This webinar combines environmental monitoring studies in various compartments (wastewater treatment plants, surface water, ground water, tap water) with field and laboratory scale experiments of key processes (advanced wastewater treatment, bank filtration, infiltration, plant uptake) for over 50 PMT/vPvM chemicals to unveil which of these chemicals occur widely in the water cycle and have the highest potential for human exposure.
The resulting dataset helps to prioritize PMT/vPvM chemicals which combine high environmental concentrations and an elevated likelihood of human exposure through crops or drinking water and are thus in need of a sophisticated toxicity assessment.
Daniel Zahn is an environmental and analytical chemist with a PhD from the University of Leipzig, Germany. In his PhD he studied the occurrence and fate of PMT/vPvM chemicals in the environment and in his current position as head of the working group transformation processes at the Helmholtz-Centre for Environmental Research he researches how a chemicals fate in the environment modulates exposure.
The slides presented can be found here: https://zenodo.org/records/15733403
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ZeroPM has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101036756
this is a 0 PM webinar um for those of you who don’t know me I’m Sarah Hail and I work for the German Water Center and for those of you who don’t know ZerPM it’s a Horizon 2020 research and innovation project where we’re looking at interlinking prevention prioritization and removal strategies to protect the hum to protect human health and the environment from these persistent and mobile substances it’s a bit of a mouthful but that’s what we’re doing in the project um today it’s my great pleasure to welcome Daniel Z and he’s going to gift the webinar today which is called chemicals without borders PMT VPVM chemicals from release to human exposure so I’ve known Daniel for a very long time uh he’s an environmental and analytical chemist he has his PhD from like in Germany he’s still working in Germany and his PhD was part of the promote project which is actually where I met Daniel he’s been looking at PMT andVPVM substances basically since as long as I can remember and at the moment he works at UFZ so Daniel I’m gonna let you take it away and bring up your slides
my presentation today is named chemicals without borders so I want to have a look with you how PMT chemicals spread in a water cycle if we have a look at the water cycle we often talk about a multibarrier system because we want the water cycle not to become a chemical cycle so we have our wastewater treatment plants where we can have biological degradation chemical degradation if there’s advanced treatment and sorption processes taking place it is similar in surface water we can have biological degradation we can absorption to soil and suspended matter and in the top layers we kind of have photo degradation then when we have the transfer to groundwater during infiltration processes again there could be biological degradation this time in the soil absorption to the soil or reaction with mineral surfaces and in the end when we treat our w our water for drinking water production it’s again the same similar processes here we have sometimes biological degradation absorption and chemical degradation so what does this in the end mean we have three processes that dominate our water cycle that dominate the barriers in our water cycle first of all we have dilution so we put a little waste water in much more clean water and in the past u often took care of things but it becomes less and less reliable because especially in hot summer months we have small rivers that are up to 50% and more waste water during the summer and with the increased water needs we have to decrease the distance between waste water and reused water either indirectly or in some countries that are really that are really dry there’s also direct waste water reuse for agriculture and sometimes even for drinking water production so you see we can’t rely on dilution that much anymore so we need to put more emphasis on the barriers we put in the water cycle and if you have a closer look all those processes here seem to pretend on two mechanisms on the one hand transformation which doesn’t work too effectively for persistent chemicals and on the other hand absorption processes which are often not too effective for mobile chemicals so PM chemicals combine all the qualities to break through these barriers and therefore spread quickly in the water cycle why is this important the chemicals that are released of course impact the ecosystem they can interact with all kinds of aquatic organisms and if they can break through the barriers we use for example for drinking water production if they can accumulate in plants there’s also potential for human exposure so we need to know which chemicals break through these barriers which one are present in high concentrations to prioritize them for sophisticated risk assessment and to implement effective counter measures if it’s required and therefore I want to take you on a bit of a journey today i want to follow the water we will go from release to possible roads of human exposure so we’ll start at a wastewater treatment plant have a look at bank filtration have a look into tap water and finally find out what happens if you irrigate with water contaminated with PM chemicals let’s start at the source and wastewater treatment plants which is the main entrance pathway for many PM chemicals into the water cycle what I want to discuss with you here is a study we did in two wastewater treatment plants one of them using powder activated carbon and the other one using ozone followed by sand filters we look for over 100 PM chemicals in there and wanted to answer three basic questions first of all we wanted to know which PM chemicals are actually present in biological affluent then how effective are those treat advanced treatment technologies in the removal of PM chemicals and finally which chemicals remain and are released in high concentrations into receiving waters this is an overview of the biological affluent of those two wastewater treatment plants here are only shown the chemicals with concentrations greater 0.1 microgram per liter in general of the 111 chemicals we detected 72 more than