GIS mapping of agricultural plastic waste in southern Europe.

The escalating use of plastics in agriculture, driven by global population growth and increasing food demand, has concurrently led to a rise in Agricultural Plastic Waste (APW) production. Effective waste management is imperative, prompting this study to address the initial step of management, that is the quantification and localization of waste generated from different production systems in diverse regions. Focused on four Southern European countries (Italy, Spain, Greece, and Portugal) at the regional level, the study uses Geographic Information System (GIS), land use maps, indices tailored to each specific agricultural application and each crop type for plastic waste mapping. Furthermore, after the data was employed, it was validated by relevant stakeholders of the mentioned countries. The study revealed Spain, particularly the Andalusia region, as the highest contributor to APW equal to 324,000 tons per year, while Portugal's Azores region had the lowest estimate equal to 428 tons per year. Significantly, this research stands out as one of the first to comprehensively consider various plastic applications and detailed crop cultivations within the production systems, representing a pioneering effort in addressing plastic waste management in Southern Europe. This can lead further on to the management of waste in this area and the transfer of the scientific proposition to other countries.

Production and characterisation of environmentally relevant microplastic test materials derived from agricultural plastics.

Soil environments across the globe, particularly in agricultural settings, have now been shown to be contaminated with microplastics. Agricultural plastics - such as mulching films - are used in close or direct contact with soils and there is growing evidence demonstrating that they represent a potential source of microplastics. There is a demand to undertake fate and effects studies to understand the behaviour and potential long-term ecological risks of this contamination. Yet, there is a lack of test materials available for this purpose. This study describes the manufacture and characterisation of five large (1-40 kg) batches of microplastic test materials derived from agricultural mulching films. Batches were produced from either polyethylene-based conventional mulching films or starch-polybutadiene adipate terephthalate blend mulching films that are certified biodegradable in soil. Challenges encountered and overcome during the micronisation process provide valuable insights into the future of microplastic test material generation from these material types. This includes difficulties in micronising virgin polyethylene film materials. All five batches were subjected to a thorough physical and chemical characterisation - both of the original virgin films and the subsequent microplastic particles generated - including a screening for the presence of chemical additives. This is a critical step to provide essential information for interpreting particle fate or effects in scientific testing. Trade-offs between obtaining preferred particle typologies and time and cost constraints are elucidated. Several recommendations emerging from the experiences gained in this study are put forward to advance the research field towards greater harmonisation and utilisation of environmentally relevant test materials.

Biodegradation of plastics in the pelagic environment of the coastal zone - Proposed test method under controlled laboratory conditions.

The increasing quantities of plastic litter accumulated in the oceans, including microplastics, represent a serious environmental threat. Despite the recent legislative actions, the plastic littering problem will not disappear in a short time. It may, however be ameliorated by replacing conventional non-degradable plastics with bio-based materials biodegradable in marine environment (targeting the non-recycled or mismanaged plastic waste). Although priority is set to prevention of plastic litter by means of the circular economy principles, biodegradability is a means of controlling unintentional plastic pollution. In this effort, the development of reliable test methods that would be used along with standard specifications for determining the biodegradability of novel polymeric materials or plastics in marine environments, is a necessary complementary component of the whole strategy to control the marine plastic litter and micro-, nano-plastics threat. The present work focuses on identifying gaps and improving available laboratory test methods for measuring the aerobic biodegradation of plastics in the seawater column within the coastal zone (pelagic environment). The research work followed a methodology that is based on recommendations of ASTM D6691:2017 concerning biodegradation of plastics in the seawater and the similar ISO 23977-1:2020. Three different implementation schemes of the test method were applied using different experimental setups and measuring techniques for monitoring the evolved CO2. The effect of critical parameters affecting nutrient adequacy (concentration in inoculum) and oxygen adequacy (bioreactor size, sample size, frequency of aeration) on the biodegradation of four tested materials was explored, and optimal values are proposed. The results allowed for the refinement of the proposed test method to improve reliability and reproducibility.

Agricultural plastics as a potential threat to food security, health, and environment through soil pollution by microplastics: Problem definition.

The dynamic expansion of the Agricultural Plastics (AP) use has allowed for improved agricultural products quality, yields, and enhanced sustainability along with multiple benefits for the Agrifood sector. The present work investigates the relationship of AP characteristics, use and End-of-Life (EoL) practices with degradation and potential generation of micro-, nanoparticles (MNP) in soil. The composition, functionalities, and degradation behaviour of the contemporary conventional and biodegradable AP categories are systematically analysed. Their market dynamics are briefly presented. The risk and the conditions for the AP potential role in soil pollution and possible MNP generation are analysed based on a qualitative risk assessment approach. AP are classified from high to low-risk products with respect to their probability for soil contamination by MNP based on worst-best scenarios. Proposed alternative sustainable solutions to eliminate the risks are briefly presented for each AP category. Characteristic quantitative estimations of soil pollution by MNP generated by AP are presented for selected case studies reported in the literature. The significance of various indirect sources of agricultural soil pollution by MNP is analysed allowing for appropriate risk mitigation strategies and policies to be designed and implemented.

