Leaching of unexpected cyazofamid degradation products into groundwater demonstrates gaps in current pesticide risk assessment.

To investigate the formation and leaching potential of degradation products N,N-dimethylsulfamide (DMS) and dimethylsulfamic acid (DMSA) from cyazofamid under real-world agricultural conditions, the fungicide cyazofamid was applied in a potato crop as part of the Danish Pesticide Leaching Assessment Programme (PLAP). Leaching of DMS, DMSA, 4-chloro-5-(4-methylphenyl)-1H-imidazole-2-carbonitrile (CCIM), and 4-chloro-5-(4-methylphenyl)-1H-imidazole-2-carboxylicacid (CTCA) was monitored in water from the variably saturated zone (suction cups) and groundwater for more than two years following the applications. In total, 424 samples were analyzed for the content of the four degradation products.

Large mercury release from the Greenland Ice Sheet invalidated.

The major input of mercury (Hg) to the Arctic is normally ascribed to long-range transport of anthropogenic Hg emissions. Recently, alarming concentrations of Hg in meltwater from the Greenland Ice Sheet (GrIS) were reported with bedrock as the proposed source. Reported Hg concentrations were 100 to 1000 times higher than in known freshwater systems of Greenland, calling for independent validation of the extraordinary concentrations and conclusions.

National Assessment of Long-Term Groundwater Response to Pesticide Regulation.

Quantitative assessments of long-term, national-scale responses of groundwater quality to pesticide applications are essential to evaluate the effectiveness of pesticide regulations. Retardation time in the unsaturated zone () was estimated for selected herbicides (atrazine, simazine, and bentazon) and degradation products (desethylatrazine (DEA), desisopropylatrazine (DIA), desethyldesisopropylatrazine (DEIA), and BAM) using a multidecadal time series of groundwater solute chemistry (∼30 years) and herbicide sales (∼60 years). The sampling year was converted to recharge year using groundwater age.

Combining reverse osmosis and microbial degradation for remediation of drinking water contaminated with recalcitrant pesticide residue.

Groundwater contamination by recalcitrant organic micropollutants such as pesticide residues poses a great threat to the quality of drinking water. One way to remediate drinking water containing micropollutants is to bioaugment with specific pollutant degrading bacteria. Previous attempts to augment sand filters with the 2,6-dichlorobenzamide (BAM) degrading bacterium Aminobacter niigataensis MSH1 to remediate BAM-polluted drinking water initially worked well, but the efficiency rapidly decreased due to loss of degrader bacteria.

Leaching of 1,2,4-triazole from commercial barley seeds coated with tebuconazole and prothioconazole.

Seed dressing with fungicide or insecticide is a standard procedure for growing major crops, but very little is known about the leaching risk and the general fate of pesticides from coated seeds. Triazole fungicides are commonly used seed dressing fungicides and recently, there has been increasing concern that 1,2,4-triazole, a major degradation product of several triazole fungicides, may leach to groundwater in concentrations exceeding the 0.1 μg/L threshold limit of the European Union.

Combined removal of organic micropollutants and ammonium in reactive barriers developed for managed aquifer recharge.

Groundwater is an important drinking water resource. To ensure clean drinking water, managed aquifer recharge (MAR) could be an attractive solution when recharging with treated wastewater. The installation of reactive barriers, e.

Leaching of herbicidal residues from gravel surfaces - A lysimeter-based study comparing gravels with agricultural topsoil.

Evidence from the past shows that pesticide use in populated areas may impact groundwater quality. The approval of herbicides such as diflufenican and glyphosate for use on paved and unpaved gravel surfaces in the European Union is based on their behaviour and fate in agricultural soils. However, this might be very different from their fate in gravel surfaces.

Low Turnover of Soil Bacterial rRNA at Low Temperatures.