once and 47 were present in both wastewater treatment plants among the highest concentration chemicals those with concentrations higher than 1 micron per liter were of course some of the well-known chemicals like benzotriazole guanilura watonic acid theotriazoic acid but also some less studied or sometimes even novel chemicals like these shown here very interesting about them are the two inorganic ones the PF6 and BF4 we found them only a couple years early we found them in 2001 2021 for the first time in the environment so what happens to this chemical first was the summary we found 72 of the 111 which resulted in a total PM burden of 100 micrograms per liter and 40 micrograms per liter depending on the waste water was a treatment plant so there are a lot of PM chemicals present in the secondary affluent next we had a look at the treatment technologies we only had a look at here at those PMI chemicals and concentrations greater 0.1 microgram per liter and here you see a breakdown of the removal with powder activated carbon and with ozonation followed by rapid filtration through a sand filter the powder activated carbon had a pretty even 1/3 1/3 split 1/3 of those chemicals were removed well so greater than 70% 1/3 was removed partially so between 30 and 70% and for one/3 there was no removal while for the oonation we see there is more chemicals where we have good removal almost half of them but a similar amount of chemicals where there was more removal and we found some chemicals where we actually observe formation because this alsation can lead to the formation of transformation products on first glance it doesn’t look too bad but if you have a look at total concentrations again the powder activated carbon only reduced the PM load from 103 to 87 micrograms per liter so while 1/3 of chemicals was good and 1/3 was partially removed the total PM was only reduced by like 10% the reason for this is that many of the high concentration chemicals we found were not really affected by powder activated carbon it mostly remove the low concentration chemicals the picture for ozone is a bit better we reduce the PM burden by almost half by half to 19 microgram per liter but still we observe more formation so both technologies only lead to a partial reduction of the PM curtain in the waste water at most by half we wanted to have a look if these technologies are complimentary so you see the removal during ozonation plotted against the removal with activated carbon and you can see there are some chemicals for which both methods are effective some for which neither methods is effective and then a range of chemicals for which there is a complimentary behavior of both methods so we had a closer look at this and the wastewater treatment plant with the ozone actually had a pilot plant connected to it where there was activated carbon filtration after the ozonation if you apply this we see the synergistic effect suddenly remove n uh 60% of the chemicals well and some of the chemicals that are formed are also reduced but we have this very rec citral core of like nine chemicals that is not removed by either technology nor the combination of both so how does this translate to concentrations even when we combine both technologies the reduction in the BM BM burden is fairly low still we see uh now I can’t see my screen anymore which is a bit annoying i did something wrong okay I can see my screen again we see even if we combine both technologies we only go down to 13 microgram per liter so one/3 of PM chemicals remain even which when we use what is the most advanced setup that’s commonly used in wastewater treatment so even this technologically sophisticated method is not an effective barrier against PM chemicals which are the chemicals that remain and how do the chemicals behave that we have here here are rather novel or not too well investigated high concentration chemicals and this is how they behave during the treatment some are removed by one of the techniques some are removed by both but some are removed by neither and all these chemicals had concentrations higher 1 micron per liter in the affluent and we can’t really do anything against it what I point want to point out a bit you see those two inorganic ions they are often used as unions for so-called ionic liquids which are organic salts they usually have either one or two organic ions combined here it’s an inorganic ion is often combined with an organic cut iron and they’re a bit designer chemicals because they can be tailored to a couple of to many many applications we had a look at more of these ionic liquid ions the other ones did not reach these high concentrations with greater one microgram per liter but we found one of them this NTF2 which is a novel PAS that we also detected only in 2021 for the first time could also not be removed and there were 11 more of this ions not removed during advanced wastewater treatment let’s sum this up we discussed for the last 10 minutes about our different advanced wastewater treatment technologies and how effective they are or not but the one important thing we have to keep in mind they are usually only implemented for large wastewater treatment plants so in many of the smaller wastewater treatment plants these high secondary effluent concentrations that we saw will be directly discharged in receiving waters the other thing that’s important to learn here while our advanced technologies are effective against some chemicals they have systematic gaps chemicals that cannot remove and we need to know which chemicals slip through our treatment to be able to of course evaluate if they are problematic and if yes take appropriate action after discussing the sources with which the chemicals can be released into the water i want to have a look with you into surface water concentrations and bank filtration which is often a step the first treatment step for drinking water production the study I want to summarize here we took a look into two river systems the river Ryan and the river Moulder and into a bank filtration site located at the river Moulder these are the chemical concentrations we found our two rivers we have a frequency of detection so how often did we detect them and we have a medium concentration of our 127 chemicals we looked for we detect 92 so many of the chemicals we were looking for were actually present however