Avelino Núñez: «If we protect the soil and water, we protect our health»
If the soil were to become truly diseased, we would all pay the price in our plates and glasses. At the heart of Campus Terra, Avelino Núñez Delgado—professor of Soil Science and Agricultural Chemistry at the Escola Politécnica Superior de Enxeñaría and member of the UXAFORES Group—has spent decades wondering how to preserve soil and water, the two discreet foundations of our daily lives.
As part of a team that combines experience and young talent, Avelino Núñez participates in the coordination of competitive projects and collaborates with institutions and companies to transform scientific evidence into viable solutions.
In this interview, he delves into the so-called emerging pollutants—antibiotics for human and veterinary use, heavy metals, and hydrocarbons, among others— the risks they pose to soil, water, and crops in Galicia, and mitigation strategies: from low-cost bioadsorbents (modified biochar, phytomass ash, mussel shells) to technical mixtures and photocatalysis. We also talk about transfer, patents, and the social utility of science versus metrics.
Looking to the future, he outlines an agenda that combines detailed soil mapping, circular economy, and food security, with a focus on sustainable agroforestry management. He also shares key insights for students and new generations of researchers: methodology, critical reading, editorial patience, and scientific ethics.
Come and read, it's well worth it...
-From your Chair in Soil Science and Agricultural Chemistry at Campus Terra, what are the big scientific questions that guide your line of research today?
-I collaborate in the research carried out by an EPSE team that also includes two other professors (Esperanza Álvarez Rodríguez and María J. Fernández Sanjurjo) and young researchers, both postdoctoral and predoctoral, who are part of a larger group called UXAFORES.
At this small group level within a larger group, the main scientific questions that guide us are those that we are able to investigate de facto because we have specific funding for research projects. In particular, the team has been working for years on assessing the presence of environmental pollutants classified as emerging, which are not as well known as others in terms of the concern they cause in society.
Among other substances, antibiotics for human and veterinary use that reach soil and water are worth highlighting. The question we want to answer could be considered to be in line with determining the degree of contamination that is actually occurring in soil, plants, and water in Galicia due to a variety of these emerging pollutants.
On the other hand, another question we aim to help answer is what means (especially low-cost ones) can be used to effectively combat this pollution when it is already present in the environment. With this objective in mind, we are mainly researching the retention capacity of different materials (especially by-products and waste of plant origin) to prevent the potential toxic effects of pollutants at various levels.
In general, our fundamental questions and concerns are focused on understanding and combating the degradation of soil and water, and the environment in general. We are aware that many issues in the world deserve attention with regard to human beings and all living beings and ecosystems, and we try to contribute in specific areas that aim to prevent the deterioration of environmental and individual health and, if possible, improve them.
-Much of your work addresses emerging contaminants in soil (veterinary antibiotics, metals, hydrocarbons). What findings would you highlight for their impact and what implications do they have for agroforestry management in Galicia?
-It is true that for more than 15 years these have been the types of pollutants we have been dealing with most, because at the time we thought it was worth focusing on them. By obtaining funding in competitive calls to study them, it was really possible to work in this field, and it is still possible for the moment.
Some of the findings I would highlight relate to the detection of certain antibiotics not only in slurry, soil, and water, but also in crops intended for livestock and human consumption, which highlights the need for careful and precise management of these drugs, which are also considered to be responsible for the highest number of deaths in the 2050s due to resistance.
Our studies have also found that some very low-cost sorbent (decontaminant) materials can consistently retain some of these contaminants when they reach the environment, thereby reducing the health risks associated with these substances.
Our team has also obtained similar results in terms of heavy metal retention using low-cost bioadsorbents.
For oil spills, effective strategies were more along the lines of treating contaminated materials using technical mixtures with various but very affordable products, such as phytomass combustion ash, lime, and others.
Overall, the implications of our studies in the areas above for agroforestry management in Galicia would be related to the results of the detection of the contaminants examined in slurry, sewage sludge, soil, water, and plants, which alert us to the need for very careful management of fertilizers applied to agricultural and forest soils, as well as the essential need to minimize the arrival of antibiotic residues, heavy metals, and any other contaminants considered a priority in slurry, wastewater, and sludge, and to treat them correctly to decontaminate them whenever necessary.
