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1.
Water Res ; 182: 115906, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32629317

RESUMO

While we increasingly turn to desalination as a secure water supply, it is still perceived as an expensive and environmentally damaging solution, affordable only for affluent societies. In this contribution, we recast desalination from one of a last resort to a far-reaching, climate change mitigating, water security solution. First, we argue that the benefits of desalination go beyond the single-use value of the water produced. If coupled with water reuse for irrigation, desalination reduces groundwater abstraction and augments the water cycle. As such, it may support both adaptation to, and mitigation of climate change impacts by deploying plentiful water for human use, with all the benefits that entails, while helping preserve and restore ecosystems. Second, we counter two arguments commonly raised against desalination, namely its environmental impact and high cost. The environmental impact can be fully controlled so as not to pose long-term threats, if driven by renewable energy. Desalination may then have a zero carbon footprint. Moreover, appropriately designed outfalls make the disposal of brine at sea compatible with marine ecosystems.. Recovery of energy, minerals and more water from brine reject (particularly in the form of vapour for cooling to enable more crops and vegetation to grow), while possible, is often hardly economically justified. However, resource recovery may become more attractive in the future, and help reduce the brine volumes to dispose of. When fresh water becomes scarce, its cost tends to go up, making desalination increasingly economic. Moreover, desalination can have virtually no environmental costs. Considering the environmental costs of over-abstraction of freshwater, desalination tilts the balance in its favour.


Assuntos
Ciclo Hidrológico , Purificação da Água , Ecossistema , Humanos , Água do Mar , Abastecimento de Água
2.
Water Res ; 177: 115753, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32302808

RESUMO

The pharmaceutical torasemide is an important loop diuretic and was 2017 one of the ten most prescribed drugs in Germany. Despite its detection in different compartments of the urban water cycle including drinking water, no studies were so far performed to elucidate its fate in the environment and the occurrence of transformation products (TPs). Therefore, we investigated the phototransformation, microbial degradation, transformation with human liver microsomes and anodic oxidation of torasemide to obtain good coverage of environmentally relevant degradation products. Overall sixteen products were identified, covering the following reaction mechanisms: aromatic and aliphatic hydroxylation, including further oxidation to carboxylic acids and quinone imines, amide cleavage, N-dealkylation, N-dearylation, and sulfonamide hydrolysis to sulfonic acids. Especially the formation of quinone imines could be of concern as they are highly reactive electrophiles. Torasemide itself was observed in all investigated wastewater treatment plant (WWTP) samples and wastewater-impacted surface waters. The maximum detected concentration was about 350 ng L-1. Only three of the sixteen transformation products were generally observed in at least one of the samples and the most frequently detected TPs were the human metabolites hydroxytorasemide (TP 364a) and carboxytorasemide (TP 378a). The complete removal of TP 364a during wastewater treatment was in agreement with the results of microbial degradation experiments. TP 364a was most likely transformed into TP 378a, which was microbially less degraded in lab experiments. Based on estimated concentrations, TP 378a could reach about 1 µg L-1 in the investigated wastewater matrices.


Assuntos
Poluentes Químicos da Água , Alemanha , Humanos , Torasemida , Águas Residuárias , Ciclo Hidrológico
3.
Water Res ; 175: 115706, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32199185