only 44 of them had a frequency of detection greater than 50% so more than half are actually present fairly sporadically however there were two chemicals we detected in really high concentrations up to 2.5 microgram per liter not as maximum concentrations but at median concentrations in surface water those were caprolactam and again the BF4 comparing our two rivers we had 72 chemicals in both river systems but we observed actually quite pronounced concentration differences in general the river Ryan was more contaminated we deserve observed higher concentrations there when you look at this graph you see basically the concentration ratio between the river mold and rin so all the chemicals you have at the top going towards 10 or above the line had higher concentrations in the river R and all the chemicals at the bottom had higher concentrations in the river mold we see we have a couple of chemicals which are in this intermediate range but almost half of our chemicals were either much more present in the river rine or much more present in the river mold showing that there can be pronounced local differences in concentrations of these chemicals and there were a couple of chemicals that were only found in either of the two rivers so what’s the first thing we learned from this in our surface waters we found 92pm chemicals and we found some concentrations of up to 19.5 microgram per liter of these chemicals so the PM purdin in surface water can be quite high and again it was dominated by few high concentration chemicals but these high concentration chemicals are exactly those we need to remove during water drinking water treatment and the first step to drinking water treatment is often bank filtration so let’s have a closer look at the bank filtration site located at the river mula what you can see here are removal rates those are recorded over a time period of a couple months therefore you can see some variations especially for those chemicals that are um in the intermediate range of removal of course we have dilution with groundwater which makes it a bit hard to determine but we took some tracer chemicals to account for this so we have like half of the chemicals were fairly well removed during bank filtration so again bank filtration is an effective barrier against a number of of these PM chemicals however the other half was only partially removed some were not removed at all and for two we even observed formation right having a closer look which chemicals were not removed we see we have caramas pine we have the PF6 we discussed before in wastewater treatment but most importantly among those non-reved chemicals were again the car product and the BF4 the two chemicals we found in the highest concentrations in surface water so like in the waste water treatment we have pretty much a similar picture the technology is effective against a number of chemicals but among the ones that slip through are some of the highest concentration chemicals we observe so what does this mean for concentrations and PM burden we still find 40 PM chemicals in the bank filtrate in varying concentrations but since some of the highest concentration chemicals slip through we can only reduce the PM burden down to 8.4 micrograms per liter a lot of which was caused by car time and B4 alone due to the high concentrations so so far we saw all the barriers we have are somewhat effective they reduce the number of chemicals they reduce the total concentrations but we have this a very reciterant core of chemicals that seem to slip through if we look at tap water it is often produced either from bank filtrate from groundwater or sometimes even directly from surface water and depending on the source water you usually have different treatment technology afterwards we wanted to know what are the PM concentrations in tap water so we did a study collecting tap water from 11 countries and three continents we had a total of 32 samples mostly out of convenience many of them were collected from Germany with 15 but we also had Botswana Czech Republic Italy Lebanon the Netherlands Norway Portugal Switzerland Sweden and even the US having a look at the raw concentrations and occurrence of these samples you can see here you can see mark with a is the concentration in microgram per liter and this line at um 0.1 microgram per liter is what’s often used as the risk indicator value for chemicals for which there’s not enough toxicological data and we can see FOD which stands for frequency of detection the blue bar is the FOD lower than 0.1 microgram per liter and the orange bar is higher than 0.1 microgram per liter the first thing we see we have two chemicals that exceed this 0.1 microgram per liter as median concentration whenever they’re present those are again the B4 we heard before and TFMSA which is an ultra short chain pie as you can see at the bottom we have seven chemicals that exceed a tap water concentration of 1 microgram per liter at least once in our data set the highest one of those is the P6 the other inorganic annion where we found a maximum concentration of 3.6 microgram per liter in tap water and to also have a look at the chemical that has been popping up again and again over the last years is this NTS2 it is present rarely it’s present in low concentration but we also found it in tap water so what kind of total burden does this reflect if you look at total tap water concentrations we are again lower than we were in surface water we are lower that we were in back filtrate here we have a tap water concentration of 0.1 microgram per liter up to 6 microgram per liter of the PM chemicals we see there’s quite a large variation and even if you look into uh waters from the same country like Germany there’s a huge variation between concentrations we observe while others look very comparable if you look at Venice and Rome so with this we wanted to do some statistical analysis to find out if we can observe patterns what you see here is a cluster analysis and the heat map the heat map gives you indications about the concentration of chemicals in certain samples and the cluster analysis is well in the end clustering them together we observed two different types of clusters we observed the cluster for samples and the clust and two clusters for chemicals for the samples we have this um cluster samples one and cluster samples two in this