Environmental Processes

The Australian agricultural sector is of high importance as a predominant contributor to GDP and export earnings. However, rapid global warming and climate change may pose obstacles to agricultural exports. Existing literature shows that the issue is not receiving enough attention from policymakers, researchers, and academicians as it should. Therefore, in this paper, we have investigated the impact of global climate change on Australian agricultural export earnings. Our analyses, based on graphical, statistical, and econometric estimation (ordinary least squares) for the data period of 1990–2022, reveal that climate change caused by environmental pollution is harming Australian agricultural export performance. Specifically, environmental degradation and the average yearly temperature increase in Australia triggered by the exponential growth of CO2 emissions have negative impacts on Australian agricultural export growth. As the agricultural sector contributes about one-third of Australia's total export earnings, the rapid decline in its export earnings may create multiple imbalances in the Australian economy in the future. Thus, the country should launch immediate preventive actions to ameliorate the environmental condition, defending its agricultural export performance and maintaining environmental sustainability.

Water quality is one of the most altered ecosystem services in watersheds at the periphery of megacities, where point sources and non-point sources of pollution derived from domestic and agricultural activities are in many cases not well regulated. Despite widespread needs for information, riparian ecosystem service management of megacities in developing countries is largely absent from the literature. To begin to understand connections between surface water quality and landscape factors (i.e. land use and topography), we examined physicochemical and biological properties of water quality at 37 sub-watersheds of the Guadalupe Dam Watershed (GDW) that lies to the northwest of Mexico City. The influences on water quality of sub-watershed versus riparian zone at 50, 100 and 200 m were compared. We applied multiple linear regressions and redundancy analysis. The latter was also used to partition the variance explained by topography (i.e. elevation and slope), land use, and their combined variation. Our results showed that elevation had the greatest influence on water quality, likely because it represents a gradient of urban influence and consequently environmental pollution. Agriculture was not a dominant predictor of water quality, and its direct impacts were somewhat masked given the interaction with other land uses and landscape factors. The shared variation of topography and land use exerted more influence on water quality than either alone, showing that topographic factors constrain certain human activities in the area. Landscape factors accounted for more variation (52 %) at 100 m of riparian zone, giving new information important for the management of riparian ecosystems. Our findings are a step forward in the understanding of the effects of human activities and natural landscape features in providing water of good quality. They will also assist natural resource managers in the challenge of managing water-related ecosystem services through scientifically-based management actions and policies, a gap faced by regulatory authorities of megacities in the developing world.

Despite its significant positive impact on environmental quality, rendering industry still suffers, on a global basis, from nuisance odour problems that can contribute to public complaints about health problems, social and individual life disruption. This study was carried out in the surroundings of the animal rendering plant in Southwest Greece, after compulsory cessation of operation in May 2020. Volatile organic compounds (VOCs) were determined in the ambient air in four sampling campaigns and the Odour Activity Values (OAVs) were calculated for odorants. Past and present odour nuisance perceived by residents was assessed through a questionnaire. The results revealed a significant reduction by half in the total concentration of VOCs. Main offensive odorants totally disappeared. The sum of OAVs decreased by 89% in 2020 and 71% in 2021, in relation to the operation period. Residents reported a significant reduction in the frequency, intensity, duration and annoyance of the odour after termination of the rendering activities. Non-specific health symptoms (nausea, respiratory problems, etc.) that participants were experiencing in the past, no longer occurred. Given that the rendering industry follows by default the concept of circular economy, and adds to environmental safety, economy and public health protection, its operation should be kept pursued but under odour abatement strategies. Rendering facilities should be settled at industrial areas and utilize existing modern and environmentally friendly technologies to effectively control odour emissions and eliminate health and social impact.

The performance of four Near-Real-Time Satellite-Based Rainfall Estimates (NRT_SREs) was evaluated across the Volta basin from January 2019 to December 2020: Global Satellite Mapping of Precipitation (GSMaP_NRT), Integrated Multi-satellitE Retrievals for Global Precipitation Measurement-Early run (IMERG-E), Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks (PERSIANN)-Cloud Classification System (PERSIANN-CCS), and PERSIANN–Dynamic Infrared Rain Rate (PDIR_NOW). They were also compared to their post-real-time counterparts: PERSIANN, IMERG-Final run (IMERG-F), IMERG-Late run (IMERG-L) and GSMaP_MVK. Quantitative and categorical metrics were used in conducting hourly and daily evaluations at individual stations across the basin, as well as at zonal and seasonal scales. The results revealed that all the NRT_SREs had weak correlations (third quartile: 0.3625) at the hourly timescale. IMERG-F had the best correlation (R) of all the SREs, but it also had the worst Root Mean Square Error (RMSE) and False Alarm Ratio (FAR), being outperformed by IMERG-E and IMERG-L. IMERG-E also outperformed the NRT_SREs in most cases. However, in the arid Sudano-Sahelian zone, PDIR_NOW had the highest probability of detecting rainfall of all SREs (at the daily timescale) and all NRT_SREs (at both timescales). This was most likely because of PDIR_NOW’s increased maximum temperature threshold. Seasonal analysis revealed that the RMSE of the NRT_SREs was significantly lower during the dry season than during the wet season, and vice versa for FAR. The findings of this study are expected to provide not only valuable feedback to algorithm developers in order to improve NRT_SREs, but also guidance to data users worldwide. • All NRT_SREs performed poorly at hourly timescale, but improved at daily timescale • IMERG-E outperformed all NRT_SREs in most cases, irrespective of the season and zone • IMERG-E had better RMSE and pBIAS than PRT IMERG-F at hourly and daily timescale • IMERG-E could supplement rainfall measurements within the basin at daily timescale