RESUMO

Elevated concentrations of sulfamate, the anion of sulfamic acid, were found in surface waters and finished drinking water in Germany with concentrations up to 580 µg/L and 140 µg/L, respectively. Wastewater treatment plant (WWTP) effluent was identified as the dominant source of sulfamate in the urban water cycle, as sulfamate concentrations correlated positively (0.77 > r < 0.99) with concentrations of the wastewater tracer carbamazepine in samples from different waterbodies. Ozonation and activated sludge experiments proved that sulfamate can be formed from chemical and biological degradation of various precursors. Molar sulfamate yields were highly compound-specific and ranged from 2% to 56%. However, the transformation of precursors to sulfamate in WWTPs and wastewater-impacted waterbodies was found to be quantitatively irrelevant, since concentrations of sulfamate in these compartments are already high, presumably due to its primary use as an acidic cleaning agent. Sulfamate concentrations in the influent and effluent of studied WWTPs ranged from 520 µg/L to 1900 µg/L and from 490 µg/L to 1600 µg/L, respectively. Laboratory batch experiments were performed to assess the recalcitrance of sulfamate for chemical oxidation. In combination with the results from sampling conducted at full-scale waterworks, it was shown that common drinking water treatment techniques, including ozonation and filtration with activated carbon, are not capable to remove sulfamate. The results of biodegradation tests and from the analysis of samples taken at four bank filtration sites indicate that sulfamate is attenuated in the sediment/water interface of aquatic systems and during aquifer passage under aerobic and anaerobic conditions. Sulfamate concentrations decreased by between 62% and 99% during aquifer passage at the bank filtration sites. Considering the few data on short term ecotoxicity, about 30% of the presented sulfamate levels in ground and surface water samples did exceed the predicted no-effect concentration (PNEC) of sulfamate, and thus effects of sulfamate on the aquatic ecosystem of wastewater-impacted waterbodies in Germany cannot be excluded so far. Toxicological estimations suggest that no risk to human health is expected by concentrations of sulfamate typically encountered in tap water.


Assuntos
Ciclo Hidrológico , Poluentes Químicos da Água , Ecossistema , Monitoramento Ambiental , Alemanha , Humanos , Ácidos Sulfônicos , Eliminação de Resíduos Líquidos , Águas Residuárias
4.
PLoS One ; 15(2): e0228537, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049986

RESUMO

Urbanization modifies land surface characteristics with consequent impacts on local energy, water, and carbon dioxide (CO2) fluxes. Despite the disproportionate impact of cities on CO2 emissions, few studies have directly quantified CO2 conditions for different urban land cover patches, in particular for arid and semiarid regions. Here, we present a comparison of eddy covariance measurements of CO2 fluxes (FC) and CO2 concentrations ([CO2]) in four distinct urban patches in Phoenix, Arizona: a xeric landscaping, a parking lot, a mesic landscaping, and a suburban neighborhood. Analyses of diurnal, daily, and seasonal variations of FC and [CO2] were related to vegetation activity, vehicular traffic counts, and precipitation events to quantify differences among sites in relation to their urban land cover characteristics. We found that the mesic landscaping with irrigated turf grass was primarily controlled by plant photosynthetic activity, while the parking lot in close proximity to roads mainly exhibited the signature of vehicular emissions. The other two sites that had mixtures of irrigated vegetation and urban surfaces displayed an intermediate behavior in terms of CO2 fluxes. Precipitation events only impacted FC in urban patches without outdoor water use, indicating that urban irrigation decouples CO2 fluxes from the effects of infrequent storms in an arid climate. These findings suggest that the proportion of irrigated vegetation and urban surfaces fractions within urban patches could be used to scale up CO2 fluxes to a broader city footprint.


Assuntos
Ciclo do Carbono/fisiologia , Dióxido de Carbono/química , Poaceae/fisiologia , Chuva , Solo , Urbanização , Arizona , Dióxido de Carbono/análise , Cidades , Clima Desértico , Humanos , Estações do Ano , Solo/química , Fatores de Tempo , Emissões de Veículos/análise , Ciclo Hidrológico/fisiologia
5.
Glob Chang Biol ; 26(2): 944-959, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31638295

