peer reviewed | Reducing the bioavailability of both cadmium (Cd) and arsenic (As) in paddy fields is a worldwide challenge. The authors investigated whether ridge cultivation combined with biochar or calcium-magnesium-phosphorus (CMP) fertilizer effectively reduces the accumulation of Cd and As in rice grains. Field trial showed that applying biochar or CMP on the ridges was similar to the continuous flooding, which maintained grain Cd at a low level, but grain As was reduced by 55.6%, 46.8% (IIyou28) and 61.9%, 59.3% (Ruiyou 399). Compared with ridging alone, the application of biochar or CMP decreased grain Cd by 38.7%, 37.8% (IIyou28) and 67.58%, 60.98% (Ruiyou399), and reduced grain As by 38.9%, 26.9% (IIyou28) and 39.7%, 35.5% (Ruiyou 399). Microcosm experiment showed that applying biochar and CMP on the ridges decreased As in soil solution by 75.6% and 82.5%, respectively, and kept Cd at a comparably low level at 0.13–0.15 μg L−1. Aggregated boosted tree (ABT) analysis revealed that ridge cultivation combined with soil amendments altered soil pH, redox state (Eh) and enhanced the interaction of Ca, Fe, Mn with As and Cd, which promoted the concerted reduction of As and Cd bioavailability. Application of biochar on the ridges enhanced the effects of Ca and Mn to maintain a low level of Cd, and enhanced the effects of pH to reduce As in soil solution. Similar to ridging alone, applying CMP on the ridges enhanced the effects of Mn to reduce As in soil solution, and enhanced the effects of pH and Mn to maintain Cd at a low level. Ridging also promoted the association of As with poorly/well-crystalline Fe/Al and the association of Cd on Mn-oxides. This study provides an effective and environmentally friendly method to decrease Cd and As bioavailability in paddy fields and mitigate Cd and As accumulation in rice grain.

One of the most serious challenges threatening agricultural sustainability in Nigeria is land degradation. Although this issue has received little attention, soil and water conservation practices have been identified as a possible pathway out of the potential problems posed by land degradation. Therefore, the central research question that this paper tries to address is the following: Do adoption of soil and water conservation (SWC) practices affect crop productivity and household welfare? This paper uses data collected by the International Institute of Tropical Agriculture (IITA) from maize farmers in rural Nigeria. We usedemploy the propensity score matching (PSM), inverse probability weighting adjusted regression model (IPWRA) approach, and the linear regression with endogenous treatment effect (LRETE) model to incorporate the typologies of SWC practices, and tested how the model affects crop productivity and household welfare. Additionally, multinomial logit was used to estimate the factors influencing the decision to adopt single and multiple SWC practices. The estimates show that education, age of the household head, access to credit, experience of drought, soil fertility, and occupational stress contribute to the decision to adopt SWC practices. The casual effect estimates reveal that both single and multiple adoptions of SWC practices had a positive and significant relationship with the crop productivity and welfare of the adopters. The results show that the adoption of combined SWC practices has a higher impact on crop productivity and welfare than single SWC practices. For instance, the adoption of a combination of three SWC practices was found to increase crop productivity and household welfare by 27.55% and 38.23%, respectively versus 13.91% and 15.11% in the case of single SWC practices. The study suggests that profile-raising agenda and efforts that focus on promoting the adoption of combination of SWC practices should be designed and implemented to enhance crop productivity and hence the welfare of the maize farming households in rural Nigeria.

The authors regret that this is not a review document, but a Research Paper. The authors would like to apologise for any inconvenience caused.