Ribosomal RNA (rRNA) is used widely to investigate potentially active microorganisms in environmental samples, including soil microorganisms and other microbial communities that are subjected to pronounced seasonal variation in temperature. This raises a question about the turnover of intracellular microbial rRNA at environmentally relevant temperatures. We analyzed the turnover at four temperatures of RNA isolated from soil bacteria amended with C-labeled uridine.

A comparison of the fate of diflufenican in agricultural sandy soil and gravel used in urban areas.

Diflufenican is used in both agricultural and urban areas to control weeds. However, in Europe pesticides are regulated using agricultural soil data only. Urban soils where the top layer is replaced by gravel (e.

History and Sources of Co-Occurring Pesticides in an Abstraction Well Unraveled by Age Distributions of Depth-Specific Groundwater Samples.

When groundwater-based drinking water supply becomes contaminated, the timing and source of contamination are obvious questions. However, contaminants often have diffuse sources and different contaminants may have different sources even in a single groundwater well, making these questions complicated to answer. Age dating of groundwater has been used to reconstruct contaminant travel times to wells; however, critics have highlighted that groundwater flow is often complex with mixing of groundwater of different ages.

Volatile emissions from thawing permafrost soils are influenced by meltwater drainage conditions.

Vast amounts of carbon are bound in both active layer and permafrost soils in the Arctic. As a consequence of climate warming, the depth of the active layer is increasing in size and permafrost soils are thawing. We hypothesize that pulses of biogenic volatile organic compounds are released from the near-surface active layer during spring, and during late summer season from thawing permafrost, while the subsequent biogeochemical processes occurring in thawed soils also lead to emissions.

Soil Domain and Liquid Manure Affect Pesticide Sorption in Macroporous Clay Till.

Pesticides frequently leach through clayey tills, even when they are expected to be strongly adsorbed. In this study, we observed that sorption of two strongly sorbing pesticides, tebuconazole and glyphosate, varied by more than an order of magnitude across soil domains in 5-m-deep clay till profiles with biopores and fractures. Eight soil domains were identified in each of the profiles: five matrix soils and three in the macropores.

Biogenic volatile release from permafrost thaw is determined by the soil microbial sink.

Warming in the Arctic accelerates thawing of permafrost-affected soils, which leads to a release of greenhouse gases to the atmosphere. We do not know whether permafrost thaw also releases non-methane volatile organic compounds that can contribute to both negative and positive radiative forcing on climate. Here we show using proton transfer reaction-time of flight-mass spectrometry that substantial amounts of ethanol and methanol and in total 316 organic ions were released from Greenlandic permafrost soils upon thaw in laboratory incubations.

Bioaugmentation of rapid sand filters by microbiome priming with a nitrifying consortium will optimize production of drinking water from groundwater.

Ammonium oxidation to nitrite and then to nitrate (nitrification) is a key process in many waterworks treating groundwater to make it potable. In rapid sand filters, nitrifying microbial communities may evolve naturally from groundwater bacteria entering the filters. However, in new filters this may take several months, and in some cases the nitrification process is never sufficiently rapid to be efficient or is only performed partially, with nitrite as an undesired end product.

Arctic and Subarctic Natural Soils Emit Chloroform and Brominated Analogues by Alkaline Hydrolysis of Trihaloacetyl Compounds.

There has been increasing recognition of the occurrence of natural, halogenated organic compounds in marine and terrestrial environments. Chloroform is an example of a halogenated organic compound with natural formation as its primary source. Chloroform emission from soil has been reported from diverse Arctic, temperate, and (sub)tropical ecosystems.

Protozoa graze on the 2,6-dichlorobenzamide (BAM)-degrading bacterium Aminobacter sp. MSH1 introduced into waterworks sand filters.

Groundwater contamination by pesticide residues often leads to the closure of drinking water wells, making the development of new techniques to remediate drinking water resources of considerable interest. Pesticide-degrading bacteria were recently added to a waterworks sand filter in an attempt to remediate pesticide-polluted drinking water. The density of the introduced bacteria, however, decreased rapidly, which was partly attributed to predation by protozoa in the sand filter.