RESUMO

The world's largest afforestation programs implemented by China made a great contribution to the global "greening up." These programs have received worldwide attention due to its contribution toward achieving the United Nations Sustainable Development Goals. However, emerging studies have suggested that these campaigns, when not properly implemented, resulted in unintended ecological and water security concerns at the regional scale. While mounting evidence shows that afforestation causes substantial reduction in water yield at the watershed scale, process-based studies on how forest plantations alter the partitioning of rainwater and affect water balance components in natural vegetation are still lacking at the plot scale. This lack of science-based data prevents a comprehensive understanding of forest-related ecosystem services such as soil conservation and water supply under climate change. The present study represents the first "Paired Plot" study of the water balance of afforestation on the Loess Plateau. We investigate the effects of forest structure and environmental factors on the full water cycle in a typical multilayer plantation forest composed of black locust, one of the most popular tree species for plantations worldwide. We measure the ecohydrological components of a black locust versus natural grassland on adjacent sites. The startling finding of this study is that, contrary to the general belief, the understory-instead of the overstory-was the main water consumer in this plantation. Moreover, there is a strict physiological regulation of forest transpiration. In contrast to grassland, annual seepage under the forest was minor in years with an average rainfall. We conclude that global long-term greening efforts in drylands require careful ecohydrologic evaluation so that green and blue water trade-offs are properly addressed. This is especially important for reforestation-based watershed land management, that aims at carbon sequestration in mitigating climate change while maintaining regional water security, to be effective on a large scale.


Assuntos
Ecossistema , Ciclo Hidrológico , China , Conservação dos Recursos Naturais , Florestas , Solo
6.
Glob Chang Biol ; 26(2): 658-668, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31386797

RESUMO

Ongoing intensification of the hydrological cycle is altering rainfall regimes by increasing the frequency of extreme wet and dry years and the size of individual rainfall events. Despite long-standing recognition of the importance of precipitation amount and variability for most terrestrial ecosystem processes, we lack understanding of their interactive effects on ecosystem functioning. We quantified this interaction in native grassland by experimentally eliminating temporal variability in growing season rainfall over a wide range of precipitation amounts, from extreme wet to dry conditions. We contrasted the rain use efficiency (RUE) of above-ground net primary productivity (ANPP) under conditions of experimentally reduced versus naturally high rainfall variability using a 32-year precipitation-ANPP dataset from the same site as our experiment. We found that increased growing season rainfall variability can reduce RUE and thus ecosystem functioning by as much as 42% during dry years, but that such impacts weaken as years become wetter. During low precipitation years, RUE is lowest when rainfall event sizes are relatively large, and when a larger proportion of total rainfall is derived from large events. Thus, a shift towards precipitation regimes dominated by fewer but larger rainfall events, already documented over much of the globe, can be expected to reduce the functioning of mesic ecosystems primarily during drought, when ecosystem processes are already compromised by low water availability.


Assuntos
Ecossistema , Pradaria , Poaceae , Chuva , Ciclo Hidrológico
7.
Plant Sci ; 290: 110146, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31779906

RESUMO

Current climate change models project that water availability will become more erratic in the future. With soil nitrogen (N) supply coupled to water availability, it is important to understand the combined effects of variable water and N supply on food crop plants (above- and below-ground). Here we present a study that precisely controls soil moisture and compares stable soil moisture contents with a controlled wetting-drying cycle. Our aim was to identify how changes in soil moisture and N concentration affect shoot-root biomass, N acquisition in wheat, and soil N cycling. Using a novel gravimetric platform allowing fine-scale control of soil moisture dynamics, a 3 × 3 factorial experiment was conducted on wheat plants subjected to three rates of N application (0, 25 and 75 mg N/kg soil) and three soil moisture regimes (two uniform treatments: 23.5 and 13% gravimetric moisture content (herein referred to as Well-watered and Reduced water, respectively), and a Variable treatment which cycled between the two). Plant biomass, soil N and microbial biomass carbon were measured at three developmental stages: tillering (Harvest 1), flowering (Harvest 2), and early grain milk development (Harvest 3). Reduced water supply encouraged root growth when combined with medium and high N. Plant growth was more responsive to N than the water treatments imposed, with a 15-fold increase in biomass between the high and no added N treatment plants. Both uniform soil water treatments resulted in similar plant biomass, while the Variable water treatment resulted in less biomass overall, suggesting wheat prefers consistency whether at a Well-watered or Reduced water level. Plants did not respond well to variable soil moisture, highlighting the need to understand plant adaptation and biomass allocation with resource limitation. This is particularly relevant to developing irrigation practices, but also in the design of water availability experiments.