cluster samples one we found many chemicals on average 20.5 + -2 and in this cluster two we found few chemicals 11.5 + – 2.2 if you have a look at the box plot down here this is something I found quite fascinating of course it’s not surprising that we have chemical samples with more and with less chemicals what was quite surprising to me is how clear this divide is it was statistically very significant with P below 0.00001 and the very clear divide of almost 10 chemicals in average on difference so this was the first very surprising thing we observed the first thing that comes to mind when you see this that this could be a consequence of different treatment technologies so we had to look at these samples and we could not observe any pattern in terms of treatment technology used so our working hypothesis right now this is mostly connected to raw water quality and indicates that raw water quality has actually a larger influence in treatment technologies especially for those very hard to remove chemicals of course this needs further confirmation the second cluster we observed was a cluster with the chemicals you again see on the top this one’s a bit harder to read this cluster chemicals one and cluster chemicals too in the figure these chemicals cluster one are chemicals with a high detection frequency they were on average detected in 77 plus – 15% of samples so those are the fairly ubiqu ubiquous PM chemicals and there was a cluster with a low detection frequency with around 33% plus – 16% and here again the two clusters are quite quite well separated and it was statistically very significant and I think it becomes very obvious also when you look into the heat map what’s quite interesting is when you compare both clusters for chemicals and for samples the cluster two chemicals so the rarely detected chemicals are also the chemicals that you rarely find in the less polluted samples while the cluster one chemicals are those that you find fairly often in the less polluted samples of course the first thing that could come in mind is that you think okay those cluster two samples also have a much lower PM burden however this is not necessarily true because if you have a look at mean concentrations of the chemicals clusters one and two you see that on average they are not statistically significantly different but many of our highest concentration chemicals are actually in this cluster too we have our inorganic annions in this cluster too we have the tree methane sulfonic acid in the cluster too so we have some of our highest concentration chemicals we found only in a few samples so they are not that widely spread apparently but when they are present they’re present in high concentrations based on this data we wanted to see or at least have a first indicator if this is relevant for human health what we did we calculated human exposure we calculated it burst on a based on a worst case approach so we took the 95th percentile concentration in our data set assumed two liters of tap water consumption a day and an average weight of 70 kg with this we calculated this human exposure you can see in the graph and we compared it to so-called karma classes what is a karma class in the end is a structure based um classification of chemicals and based on the structure the chemicals get design assigned a karma class and these karma classes have estimated toxicity values with this you can calculate a threshold dose grammar class 3 was the class where most of our chemicals fell into and it’s also the class with the lowest threshold it has a threshold of 1.5 micro gram per kilogram in day and all of our chemicals were at least one order of magnitude below this threshold value of course there are several things to consider only a part of the human exposure is through drinking water so it should only account for roughly 20% of human exposure and this grammar class is really an estimate only it’s based on the structure it’s not based on toxicity data for these chemicals so they could be much less toxic or in some cases maybe more toxic and if you have a look among our highest human exposure chemicals three of them could not be assigned to karma class by the tox software we used because they were structurally too different this indicates that at least on first glance with this rough estimation approach there doesn’t seem to be a critical human exposure but there are many uncertainties that have to be taken into account like toxicity of individual chemicals and the effect of the chemicals that cannot be assigned to class and of course cumulative human exposure through different sources looking at this whole pathway from wastewater treatment plant over bank filtration to drinking water there’s some conclusions we have to draw first of all bank filtration and even advanced water treatment is only partially effective against PM chemicals we saw removal in every step but we also see the same chemicals popping up again and again because they can break through these barriers and they are some of the high concentration chemicals we saw that source water quality seems to have a large effect on tap water concentrations and this leads us to one main conclusion at least from my perspective and this is that drinking water production begins at the source we have to take actions at the source against those most critical PM chemicals for which there’s no effective removal technology if they prove to have adverse health effects this concludes the field studies I wanted to talk to with you but we also had a lab study we did in a project where we wanted to assess what happens if you use waste water for agriculture what effect do PM chemicals in this water have is there plant uptake so is this another human exposure route and can there be infiltration into groundwater to do so we did two studies one of them is already finished i will focus on this one where we um used rockets and planted in a greenhouse and irrigated it with spiked fresh water to 80% field capacity here we wanted to find out which of these PM chemicals are taken up by plant and if they’re transported to the edible parts or not and another study this is currently still in progress we’re currently still evaluating the data here only give you a quick sneak peek where we want to find out with soil column studies which of these PM chemicals actually has a high likelihood of