Establishment of Bacterial Herbicide Degraders in a Rapid Sand Filter for Bioremediation of Phenoxypropionate-Polluted Groundwater.

In this study, we investigated the establishment of natural bacterial degraders in a sand filter treating groundwater contaminated with the phenoxypropionate herbicides (RS)-2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP) and (RS)-2-(2,4-dichlorophenoxy)propanoic acid (DCPP) and the associated impurity/catabolite 4-chlorophenoxypropanoic acid (4-CPP). A pilot facility was set up in a contaminated landfill site. Anaerobic groundwater was pumped up and passed through an aeration basin and subsequently through a rapid sand filter, which is characterized by a short residence time of the water in the filter.

Degradation of trace concentrations of the persistent groundwater pollutant 2,6-dichlorobenzamide (BAM) in bioaugmented rapid sand filters.

Groundwater is an important drinking water resource. Yet, this resource is threatened by pollution from chemicals, such as pesticides and their degradation products. To investigate the potential for remediation of groundwater polluted by trace concentrations of the pesticide residue 2,6-dichlorobenzamide (BAM), we established a pilot waterworks including two sand filters.

Groundwater chemistry determines the prokaryotic community structure of waterworks sand filters.

Rapid sand filtration is essential at most waterworks that treat anaerobic groundwater. Often the filtration depends on microbiological processes, but the microbial communities of the filters are largely unknown. We determined the prokaryotic community structures of 11 waterworks receiving groundwater from different geological settings by 16S rRNA gene-based 454 pyrosequencing and explored their relationships to filtration technology and raw water chemistry.

Formation mechanisms of trichloromethyl-containing compounds in the terrestrial environment: a critical review.

Natural trichloromethyl compounds present in the terrestrial environment are important contributors to chlorine in the lower atmosphere and may be also a cause for concern when high concentrations are detected in soils and groundwater. During the last decade our knowledge of the mechanisms involved in the formation of these compounds has grown. This critical review summarizes our current understanding and uncertainties on the mechanisms leading to the formation of natural trichloromethyl compounds.

Is biological treatment a viable alternative for micropollutant removal in drinking water treatment processes?

In western societies, clean and safe drinking water is often taken for granted, but there are threats to drinking water resources that should not be underestimated. Contamination of drinking water sources by anthropogenic chemicals is one threat that is particularly widespread in industrialized nations. Recently, a significant amount of attention has been given to the occurrence of micropollutants in the urban water cycle.

Fungal-bacterial consortia increase diuron degradation in water-unsaturated systems.

Bioremediation of pesticide-polluted soil may be more efficient using mixed fungal-bacterial cultures rather than the individual strains alone. This may be due to cooperative catabolism, where the first organism transforms the pollutant to products which are then used by the second organism. In addition, fungal hyphae may function as transport vectors for bacteria, thereby facilitating a more effective spreading of degrader organisms in the soil.

Fungal hyphae stimulate bacterial degradation of 2,6-dichlorobenzamide (BAM).

Introduction of specific degrading microorganisms into polluted soil or aquifers is a promising remediation technology provided that the organisms survive and spread in the environment. We suggest that consortia, rather than single strains, may be better suited to overcome these challenges. Here we introduced a fungal-bacterial consortium consisting of Mortierella sp.

Using 2,6-dichlorobenzamide (BAM) degrading Aminobacter sp. MSH1 in flow through biofilters--initial adhesion and BAM degradation potentials.

Micropollutants in groundwater are given significant attention by water companies and authorities due to an increasing awareness that they might be present even above the legal threshold values. As part of our investigations of the possibility to remove the common groundwater pollutant 2,6-dichlorobenzamide (BAM) by introducing the efficient BAM degrader Aminobacter sp. MSH1 into biologically active sand filters, we investigated if the strain adheres to filters containing various filter materials and if the initial adherence and subsequent degradation of BAM could be optimized.