Assuntos
Carbono/análise , Nitrogênio/análise , Microbiologia do Solo , Solo/química , Triticum/crescimento & desenvolvimento , Ciclo Hidrológico , Bactérias/metabolismo , Biomassa , Triticum/metabolismo
8.
Artigo em Inglês | MEDLINE | ID: mdl-31726689

RESUMO

Stable hydrogen and oxygen isotopes are important indicators for studying water cycles. The isotopes are not only affected by climate, but are also disturbed by human activities. Urban construction has changed the natural attributes and underlying surface characteristics of river basins, thus affecting the isotopic composition of river water. We collected urban river water isotope data from the Global Network for Isotopes in Rivers (GNIR) database and the literature, and collected river water samples from the Naqu basin and Huangshui River basin on the Tibetan Plateau to measure hydrogen and oxygen isotopes. Based on 13 pairs of urban area and non-urban area water samples from these data, the relationship between the isotopic values of river water and the artificial surface area of cities around rivers was analyzed. The results have shown that the hydrogen and oxygen isotope (δD and δ18O) values of river water in urban areas were significantly higher than those in non-urban areas. The isotopic variability of urban and non-urban water was positively correlated with the artificial surface area around the rivers. In addition, based on the analysis of isotope data from 21 rivers, we found that the cumulative effects of cities on hydrogen and oxygen isotopes have led to differences in surface water line equations for cities with different levels of development. The combined effects of climate and human factors were the important reasons for the variation of isotope characteristics in river water in cities. Stable isotopes can not only be used to study the effects of climate on water cycles, but also serve as an important indicator for studying the degree of river development and utilization.


Assuntos
Monitoramento Ambiental/métodos , Hidrogênio/química , Oxigênio/química , Rios/química , Cidades , Humanos , Isótopos/análise , Isótopos de Oxigênio , Ciclo Hidrológico
9.
Environ Sci Process Impacts ; 21(12): 2128-2140, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31681920

RESUMO

Determining inorganic nutrient profiles to support understanding of nitrogen transformations in stream sediments is challenging, due to nitrification and denitrification being confined to particular conditions in potentially heterogeneous sediment influenced by benthic microalgae, rooted aquatic plants and/or diel light cycles. The diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques allow in situ determination of porewater concentration profiles, and distributions for some solutes. In this study, DGT, DET and conventional porewater extraction (sectioning and centrifugation) methods were compared for ammonium and nitrate in stream sediments under light and dark conditions. Two-dimensional distributions of Fe(ii) and PO4-P were also provided to indicate the degree of spatial and temporal heterogeneity in sediment porewater, which can explain the sources and sinks of ammonium at various depths in the sediments. Although the conventional porewater extraction method consistently measured higher NH4-N concentrations than the DGT and DET techniques, the study showed that the DET measurements were the most reliable indicator of porewater NH4-N concentrations, with the DGT data being usefully supplementary. However, a large proportion of the NO3-N concentrations measured by DGT and DET were close to or below the method detection limits. Therefore, further development of these techniques is required to reduce the blanks and detection limits to allow natural low sediment porewater NO3-N concentrations to be accurately monitored using DGT and DET. The study indicated that benthic microalgae had direct and indirect influences on porewater nutrient distributions over light-dark cycles. Overall, DGT and DET techniques can be useful for monitoring porewater nutrient concentrations and profiles and for determining how biological processes drive changes in sediment nutrient concentrations and distributions.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Rios/química , Ciclo Hidrológico , Poluentes Químicos da Água/análise , Amônia/análise , Difusão , Nitratos/análise
10.
Isotopes Environ Health Stud ; 55(6): 550-565, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31645132