The hydrometallurgical treatment of waste printed circuit boards for the recovery of precious metals generates acidic wastewater containing nitrate, chloride and residual base metals. The scope of this work is the study of a biological treatment process for the concurrent metal sequestering, nitrate reduction and wastewater neutralization. A pilot-scale packed-bed biofilm reactor was set up, inoculated with the strain H. denitrificans and experimentally monitored. The range of operating parameters examined included: (a) nitrate concentration 750–5750 mg/L NO3−; (b) pH 3–8; (c) Cu, Ni, Zn and Fe at 50 mg/L and 100 mg/L; and (d) chloride concentration 5%–10% as NaCl. The presence of metals did not affect denitrification at the concentrations examined. H. denitrificans completely reduced nitrate and the intermediately produced nitrite at elevated chloride levels. Denitrification shifted pH towards circumneutral to alkaline values, where iron, zinc, copper and nickel were sequestered quantitatively from solution via bioprecipitation. The proposed simple, robust and low-cost biological treatment unit is advantageous compared to the conventional wastewater treatment, where metal precipitation is based on chemical neutralization and the problem of nitrate removal remains unresolved.

The lockdowns instigated to slow the spread of the COVID-19 pandemic offered a unique opportunity to assess how restrictions on human activity affect street litter. We recorded daily litter arrival rates for 50 days in two South African cities from the time of strictest lockdown through two successive easings in regulations. The strict lockdown had no marked impact on litter composition, which was dominated by convenience foods and beverages (29% by number, 34% by mass) and tobacco products (33% by number, 3% by mass). The ban on the sale of tobacco products during the lockdown did not greatly reduce the number of cigarette butts and associated packaging. Vehicle parts accounted for <1% of litter items (2% by mass) whereas household waste spilled from bins prior to or during collection accounted for 3% of litter items (14% by mass). Street litter loads decreased roughly by a factor of three during the strict lockdown. The increase in litter was gradual, suggesting a reduction in compliance with regulations as the lockdown continued. Our results show a clear link between human activity levels and littering. • Street litter loads increased three-fold in two cities as Covid lockdowns eased. • Cigarette butts made up 33% of litter by number despite a ban on tobacco sales. • There is a clear link between human activity levels and littering.

Different initiatives have been implemented to improve air quality in large cities, such as encouraging travel by sustainable modes of transport, promoting electro-mobility, or the car-free day. However, to date, we have not found statistics that indicate to what extent the concentration levels of particulate matter PM2.5, PM10 and nitrogen oxides (NOx) pollutants decrease as a result of public policy. We used official data from the Chilean Government’s national air quality information system (SINCA) for the Santiago metropolitan region and estimated the impact of the confinement by COVID-19 on the ambient concentration average values of NOx gases and particulate matter PM2.5 and PM10, which are the main air pollutants produced by the transport sector after CO2. We found that in general there are significant differences between the average levels of gas emissions for 2020 compared to 2019. In particular, we found that, for the months of total confinement May-July, the monthly average levels decreased between 7% and 19% for particulate matter PM2.5, between 18% and 50% for PM10 and between 34% and 48% for NOx. With the return to the new normality, these improvements in ambient concentration levels may be affected by the increase in private transport trips, due to the reluctance of citizens to return to mass public transport. Our results, therefore, represent the maximum impact that can be expected in reducing ambient concentration levels in the city of Santiago of Chile when a mobility reduction of gasoline vehicles is implemented. The reduction of PM2.5, PM10 and NOx was no more than 7%, 18% and 34%, respectively. The average concentration of PM2.5 decreased by 7–19% compared to previous years. The average concentration of PM10 decreased by 18% and 50% compared to previous years. Concentrating commuting on public transport would help reduce levels of PM10 and PM2.5.