reaching groundwater let’s have a look at the plant uptake first when you irrigate plants with water containing chemicals there are several factors that may influence the concentration in a plant ultimately you have of course to soil which is likely less relevant for many of the PM chemicals we are investigating we have always the question how much of the water containing the chemicals is actually taken up by the plant which can hugely vary with experimental time and we have the potential of elimination of chemicals either through volatilization which is also less likely in this study because none of the chemicals we use is specially volatile and there’s of course potential for transformation in a plant of these factors we found this amount of water taking up likely leads to the largest variance between different studies because this can very much depend on the growth period it can very much depend how long is the experiment running so we decided to closely monitor the water taken up by the plant we had non-planted pots in which we estimated evaporation we closely monitor toward the irrigation and we analyzed how much water remained in the soil after the experiment and which this we calculate for each individual plant how much water was taken up over the experiment period with this information we calculate then what we call the relative uptake this is the total amount of chemical we find in the plant at the end of the experiment divided by the total amount of chemical in the water the plant has taken up so the total amount of water multiplied by the concentration in the water so how does this look like what you see here are the relative act values for the chemicals we investigated first of all this is a kind of metric you don’t really see often so the first thing we need is an anchor point therefore we look at carbon mass this is a chemical very frequently studied for plant uptake it has been studied in all kinds of different plants and it’s usually among the highest if not the highest plant uptake chemicals in many studies if you have a look at our data 44 of the chemicals we detected have a relative uptake below 20% and only roughly 10 chemicals have a relative uptake higher so we again have the picture here that some chemicals show exceptional behavior what was quite remarkable for me that we have several chem seven several chemicals with a relative uptake higher than that of carbon mazopine which is usually the top end or near the top end in many studies if we have a look at these chemicals we again have our two inorganic annions popping up we have one pharmaceutical with oxipurinol and we have four short chain pas we have the widely known free throw acetic acid that you can by this point find pretty much everywhere in the environment we have free propionic acid which is just one chain longer we have the tree flu methane sulfonic acid we also found high concentrations of tap water and again we have this bis tree flimid this novel pas that’s often connected to energy storage because it’s used in lithium ion batteries so with some of these chemicals taking up exceptionally well the next question for us was do they remain in the roots or are they transported to edible parts of rocket therefore we calculate transformation transllocation factors which is basically just a concentration ratio between the chemicals in the roots and the chemicals in the leaves of the rocket transllocation factor greater one means we have enrichment in the leaves the chemicals are predominantly transported towards leaves and below one means they mainly remain in the roots we have around two/3s of our chemicals with a translocation factor greater than one again we have the ka musipine as our anchor point with a transllocation factor of 23 so you see it’s very effectively transported into the leaves our pas and inorganic ann ions all show transportation to the leaves as well some of them very strongly with transllication factors between five up to 43 and our oxipor is also mainly transported to the leaves with a transllication factor of three what was quite interesting here that we have three either guanidines with yanog guuanine and the dpg or is chemically similar compound with the aretto guamine with very high transllocation factor so these chemicals seem to be very effectively transported to the leaf of rocket from this data we can learn that our high uptake chemicals not don’t remain in the roots but they are also affected to transported to the leaves so to the edible parts of rocket we wanted to compare our data to literature since the RU is not right reduced we calculated bio uh bio acccumulation fac bio concentration factors since we have low absorption to soil and you often use soil concentrations to plant concentrations we decided to compare it to hydroponic studies and calculate a bio transformation factor from water to um plant because otherwise this would be quite pointless exercise for chemicals that do not absorb to the soil because it only depends on how much how wet the soil is at this point to make it somewhat comparable we only looked at experiments in literature that use similar plants so rocket lettuce or spinach and fairly long cultivation times 21 to 55 days if you look at the figure A here you see the buying concentration factors by concentration factor in our study was higher it was somewhat sign statistically significant with a p value below 0.05 but this can at least partially be explained by a longer experimental time this again highlights the use of IU that really accounts for the experimental time that accounts for the water uptake so this difference in the bio concentration factor is somewhat significant but not too astonishing what was much more interesting was the much stronger transllocation to the edible parts of the plant to the leaves of the rocket in this case our very polar chemicals from this study were by an order of magnitude stronger transported to the leaf than less polar chemicals from literature so it indicates that while very polar chemicals might not be taken up by plants much stronger they are much more readily transported to edible parts apparently of course we can only speak for leafy greens right now for chemic for plants like tomatoes that would need additional studies another thing I want to point out is that we observed high uptake for paraffluroxilic acid