Furthermore, our studies also point to the possibility of using very low-cost materials to control this pollution, knowing that they will also have positive effects on the nutrient content and structural stability of soils treated in this way.
Overall, our results could facilitate the fight against soil and water degradation in agricultural and forestry environments.
-You coordinate and co-lead projects such as PID2021-122920OB-C21 on ionophore antibiotics (2022–2025). What specific objectives do they pursue and what preliminary results can be anticipated?
-In line with previous projects in which our team worked with other antibiotics and contaminants of different types, the main objectives of this project are, first, to determine the degree of presence of specific biocides in slurry and various components of the environment in Galicia (agricultural soils, crops, water), and second, to determine the retention potential of these pollutants by different materials.
Once again, the main aim is to use low-cost by-products and materials to retain the pollutants, as this will make it easier to absorb the economic impact of the treatments.
Occasionally, more high-tech and therefore more expensive materials are also tested, mainly because some of our partners in other countries who have a special interest in these alternatives require them.
The results obtained indicate that within the wide range of decontaminating materials evaluated, we find several that, either individually or in combination with others, allow for the retention of high proportions of one or more of the pollutants we examined.
In each case, we determine which doses of adsorbent (decontaminating) materials, individually or in combination, are most appropriate for achieving positive decontamination effects.
At the same time, many of the decontaminants we use progressively supply organic matter and nutrients to the soil and can provide a variety of benefits, such as correcting the pH values of some soils, thus promoting their nutritional response and hindering their degradation.
Some of the materials evaluated are more geared toward retaining contaminants in water, which means that practical management on a larger scale than the laboratory would require complementary means and not just a superficial application or simple mixture, which could be the case for soils.
-You have published more than 400 papers and are among the top 2% of most cited researchers in international rankings. Beyond the metrics... How do you assess the quality and social utility of the knowledge you produce?
-Most of these publications are not individual, but were produced by research teams, essentially the team I am part of in Lugo, but also other groups in Galicia, Spain, and internationally. Hence, the achievements are never mine alone, but belong to all the staff involved in the experimental work and in the preparation of the texts and material that is publicly disseminated.
Regarding the potential social usefulness of the knowledge derived from our work, our track record includes results that initially evaluated the risks of contamination from slurry applied to meadows and, more specifically, alternatives to minimize this diffuse contamination.
Subsequently, results on wastewater contamination levels in small towns and proposals for complementary designs to increase their purification efficiency. Subsequently, the use of technical mixing procedures to recover sewage sludge, phytomass ash, and other waste or by-products, including composting in subsequent phases. And later, studies that over the years evaluated different materials to retain a variety of contaminants present in water, sludge, slurry, and soil, primarily.
All of this research and other studies in which I participated with various teams provided results that had the potential to be used in real life to some extent.
As this information is published and available, I hope that it has been useful in practice, and in some cases I know that it has been. But, in any case, our job is to try to contribute knowledge through research, some with the potential for faster and more direct application, and others more basic, which may require further study.
Personally, I have thought that both the work I did and do at the university, as well as any other job I could have done, is or would be integrated into society, providing a service to the extent possible. As a child, I helped out in my parents' grocery store, and then I thought I could do that job as an adult, serving the people who came to shop.
Later on, I studied and ended up doing what I do today, but both jobs could be a way for me to participate in society, and both have the same value.
-Your group has explored solutions based on materials (biochar, ash, by-products such as mussel shells) and also physical-chemical approaches (photocatalysis). Which technologies do you see as most mature for transfer to the agroforestry sector and to water and soil treatment?
-Our team in Lugo has worked for many years with phytomass ash and mussel shells, seeing great potential for recycling and recovery (mainly by combining these materials with others in technical mixtures designed to minimize the problems of some individual materials).
The main benefit of the mixtures was achieved when they were applied to soils with needs that were met by the specific combinations that had been designed, and the recipients could include various types of degraded soils.
