Publications by authors named "Peter Holm"

97 Publications

Fast peroxydisulfate oxidation of the antibiotic norfloxacin catalyzed by cyanobacterial biochar.

J Hazard Mater 2022 Jul 21;439:129655. Epub 2022 Jul 21.

Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.

Peroxydisulfate (PDS) is a common oxidant for organic contaminant remediation. PDS is typically activated by metal catalysts to generate reactive radicals. Unfortunately, as radicals are non-selective and metal catalysts may cause secondary contamination, alternative selective non-radical pathways and non-metal catalysts need attention. Here we investigated PDS oxidation of commonly detected antibiotic Norfloxacin (NOR) using cyanobacterial nitrogen rich biochars (CBs) as catalysts. NOR was fully degraded by CB pyrolysed at 950 °C (CB950) within 120 min. CB950 caused threefold faster degradation than low pyrolysis temperature (PT) CBs and achieved a maximum surface area normalized rate constant of 4.38 × 10 min m L compared to widely used metal catalysts. CB950 maintained full reactivity after four repeated uses. High defluorination (82%) and mineralization (>82%) were observed for CB950/PDS. CBs were active over a broad pH range (3-10), but with twice as high rates under alkaline compared with neutral conditions. NOR is degraded by organic, OH and SO radicals in low PT CBs/PDS systems, where the presence of Mn promotes radical generation. Electron transfer reactions with radicals supplemented dominate high PT CBs/PDS systems. This study demonstrates high PT biochars from algal bloom biomass may find use as catalysts for organic contaminant oxidation.
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http://dx.doi.org/10.1016/j.jhazmat.2022.129655DOI Listing
July 2022

Temporal patterns of multi-morbidity in 570157 ischemic heart disease patients: a nationwide cohort study.

Cardiovasc Diabetol 2022 05 31;21(1):87. Epub 2022 May 31.

Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark.

Background: Patients diagnosed with ischemic heart disease (IHD) are becoming increasingly multi-morbid, and studies designed to analyze the full spectrum are few.

Methods: Disease trajectories, defined as time-ordered series of diagnoses, were used to study the temporality of multi-morbidity. The main data source was The Danish National Patient Register (NPR) comprising 7,179,538 individuals in the period 1994-2018. Patients with a diagnosis code for IHD were included. Relative risks were used to quantify the strength of the association between diagnostic co-occurrences comprised of two diagnoses that were overrepresented in the same patients. Multiple linear regression models were then fitted to test for temporal associations among the diagnostic co-occurrences, termed length two disease trajectories. Length two disease trajectories were then used as basis for constructing disease trajectories of three diagnoses.

Results: In a cohort of 570,157 IHD disease patients, we identified 1447 length two disease trajectories and 4729 significant length three disease trajectories. These included 459 distinct diagnoses. Disease trajectories were dominated by chronic diseases and not by common, acute diseases such as pneumonia. The temporal association of atrial fibrillation (AF) and IHD differed in different IHD subpopulations. We found an association between osteoarthritis (OA) and heart failure (HF) among patients diagnosed with OA, IHD, and then HF only.

Conclusions: The sequence of diagnoses is important in characterization of multi-morbidity in IHD patients as the disease trajectories. The study provides evidence that the timing of AF in IHD marks distinct IHD subpopulations; and secondly that the association between osteoarthritis and heart failure is dependent on IHD.
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http://dx.doi.org/10.1186/s12933-022-01527-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9158400PMC
May 2022

A critical review of phytoremediation for acid mine drainage-impacted environments.

Sci Total Environ 2022 Mar 8;811:152230. Epub 2021 Dec 8.

Section for Environmental Chemistry and Physics, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1187 Frederiksberg C, Denmark; Sino-Danish Center for Education and Research, Denmark.

Acid mine drainage (AMD), a waste product of mining activities containing sulfates, iron and heavy metals, causes severe environmental degradation and pose risks to human health and sustainable development. Areas impacted by AMD are lacking remediation techniques that holistically address the ecologic, social, and economic needs of affected communities, for which phytoremediation is a promising solution. This review article introduces AMD and AMD-impacted environments and critically discusses phytomanagement, phytoprotection, and phytorestoration approaches towards AMD-impacted environments. Continued research and application of such approaches will help optimize resource and revenue-generating potentials, address biodiversity loss and carbon storage concerns of climate change, and promote sustainable agricultural management. With a focus on energy crops, phytomining critical elements, carbon storage, co-cropping, allelopathy, and ecosystem restoration, this review examines phytoremediation research that addresses positive economic and environmental opportunities for AMD-impacted environments.
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http://dx.doi.org/10.1016/j.scitotenv.2021.152230DOI Listing
March 2022

Fomepizole dosing during continuous renal replacement therapy - an observational study.

Clin Toxicol (Phila) 2022 Apr 29;60(4):451-457. Epub 2021 Sep 29.

Norwegian National Unit for CBRNE Medicine, Department of Acute Medicine, Oslo University Hospital, Oslo, Norway.

Background: Fomepizole is the preferred antidote for treatment of methanol and ethylene glycol poisoning, acting by inhibiting the formation of the toxic metabolites. Although very effective, the price is high and the availability is limited. Its availability is further challenged in situations with mass poisonings. Therefore, a 50% reduced maintenance dose for fomepizole during continuous renal replacement therapy (CRRT) was suggested in 2016, based on pharmacokinetic data only. Our aim was to study whether this new dosing for fomepizole during CRRT gave plasma concentrations above the required 10 µmol/L. Secondly, we wanted to study the elimination kinetics of fomepizole during CRRT, which has never been studied before.

Methods: Prospective observational study of adult patients treated with fomepizole and CRRT. We collected samples from arterial line (pre-filter) = plasma concentration, post-filter and dialysate for fomepizole measurements. Fomepizole was measured using high-pressure liquid chromatography with a reverse phase column.