especially for the short chain ones this is in line with literature quite expected what was unexpected was this remarkably high uptake for TFMSA because usually the fluinated sulfonic acids show fairly low plant uptake it was the same in our study they showed very low plant uptake until we reach the TFMSA where the plant uptake suddenly skyrocket which means maybe at this very short range different mechanisms play a role finally after we looked at the plant uptake I want to give you a first sneak peek in our study for the infiltration what you see here is uh the retardation coefficient so we used the tracer broomemide and calculated how much faster was the the tracer leaves the column than our chemicals and basically built four categories out of this category one the green ones are tracer like So they reached the end of the column with the tracer only shortly after then the categories two and three are somewhere in between and the category 4 did not leave the column during the experimental time what you can see here we have more or less a split half and half we have a small section in the middle of chemicals that leave the column but are somewhat retained and then we have two majorities of chemicals one that does not leave the column either they are strongly sorbed there or they undergo transformation and one that leaves the column really quickly together with a broomemide tracer from these results we can draw some conclusions for agricultural wastewater reuse the first thing is that this relative uptake seems quite effective to increase comparability between studies we see that some PM PM chemicals are taken up readily by rocket and it rich in its edible parts this was especially true for ultra short chain pas and those two inorganic annions we have and lastly that some PM chemicals show tracer-like behavior showing that there’s a high likelihood to huge groundwater from this we conclude that it is important to include ppm chemicals into risk assessment and quality control for agricultural wastewater reuse with this we finished our way through the water cycle but now I want to have a closer look what we can learn by comparing these studies to one another we saw this plant uptake but of course a chemical that’s taken up well doesn’t mean it’s present in high concentrations it doesn’t mean it has a high human exposure because it also depends on the concentrations present so we took the study from Mushkad Al who also had a look at several German wastewater treatment plants and plotted the median concentration in the wastewater treatment plant against the relative uptake and you see the chemicals on the top right they combine high waste water concentration with high plant uptake and we call this the human exposure potential so they have a high potential for human exposure and agricultural wastewater reuse we see on the very right side we see our high uptake chemicals BF4 PF6 carbon masopine with high waste water concentrations and then below you can see the parafflur propionic acid TFMSA and TF2 they all had a high plant uptake but were present in much lower concentrations in the waste water in this wastewater study TFA was not present but if you wouldn’t you would assume general TFA concentration of the waste water it would also be at the top right side of course this is only based on exposure potential so chemicals that are toxic or may have hot spots might have a high priority as well we then tried to transfer the same approach to groundwater here we took the relative amount in the affluent of our column so how much of what we added left the column in our experimental time and plot it against the same waste water concentrations you can see some of the same chemicals popping up at the top like the PF4 if you then start to plot both against each other the human exposure and the groundwater exposure potential you can see which chemicals may be very critical for agricultural wastewater reuse and no surprise this BF4 shows up at the very top right because it has a very high potential to reach groundwater it has a very high potential to reach humans so we can see here that PM chemicals pose a challenge to agricultural wastewater reuse and they pose it not only for human exposure they also pose it for contam for groundwater contamination so we have to have a closer look here what’s the next thing we saw we saw that there is quite a variation in PM concentration and PM presence in different samples in our two wastewater treatment plants we saw that quite a few chemicals were only present in one of them including high concentration chemicals in our two river systems we observed the same thing we had a lot of chemicals that were present in both in comparable concentrations but roughly 1/4 of our chemicals were only present in one of the river systems and this also includes some of the high concentration chemicals as in our tap water we also saw we have those less frequently detected chemicals that contain some of the highest concentrations so local local sources seem to play be very relevant for PM chemicals and for water quality so we have to have a closer look the problem with these less frequently detected chemicals they might easily escape screening approaches if you don’t have the right samples another thing that’s quite important to me is if you have a look in our barriers at some point they all rely on transformation as a major mechanism we saw it in a wastewater treatment the transformation can lead to formation even though we didn’t intentionally include transformation products here in the same wastewater treatment plant with the ozone treatment and the activated carbon we only had a non-targets we also had a non-target screening i don’t want to go into too much detail here but every dot repens is a feature so something we detected a pair of a mass and a retention time the purple and the red dots are chemicals formed during ozonation so those are transformation products that are newly formed and the red dots are those products formed during ozonation that are not removed by subsequent filtration through activated carbon so you see there’s a huge potential to form mobile transformation products that is so far rarely accounted for and this is I think still a gap we have in chemicals management and need to address more and the final thing I want to talk about is there were a couple chemicals