Therefore, they clearly have potential in the agroforestry field and in the fight against soil degradation.
Work on biochar and photocatalysis is more recent, mainly involving international teams, and it can also be said that they are seen as having a promising future, especially in the case of biochar modified to improve its initial characteristics greatly.
Photocatalysis is expected to be very useful in the treatment of certain pollutants present in urban wastewater and some industrial effluents.
-As a member of UXAFORES, what does the “sustainable environmental and forest management” approach bring to teaching and knowledge transfer? Can you cite any projects or cases where collaboration with government agencies or companies has been key?
-In teaching, some of the subjects I dealt with years ago (at undergraduate and postgraduate level) allowed me to clearly and directly show certain aspects related to sustainable environmental and forest management. Currently, in the undergraduate subjects I teach, the content is not directly related to these aspects.
In master's degree teaching, my participation can only indirectly touch on these issues. However, the results achieved by the team are available to the entire UXAFORES group, and overall the synergy is very positive both in terms of research and potential use in the teaching of different subjects by the faculty.
Regarding transfer, the team has registered patents, and several members participate in talks, conferences, informative sessions, interviews, etc., to try to publicize details of our work when requested. Regarding collaboration with companies and administrations, the Lugo team has had. It continues to have close relationships, ranging from the provision of direct services (such as analysis and advice on agricultural soils) to the development of research projects, with collaborations and even direct participation from companies and non-profit organizations.
On several occasions, we have received written support from various government bodies and companies when we have applied for competitive research projects. In addition, the vast majority of the research projects in which we have participated were funded by different public administrations.
-In the classroom and the laboratory: What skills do you try to prioritize in your students at the Escola Politécnica Superior de Enxeñaría so that they are prepared for challenges such as diffuse pollution or the circular economy?
-As I mentioned, I currently teach subjects in which these topics are not directly addressed, so I can only comment on specific points that may be relevant.
However, years ago, I did cover some of these topics in detail, even with examples from my experimental work, when I was teaching other subjects. For instance, we discussed the design of «green filters», understood as strips of land with mainly herbaceous vegetation that slow down pollution from runoff water in sloping areas, usually near surface watercourses, and which constitute a strategy for combating diffuse pollution.
These topics were also covered in final degree projects, postgraduate subjects, and some of the work that formed part of the doctoral theses that I co-supervised.
-You have worked as an editor and reviewer for high-impact publishers and journals (Springer-Nature, Elsevier, etc.). From that perspective, what advice would you give to young researchers at Campus Terra on how to publish soundly and ethically?
-Producing publications is a complex process that requires first going through stages of learning, starting with reading scientific papers on the subject to be worked on in the laboratory and in the field, followed by acquiring the skills corresponding to those experimental works in the laboratory and in the field, and then beginning to process the empirical results obtained through calculations, statistical treatments, and modeling, when appropriate.
Reading many scientific papers on the subject will allow researchers in training to learn what others have done and what was considered valid for publication. It will make it easier for them to write introductions for their own work, as well as to discuss their own results compared to previous high-quality ones, taking advantage of all the positive aspects of what others have done before, which can help interpret, for example, mechanisms that affect events detected in the specific experiments of researchers who are taking their first steps in the process of writing scientific publications.
There are aspects that everyone must always consider when designing experiments, following the scientific method, with sufficient replicates and sample sizes to allow the statistics to be potentially significant, and working globally so that the results obtained are as reliable as possible under the conditions and with the means available to the team.
However, it should be borne in mind that even if all the laboratory and field work, calculations, modeling, tables, graphs, and honest and correct writing of a research paper have been done, anyone can find that it is rejected without even being sent to external reviewers of the journal to which it was submitted, with arguments such as that it is not innovative enough or that it is not of sufficient quality for that particular research journal.
In such cases, as in cases where papers are rejected with detailed negative reports from several external reviewers, we should not be discouraged but rather see if any or all of the comments received can really improve our work, and then try another journal. Millions of papers are submitted to scientific journals every year, and researchers (new or otherwise) must also be patient at these stages.