Microalgae and blue mussels are known to accumulate undesirable substances from the environment, including arsenic (As). Microalgae can biotransform inorganic As (iAs) to organoarsenic species, which can be transferred to blue mussels. Knowledge on As uptake, biotransformation, and trophic transfer is important with regards to feed and food safety since As species have varying toxicities. In the current work, experiments were conducted in two parts: (1) exposure of the microalgae Diacronema lutheri to 5 and 10 μg/L As(V) in seawater for 4 days, and (2) dietary As exposure where blue mussels (Mytilus edulis L.) were fed with D. lutheri exposed to 5 and 10 μg/L As(V), or by aquatic exposure to 5 μg/L As(V) in seawater, for a total of 25 days. The results showed that D. lutheri can take up As from seawater and transform it to methylated As species and arsenosugars (AsSug). However, exposure to 10 μg/L As(V) resulted in accumulation of iAs in D. lutheri and lower production of methylated As species, which may suggest that detoxification mechanisms were overwhelmed. Blue mussels exposed to As via the diet and seawater showed no accumulation of As. Use of linear mixed models revealed that the blue mussels were gradually losing As instead, which may be due to As concentration differences in the mussels’ natural environment and the experimental setup. Both D. lutheri and blue mussels contained notable proportions of simple methylated As species and AsSug. Arsenobetaine (AB) was not detected in D. lutheri but present in minor fraction in mussels. The findings suggest that low-trophic marine organisms mainly contain methylated As species and AsSug. The use of low-trophic marine organisms as feed ingredients requires further studies since AsSug are regarded as potentially toxic, which may introduce new risks to feed and food safety. | publishedVersion

Arctic rivers are receiving increased attention for their contributing of mercury (Hg) to the Arctic Ocean. Despite this, the knowledge on both the terrestrial release sources and the levels of Hg in the rivers are limited. Within the Arctic, the Barents region has a high industrial development, including multiple potential Hg release sources. This study presents the first overview of potential Hg release sources on Norwegian and Russian mainland draining to the Barents Sea. Source categories cover mining and metallurgy industry; historical pulp and paper production; municipal and industrial solid waste handling; fossil fuel combustion; and past military activities. Available data on Hg in freshwater bodies near the identified potential release sources are reviewed. Levels of Hg were occasionally exceeding the national pollution control limits, thereby posing concern to the local human population and wildlife. However, the studies were sparse and often unsystematic. Finally, we present new data of Hg measured in five Barents rivers. These data reveal strong seasonality in the Hg levels, with a total annual flux constituting 2% of the panarctic total. With this new insight we aspire to contribute to the international efforts of reducing Hg pollution, such as through the effective implementation of the Minamata Convention. Future studies documenting Hg in exposed Barents freshwater bodies are warranted. | publishedVersion

In the present study, polyethylene (PE) microplastics (150–300 μm) were added to Atlantic cod (Gadus morhua) feeds at 1 %, either in their present form (Virgin PE) or spiked with PCB-126 (Spiked PE). The feeds were given to juvenile cod for a 4-week period. The fish grew from 11 to 23 g with no significant difference between dietary treatments. Cod fed spiked PE showed a significantly higher concentration of PCB-126 in liver and muscle samples compared to control and fish ingesting virgin PE. In accordance with the accumulation of PCB-126 in the liver, the expression of hepatic cyp1a was higher in cod fed spiked PE. Notably, we observed that spiked PE, as well as virgin PE, have an effect on skin. Overall changes indicated a reduced skin barrier in fish fed a diet containing PE. Indicating that PE itself through interaction with gut tissue may influence skin health in fish. | publishedVersion