that popped up again and again and again throughout the water cycle we discussed today that showed poor removal during advanced water treatment poor removal during bank filtration strong uptake to plants and transllocation to edible parts we had a high potential to reach groundwater they were present in drinking water and almost all of them fall into this chemical space of small very persistent annions we have of course our inorganic chemicals here and the pifas some of them like TFA and the propionic acid alone for a long time but some of them we discovered fairly recently in the last 5 to 10 years so this is a chemical space that is worth further investigation those small very persistent annions because here we seem to have the highest potential to combine negative effects uh negative properties of chemicals with this I come to an end due to the time I could only give you a short overview if you want a deeper dive in these topics I recommend the following papers and in the end I want to thank the people that did most of the work the first authors of three of the studies I presented today Isabel Noval Matias Mushkin and Alina Zelk of course all the co-authors that contributed to this work and the project partners and the BNBF for funding the projects protect and poor in which the work I showed to you today was performed in with this I’m done and I’m looking forward to your questions many thanks Daniel that was an excellent presentation and uh really enjoyed going through this work that you’ve done recently and how you kind of connected the entire water cycle i’m just going to remind everybody that we have 12 minutes for Q&A so if you have any questions to Daniel please put them in the chat and I will uh ask them and I also have some of my own questions um and just to introduce myself I’m Hans Spir from Norwegian Geotechn Technical Institute um so yeah the first is from an anonymous attendee first question they ask “Is there any chemicals excluded from the study due to the source being pesticides such as TFA?” But I think maybe you could also answer that by saying like how do you choose what chemicals that you decide to include in your studies um it was mainly based on work we did at the beginning of the protect project in 2021 we did uh suspect and non-target screening in different waters mostly surface water and based on the results there we prepared the list for the following studies mhm yeah so uh so just to specifically answer that question um that that was the basis like if they’re from transformation of pesticides that was uh we did not consider this no
no and I recall it’s mainly had an industrial chemical focus like a
we had an industrial chemical focus we took different lists of supposed PM chemicals of course a starting point for our um screening approach including the one of Uber
mhm great thank you and so next question uh do we know more about the toxicity of N2F2 is it a byproduct or used as such for battery production it is used as ion in the electrolyte of batteries but of course the batteries alone cannot explain this wide spread occurrence of this chemical we find it in low concentrations but we find it pretty much everywhere of course it’s known to have hot spots that are near battery production battery recycling but I don’t think batteries alone are enough to explain this widespread occurrence so there must be other sources we don’t really know of or don’t know of yet and this chemical is quite interesting because it combines so many detrimental effects it’s very persistent it’s not destroyed by any treatment technology even if you do a top essay which is very strong oxidative conditions this chemical remains untransformed it can reach groundwater it’s readily taken up by plants it makes its way to drinking water it’s not really removed what we don’t know much of is the toxicity but other than that it combines pretty much every negative effect the chemical can have so it has all it needs to spread quickly in the water cycle the question that remains is how it’s affect mhm yes and the next question is is related um so the focus on public debate currently is oh and I should said yeah it was you that asked that previous question on NTF2 the next question is a anonymous uh question uh the focus on the public debate is mostly on TFA when it comes to very persistent annions past do we know about the toxic properties of the other ones that you showed that have the highest potential of negative effects so maybe just extend your previous answer to other annions they are not well investigated yet the TFA is the one where we know the most we have now very recently this reclassification that was proposed from Germany that it has um reprotoxic effects but of course the others are not that well studied yet for TFMSA there was a study that said it has adverse effects in the um on the gut microbiome of mice but there is not much more that I’m aware of and u well one thing I think that that was quite interesting with your results also and I think is it should probably be a thing that we look more into is the uh yeah the accumulation of these small antic substances in in plants because this could be a huge part of the exposure to these chemicals the focus for instance of TFA has been on water exposure which can be quite substantial in some areas uh but the the the the numbers that we’re seeing coming in from the plant uptake studies are huge and so that there’s haven’t been any good estimates on diet from plants versus water but what is your feeling about based on your work with rockets are you more do you think what is your suspicion like to to explore and further further research are are plants and vegetables a higher source of these chemicals than water