RESUMO

The north-east of Iran is a semi-arid region and faces a water shortage crisis. Therefore, monitoring water resources using accurate methods such as stable isotopes technique is vitally important. In this study, precipitation events were sampled in 10 stations in the Mashhad basin and the Bojnourd region in 2008, 2009, 2011, and 2015, additional surface and groundwater. These samples were analysed at the Ottawa University for both oxygen and hydrogen isotopes. In addition, the moisture sources were determined using the backward trajectories of the HYSPLIT model. The backward trajectories showed that both high- and low-latitude water bodies provide moisture for the north-east of Iran. However, the role of high-latitude water bodies including the Caspian, the Black, and the Mediterranean Seas is stronger. On the other hand, the stable isotopes showed large variations and the developed meteoric water lines deviated in both slope and intercept from the global meteoric water line. This showed that the precipitation events of the north-east of Iran were provided by various air masses and moisture sources. Finally, plotting the isotope values of the surface water resources on high- and low-latitude meteoric water lines demonstrated that these water resources were dominantly recharged by precipitation events originating from high-latitude water bodies.


Assuntos
Deutério/análise , Monitoramento Ambiental/métodos , Água Doce/análise , Isótopos de Oxigênio/análise , Chuva/química , Recursos Hídricos/provisão & distribução , Água Doce/química , Água Subterrânea/química , Irã (Geográfico) , Estações do Ano , Ciclo Hidrológico
11.
Bull Environ Contam Toxicol ; 103(5): 663-669, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31473775

RESUMO

Climate change is expected to alter hydrological cycles on global and regional scales, impacting groundwater and surface water inputs to stream habitats. In the midwestern United States, the volume and frequency of inputs are expected to become increasingly variable. This region has a high incidence of agriculture, creating enormous potential for transport of pesticides and herbicides into aquatic ecosystems. Metolachlor, an herbicide for corn and soybean crops, has been demonstrated to contaminate surface water and groundwater in the region. This study examines the impact of variable flow conditions on the toxicity of environmentally relevant concentrations of metolachlor in a macroinvertebrate found in midwestern streams, the rusty crayfish (Faxonius rusticus). Changes in crayfish foraging behavior were analyzed using a Mixed Model ANCOVA. Under toxicant exposure, crayfish significantly increased their consumption of macrophytes, but only under the variable flow regime. Thus, the increased variability in toxicant exposure impacted crayfish foraging behavior more than other flow regimes. This significant interaction between flow regime and metolachlor exposure suggests that the greater variability in toxicant inputs to streams may lead to more severe changes in behavior for exposed organisms.


Assuntos
Acetamidas/toxicidade , Astacoidea/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Herbicidas/toxicidade , Ciclo Hidrológico , Poluentes Químicos da Água/toxicidade , Animais , Astacoidea/fisiologia , Ecossistema , Água Subterrânea/química , Meio-Oeste dos Estados Unidos , Rios/química
12.
Artigo em Inglês | MEDLINE | ID: mdl-31547208

RESUMO

The application of agricultural pesticides in Africa can have negative effects on human health and the environment. The aim of this study was to identify African environments that are vulnerable to the accumulation of pesticides by mapping geospatial processes affecting pesticide fate. The study modelled processes associated with the environmental fate of agricultural pesticides using publicly available geospatial datasets. Key geospatial processes affecting the environmental fate of agricultural pesticides were selected after a review of pesticide fate models and maps for leaching, surface runoff, sedimentation, soil storage and filtering capacity, and volatilization were created. The potential and limitations of these maps are discussed. We then compiled a database of studies that measured pesticide residues in Africa. The database contains 10,076 observations, but only a limited number of observations remained when a standard dataset for one compound was extracted for validation. Despite the need for more in-situ data on pesticide residues and application, this study provides a first spatial overview of key processes affecting pesticide fate that can be used to identify areas potentially vulnerable to pesticide accumulation.