Results: Ten patients were included in the study. Seven were treated with continuous veno-venous hemodialysis (CVVHD) and three with continuous veno-venous hemodiafiltration (CVVHDF). Ninety-eight percent of the plasma samples were above the minimum plasma concentration of 10 µmol/L. Fomepizole was removed during CRRT with a median saturation/sieving coefficient of 0.85 and dialysis clearance of 28 mL/min.

Conclusion: Fomepizole was eliminated during CCRT. The new dosing recommendations for fomepizole and CRRT appeared safe, by maintaining the plasma concentration above the minimum value of 10 µmol/L. Based on these data, the fomepizole maintenance dose during CRRT could be reduced to half as compared to intermittent hemodialysis.
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http://dx.doi.org/10.1080/15563650.2021.1980581DOI Listing
April 2022

Quantitative source apportionment, risk assessment and distribution of heavy metals in agricultural soils from southern Shandong Peninsula of China.

Sci Total Environ 2021 May 28;767:144879. Epub 2021 Jan 28.

Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address:

The heavy metals, including cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), zinc (Zn), and the metalloid arsenic (As) were detected in surface and core soil samples collected from a tobacco growing region in Shandong Peninsula on the east coast of China to evaluate their pollution levels, ecological and health risks, and to analyze their spatial and vertical distributions. The heavy metal sources were identified quantitatively using the positive matrix factorization (PMF) receptor model. In accordance, most of the soils did not have accumulations and were not contaminated by As, Cr, Cu, Ni, Pb, and Zn. High accumulations of Cd and Hg occurred in the soils, posing an ecological risk to the local agricultural environment, while Cr and Ni levels presented a carcinogenic health risk to humans. Four main sources of heavy metals in the soils were identified. Correspondingly Ni and Cr were mainly originated from natural sources, Hg from coal combustion, Cd from agricultural practices, Cu, Pb, and Zn from agricultural practices and industrial activities, and As from industrial activities.
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http://dx.doi.org/10.1016/j.scitotenv.2020.144879DOI Listing
May 2021

Rare earth elements in surface specific urban runoff in Northern Beijing.

Sci Total Environ 2020 May 30;717:136969. Epub 2020 Jan 30.

Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark; Sino Danish Center for Education and Research (SDC), China.

Rare earth elements (REEs) have been increasingly diffused to the environment through mining activities and the extensive use in modern commodities, vehicular activities, coal burning and various environmental and agricultural applications. Studies of REEs in urban environments are limited with no data on REEs in urban runoff. To investigate the concentration and distribution of REEs, a total of 150 runoff samples were collected from trafficked areas, rooftops and residential parking lots in a moderate to densely populated area in Beijing, China. The runoff samples were separated into dissolved and particulate phases and analyzed by ICP-MS. The REEs were mainly (>80%) found in the runoff particulate material. The sum of REEs (ΣREE) total concentrations in urban stormwater runoff samples ranged from 0.16 to 185 μg/l. The observed mean total concentration of ΣREE in the runoff samples were 3-14 folds higher and dissolved fractions 1.5 to 6 times higher than published concentrations for recipients such as sewage channels and rivers. The distribution of REEs in runoff was dominated by light REE. Cluster analysis and Pearson's correlations revealed a strong association between the individual REEs pointing to a similar source. Higher Ce concentrations compared to other REEs indicated strong influence from traffic emission particulates. The La/Sm (5.90-8.05), La/Ce (0.53-0.58) and Ce/Yb (31.0-42.7) ratios pointed to REE sources from traffic emissions and coal burning thus defining an urban fingerprint.
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http://dx.doi.org/10.1016/j.scitotenv.2020.136969DOI Listing
May 2020

Population projections of an endangered cactus suggest little impact of climate change.

Oecologia 2020 Feb 14;192(2):439-448. Epub 2020 Jan 14.

Organ Pipe Cactus National Monument, National Park Service, Ajo, AZ, USA.

Population projections coupled with downscaled climate projections are a powerful tool that allows predicting future population dynamics of vulnerable plants in the face of a changing climate. Traditional approaches used to predict the vulnerability of plants to climate change (e.g. species distribution models) fail to mechanistically describe the basis of a population's dynamics and thus cannot be expected to correctly predict its temporal trends. In this study, we used a 23-year demographic dataset of the acuña cactus, an endangered species, to predict its population dynamics to the end of the century. We used integral projection models to describe its vital rates and population dynamics in relation to plant volume and key climatic variables. We used the resulting climate-driven IPM along with climatic projections to predict the population growth rates from 1991 to 2099. We found the average population growth rate of this population between 1991 and 2013 to be 0.70 (95% CI 0.61-0.79). This result confirms that the population of acuña cactus has been declining and that this decline is due to demographic structure and climate conditions. However, the projection model also predicts that, up to 2080, the population will remain relatively stable mainly due to the survival of its existing adult individuals. Notwithstanding, the long-term viability of the populations can only be achieved through the recruitment of new individuals.
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http://dx.doi.org/10.1007/s00442-020-04595-yDOI Listing
February 2020

Linking glycemic dysregulation in diabetes to symptoms, comorbidities, and genetics through EHR data mining.

Elife 2019 12 10;8. Epub 2019 Dec 10.

Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark.

