. Finally, a case study of Guangdong province, an area prone to natural disasters, is given. The modified Bayesian network is carried out to analyze this area's Natech scenario. After diagnostic analysis and sensitivity analysis of human factors and the natural factor, we are able to locate the key nodes in the cascading disaster chain. Findings can provide useful theoretical support for urban managers of industrial cities to enhance disaster prevention and mitigation ability.

Understanding the dynamics of water-energy-food (WEF) nexus interactions with climate change and human intervention helps inform policymaking. This study demonstrates the WEF nexus behavior under ensembles of climate change, transboundary inflows, and policy options, and evaluates the overall nexus performance using a previously developed system dynamics-based WEF nexus model—WEF-Sask. The climate scenarios include a baseline (1986–2014) and near-future climate projections (2021–2050). The approach is demonstrated through the case study of Saskatchewan, Canada. Results show that rising temperature with increased rainfall likely maintains reliable food and feed production. The climate scenarios characterized by a combination of moderate temperature increase and slightly less rainfall or higher temperature increase with slightly higher rainfall are easier to adapt to by irrigation expansion. However, such expansion uses a large amount of water resulting in reduced hydropower production. In contrast, higher temperature, combined with less rainfall, such as SSP370 (+2.4 °C, −6 mm), is difficult to adapt to by irrigation expansion. Renewable energy expansion, the most effective climate change mitigation option in Saskatchewan, leads to the best nexus performance during 2021–2050, reducing total water demand, groundwater demand, greenhouse gas (GHG) emissions, and potentially increasing water available for food&feed production. In this study, we recommend and use food&feed and power production targets and provide an approach to assessing the impacts of hydroclimate and policy options on the WEF nexus, along with suggestions for adapting the agriculture and energy sectors to climate change.