Impacts of saltwater intrusion on soil nematodes community in alluvial and acid sulfate soils in paddy rice fields in the Vietnamese Mekong Delta

© 2020 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license. https://creativecommons.org/licenses/by-nc-nd/4.0/Saltwater intrusion is a potential risk damaging crop diversity and productivity due to degraded soil physicochemical properties. However, little is known about how salinity affects the structure and function of soil nematodes community in intensive rice cultivated area. This study aimed (1) to assess the impacts of saltwater intrusion on the nematode community in alluvial and acid sulfate soils; and (2) to evaluate its relation with soil conditions. Saltwater intrusion reduced the abundance of both free-living nematodes (FLN) and plant-parasitic nematodes (dominated by Hirschmanniella) in soils. FLN community was different among sites with different physicochemical properties. The omnivorous genera Aporcelaimellus and Thornenema were only found in non-salt-affected alluvial soil, whilst Mesodorylaimus was dominant in salt-affected acid sulfate soil, suggesting that this genus might be tolerant to higher EC and soluble Na+, K+, Ca2+. The bacterivorous nematodes (dominant taxa Chronogaster, Rhabdolaimus) were dominant in both non-salt affected and salt-affected alluvial soils, which accounted for 48% and 40%, respectively, whilst it accounted for 21% in salt-affected acid sulfate soil. The abundance of fungivorous nematodes (Aphelenchoides, Ditylenchus, Filenchus) were greater in salt-affected alluvial soil in contrast to the other treatments, suggesting that these might be tolerant to salinity and low pH. Saltwater intrusion reduced biological diversity (Margalef, Shannon-Wiener, and Hill’s indices), maturity index (∑MI, MI25), and clearly affected functional guilds of nematode community, especially c-p 5 group was reduced in both salt-affected soils. This study suggests that saltwater intrusion showed a potential risk in the degradation of soil properties, as indicated by the altered nematode community, trophic structure, functional guilds and their ecological indices in paddy fields.Peer reviewedFinal Published versio

Utilizing a biology-driven approach to map the exposome in health and disease:An essential investment to drive the next generation of environmental discovery

BACKGROUND: Recent developments in technologies have offered opportunities to measure the exposome with unprecedented accuracy and scale. However, because most investigations have targeted only a few exposures at a time, it is hypothesized that the majority of the environmental determinants of chronic diseases remain unknown. OBJECTIVES: We describe a functional exposome concept and explain how it can leverage existing bioassays and high-resolution mass spectrometry for exploratory study. We discuss how such an approach can address well-known barriers to interpret exposures and present a vision of next-generation exposomics. DISCUSSION: The exposome is vast. Instead of trying to capture all exposures, we can reduce the complexity by measuring the functional exposome— the totality of the biologically active exposures relevant to disease development—through coupling biochemical receptor-binding assays with affinity purification–mass spectrometry. We claim the idea of capturing exposures with functional biomolecules opens new opportunities to solve critical problems in exposomics, including low-dose detection, unknown annotations, and complex mixtures of exposures. Although novel, biology-based measurement can make use of the existing data processing and bioinformatics pipelines. The functional exposome concept also complements conven-tional targeted and untargeted approaches for understanding exposure-disease relationships. CONCLUSIONS: Although measurement technology has advanced, critical technological, analytical, and inferential barriers impede the detection of many environmental exposures relevant to chronic-disease etiology. Through biology-driven exposomics, it is possible to simultaneously scale up discovery of these causal environmental factors. https://doi.org/10.1289/EHP8327