Assuntos
Modelos Teóricos , Resíduos de Praguicidas , Poluentes do Solo , Análise Espacial , África , Agricultura , Praguicidas , Solo , Volatilização , Ciclo Hidrológico
13.
Isotopes Environ Health Stud ; 55(6): 532-549, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31547680

RESUMO

Water scarcity is a leading concern in both developing and developed nations. Coping with water scarcity requires an understanding of various hydrological processes that act upon precipitation, surface and groundwater at a local scale. We measured isotopic signatures of several water samples from two distinct ecosystems, i.e. tropical savanna in the West and the warm semi-arid region in the East lying across the Western Ghats mountain range, India, to understand the hydrological processes. The results show that the hydrogeological conditions strongly influence the isotopic characteristics of water of different resources, governed by different hydrological processes, even at close spatial scales. Based on the local evaporation lines of different water resources within a particular ecosystem, it is inferred that the water resources are well linked at one site, but have diverse connectivity at the other site. Further, the isotopic signatures of all the water resources are systematically affected by the monsoon precipitation. In addition, anomalously depleted isotopic signatures are observed during known hailstorm events. This may provide a means to trace their signature in the existing water resources.


Assuntos
Água Subterrânea/química , Chuva/química , Rios/química , Ciclo Hidrológico , Recursos Hídricos/provisão & distribução , Deutério/análise , Ecossistema , Hidrologia , Índia , Isótopos de Oxigênio/análise
14.
Isotopes Environ Health Stud ; 55(6): 511-525, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31533477

RESUMO

Freshwater bivalve shell oxygen isotope values (δ18OS) may act as a recorder of river δ18O variations that can then be interpreted in terms of hydrology (e.g. precipitation-evaporation balance, precipitation and river discharge patterns). We investigated the potential of this proxy measured across the hinge of South American unionid shells: Anodontites elongatus collected in Peru and A. trapesialis in Brazil. The isotopic signatures were reproducible between individuals of the same species. A. trapesialis clearly showed a strong δ18OS cyclicity in accordance with its growth patterns while A. elongatus presented less clear δ18OS with lower amplitude. We confirm that the deposition of successive growth lines and increments is annual, with growth line corresponding to the wet season. Also, we suggest that low amplitude of δ18OS in the A. elongatus shells indicates a habitat close to the river while large amplitude of δ18OS cycles observed in A. trapesialis shells would reflect a floodplain lake habitat, seasonally disconnected from the river and thus subjected to higher seasonal fluctuations in water δ18O. Considering these promising first results, future studies could be directed towards the use of fossil shells to reconstruct the past and present hydrological and geochemical conditions of the Amazon.


Assuntos
Exoesqueleto/química , Bivalves/química , Monitoramento Ambiental/métodos , Isótopos de Oxigênio/análise , Rios/química , Ciclo Hidrológico , Animais , Brasil , Lagos/química , Estações do Ano
15.
Water Res ; 165: 114973, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31430651

RESUMO

Hexamethoxymethylmelamine (HMMM) is a crosslinker of melamine resins and widely used in the production of coatings and plastics, e.g. for cans, coils and automobiles. Despite its widespread application little is known about the occurrence of HMMM in municipal wastewater, the extent of its removal in wastewater treatment and the fate of transformation products that may be formed from it. A lab degradation experiment with activated sludge showed that HMMM is transformed but not mineralized under aerobic conditions. By LC-UV and LC-HRMS analyses 21 transformation products (TPs) were detected and tentatively identified, with modified di(methoxymethyl)amino side chains, and a pathway for their formation was proposed. The major TP after 28 days was methylol-1,3,5-triazin-2,4,6-triamin. LC-UV and LC-HRMS response of the TPs in the lab experiment was used to quantitatively assess the concentration of TPs also in environmental samples. In municipal wastewater HMMM and its two TPs TetraMMM and DiMMM added up to median concentrations of 2.8 µg/l (7.5 nmol/L) in three wastewater treatment plants (WWTPs), and to 17.9 µg/l (66 nmol/L) in another plant with a higher contribution of industrial wastewater. Their concentration increased in the WWTPs by a factor of 2-4, likely due to ongoing formation from HMMM-related precursor compounds. Also melamine concentrations increased in the four WWTPs (to 3-8 µg/L), but this did not seem to be linked to HMMM transformation. In surface water affected by WWTP discharges HMMM and 12 TPs were determined, at median total concentrations of 5 µg/L, with an even higher proportion of the TPs relative to HMMM compared to the WWTP effluents. During bank filtration HMMM, TetraMMM and DiMMM, together with some cationic TPs, were largely removed, while three TPs, all carrying one carbonylated side chain were eventually determined in raw waters used for drinking water production, in median concentrations ranging from 0.1 to 1 µg/L. It appears that HMMM, while falling under the exemptions of REACH registration, is a precursor for widely found persistent and mobile TPs, that can reach raw waters used for drinking water production.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Esgotos , Ciclo Hidrológico
16.
Environ Monit Assess ; 191(9): 533, 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31375936