Diabetes is a diverse and complex disease, with considerable variation in phenotypic manifestation and severity. This variation hampers the study of etiological differences and reduces the statistical power of analyses of associations to genetics, treatment outcomes, and complications. We address these issues through deep, fine-grained phenotypic stratification of a diabetes cohort. Text mining the electronic health records of 14,017 patients, we matched two controlled vocabularies (ICD-10 and a custom vocabulary developed at the clinical center Steno Diabetes Center Copenhagen) to clinical narratives spanning a 19 year period. The two matched vocabularies comprise over 20,000 medical terms describing symptoms, other diagnoses, and lifestyle factors. The cohort is genetically homogeneous (Caucasian diabetes patients from Denmark) so the resulting stratification is not driven by ethnic differences, but rather by inherently dissimilar progression patterns and lifestyle related risk factors. Using unsupervised Markov clustering, we defined 71 clusters of at least 50 individuals within the diabetes spectrum. The clusters display both distinct and shared longitudinal glycemic dysregulation patterns, temporal co-occurrences of comorbidities, and associations to single nucleotide polymorphisms in or near genes relevant for diabetes comorbidities.
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http://dx.doi.org/10.7554/eLife.44941DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6904221PMC
December 2019

Preparation of a silicon-iron amendment from acid-extracted copper tailings for remediating multi-metal-contaminated soils.

Environ Pollut 2020 Feb 4;257:113565. Epub 2019 Nov 4.

Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark; Sino-Danish Center for Education and Research, Beijing 100190, China.

Industrial by-products provide materials for remediation measures. In this study, a silicon-iron amendment was prepared from residue originating from acid-extracted copper (Cu) tailings based on thermal activation at temperatures ranging from 550 °C to 1150 °C for 30 min with the use of additives (CaO, NaCO, NaOH). The remediation performance of the amendment was evaluated through soil incubation and greenhouse pot experiments with vetiver (Vetiveria zizanioides). The results showed that the highest levels of soluble Si (6.11% of the total Si) and Fe (2.3% of the total Fe) in the amendment were achieved with thermal activation at 1150 °C for 30 min using an optimal ratio between residue and additives (residue: CaO: NaCO: NaOH = 1: 0.4: 0.4: 0.2). Heavy metal release indicated that the amendment could be safely used for soil remediation. The incubation experiments showed that the DTPA-extractable Cd, Cr and Pb in contaminated soils decreased with increasing amendment rate, which was not observed for As. The amendment-induced decrease in the Cd, Cr and Pb availability in contaminated soils could be explained by pH-change induced immobilization, Fe-induced chemisorption, Si-induced co-precipitation, and Ca-induced ion exchange. Correlation analysis suggested that there were significant negative correlations between DTPA-extractable Cd, Cr and Pb and the pH, Fe, Si, and Ca in soil pore water and soil. The most suitable amendment rate was determined to be 1% by balancing the efficacy and wise utilization of the amendment. The pot experiment demonstrated that the amendment promoted the vetiver growth and stimulated the accumulation of Cd and Cr in the roots. The amendment was proved to be promising for the phytostabilization of Cd, Cr and Pb in contaminated soils. Further investigations are required to determine whether the amendment is a tool for the long-term remediation of multi-metal-contaminated soils at the field scale.
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http://dx.doi.org/10.1016/j.envpol.2019.113565DOI Listing
February 2020

Improving folding properties of computationally designed proteins.

Protein Eng Des Sel 2019 12;32(3):145-151

The Linderstrøm-Lang Centre for Protein Science, Section for Biomolecular Sciences, Department of Biology, University for Copenhagen, Ole Maaloes Vej 5, DK-2200 Copenhagen N, Denmark.

While the field of computational protein design has witnessed amazing progression in recent years, folding properties still constitute a significant barrier towards designing new and larger proteins. In order to assess and improve folding properties of designed proteins, we have developed a genetics-based folding assay and selection system based on the essential enzyme, orotate phosphoribosyl transferase from Escherichia coli. This system allows for both screening of candidate designs with good folding properties and genetic selection of improved designs. Thus, we identified single amino acid substitutions in two failed designs that rescued poorly folding and unstable proteins. Furthermore, when these substitutions were transferred into a well-structured design featuring a complex folding profile, the resulting protein exhibited native-like cooperative folding with significantly improved stability. In protein design, a single amino acid can make the difference between folding and misfolding, and this approach provides a useful new platform to identify and improve candidate designs.
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http://dx.doi.org/10.1093/protein/gzz025DOI Listing
December 2019

Influence of CaO-activated silicon-based slag amendment on the growth and heavy metal uptake of vetiver grass (Vetiveria zizanioides) grown in multi-metal-contaminated soils.

Environ Sci Pollut Res Int 2019 Nov 9;26(31):32243-32254. Epub 2019 Sep 9.

Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg, Denmark.

Few plant species used for revegetation grow well in multi-metal-contaminated soils. Vetiver grass (Vetiveria zizanioides) is known to be tolerant of heavy metals. Vetiver has been reported to be effective for revegetation and heavy metal phytoextraction by applying targeted amendments due to its large biomass. In this study, a greenhouse vetiver pot experiment and soil incubation were performed to investigate the growth and Cd, Cr, Cu, Pb, and Zn uptake of vetiver grown in multi-metal-contaminated soils treated with a CaO-activated Si-based slag amendment (0, 0.5, 1.0, and 2.0% w/w). The results showed that the effects of slag amendment on plant growth and heavy metal uptake and distribution were dependent on the amendment dosages and metal species. Although vetiver could grow in contaminated soils, its growth was obviously inhibited. The slag amendment enhanced the vetiver growth and the highest biomass (2.62-fold over the control) was determined at a 1.0% amendment rate. The slag amendment improved plant growth by alleviating the toxicity of heavy metals in plants. This result was mainly attributed to the increases in soil pH and citric acid-extractable Si caused by alkaline amendment. The results suggest that vetiver can be applied to remediate multi-metal-contaminated soils in conjunction with the application of CaO-activated Si-based slag amendment.
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http://dx.doi.org/10.1007/s11356-019-06429-8DOI Listing
November 2019

Urban Allotment Gardens for the Biomonitoring of Atmospheric Trace Element Pollution.