-Your career includes patents and international collaborations in Europe, Asia, and other continents. What strategies facilitated these synergies, and how can the Campus Terra groups expand them?
-Our patents are in any case derived from work carried out in Galicia, although for one of them the USC took steps to extend protection to the European level. The team I am part of in Lugo collaborates with researchers from other countries, mainly in Europe and Africa.
The reasons mainly have to do with the fact that these foreign teams read some of our publications and considered it interesting to send new researchers to train with us at the doctoral level.
After the initial contacts, in cases where it was possible, they moved to Lugo and worked with us for a while. In general, the results are satisfactory for all parties involved.
Our group has co-supervised several doctoral theses with students who are now doctors in their own countries, and the resulting collaborations and publications, continue to be produced.
On an individual level, I collaborate with several teams on different continents, either in research and publications or in editorial work for books or special issues of research journals in which these researchers participate as guest editors.
In these cases, too, the reasons for initiating the collaborations have to do with the fact that foreign researchers read our work and decided to contact us to propose collaborations. Unfortunately, both at the Lugo team level and individually, we have been in a situation for some time now where we have had to reject most new proposals because both the physical capacity of the laboratories and the physical and mental work capacities of the people (specifically mine) are limited.
-Looking to the future: if you had to define a research agenda for the next 5–10 years in Soil Science and Agricultural Chemistry, what priorities would you put on the table and what opportunities do you see for Galicia and the northwestern Iberian Peninsula?
-To talk about priorities in Soil Science and Agricultural Chemistry research over the next 5-10 years, I think we would have to start by considering the systematic basic characterization work that could be done to cover the territory in question, whether it be Galicia, Spain, or any other country or geographical area.
In other words, in Galicia, there is still work to be done to determine the characteristics of soils that have not been sufficiently studied to date, either because there are areas that have yet to be characterized or because they could be explored in much greater detail. These results would enable different types of detailed and comprehensive maps to be produced of the properties analyzed.
The most graphic and synthetic could be maps in which different layers presented as a geographic information system would show the details of interest in each case at sufficiently fine scales.
The potential applications of having already achieved such broad and detailed knowledge range from implications at the level of plant nutrition and environmental health (also considering micro and macrobiota) to the assessment of current and future risks (also in the face of changing situations that can be modeled) due to pollution or any other form of soil degradation and subsequent impact on water, plants (including crops), and animals, which could include the possible loss of carbon storage capacity, with tremendous repercussions on the accelerated global warming of the planet.
However, this relatively basic work (systematic characterization of basic properties throughout the territory at a detailed scale) may not be seen as innovative, which could make it difficult to obtain funding to carry it out. At the other extreme, research that could a priori be classified as more innovative could be considered, and here each researcher can let their imagination run wild, as I myself did in a publication last year.
But suppose we have to focus on priorities that represent opportunities for Galicia and the Iberian Northwest. In that case, I think it is only fair to remember that the first thing is to guarantee the livelihood and quality of life of the population, so we cannot neglect primary production of goods (essentially food), which is fundamentally rooted in healthy soils.
Sustainable and environmentally friendly food production has the potential not only to meet local consumption needs, but also to trade high-value products with other countries or geographical areas.
Preserving the soil and the environment also means attracting visitors who appreciate natural landscapes and bring economic resources to the regions they visit. Therefore, research is needed to determine the extent to which priority pollutants affect soil and water (some of which may be highly toxic, but others may include fertilizers that can damage the environment through processes such as eutrophication when applied in excess and/or under unsuitable conditions) will remain essential for decades to come, as will everything related to assessing the degree of soil degradation through chemical or physical means and the effects on water bodies.
Similarly, being able to propose measures to minimize or control all these processes of contamination or degradation in general will remain crucial forever.
In short, researchers focused on soil science and environmental sciences may feel highly motivated to carry out a specific project on a particular aspect, which may be very innovative. Still, at a global level, the major problems I mentioned will continue to require the efforts of current and future generations, knowing that each researcher or group will have to do what is within their power, which will be only a small part of the overall context.