Stream denitrification across biomes and its response to anthropogenic nitrate loading

Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 452 (2008): 202-205, doi:10.1038/nature06686.Worldwide, anthropogenic addition of bioavailable nitrogen (N) to the biosphere is increasing and terrestrial ecosystems are becoming increasingly N saturated, causing more bioavailable N to enter groundwater and surface waters. Large-scale N budgets show that an average of about 20-25% of the N added to the biosphere is exported from rivers to the ocean or inland basins, indicating substantial sinks for N must exist in the landscape. Streams and rivers may be important sinks for bioavailable N owing to their hydrologic connections with terrestrial systems, high rates of biological activity, and streambed sediment environments that favor microbial denitrification. Here, using data from 15N tracer experiments replicated across 72 streams and 8 regions representing several biomes, we show that total biotic uptake and denitrification of nitrate increase with stream nitrate concentration, but that the efficiency of biotic uptake and denitrification declines as concentration increases, reducing the proportion of instream nitrate that is removed from transport. Total uptake of nitrate was related to ecosystem photosynthesis and denitrification was related to ecosystem respiration. Additionally, we use a stream network model to demonstrate that excess nitrate in streams elicits a disproportionate increase in the fraction of nitrate that is exported to receiving waters and reduces the relative role of small versus large streams as nitrate sinks.Funding for this research was provided by the National Science Foundation

Razão de perdas de solo e fator c para as culturas de soja e trigo em três sistemas de preparo em um cambissolo húmico alumínico

Utilizando dados obtidos em experimento de perdas de solo e água sob chuva natural em Lages (SC), de novembro de 1992 a outubro de 1998, calcularam-se a razão de perdas de solo (RPS) e o fator C da equação universal de perda de solo, para três sistemas de preparo do solo e duas culturas. Foram estudados os tratamentos aração+duas gradagens (A + G), escarificação+gradagem (E + G) e semeadura direta (SDI), submetidos à sucessão das culturas de soja (Glycine max) e trigo (Triticum aestivum L.), comparados à aração + duas gradagens sem culturas (SSC), sobre um Cambissolo Húmico alumínico com declividade média de 0,102 m m-1. O ciclo de ambas as culturas foi dividido em cinco estádios, com igual intervalo de tempo entre eles. Tanto as RPS quanto os fatores C variaram ampla-mente entre os sistemas de preparo do solo e entre os estádios durante o ciclo das culturas, bem como entre os ciclos na mesma cultura e entre as culturas, indicando forte efeito do manejo do solo, da época do ano, da cultura e da chuva sobre essas variáveis. Os valores médios de RPS na cultura de soja foram de 0,1711, 0,1061 e 0,0477 Mg ha Mg-1 ha-1, para a A + G, E + G e SDI, respectivamente, enquanto, para o trigo, as referidas RPS, para os respectivos sistemas de preparo do solo, foram de 0,2416, 0,1874 e 0,0883. Os valores médios do fator C, para os respectivos sistemas de preparo do solo, foram de 0,1437, 0,0807 e 0,0455 Mg ha Mg-1 ha-1, para a cultura de soja; de 0,2158, 0,1854 e 0,0588 Mg ha Mg-1 ha-1, para o trigo, e, para a sucessão das referidas culturas, de 0,3713, 0,2661 e 0,1043 Mg ha Mg-1 ha-1

Analyzing wastewater samples collected during census to determine the correction factors of drugs for wastewater-based epidemiology: the case of codeine and methadone