In the coming years, the use of microalgal biomass as agricultural biofertilizers has shown promising results. The use of wastewater as culture medium has resulted in the reduction of production costs, making microalgae-based fertilizers highly attractive for farmers. However, the occurrence of specific pollutants in wastewater, like pathogens, heavy metals and contaminants of emerging concern (CECs), such as pharmaceuticals and personal care products may pose a risk on human health. This study presents an holistic assessment of the production and use of microalgal biomass grown in municipal wastewater as biofertilizer in agriculture. Results showed that pathogens and heavy metals concentrations in the microalgal biomass were below the threshold established by the European regulation for fertilizing products, except for cadmium. Regarding CECs, 25 out of 29 compounds were found in wastewater. However, only three of them (hydrocinnamic acid, caffeine, and bisphenol A) were found in the microalgae biomass used as biofertilizer. Agronomic tests were performed for lettuce growth in greenhouse. Four treatments were studied, comparing the use of microalgae biofertilizer with a conventional mineral fertilizer, and also a combination of both of them. Results suggested that microalgae can help reducing the mineral nitrogen dose, since similar fresh shoot weights were obtained in the plants grown with the different assessed fertilizers. Lettuce samples revealed the presence of cadmium and CECs in all the treatments including both negative and positive controls, which suggests that their presence was not linked to the microalgae biomass. On the whole, this study revealed that wastewater grown microalgae can be used for agricultural purposes reducing mineral N need and guaranteeing health safety of the crops. | This research was supported by the European Commission (FERTILWASTES-EFA307/19) and the Spanish Ministry of Science and Innovation (CYRCLE-PID2020-113866RA-I00). E. Uggetti and R. Díez- Montero would like to thank the Spanish Ministry of Industry and Economy for their research grants [RYC2018-025514-I and ICJ2019- 042069-I, respectively]. A. Álvarez-González kindly acknowledge the Departament de Recerca i Universitats de la Generalitat de Catalunya for her PhD scholarship (FI AGAUR, 2022FI_B 00488). E. Gonzalez-Flo would like to thank the European Union-NextGenerationEU, Ministryof Universities and Recovery, Transformation and Resilience Plan for her research grant (2021UPF-MS-12). M. Escolà Casas wants to thank the Beatriu de Pinós 2018 grant-programme (MSCA grant agreement number 801370) for the funding.

Barium (Ba) in recent marine sediments can originate from natural and anthropogenic sources including discharges from the oil and gas industry. In this study, we use data from the Norwegian and Barents Seas to assess whether Ba in recent marine sediments has increased due to these discharges. To account for Ba in detrital material, we normalise all samples with respect to aluminosilicate by calculating an enrichment factor. We use statistical modelling to control for parameters related to sedimentation. We present results that suggest increased Ba levels in recent sediments that coincide with the timing of hydrocarbon drilling and production. This is supported by geographical differences on a large scale that relate to proximity to hydrocarbon drilling and production. Among 243 sampling stations, we identify 73 locations exhibiting enrichment of Ba in the upper 6 of sediment. At these locations, Ba is 1.55 to 3.55 times higher than the levels that can be expected from the shale average when Ba in detrital matter is accounted for. Excess Ba is reported in sediment surface samples in areas important to fisheries like the Lofoten area and the western Barents Sea. | publishedVersion

A crucial factor in the long-term survival of benthic macrophyte communities under light-reduction stress is how they balance carbon metabolism during photosynthesis and respiration. In turn, the dissolved organic carbon (DOC) released by these communities, which can be highly light-dependent, stands as a source of carbon, fuelling marine communities and playing an important role in the ocean carbon sequestration. This is the first study to evaluate light-reduction stress and recovery in the seagrass Zostera noltei and the macroalga Caulerpa prolifera. Light reduction led to a significant decrease in the production of both communities from autotrophic to heterotrophic. Results indicated that most of the DOC released by vegetated coastal communities comes from photosynthetic activity, and that the net DOC fluxes can be greatly affected by shading events. Finally, both communities showed resilience underpinned by high recovery but low resistance capacity, with C. prolifera showing the highest resilience to unfavourable light conditions.

Gillnets are among the most common fishing gears worldwide. They are often made of thin twine, which is prone to wear and tear, limiting the lifespan of the gillnet. This increases gillnet turnover, and consequently increased risk of gear discarding, gear loss, ghost fishing and marine pollution. This might be mitigated by increasing twine thickness, and thereby breaking strength. However, the tolerable increase in thickness for gillnet durability without compromising the catch efficiency is unknown. Therefore, this study conducted gillnet fishing trials under commercial conditions in the Northeast-Arctic cod gillnet fishery analysing and comparing ways of capture and efficiency between gillnets with two different twine thicknesses for two different mesh sizes. The results demonstrated that a 30 % increase in breaking strength and twine stiffness did not affect catch performance. Therefore, thicker gillnet twine can potentially reduce marine litter by plastic debris from damaged and lost gears without compromising catch performance. | publishedVersion