J Environ Qual 2019 Mar;48(2):518-525

This study evaluates the results of the characterization of air pollution in urban green areas using edible plants. To this purpose, we examined the effect of location (i.e., three different levels of pollution), substrate (peat moss and vermiculite), and plant species (oilseed rape [ L.] and kale [ L.]) on the accumulation of trace elements on leaves. A total of 36 samples of unwashed leaves were digested with HNO-HO and analyzed for 27 elements by inductively coupled plasma mass spectrometry. Considering the location, plants exposed next to the road showed higher contents of traffic-related elements, and additionally, outdoors samples were enriched in marine aerosol ions. Cadmium and Pb concentrations did not exceed the European legal maximum levels for vegetables, so their consumption would be safe for human health. Results support the hypothesis that edible plants such as kale and rapeseed could be used as bioindicators of atmospheric pollution.
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http://dx.doi.org/10.2134/jeq2018.06.0232DOI Listing
March 2019

Metals in surface specific urban runoff in Beijing.

Environ Pollut 2019 May 22;248:584-598. Epub 2019 Feb 22.

Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark; Sino-Danish Center for Education and Research (SDC), China. Electronic address:

Metals are among the most toxic pollutants in urban stormwater. To investigate the concentration of dissolved and particulate fractions, the temporal variation during rain events, the effect of wash-off surface, and to assess the pollution status of metals in urban runoff, a total of 155 samples were collected mainly from trafficked areas, roofs and parking lots in Beijing from March to November 2015. Most of the metals were found mainly in the particulate fraction (68-96%) from trafficked surfaces, while for roof runoff Cd, Fe, Mn and Zn were found more equally in dissolved and particulate fractions. Metal concentrations were higher during start of a rain event than later (p < 0.05), and also were higher the longer the period of antecedent dry days. The mean concentration of all metals in trafficked areas exceeded both the Chinese standard Level III (swimming and fishery waters) and the European standards (surface water). Mean concentrations of Cd, Mn, Zn, Al, Fe, Pb and Ni from trafficked areas were 2-10 times higher due to higher traffic intensity and substantial atmospheric deposition, while Sb was 20 times higher than in any other reported data for urban runoff. Cluster analysis (CA) and principal component analysis (PCA) together with Pearson's correlation co-efficient suggested that Cd, Cr, Cu, Mn, Ni, Pb, and Zn mainly originates from vehicular activities, while Mn and Zn in roof runoff is due to atmospheric deposition. The geo-accumulation and pollution indices show that runoff from trafficked areas are moderately to heavily polluted by most metals, except Cu and Zn. Thus, Beijing urban runoff presents an environmental risk towards lakes, bathing water and drinking water. The results can be used as basis for development of stormwater and pollution control strategies.
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http://dx.doi.org/10.1016/j.envpol.2019.02.039DOI Listing
May 2019

Evaluation of pH-Dependent Metal Speciation Artifacts in Whole-Cell Bioreporter Analysis.

J Environ Qual 2019 01;48(1):199-204

Whole-cell bacterial biosensors (bioreporters) are commonly applied for determination of metal toxicity and bioavailability in environmental samples. This is accomplished using a standard procedure whereby the sample is mixed with bioreporter cells suspended in a buffered medium at a fixed pH (set-point pH assay). This experimental approach can alter the sample pH. We therefore hypothesized that metal speciation artifacts compromising our ability to use bioreporters for determination of the "true" metal bioavailability in environmental samples may be introduced. Using the copper-specific bioreporter DF57-Cu15 as a model, we compared the conventional set-point pH assay to a flexible pH assay allowing for bioavailability determination at in situ sample pH. Our results demonstrate that pH-dependent metal speciation bias may occur when using the conventional set-point pH assay, and we recommend performing bioreporter measurements and calibrations at in situ sample pH. Although we only studied copper bioavailability, our results also have implications for bioreporter determination of other analytes displaying pH-dependent speciation such as other metals and some organics. We call for additional bioreporter studies of chemical speciation artifacts as this represents a problem hitherto overlooked in bioreporter literature. We thus conclude that there may be considerable scope for optimization of existing bioreporter assays for assessment of environmental pollutant bioavailability.
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http://dx.doi.org/10.2134/jeq2018.10.0352DOI Listing
January 2019

Long-term soil metal exposure impaired temporal variation in microbial metatranscriptomes and enriched active phages.

Microbiome 2018 12 13;6(1):223. Epub 2018 Dec 13.

Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark.

Background: It remains unclear whether adaptation and changes in diversity associated to a long-term perturbation are sufficient to ensure functional resilience of soil microbial communities. We used RNA-based approaches (16S rRNA gene transcript amplicon coupled to shotgun mRNA sequencing) to study the legacy effects of a century-long soil copper (Cu) pollution on microbial activity and composition, as well as its effect on the capacity of the microbial community to react to temporal fluctuations.

Results: Despite evidence of microbial adaptation (e.g., iron homeostasis and avoidance/resistance strategies), increased heterogeneity and richness loss in transcribed gene pools were observed with increasing soil Cu, together with an unexpected predominance of phage mRNA signatures. Apparently, phage activation was either triggered directly by Cu, or indirectly via enhanced expression of DNA repair/SOS response systems in Cu-exposed bacteria. Even though total soil carbon and nitrogen had accumulated with increasing Cu, a reduction in temporally induced mRNA functions was observed. Microbial temporal response groups (TRGs, groups of microbes with a specific temporal response) were heavily affected by Cu, both in abundance and phylogenetic composition.