The correction factor (CF) is a critical parameter for back-estimating the consumption of a drug via wastewater-based epidemiology (WBE). The CF is usually the excretion factor (EF) of the drug or metabolite (the fraction of drug excreted after consumption and the molecular mass ratio of parent drug/metabolite) traditionally determined by human pharmacokinetic studies. An alternative approach to derive CFs is to compare the consumption data with the loads measured by WBE in representative wastewater samples. For this purpose, during the 2016 Australian Census week, more than 500 wastewater samples were collected from 83 wastewater treatment plants across Australia (covering >60% of the Australian population) and analyzed for codeine, methadone, and methadone metabolite, EDDP. National sales data for codeine and methadone to local pharmacies were obtained to estimate the CFs for the three biomarkers. The CFs estimated for codeine and EDDP in this study, 29% (95% CI = 28%-30%) and 50% (95% CI = 49%-52%), respectively, are significantly different from the EFs deduced from pharmacokinetic data (60% and 25%), while methadone's CF is relatively similar to previously used values (22% vs 27.5%). The newly derived CFs were applied to available data in the literature and produced better matches between estimates and consumption data than previously reported. It is thus suggested that the new approach be used to derive the CFs of other drugs of interest for WBE application when limited pharmacokinetic data are available

Wastewater treatment plants as a source of plastics in the environment: a review of occurrence, methods for identification, quantification and fate

Plastics accumulate in the natural environment due to their durability and low recycling volumes. Wastewater treatments plants (WWTPs) have been identified as important sources for the release of plastics into aquatic and terrestrial environments that may lead to further contamination. This review provides a comprehensive summary of current knowledge on plastic pollution from WWTPs. Specifically, this article presents the current status on the sources of plastics entering WWTPs via influent, the occurrence of plastics in WWTP influent, treated effluent and sewage sludge as well as the techniques used for sampling and analysing plastics in WWTP derived samples. The fate and transfer of plastics from WWTPs to aquatic and terrestrial ecosystems is also discussed. While various studies have reported the presence of plastics in WWTP samples, which have certainly improved our level of understanding on the fate of plastics within the WWTP treatment chain, many unanswered questions still remain. A major gap is the lack of standardized methods and robust analytical techniques for the sampling, identification and quantification of plastics including nano-sized plastics in WWTP derived samples, leading to the potential underestimation of total plastics. To aid comparison of data generated by different researchers, we advocate for the harmonisation of sampling approaches, extraction methods, analytical techniques and reporting units for plastics abundance. Future studies should focus on enhanced methods that can also include estimates of nano-sized plastics

Extraction and Pyrolysis-GC-MS analysis of polyethylene in samples with medium to high lipid content

While it is recognised that humans are constantly exposed to plastics, there are limitations in understanding the extent of this exposure, particularly dietary exposure. This lack of information is partly due to challenges with the analysis of complicated matrices. This study aimed to assess the impact of medium to high lipid content (> 3%) food samples on the accurate quantification of polyethylene (PE), using pyrolysis-gas chromatography mass spectrometry, and develop an alternative sample processing strategy. Analysis of saturated, monounsaturated and polyunsaturated fats was demonstrated to form the same pyrolysis products as PE, producing a significant interference hindering quantification. An extraction protocol was developed that involves enzyme digestion to break the lipids into smaller chain fatty acids, removal of these interferences with pressurised liquid extraction washes, before a final extraction of the PE by pressurised liquid extraction. This new method was validated through the analysis of three medium- to high-fat content foods: cow’s milk, eggs and lamb meat, where PE recoveries were acceptable (104% to 127%). Method detection limits were also significantly reduced from 1.9 to 0.05 µg/injection (380 to 10 µg/g) with the new protocol, through the removal of matrix background. PE traces were observed in the three food matrices of 72-240 µg/g, significantly reduced as compared to samples extracted with the old method where concentrations of 12-32 mg/g were calculated, demonstrating the potential for overestimation of dietary exposure. Finally, a simple protocol is reported for future studies to (i) determine if an interference is present and (ii) sample processing methods to remove identified interferences

Critical assessment of the chemical space covered by LC-HRMS non-targeted analysis

