Estuarine environments are considered to be nutrient buffer systems as they regulate the delivery of nutrients from rivers to the ocean. In the Humber Estuary (UK) seawater and freshwater mixing during tidal cycles leads to the mobilisation of oxic surface sediments (0-1 cm). However, less frequent seasonal events can also mobilise anoxic subsurface (5-10 cm) sediments, which may have further implications for the estuarine geochemistry. A series of batch experiments were carried out on surface and subsurface

Intertidal mudflats are fluctuating environments that support highly diverse microbial communities. The highly variable physico-chemical conditions complicate the understanding of the environmental controls on diversity patterns in estuarine systems. We investigated the bacterial diversity in the surface and subsurface sediments along the salinity gradient of the Humber estuary (UK) using amplicon sequencing of the 16S rRNA gene and correlated its variations with environmental variables. The sediment depths sampled were selected based on the local resuspension patterns. In general, bacterial communities showed similar composition at the different sites and depths, with Proteobacteria being the most abundant phylum. The richness of operational taxonomic units (OTUs) was uniform along the salinity gradient. However, Hill numbers, as bacterial diversity measures, showed that the common and dominant OTUs exhibited a decreasing trend from the inner towards the outer estuary sites. Additionally, surface and subsurface bacterial communities were separated by non-metric multi-dimensional scaling (NMDS) analysis only in the mid-and outer estuary samples, where redox transitions with depth were more abrupt. Salinity, porewater ammonium concentration and acid-extractable Fe(II) in solids were the subset of environmental factors that best correlated with community dissimilarities. Analysis of regional diversity indicated that the dataset may include 2 potentially distinct communities: (1) a near-surface community that is the product of regular mixing and transport and is subjected to a wide range of salinity conditions, and (2) a bacterial community indigenous to the more reducing subsurface sediments of the mudflats of the mid-and outer estuary.

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Welcome to this special edition of Women in Soil Science. The Spanish Journal of Soil Science is proud to offer this platform to celebrate the achievements of women in the field of Soil Science and hopefully inspire the next generation of female soil scientists.Led by Dr. Andrea Vidal, Dr. Michele Francis and Prof. Rosa Maria Poch, this Special Issue highlights the latest research from women in the Soil Science field from across the globe.At present, less than 30% of researchers worldwide are women. For example, in the US women represent only 24% of the soil scientists in academic faculty positions. Long-standing biases and gender stereotypes are discouraging girls and women away from science-related fields, and STEM research in particular. It is essential for both the progress of the field and the fulfilment of the UN Sustainable Development Goals (SDG) to change traditional mindsets and promote gender equality within the Soil Science field, as well as science more broadly.In this edition, we celebrate the women working in the wider field of Soil Science and we recognise their struggles to become scientists, especially in countries where the playing field is not level. Without an early education focused on strong reading and mathematical skills, a scientific career cannot follow.The eight papers presented here highlight the diversity of research performed across the entire breadth of Soil Science led by women. Four of the papers deal explicitly with the issue of gender in soil science, either from historical or geographical perspectives, giving visibility to women soil scientists whose contribution to Soil Science has not been given the recognition it merits. The remaining four papers illustrate soil research carried out or led by women in Mexico, Spain, Canada and Brazil showing excellence in science regardless of the authors' gender.Díaz-Raviña and Caruncho are the authors of the interesting review: "A brief analysis of the contribution of women to Soil Science." They present data on female soil scientist ratios in several countries from a time perspective, along with the socioeconomic and political reasons for their evolution. They explain what makes research led by women necessary for the advance of soil science and give reasons for its promotion from the early school years. Special attention is given to Russian and former soviet female soil scientists. Gerasimova's contribution entitled "Maria Glazovskaya -A pioneer soil scientist and geochemist ahead of her time " gives an account of one of these "forgotten" Russian soil scientists, who made essential contributions to the knowledge of the world soils and of soil geochemistry, establishing the bases for quantitative soil classification and putting forward some concepts considered hot issues today such as soil carbon pools and emissions; and environmental time bombs applied to soil pollution.The paper "Reevaluating diversity and the history of Women in soil sciences: a necessary step for a real change" (Reyes-Sánchez and Irazoque) deals with the implications...