Conclusion: Altogether, results point toward a Cu-mediated "decoupling" between environmental fluctuations and microbial activity, where Cu-exposed microbes stopped fulfilling their expected contributions to soil functioning relative to the control. Nevertheless, some functions remained active in February despite Cu, concomitant with an increase in phage mRNA signatures, highlighting that somehow, microbial activity is still happening under these adverse conditions.
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http://dx.doi.org/10.1186/s40168-018-0606-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6292020PMC
December 2018

Assessment of biochar and zero-valent iron for in-situ remediation of chromated copper arsenate contaminated soil.

Sci Total Environ 2019 Mar 14;655:414-422. Epub 2018 Nov 14.

Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark. Electronic address:

Chromated copper arsenates (CCA) have been extensively used as wood impregnation agents in Europe and North America. Today, CCA contaminated sites remain abundant and pose environmental risks that need to be properly managed. Using a TRIAD approach that combined chemical, ecotoxicological and ecological assessment of soil quality, we investigated the abilities of biochar and zero-valent iron (ZVI) to remediate CCA contaminated soil in a microcosm experiment. Soil samples from a highly contaminated CCA site (1364, 1662 and 540 μg g of As, Cu and Cr, respectively) were treated with two different biochars (fine and coarse particle size; 1% w w) and ZVI (5% w w), both as sole and as combined treatments, and incubated for 56 days at 15 °C. In general, bioavailable As (As) and Cu (Cu) determined by whole-cell bacterial bioreporters corresponded well to water-extractable As and Cu (As and Cu). However, in biochar treatments, only Cu and not Cu was significantly reduced. In contrast, under ZVI treatments only Cu and not Cu was reduced, demonstrating the value of complementing analytical with bacterial bioreporter measurements to infer bioavailability of elements to soil microorganisms. The combined fine particle size biochar and ZVI treatment effectively reduced water extractable concentrations of Cr, Cu, and As on site by 45%, 45% and 43% respectively, and led to the highest ecological recovery of the soil bacterial community, as measured using the [H]leucine incorporation technique. We conclude that the combined application of biochar and ZVI as soil amendments holds promise for in-situ stabilization of CCA contaminated sites.
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http://dx.doi.org/10.1016/j.scitotenv.2018.11.193DOI Listing
March 2019

Factors governing the solid phase distribution of Cr, Cu and As in contaminated soil after 40 years of ageing.

Sci Total Environ 2019 Feb 18;652:744-754. Epub 2018 Oct 18.

British Geological Survey, Keyworth, Nottingham NG12 5GG, UK.

The physico-chemical factors affecting the distribution, behavior and speciation of chromium (Cr), copper (Cu) and arsenic (As) was investigated at a former wood impregnation site (Fredensborg, Denmark). Forty soil samples were collected and extracted using a sequential extraction technique known as the Chemometric Identification of Substrates and Element Distributions (CISED) and a multivariate statistical tool (redundancy analysis) was applied. CISED data was linked to water-extractable Cr, Cu and As and bioavailable Cu as determined by a whole-cell bacterial bioreporter assay. Results showed that soil pH significantly affected the solid phase distribution of all three elements on site. Additionally, elements competing for binding sites, Ca, Mg and Mn in the case of Cu, and P, in the case of As, played a major role in the distribution of these elements in soil. Element-specific distributions were observed amongst the six identified soil phases including residual pore salts, exchangeable, carbonates (tentative designation), Mn-Al oxide, amorphous Fe oxide, and crystalline Fe oxide. While Cr was strongly bound to non-extractable crystalline Fe oxide in the oxic top soil, Cu and notably, As were associated with readily extractable phases, suggesting that Cu and As, and not Cr, constitute the highest risk to environmental and human health. However, bioavailable Cu did not significantly correlate with CISED identified soil phases, suggesting that sequential extraction schemes such as CISED may not be ideally suited for inferring bioavailability to microorganisms in soil and supports the integration of receptor-specific bioavailability tests into risk assessments as a complement to chemical methods.
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http://dx.doi.org/10.1016/j.scitotenv.2018.10.244DOI Listing
February 2019

Soil threshold values for cadmium based on paired soil-vegetable content analyses of greenhouse vegetable production systems in China: Implications for safe food production.

Environ Pollut 2018 Oct 17;241:922-929. Epub 2018 Jun 17.

University of Copenhagen, Faculty of Science, Department of Plant and Environmental Sciences, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark; Sino-Danish Center for Education and Research (SDC), China.

Greenhouse vegetable production (GVP) is the major type of vegetable production in China. However, dietary exposure of heavy metals through vegetable consumption has been identified as a potential risk to human health. To ensure safety of vegetables, soil threshold values (STVs) of cadmium (Cd) in GVP systems were assessed based on analysis of soil-vegetable Cd contents in relation to human health risk. Contents of Cd were determined in 324 sampled soil-vegetable pairs from five GVP systems in three Chinese provinces. Soil Cd contents ranged from 0.07 to 1.32 mg kg, with 17.9% of sampled soils exceeding current Chinese threshold values. Vegetable Cd contents ranged from 0.0003 to 0.546 mg kg, with 8.6% exceeding permissible maxima. Vegetable type and soil pH significantly affected Cd transfer from soil to vegetable with lower transfer at neutral (6.5 < pH ≤ 7.5) to alkaline (pH > 7.5) soils and uptake decreasing in the order: Leafy > rootstalk > fruit. Consequently, both soil pH and vegetable type should be taken into consideration as suggested when revising current STVs for Cd in GVP systems in order to capture the health risk correctly and ensure safe vegetable consumption.
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http://dx.doi.org/10.1016/j.envpol.2018.06.034DOI Listing
October 2018

Source identification of heavy metals in peri-urban agricultural soils of southeast China: An integrated approach.

Environ Pollut 2018 Jun 15;237:650-661. Epub 2018 Mar 15.