Non-targeted analysis (NTA) has emerged as a valuable approach for comprehensive monitoring of chemicals of emerging concern (CECs) in the exposome. The NTA approach, theoretically, is able to identify compounds with diverse physicochemical properties and sources. Non-targeted analysis methods, even though generic and wide scoping, have been shown to have limitations in terms of their coverage of the chemical space, as the number of the identified chemicals in each sample is very low (e.g. < 5%). Investigating the chemical space covered by each NTA assay is crucial for understanding the limitations and challenges associated with the workflow from experimental methods to the data acquisition and data processing. In this review, we examined recent NTA studies published between 2017 and 2023 that employed liquid chromatography-high resolution mass spectrometry. The parameters used in each study were documented and reported chemicals at the confidence level 1 and 2 were retrieved. The chosen experimental setups and the quality of reporting were critically evaluated and discussed. The findings revealed that only around 2% of the estimated chemical space was covered by the NTA studies investigated. Little to no trend was found between the experimental setup and the observed coverage, due to the generic and wide scope of NTA studies. The limited coverage of chemical space by the NTA studies highlights the necessity for a more comprehensive approach in experimental and data processing setups to enable the exploration of a broader range of chemical space, with the ultimate goal of protecting human and environmental health. Recommendations to further explore a wider range of the chemical space were given

"Antropologia culturale e costruzione sociale del rischio"

The use of organophosphate esters (PFRs) as flame retardants and plasticizers has increased due to the ban of some brominated flame retardants. There is however some concern regarding the toxicity, particularly carcinogenicity and neurotoxicity, of some of the PFRs. In this study we applied wastewater analysis to assess use of PFRs by the Australian population. Influent samples were collected from eleven wastewater treatment plants (STPs) in Australia on Census day and analysed for PFRs using gas chromatography coupled with mass spectrometry (GC-MS). Per capita mass loads of PFRs were calculated using the accurate Census head counts. The results indicate that tris(2-butoxyethyl) phosphate (TBOEP) has the highest per capita input into wastewater followed by tris(2-chloroisopropyl) phosphate (TCIPP), tris(isobutyl) phosphate (TIBP), tris(2-chloroethyl) phosphate (TCEP) and tris(1,3-dichloroisopropyl) phosphate (TDCIPP). Similar PFR profiles were observed across the Australian STPs and a comparison with European and U.S. STPs indicated similar PFR concentrations. We estimate that approximately 2.1 mg person−1 day−1 of PFRs are input into Australian wastewater which equates to 16 tonnes per annum

Population socioeconomics predicted using wastewater

Municipal wastewater typically contains many drugs and anthropogenic chemicals or biomarkers. The occurrence of these chemicals in wastewater is linked to the socioeconomic characteristics of the contributing population. Based on these relationships, we propose, execute and evaluate a novel model for predicting population socioeconomics. Specifically, we used biomarkers in wastewater to predict 37 socioeconomic characteristics of populations during the Australian Census. The resultant model was further tested on nine other populations separate from the training data set. Prediction performance in the test populations (defined as accuracy +/- SD) fit within 75% and 125% for many features such as catchment median age, and specific measures of educational attainment (e.g., high school completion) and employment (e.g., managerial employment). Considering the relative ease, low cost and high frequency at which wastewater samples can be collected and analyzed, wastewater analysis could be used as a complementary technique for assessing population socioeconomics

Population Socioeconomics Predicted Using Wastewater

Municipal wastewater typically contains many drugs and anthropogenic chemicals or biomarkers. The occurrence of these chemicals in wastewater is linked to the socioeconomic characteristics of the contributing population. Based on these relationships, we propose, execute and evaluate a novel model for predicting population socioeconomics. Specifically, we used biomarkers in wastewater to predict 37 socioeconomic characteristics of populations during the Australian Census. The resultant model was further tested on nine other populations separate from the training data set. Prediction performance in the test populations (defined as accuracy ± SD) fit within 75% and 125% for many features such as catchment median age, and specific measures of educational attainment (e.g., high school completion) and employment (e.g., managerial employment). Considering the relative ease, low cost and high frequency at which wastewater samples can be collected and analyzed, wastewater analysis could be used as a complementary technique for assessing population socioeconomics