they can be fairly relevant for several reasons of course we observed this really high uptake it was in rocket it’s a leafy green of course we have to have a look in other plants like tomatoes etc if it’s also accumulating there but of course there is a high potential for these plants to be exposed to TFA tfa is in rain so it can be exposed to rain it’s also a metabolite of quite some pesticides so there are many ways that the plants can be exposed to high levels of TSH so this could be a substantial human exposure pathway and this next question comes from Evan Bolton from Pupcam and others uh exploratory question with so many concerning PM chemicals only recently discovered what else is PM in the water that we are not looking for sample will that different columns or approaches might be able to separate out so what are the next ones you’re going to be looking for i think in my last slide I tried to point out a bit that this chemical space of this small persistent annions might be especially interesting because the chemicals we found there seem to have those negative effects of being able to spread very effectively not being removed accumulate into plants this is one avenue we have to look at and the other one is this issue with transformation products we have some chemicals that may be formed from many many precursors so usually the idea is when you have a chemical you release it in the environment transformation products are not so relevant because many transformation products are formed from one precursor concentrations get lower this is often an argument why transformation products are not so relevant but of course you can have it the other way around especially when you have the small very basic molecules that may be formed you can have many transformation products uh one transformation of few transformation I found for many precursors there was a very nice presentation at CEK from Emma Palmer about this and ZM that showed that especially for those very simple molecules you can have many precursors so concentrations of individual transformation works can be much higher than you would expect this is another way to go and I think one that’s still difficult to tackle and we have where we are still exploring what’s the best way to tackle this yes absolutely and it’s also important to point out that a lot of transformation products are negative right because it goes through oxidation which can form things like caroxyic acids uh next question um from Rita Beneti thank you for your excellent work and clear presentation a lot of attention is given to the quality of purified waste water for reuse in agriculture but as also partly highlighted during your presentation less is known about the quality of water of both groundwater and especially surface water do you think this approach I mean risk assessment like you did should be applied to any type of water use agriculture i did it with wastewater here because the project was based on agricultural wastewater reuse in which we did it but if you have a close look the one of the chemicals that was near the top for this human exposure potential for wastewater reuse was again the BF4 which is also a chemical that’s present in very high concentrations in surface water so even if you use surface water for irrigation I would not expect the human exposure potential to be much lower because also in surface water we saw concentrations up to 2.6 microgram per liter so some of these high concentration PM chemicals they can also be a agriculture can also be a significant source of exposure even if you don’t use waste water if you use surface water we also had this example with TFA using waste water should would probably not have that much an influence on the TFA concentration because a lot of it is also from rain a lot of it is from metabolites from plant protection products so there are selected chemicals for which irrigation with surf with um surface water won’t make a large difference thanks and suddenly we got an explosion of questions in the Q&A so I don’t know I don’t think we’ll be able to answer all them in the next minute and a half uh some of them are from anonymous attendees but what we will do is we will if if there’s a name next to your question we will send it to Daniel and see if he’s got time to answer it if you want to increase your chances of that please repost your question uh not as anonymous but the actual person so we can get in contact with you or Daniel can with his answer um and we got okay um we a question just going ran down the list uh from Michael Noyman thanks for the great overview and your conclusion at the end how to regulate in inorganic small annions as they are excluded from the new VPBM hazard class under CLP any ideas how do we regulate those i know you’re not a regulator but you question I actually would want to reflect back to Dum as your regulator michael we should ask you that question i don’t know what’s a good way to address these chemicals we saw those two inorganic ones that really pop up again and again because they have high concentrations of course most what we look at or organic chemicals because we expect a higher potential to be toxic for them for these two inorganic chemicals we actually don’t really know the problem is those ionic liquids are often tested as salt so it can be the toxicity there is mainly dominated by the cat eye but we are not 100% sure so for these chemicals we just need to answer the question about toxicity and adverse effects I think
mhm but in general we should avoid high concentration chemicals in our plants and in our tap water no I think that’s very good and I’m looking at the time and there’s some very good questions from Evan Bolton thanks um we’ll get back to you on that and from uh Mhome maybe Yeah we’re out of time but uh so I think we tried to end these on time but I want to thank you Daniel for your excellent presentation uh it stirred up a lot of interesting conversation and your results are extremely important as we go forward um also our project towards zero pollution of persistent mobile substances so I’d like to thank you again and I’d like to thank the audience for your participation and if you’re interested in webinars like this please follow us on LinkedIn where we announce this and I’m also going to highlight we have a special workshop in Greece in October 7th to 8th on removal of persistent mobile substances so if you’re interested in talking about how to remove these from waste water from drinking water uh surface water this is the kind of workshop you need to go to it’s in Greece more info is on our LinkedIn and websites and with that we will close this webinar so I’d like to thank you on behalf of 0 p.m from me Hanssp and from Sarah Hail and thank you thanks again Daniel goodbye
thanks for having me
0 p.m zero pollution of persistent and mobile substances this project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement number 1036756 six
1 Comment
This was very good. Shame I missed it!