University of Copenhagen, Faculty of Science, Department of Plant and Environmental Sciences, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark; Sino-Danish Center for Education and Research (SDC), China.

Intensive human activities, in particular agricultural and industrial production have led to heavy metal accumulation in the peri-urban agricultural soils of China threatening soil environmental quality and agricultural product security. A combination of spatial analysis (SA), Pb isotope ratio analysis (IRA), input fluxes analysis (IFA), and positive matrix factorization (PMF) model was successfully used to assess the status and sources of heavy metals in typical peri-urban agricultural soils from a rapidly developing region of China. Mean concentrations of Cd, As, Hg, Pb, Cu, Zn and Cr in surface soils (0-20 cm) were 0.31, 11.2, 0.08, 35.6, 44.8, 119.0 and 97.0 mg kg, respectively, exceeding the local background levels except for Hg. Spatial distribution of heavy metals revealed that agricultural activities have significant influence on heavy metal accumulation in the surface soils. Isotope ratio analysis suggested that fertilization along with atmospheric deposition were the major sources of heavy metal accumulation in the soils. Based on the PMF model, the relative contribution rates of the heavy metals due to fertilizer application, atmospheric deposition, industrial emission, and soil parent materials were 30.8%, 33.0%, 25.4% and 10.8%, respectively, demonstrating that anthropogenic activities had significantly higher contribution than natural sources. This study provides a reliable and robust approach for heavy metals source apportionment in this particular peri-urban area with a clear potential for future application in other regions.
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http://dx.doi.org/10.1016/j.envpol.2018.02.070DOI Listing
June 2018

DGT technique to assess P mobilization from greenhouse vegetable soils in China: A novel approach.

Sci Total Environ 2018 Jul 23;630:331-339. Epub 2018 Feb 23.

Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark; Sino-Danish Center for Education and Research (SDC). Electronic address:

Intensive phosphorus (P) inputs to plastic-covered greenhouse vegetable production (PGVP) in China has led to excessive soil P accumulation increasing the potential for leaching to surface waters. This study examined the mobility and hence the potential risk of P losses through correlations between soil solution P (P) and soil extractable P as determined by conventional soil P test methods (STPs) including degree of P saturations (DPSs), and diffusive gradient in thin-films (DGT P) technique. A total of 75 topsoil samples were chosen from five representative Chinese PGVPs covering a wide range of physiochemical soil properties and cultivation history. Total P and Olsen P contents varied from 260 to 4900, and 5 to 740mgkg, respectively, while P concentrations were between 0.01 and 10.8mgL reflecting the large differences in vegetation history, fertilization schemes, and soil types. Overall, DGT P provided the best correlation with P (r=0.97) demonstrating that DGT P is a versatile measure of P mobility regardless of soil type. Among the DPSs tested, oxalate extractable Al (DPS) had the best correlation with P (r=0.87). In the STP versus P relationships, STP break-points above which P mobilization increases steeply were 513μgL and 190mgkg for DGT P or Olsen P, respectively, corresponding to P concentration of 0.88mgL. However, for P concentration of 0.1mgL that initiates eutrophication, the corresponding DGT P and Olsen P values were 27μgL and 22mgkg, respectively. Over 80% of the investigated soils had DGT P and Olsen P above these values, and thus are at risk of P mobilization threatening receiving waters by eutrophication. This paper demonstrates that the DGT extracted P is a powerful measure for soluble P and hence for assessment of P mobility from a broad range of soil types.
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http://dx.doi.org/10.1016/j.scitotenv.2018.02.228DOI Listing
July 2018

Interaction mechanisms between polycyclic aromatic hydrocarbons (PAHs) and organic soil washing agents.

Environ Sci Pollut Res Int 2018 Jan 15;25(1):299-311. Epub 2017 Oct 15.

Department of Plant and Environmental Sciences Faculty of Science, University of Copenhagen, Copenhagen, Denmark.

Understanding interaction mechanisms between polycyclic aromatic hydrocarbons (PAHs) and soil-washing agents can help in choosing efficient agents which are able to desorb and solubilize PAHs. This study investigated interaction mechanisms between pyrene and four washing agents including: two dissolved organic matters (DOM) F-DOM and CRC-DOM, and two commercial bio-based surfactants BBE-1000 and Supersolv using fluorescence spectroscopy combined with multivariate curve resolution alternating regression (MCR-AR). The efficiencies of these washing agents in removing PAHs from the soil were tested in a soil washing experiment. Pyrene showed π-π interactions with F-DOM and no interaction with CRC-DOM. This could be attributed to the more aromatic structures in F-DOM compared to CRC-DOM. The two DOMs were inefficient in soil washing which might be attributed to the relatively weak effect of π-π interactions in releasing PAHs from the soil. Interaction mechanisms between pyrene and the bio-based surfactants were elucidated with MCR-AR, which resolved three spectroscopically active species from pyrene emission spectra as a function of pyrene and bio-based surfactants concentrations. These species resembled pyrene emission in a polar and nonpolar microenvironment, respectively and of an excimer. Concentration profiles retrieved by the model for the three species showed that, below the critical micelle concentration (CMC), Supersolv created more nonpolar interactions with pyrene compared to BBE-1000. In soil washing, Supersolv showed the highest efficiency in extracting PAHs from the soil. This highlighted the importance of nonpolar interactions in desorbing PAHs from soils, which could then be solubilized in micelles. This study demonstrated the potential of fluorescence spectroscopy combined with the MCR-AR model for selecting efficient soil-washing agents.
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http://dx.doi.org/10.1007/s11356-017-0374-7DOI Listing
January 2018

Corrigendum to "Phosphorus saturation and mobilization in two typical Chinese greenhouse vegetable soils" [Chemosphere 172 (2017) 316-324].

Chemosphere 2017 11 31;187:440-441. Epub 2017 Aug 31.

Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark; Sino-Danish Center for Education and Research (SDC), China. Electronic address:

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http://dx.doi.org/10.1016/j.chemosphere.2017.08.081DOI Listing
November 2017

Heavy Metal Leaching as Affected by Long-Time Organic Waste Fertilizer Application.

J Environ Qual 2017 Jul;46(4):871-878

The recycling of urban waste products as fertilizers in agriculture may introduce contaminants such as heavy metals into soil that may leach and contaminate groundwater. In the present study, we investigated the leaching of heavy metals from intact soil cores collected in the long-term agricultural field trial CRUCIAL. At the time of sampling, the equivalent of >100 yr of urban waste fertilizers following Danish legislation had been applied. The leaching of Cu was significantly increased in the treatments receiving organic waste products compared with the unfertilized control but remained below the permissible level following Danish drinking water guidelines. The leaching of Cu was controlled primarily by the topsoil Cu content and by the leaching of dissolved organic carbon (DOC) but at the same time significantly correlated with leaching of colloids in soils that had not received fertilizer or had received an organic fertilizer with a low concentration of Cu. The leaching of Zn, Cd, and Co was not significantly increased in urban waste-fertilized treatments. The leaching of Mo was elevated in accelerated waste treatments (both agricultural and urban), and the leaching of Mo was linked to the leaching of DOC. Since leaching of Cr and Pb was strongly linked to the level of colloid leaching, leaching of these metals was reduced in the urban waste treatments. Overall, the results presented should not raise concern regarding the agricultural use of urban waste products in agriculture as long as the relevant guidelines are followed.
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http://dx.doi.org/10.2134/jeq2016.11.0458DOI Listing
July 2017

Long-term changes in abundances of Sonoran Desert lizards reveal complex responses to climatic variation.

Glob Chang Biol 2017 12 17;23(12):5492-5508. Epub 2017 Aug 17.

National Park Service, Organ Pipe Cactus National Monument, Ajo, AZ, USA.

Understanding how climatic variation affects animal populations and communities is essential for addressing threats posed by climate change, especially in systems where impacts are projected to be high. We evaluated abundance dynamics of five common species of diurnal lizards over 25 years in a Sonoran Desert transition zone where precipitation decreased and temperature increased across time, and assessed hypotheses for the influence of climatic flux on spatiotemporal variation in abundances. We repeatedly surveyed lizards in spring and summer of each year at up to 32 sites, and used hierarchical mixture models to estimate detection probabilities, abundances, and population growth rates. Among terrestrial species, abundances of a short-lived, winter-spring breeder increased markedly by an estimated 237%-285% across time, while two larger spring-summer breeders with higher thermal preferences declined by up to 64%. Abundances of two arboreal species that occupy shaded and thus sheltered microhabitats fluctuated but did not decline systematically. Abundances of all species increased with precipitation at short lag times (1-1.5 years) likely due to enhanced food availability, but often declined after periods of high precipitation at longer lag times (2-4 years) likely due to predation and other biotic pressures. Although rising maximum daily temperatures (T ) are expected to drive global declines of lizards, associations with T were variable and weak for most species. Instead, abundances of all species declined with rising daily minimum temperatures, suggesting degradation of cool refugia imposed widespread metabolic or other costs. Our results suggest climate warming and drying are having major impacts on lizard communities by driving declines in species with traits that augment exposure to abiotic extremes and by modifying species interactions. The complexity of patterns we report indicates that evaluating and responding to the influence of climate change on biodiversity must consider a broad array of ecological processes.
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http://dx.doi.org/10.1111/gcb.13813DOI Listing
December 2017

Method for assessment of stormwater treatment facilities - Synthetic road runoff addition including micro-pollutants and tracer.

J Environ Manage 2017 Aug 23;198(Pt 2):107-117. Epub 2017 May 23.

Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark.

Stormwater treatment facilities (STFs) are becoming increasingly widespread but knowledge on their performance is limited. This is due to difficulties in obtaining representative samples during storm events and documenting removal of the broad range of contaminants found in stormwater runoff. This paper presents a method to evaluate STFs by addition of synthetic runoff with representative concentrations of contaminant species, including the use of tracer for correction of removal rates for losses not caused by the STF. A list of organic and inorganic contaminant species, including trace elements representative of runoff from roads is suggested, as well as relevant concentration ranges. The method was used for adding contaminants to three different STFs including a curbstone extension with filter soil, a dual porosity filter, and six different permeable pavements. Evaluation of the method showed that it is possible to add a well-defined mixture of contaminants despite different field conditions by having a flexibly system, mixing different stock-solutions on site, and use bromide tracer for correction of outlet concentrations. Bromide recovery ranged from only 12% in one of the permeable pavements to 97% in the dual porosity filter, stressing the importance of including a conservative tracer for correction of contaminant retention values. The method is considered useful in future treatment performance testing of STFs. The observed performance of the STFs is presented in coming papers.
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http://dx.doi.org/10.1016/j.jenvman.2017.04.097DOI Listing
August 2017

Comparison of Metals and Tetracycline as Selective Agents for Development of Tetracycline Resistant Bacterial Communities in Agricultural Soil.

Environ Sci Technol 2017 03 23;51(5):3040-3047. Epub 2017 Feb 23.

Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen , Thorvaldsensvej 40, 1871 Frederiksberg, Denmark.

