Environmental Chemistry

What happens to a pesticide, a heavy metal, an antibiotic, a detergent or a natural toxin when it is introduced to a soil, a freshwater body or as runoff in urban environments?

About the group

Will it degrade and how, will it bind to the sediment particles, can it photodegrade, will it leach or evaporate, are the concentrations so high that they will kill soil animals or be taken up in plants?

Many questions that immediately turns up for whatever pollutant that hits the soil coming from various sources such as the air, fertilizers, manure, waste, traffic and chemical spills/deposits. The questions are at the core of what we work with in the Environmental Chemistry research group. We are searching for molecular insight in fate of chemicals, and we provide data to safeguard the use of chemicals. 

Group leader

We also work with methods by which we can clean polluted soils and waters, for instance making filters, by introducing reactive nanomaterials to polluted groundwater, or by extracting toxic metals. In our work we are measuring concentrations and chemical properties, and hence use a large variety of instruments and methods.

You can read more about our work in the following pages, by clicking the members of the research group providing access to our publications or simply by contacting us - and maybe meet for a coffee. 

Fate of Contaminants

Natural toxins

Natural toxins are compounds produced by organisms typical as a chemical weapon against predators and competing species. Many such natural compounds are toxic to highly toxic - just think about ricin from the castor oil plant, amatoxins from mushrooms, coniine from poison hemlock, cyanogenic glucosides from clover, microcystins from cyanobacteria, or phytoestrogenic isoflavanoids from beans. There is a huge diversity of such toxins, with more than 50,000 different compounds. In our research group we work with these toxins because we think they are as important for the quality of natural waters including drinking water as are industrial pollutants. Today we know very little about the fate of these compounds in the environment and data are ugently needed. Also for natural toxins we need to know their fate in the environment. We also need to know how much of the toxins are produced, how much is deposited into the soil, and when the toxins released. One example is the compound ptaquiloside – a carcinogenic glucosidic compound produced by bracken. Ptaquiloside is highly soluble in water and leach fast through in soils to surface water and groundwater in rural and forest areas with bracken. We focus on fate and pathway from plants, fungi, animals and microorganisms that produce toxic compounds to our drinking water to improve the risk assessment and damage control of this poisonous toxin.

We are currently running a bigger initiative in the area called NaToxAq where we together with a number of research groups in Europe study how natural toxins may end up in drinking waters from plant or bacterial sources.

Pesticides and other xenobiotics

Pesticides are designed to protect crops from pests to ensure high quality food products. It is inevitable that some will be spread in the environment and hit non-target organisms in soil and freshwater. Understanding sorption and degradation kinetics of pesticides in agricultural soils allow us to reduce non-target exposure and effects to organisms in streams after leaching via drain and surface run-off. We study sorption and desorption to minerals and mobile particles coated with natural organic matter, and thus the retention of pesticides in the soil. As for pesticides many other organic contaminants are added to soils with manure or waste, e.g. antibiotics, steroidhormones, and plasticizers. Also here we investigate degradation and sorption to assess the risk of leaching to the aquatic environment.

Heavy metals and speciation

Heavy metals and other toxic elements are unfortunate bioactive pollutants in the soil-water continuum. The fundamental knowledge of microbial ecosystem functioning and fate of toxic elements in food production systems is used for better risk evaluation and efficient remediation in soils, sediments and freshwaters in both urban and agricultural areas. We study the speciation, complexation, sorption and leaching processes of elements in the environment. For instance we investigate and optimize element speciation analysis techniques for the determination of microbiological available Cu and Zn in the soil-water-manure system. 

Molecular soil remediation

Nano-particles for advanced reduction/oxidation

In this field our work concentrate on layered metal hydroxides - where socalled green rusts - greenish or blue metal hydroxides containing both di- and trivalent iron is in focus. Green rusts are very appealing due to their high reactivity in particular for reduction processes. Thus green rusts have potential for remediation of contaminants such as nitrate, halogenated aliphatic compounds (e.g. chlorinated solvents), nitro aromatic compounds, and selenate. We are modifying green rusts to make metal hydroxide - organo hybride materials to make them strong sorbents as well as strong reductants. For instance, when introduced to polluted aquifers – they can both sorb and dehalogenate chlorinated solvents. In a recent innovation we delaminated oxidized green rusts in order to produce single sheets of iron oxides. Such materials are of substantial interest as sorbents, electro- and photocatalysts.

Phosphorus retention and recycling

Phosphorus is an essential nutrient, with increasing global consumption, decreasing mineral reserves and the main cause of eutrophication of surface waters. Our research follow two lines: i) synthesis and testing of filter materials which retain phosphorus from agricultural drainage waters and other high-volume waters, and ii) phosphorus mobilization/retention in wetlands. The challenge is to develop a fast, strongly and irreversible binding filter material which is one of the focal points in the project SupremeTech and now in the project NuReDrain. In wetlands - which also has been allocated function as phosphorus traps - we focus on phosphorus retention and release during anoxic conditions including a battery of many geochemical reactions: dissolution, re-adsorption and precipitation processes. In particular the role of vivianite (Fe3(PO4)2 8 H2O) is being studied.

Soil washing

Current soil remediation techniques for heavy metals and strongly sorbed organic contaminants suffers from being costly, inefficient and slow. Soil wash is an alternative which involves the extraction of contaminants from the soil solid phases by a washing solution with reactive agents such as acids, bases and chelatants. Together with the Analytical Chemistry research group we study environmentally safe soil washing agents potential for remediation of soil. We found biosurfactants to be promising for simultaneous remediation of heavy metals and PAHs, a mixed contamination type commonly found in city and industrial soils.

Water chemistry and technology

Water quality

Intensive land use like agriculture and horticulture has strong impacts on the quality of natural waters causing pollution with nutrients, pesticides and heavy metals, but also veterinary drugs, hormones and even natural toxins. Situations become aggravated during storms and flooding, causing contaminant flushes and drowned landscapes with substantial releases of contaminants. For cities flooding may give rise to bursts of contaminants. We study the bioavailability, mobility and transport of contaminants in relation to different land uses, changing climate and fluctuating natural conditions such as flooding.

Urban water

In the recent years landscape-based management of stormwater runoff in urban areas has gained ground. This approach entails that stormwater runoff is delayed and possibly treated locally. The water may be used to provide amenity assets by exposing it in channels or ponds, and/or infiltrated into the soil, or discharged at a reduced rate to a natural water body like a stream or groundwater, or to the conventional sewer system. Our research is focused on characterizing the pollutant profile of stormwater runoff from different catchment areas, as well as improving the treatment ability. This is done in close collaboration with among others Municipalities and Supply Companies, as well as colleagues at IGN.

  • China-EU Cooperation on Sponge Cities, China-EU Water Platform Project (CEWP), 2017 - 2021
  • DFC Water Course F19 and E19, Danida, 2018-2019
  • GreenCat - Removing chlorinated solvents from groundwater and soil
  • MagS3 - Phosphorus capture and recycling by magnetically anchored singlesheet sorbents. Danish Reseach Council (FTP), 2017 - 2020 (Coordinator)
  • NuReDrain- Nutrients Removal and Recovery from Drainage Water. EU-Interreg, 2017 - 2021
  • Phosphorus Risk Mapping - P bonding in meadow soils, Danish EPA, 2017-2020
  • Sino-Danish Center, Water & Environment, SDC, 2012 -
  • Soil Tracker - Forensic Toolkit for fingerprinting soil. Innovation Fund, 2017 - 2019
  • Water in Urban areas, Innovationnetwork, 2010 - 2018

Contact

Hans Christian Bruun Hansen
Professor