Fermentation development using fruit waste derived mixed sugars for poly(3-hydroxybutyrate) production and property evaluation.

Free sugars from fruit wastes were evaluated for the production of poly(3-hydroxybutyrate) (PHB) in Paraburkholderia sacchari fed-batch bioreactor fermentations. Different initial sugar concentration, carbon to inorganic phosphorus (C/IP) ratio, IP addition during feeding and volumetric oxygen transfer coefficient (kLa) were evaluated to promote PHB production. The highest intracellular PHB accumulation (66.6%), PHB concentration (108.3 g/L), productivity (3.28 g/(L·h)) and yield (0.33 g/g) were achieved at 40 g/L initial sugars, C/IP 26.5, 202.6 h-1kLa value and 20% IP supplementation in the feeding solution. The effect of different microbial mass harvesting time on PHB properties showed no influence in weight average molecular weight and thermal properties. The harvest time influenced the tensile strength that was reduced from 28.7 MPa at 22 h to 13.3 MPa at 36 h. The elongation at break and Young's modulus were in the range 3.6-14.8% and 830-2000 MPa, respectively.

Development of biodegradable films using sunflower protein isolates and bacterial nanocellulose as innovative food packaging materials for fresh fruit preservation.

This study presents the valorization of side streams from the sunflower-based biodiesel industry for the production of bio-based and biodegradable food packaging following circular economy principles. Bacterial cellulose (BC) was produced via fermentation in 6 L static tray bioreactors using nutrient-rich supplements derived from the enzymatic hydrolysis of sunflower meal (SFM) combined with crude glycerol as carbon source. Novel biofilms were produced using either matrices of protein isolates extracted from sunflower meal (SFMPI) alone or SFMPI matrices reinforced with nanocellulose biofillers of commercial or bacterial origin. Acid hydrolysis was employed for ex-situ modification of BC to nanostructures (56 nm). The biofilms reinforced with bacterial nanocellulose structures (SFMPI-BNC) showed 64.5% higher tensile strength, 75.5% higher Young's modulus, 131.5% higher elongation at break, 32.5% lower water solubility and 14.1% lower water vapor permeability than the biofilms produced only with SFMPI. The biofilms were evaluated on fresh strawberries packaging showing that the SFMPI-BNC-based films lead to effective preservation at 10 °C considering microbial growth and physicochemical profile (weight loss, chemical characterization, color, firmness and respiration activity). The SFMPI-BNC-based films could be applied in fresh fruit packaging applications.

Analysis of long-term degradation behaviour of polyethylene mulching films with pro-oxidants under real cultivation and soil burial conditions.

Apart from the conventional polyethylene and the bio-based or mainly bio-based biodegradable in soil mulching films, polyethylene mulching films of controlled degradation in soil are already used in agriculture. The use of special pro-oxidants as additives is expected to accelerate the abiotic oxidation and the subsequent chain scission of the polymer under specific UV radiation or thermal degradation conditions, according to the literature. The role of pro-oxidants in the possible biodegradation of polyethylene has been theoretically supported through the use of controlled laboratory conditions. However, results obtained in real soil conditions, but also several laboratory test results, are not supporting these claims and the issue remains disputed. Mulching films made of linear low-density polyethylene (LLDPE) with pro-oxidants, after being used for one cultivation period in an experimental field with watermelon cultivation, were buried in the soil under real field conditions. This work presents the analysis of the degradation of the mulching films during the cultivation period as compared to the corresponding changes after a long soil burial period of 8.5 years. The combined effects of critical factors on the photochemical degradation of the degradable mulching LLDPE films with pro-oxidants under the cultivation conditions and their subsequent further degradation behaviour in the soil are analysed by testing their mechanical properties and through spectroscopic and thermal analysis.

Review, mapping and analysis of the agricultural plastic waste generation and consolidation in Europe.

A review of agricultural plastic waste generation and consolidation in Europe is presented. A detailed geographical mapping of the agricultural plastic use and waste generation in Europe was conducted focusing on areas of high concentration of agricultural plastics. Quantitative data and analysis of the agricultural plastic waste generation by category, geographical distribution and compositional range, and physical characteristics of the agricultural plastic waste per use and the temporal distribution of the waste generation are presented. Data were collected and cross-checked from a variety of sources, including European, national and regional services and organizations, local agronomists, retailers and farmers, importers and converters. Missing data were estimated indirectly based on the recorded cultivated areas and the characteristics of the agricultural plastics commonly used in the particular regions. The temporal distribution, the composition and physical characteristics of the agricultural plastic waste streams were mapped by category and by application. This study represents the first systematic effort to map and analyse agricultural plastic waste generation and consolidation in Europe.