Environmental selection of antibiotic resistance may be caused by either antibiotic residues or coselecting agents. Using a strictly controlled experimental design, we compared the ability of metals (Cu or Zn) and tetracycline to (co)select for tetracycline resistance in bacterial communities. Soil microcosms were established by amending agricultural soil with known levels of Cu, Zn, or tetracycline known to represent commonly used metals and antibiotics for pig farming. Soil bacterial growth dynamics and bacterial community-level tetracycline resistance were determined using the [H]leucine incorporation technique, whereas soil Cu, Zn, and tetracycline exposure were quantified by a panel of whole-cell bacterial bioreporters. Tetracycline resistance increased significantly in soils containing environmentally relevant levels of Cu (≥365 mg kg) and Zn (≥264 mg kg) but not in soil spiked with unrealistically high levels of tetracycline (up to 100 mg kg). These observations were consistent with bioreporter data showing that metals remained bioavailable, whereas tetracycline was only transiently bioavailable. Community-level tetracycline resistance was correlated to the initial toxicant-induced inhibition of bacterial growth. In conclusion, our study demonstrates that toxic metals in some cases may exert a stronger selection pressure for environmental selection of resistance to an antibiotic than the specific antibiotic itself.
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http://dx.doi.org/10.1021/acs.est.6b05342DOI Listing
March 2017

Phosphorus saturation and mobilization in two typical Chinese greenhouse vegetable soils.

Chemosphere 2017 Apr 30;172:316-324. Epub 2016 Dec 30.

Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark; Sino-Danish Center for Education and Research (SDC), China. Electronic address:

Chinese greenhouse vegetable production can cause eutrophication of fresh waters due to heavy use of fertilizers. To address this, phosphorus (P) leaching was compared between two major greenhouse vegetable soils from Jiangsu Province, Southeast China: clayey and acid-neutral Guli Orthic Anthrosols and sandy and alkaline Tongshan Ustic Cambosols. A total of 20 intact soil columns were collected based on differences in total P content varying between 1360 and 11,220 mg kg. Overall, six leaching experiments were carried out with collection of leachates over 24 h. Very high P concentrations, with a mean of 3.43 mg L, were found in the leachates from P rich Tongshan soils. In contrast, P leaching from fine-textured but less P rich Guli soils rarely exceeded the suggested environmental P threshold of 0.1 mg L. Strong linear correlations were found between different soil test P measures (STPs) or degree of P saturations (DPSs) and dissolved reactive P (DRP) for Tongshan soil columns. The correlations with Olsen P (r = 0.91) and DPS based on MehlichIII extractable calcium (DPS) (r = 0.87) were the most promising. An Olsen P value above 41 mg kg or a DPS above 3.44% led to DRP leaching exceeding 0.1 mg L. Accordingly, more than 80% of Tongshan soils resulted in DRP leaching exceeding the environmental P threshold. In conclusion P rich alkaline sandy soils used for greenhouse vegetable production are at high risk of P mobilization across China.
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http://dx.doi.org/10.1016/j.chemosphere.2016.12.147DOI Listing
April 2017

China's Soil Pollution Control: Choices and Challenges.

Environ Sci Technol 2016 12 8;50(24):13181-13183. Epub 2016 Dec 8.

Department of Plant and Environmental Sciences, University of Copenhagen and Sino-Danish Centre for Education and Research (SDC) , Copenhagen, Denmark.

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http://dx.doi.org/10.1021/acs.est.6b05068DOI Listing
December 2016

Diffusive Gradients in Thin Films as a Reference Method for Assessing Soil Phosphorus by Visual and Near-Infrared Spectroscopy.

J Environ Qual 2016 Nov;45(6):2060-2066

Phosphorus (P) deficiency is a severe challenge in many agricultural areas around the globe, while at the same time, aquatic environments are threatened by leaching and runoff of excess P in other areas. Accurate, cheap, and rapid assessment of crop P needs and risk of P loss is therefore necessary to optimize the use of P fertilizer worldwide. The purpose of this study was to develop a method to predict soil P concentrations by visual and near-infrared spectroscopy using reference P concentrations determined by diffusive gradients in thin films (DGT); Olsen P results were included for comparison. The study was conducted on paddy soils from six main rice-producing ( L.) provinces in southern China. Using DGT P as a reference resulted in a better visual and near-infrared calibration to predict soil P concentrations, as compared with using Olsen P.
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http://dx.doi.org/10.2134/jeq2016.05.0195DOI Listing
November 2016

Unraveling the Complex Behavior of AgNPs Driving NP-Cell Interactions and Toxicity to Algal Cells.

Environ Sci Technol 2016 11 26;50(22):12455-12463. Epub 2016 Oct 26.

Future Industries Institute, University of South Australia , Mawson Lakes Campus, Adelaide, South Australia 5095, Australia.

While the importance of nanoparticle (NP) characterization under relevant test conditions is widely recognized in nanotoxicology, few studies monitor NPs behavior in the presence of exposed organisms. Here we studied the behavior of nine types of silver nanoparticles (AgNPs) during the 48 h algal toxicity test. In particular, we investigated NP aggregation and dissolution by time-resolved inductively coupled plasma mass spectrometry and ultrafiltration and performed mass balance measurements to study the distribution of Ag in the test system. We also determined the amount of extra- and intracellular Ag by chemically etching AgNPs on the surface of algal cells and used dark field microscopy for their imaging. We observed that positively charged branched polyethilenimine (bPEI)-coated AgNPs tend to aggregate in the presence of algae and interact with test vessels and algal cells, while citrate-coated AgNPs have a tendency to dissolve. On the other hand, with large variation of half-maximum effective concentration (EC50) across tested NPs (5.4 to 300 ngAg mL), Ag internalized by the algal cells at EC50 was similar (0.8 to 3.6 ngAg mL) for all AgNP types. These data show that while sorption to the vessels, dissolution, and aggregation impact on the distribution of AgNPs in the test system and on interactions with algal cells, AgNP toxicity is strongly correlated with the NP-cell surface interaction and internalization of Ag.
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http://dx.doi.org/10.1021/acs.est.6b03470DOI Listing
November 2016
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