Marine plastic debris is well characterized in terms of its ability to negatively impact terrestrial and marine environments, endanger coastal wildlife, and interfere with navigation, tourism and commercial fisheries. However, the impacts of potentially harmful microorganisms and pathogens colonising plastic litter are not well understood. The hard surface of plastics provides an ideal environment for opportunistic microbial colonisers to form biofilms and might offer a protective niche capable of supporting a diversity of different microorganisms, known as the "Plastisphere". This biotope could act as an important vector for the persistence and spread of pathogens, faecal indicator organisms (FIOs) and harmful algal bloom species (HABs) across beach and bathing environments. This review will focus on the existent knowledge and research gaps, and identify the possible consequences of plastic-associated microbes on human health, the spread of infectious diseases and bathing water quality.

Summary: The Green Revolution successfully increased food production but in doing so created a legacy of inherently leaky and unsustainable agricultural systems. Central to this are the problems of excessive nutrient mining. If agriculture is to balance the needs of food security with the delivery of other ecosystem services, then current rates of soil nutrient stripping must be reduced and the use of synthetic fertilisers made more efficient. We explore the global extent of the problem, with specific emphasis on the failure of macronutrient management (e.g. nitrogen, phosphorus) to deliver continued improvements in yield and the failure of agriculture to recognise the seriousness of micronutrient depletion (e.g. copper, zinc, selenium). Nutrient removals associated with the relatively immature, nutrient‐rich soils of the UK are contrasted with the mature, nutrient‐poor soils of India gaining insight into the emerging issue of nutrient stripping and the long‐term implications for human health and soil quality. Whilst nutrient deficiencies are rare in developed countries, micronutrient deficiencies are commonly increasing in less‐developed countries. Increasing rates of micronutrient depletion are being inadvertently accomplished through increasing crop yield potential and nitrogen fertiliser applications. Amongst other factors, the spatial disconnects caused by the segregation and industrialisation of livestock systems, between rural areas (where food is produced) and urban areas (where food is consumed and human waste treated) are identified as a major constraint to sustainable nutrient recycling. Synthesis and applications. This study advocates that agricultural sustainability can only be accomplished using a whole‐systems approach that thoroughly considers nutrient stocks, removals, exports and recycling. Society needs to socially and environmentally re‐engineer agricultural systems at all scales. It is suggested that this will be best realised by national‐scale initiatives. Failure to do so will lead to an inevitable and rapid decline in the delivery of provisioning services within agricultural systems.

Polycyclic aromatic hydrocarbons (PAHs) in the environment originate mainly from incomplete combustion of fossil fuels, and pose a significant human health risk. Soils act as environmental sinks for PAHs, as they become strongly absorbed onto soil particles; degradation is mainly driven by microbial catabolism, although it is dependent on PAH bioavailability. There is current interest in burying biochar in soil as a long‐term soil carbon store; however, biochar inherently contains varying levels of PAHs and its application could contaminate soil, and its high sorptive capacity may facilitate the persistence of PAHs in the environment. The aim of this study was to determine the effect of adding biochar to soil on microbial mineralization of PAHs, and to quantify whether or not soils amended with biochar were less likely to leach PAHs. We used contrasting agricultural soils (Eutric Cambisol and Cambic Podzol) spiked with the labelled PAH compound ¹⁴ C ‐phenanthrene and amended with either wood biochar or rice husk biochar. Mineralization was quantified by measuring the release of ¹⁴ CO ₂ and simulated rain used to quantify leaching of PAH through biochar‐amended soil. Rice husk biochar had higher concentrations of PAHs (64.65 mg kg⁻¹) than wood biochar (9.56 mg kg⁻¹), and both soil types contained quantifiable levels of PAHs. However, soil that had contained biochar for 3 years had significantly higher levels of PAH (1.95 mg kg⁻¹) compared to unamended soil (1.13 mg kg⁻¹). PAH catabolism in soil was reduced when amended with biochar, although biochar amendment did not consistently decrease PAH leaching. Biochar‐mediated inhibition of PAH mineralization is a consequence of increased sorption and reduced bioavailability. Before large scale biochar addition to soils is adopted, future work is needed to address the dynamic between sorbent saturation and microbial activity and how this relates to the concentration of PAHs in soil solution and their persistence in the environment.