Routine waterway dredging activities generate huge volumes of dredged sediment. The remediation of dredged contaminated sediment is a worldwide challenge. Novel and sustainable ex-situ remediation technologies for contaminated sediment have been developed and adopted in recent years. In this review paper, the state-of-art ex-situ treatment technologies and resource utilisation methods for contaminated sediment were critically reviewed. By applying different techniques, sediment could been successfully transformed into sustainable construction materials, such as ceramsite, supplementary cementitious materials, fill materials, paving blocks, partition blocks, ready-mixed concrete, and foamed concrete. We highlighted that proper remediation technologies should be cleverly selected and designed according to the physical and chemical characteristics of sediment, without neglecting important aspects, such as cost, safety, environmental impacts, readiness level of the technology and social acceptability. The combination of different assessment methods (e.g., environmental impact assessment, cost-benefit analysis, multi-criteria decision analysis and life cycle assessment) should be employed to comprehensively evaluate the feasibility of different sustainable remediation technologies. We call on the scientific community in a multidisciplinary fashion to evaluate the sustainability of various remediation technologies for contaminated sediment.

Cadmium (Cd) uptake and accumulation in crop plants, especially in wheat (Triticum aestivum) and rice (Oryza sativa) is one of the main concerns for food security worldwide. A field experiment was done to investigate the effects of limestone, lignite, and biochar on growth, physiology and Cd uptake in wheat and rice under rotation irrigated with raw effluents. Initially, each treatment was applied alone at 0.1% and combined at 0.05% each and wheat was grown in the field and then, after wheat harvesting, rice was grown in the same field without additional application of amendments. Results showed that the amendments applied increased the grain and straw yields as well as gas exchange attributes compared to the control. In both crops, highest Cd concentrations in straw and grains and total uptake were observed in control treatments while lowest Cd concentrations was observed in limestone + biochar treatment. No Cd concentrations were detected in wheat grains with the application of amendments except limestone (0.1%). The lowest Cd harvest index was observed in limestone + biochar and lignite + biochar treatments for wheat and rice respectively. Application of amendments decreased the AB-DTPA extractable Cd in the soil while increasing the Cd immobilization index after each crop harvest. The benefit-cost ratio and Cd contents in plants revealed that limestone + biochar treatment might be an effective amendment for increasing plant growth with lower Cd concentrations.

Ammonia (NH₃) emissions, the majority of which arise from livestock production, are linked to high concentration of PM₂.₅ and lower air quality in China. NH₃ mitigation options were well studied at the small-scale (laboratory or pilot), however, they lack of a large-scale test in China. This study fills this crucial gap by evaluating the cost-benefit of pioneering NH₃ mitigation projects carried out for a whole county – Sheyang, Jiangsu province, China. Measures were implemented in 2019 following two distinct strategies, improved manure treatment for industrial livestock farms, and collection and central treatment for traditional livestock farms. Emission reductions of 16% were achieved in a short time. While this is remarkable, it falls short of expectations from small-scale studies. If measures were fully implemented according to purpose and meet expectations from the small scale, higher emission reductions of 42% would be possible. The cost benefit analysis presented in this study demonstrated advantages of central manure treatment over in-farm facilities. With improved implementation of mitigation strategies in industrial livestock farms, traditional livestock farms may play an increasing role in total NH₃ emissions, which means such farms either need to be included in future NH₃ mitigation policies or gradually replaced by industrial livestock farms.The study found an agricultural NH₃ reduction technology route suitable for China's national conditions (such as the “Sheyang Model”).

The continued rise in atmospheric carbon dioxide (CO2) levels is driving climate change and temperature shifts at a global scale. CO2 Capture and Storage (CCS) technologies have been suggested as a feasible option for reducing CO2 emissions and mitigating their effects. However, before CCS can be employed at an industrial scale, any environmental risks associated with this activity should be identified and quantified. Significant leakage of CO2 from CCS reservoirs and pipelines is considered to be unlikely, however direct and/or indirect effects of CO2 leakage on marine life and ecosystem functioning must be assessed, with particular consideration given to spatial (e.g. distance from the source) and temporal (e.g. duration) scales at which leakage impacts could occur. In the current mesocosm experiment we tested the potential effects of CO2 leakage on macrobenthic assemblages by exposing infaunal sediment communities to different levels of CO2 concentration (400, 1000, 2000, 10,000 and 20,000 ppm CO2), simulating a gradient of distance from a hypothetic leakage, over short-term (a few weeks) and medium-term (several months). A significant impact on community structure, abundance and species richness of macrofauna was observed in the short-term exposure. Individual taxa showed idiosyncratic responses to acidification. We conclude that the main impact of CO2 leakage on macrofaunal assemblages occurs almost exclusively at the higher CO2 concentration and over short time periods, tending to fade and disappear at increasing distance and exposure time. Although under the cautious perspective required by the possible context-dependency of the present findings, this study contributes to the cost-benefit analysis (environmental risk versus the achievement of the intended objectives) of CCS strategies.

Beach nourishment practices are a key aspect in coastal management plans for stakeholders and communities. Stemming from a concrete case-study (Tuscany), this research analyzes: (i) principal problems of current law regulating dredging, (ii) gaps in technical guidelines, (iii) advantages of integrated approaches to the decision-making process, (iv) possible applicable nourishment options and their costs and benefits. Our results show that sand compatibility is driven mainly by grain-size stability due to the occurrence of lower pollution levels in off-shore deposits than in threatened beaches, thus current laws and guidelines should be improved to fill the evident gap in the evaluation process and to include a more complete approach to data evaluation and an integrated approach to ecotoxicity evaluation, which is relevant in cases of geochemical anomalies. The cost-benefit analysis performed indicates that only dredging intended to manage more than 1millionm3 of aggregates would represent a real advantage for local communities.

An experiment was conducted to study the influence of environmental parameters and stocking density on growth, survival, feed utilization, and economic feasibility of a high value butter catfish, Ompok bimaculatus in floating cages in a large tropical reservoir of India for 180 days. The fingerlings (11.44 ± 1.33 cm; 8.05 ± 3.27 g) were stocked at three stocking densities, viz., 15, 25 and 35 fingerlings m⁻³ in GI cages (32m³) in triplicates. Commercial floating pellets were fed to fish at 5–3% of fish biomass. The results indicated that the fishes at the lowest stocking density of 15 fingerlings m⁻³ had significantly higher (p < 0.05) growth in relation to weight gain percentage (717.67 ± 39.10) and specific growth rate (1.14 ± 0.05). Survival percentage was also significantly higher (p < 0.01) at lower stocking densities compared with 35 fingerlings m⁻³. Similarly, the feed conversion efficiency (0.423 ± 0.025), protein efficiency ratio (1.37 ± 0.15) and feed conversion ratio (FCR) (2.37 ± 0.16) were significantly better at density of 15 fingerlings m⁻³. The fish growth and feed utilization efficiency did not vary significantly (p > 0.05) between stocking densities of 15 fingerlings m⁻³ and 25 fingerlings m⁻³. The condition factor was insignificantly higher at lower densities and its values close to 1 indicated congeniality of reservoir ecosystem for cage culture of the species. The coefficient of variation of weight was significantly higher (24.19 ± 1.20) at 35 fingerlings m⁻³. The highest economic gains in terms of benefit cost ratio (1.77) were achieved at the lowest stocking density. The present study indicated better growth and economic returns at lower stocking densities of 15–25 fingerlings m⁻³. The nutrient load and plankton abundance were higher at culture site, however, did not vary significantly from reference sites throughout the culture period. Although most of the environmental parameters showed significant seasonal variations, dissolved oxygen showed significant positive relation (r = 0.86) with the growth of the fish. This is the first study reporting feasibility of cage culture of this highly renumerative species in open waters. The cage culture of this species will not only ensure better economic returns to the marginal cage farmers but will aid in the conservation of this species in natural ecosystem. Being a low volume high value species, the impact on environment will be less compared with high volume low value species. This study will serve as baseline for standardization of its grow-out protocol in cages and will be a step towards much needed species diversification for sustainable small scale cage farming in tropical reservoirs of Asia.

Assessment of environmental consequences of agri-food products during their life cycle is currently identified as the most important and efficient way to investigate agricultural systems. In addition to the environmental impacts, energy and economic issues are considered major issues in the life cycle of products. The present study aimed to investigate and assess the energy flow, environmental, and economic dimensions during shallot production in farms of Iran. Given the limited number of shallot farmers, the required data were collected from 22 shallot farms through the census method in the Shahrekord region. Based on the results obtained from the energy analysis, energy input and output and energy ratio (ER) were obtained as 107,145 and 36,243 MJ ha⁻¹ and 0.4, respectively. Also, electricity was identified as major contributor to energy consumption with the contribution of 74%. Results related to the economic analysis of shallot production revealed that the values of total production, economic productivity, and benefit-cost ratio (BCR) are 15,672 US$ ha⁻¹, 10.89 kg US$⁻¹, and 8.45, respectively. Based on the life cycle assessment results, the contribution of input consumption in the farms and input production to total environmental impacts were determined as 55 and 45%, respectively. Also, normalization of results showed that the marine ecotoxicity (ME) and global warming potential (GWP) impact categories were the main environmental impacts during shallot production. ME and GWP impacts can be attributed to the indirect emissions of electricity and direct emissions of inputs in the farm, respectively.