RESUMO

Long-term increased nutrient influx into normally nutrient-limited peatlands in combination with altered hydrological conditions may threaten a peatland's carbon storage function and affect its greenhouse gas (GHG) budget. However, in situ studies on the effects of long-term altered conditions on peatland functioning and GHG budgets are scarce. We thus quantified GHG fluxes in a peatland exposed to enhanced water level fluctuations and long-term nutrient infiltration in Ontario, Canada, via eddy-covariance and flux chamber measurements. The peatland was a prominent sink of - 680 ± 202 g carbon dioxide (CO2) and a source of 22 ± 8 g methane (CH4) m-2 year-1, resulting in a negative radiative forcing of - 80 g CO2 eq. m-2 y-1. During the growing season CH4 fluxes were constantly high (0.1 g m-2 s-1). Further, on three dates, we measured nitrous oxide (N2O) fluxes and observed a small flux of 2.2 mg m-2 day-1 occurring during the thawing period. Taking the studied ecosystem as a model system for other peatlands exposed to long-term increased nutrient infiltration and enhanced water level fluctuations, our data suggest that such peatlands can maintain their carbon storage function and CO2 sequestration may outweigh emissions of CH4.


Assuntos
Sequestro de Carbono , Monitoramento Ambiental/métodos , Gases de Efeito Estufa/análise , Metano/análise , Ciclo Hidrológico , Dióxido de Carbono/análise , Ecossistema , Óxido Nitroso/análise , Ontário , Estações do Ano
17.
Environ Monit Assess ; 191(9): 548, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31392422

RESUMO

Global warming portends an accelerated water cycle as increased evaporation feeds atmospheric moisture and precipitation. To monitor effects on surface water levels, we describe a low-cost hydrologic observatory suitable for small to medium size lakes. The observatory comprises sensor platforms that were built in-house to compile continuous, sub-daily water budgets. The variables measured directly are lake stage (S), evaporation (E), and precipitation (P). A net inflow term (Qnet) is estimated as a residual in the continuity equation: ∆S = P - E + Qnet. We describe how to build in-lake stilling wells and floating evaporation pans using readily available materials. We assess their performance in laboratory tests and field trials. A 3-month deployment on a small Wisconsin lake (18 ha, 10 m deep) confirms that continuous estimates of ∆S, E, P, and Qnet can be made with good precision and accuracy at hourly time scales. During that deployment, daily estimates of E from the floating evaporation pans were comparable with estimates made using the more data-intensive Bowen ratio energy balance method and a mass transfer model. Since small lakes are numerically dominant and widely distributed across the globe, a network of hydrologic observatories would enable the calibration and validation of climate models and consumptive use policies at local and regional scales. And since the observatories are inexpensive and relatively simple to maintain, citizen scientists could facilitate the expansion of spatial coverage with minimal training.


Assuntos
Monitoramento Ambiental/métodos , Hidrologia/métodos , Lagos/análise , Clima , Aquecimento Global , Ciclo Hidrológico , Wisconsin
18.
Integr Comp Biol ; 59(3): 503-516, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31270548

RESUMO

Temporal variation is a powerful source of selection on life history strategies and functional traits in natural populations. Theory predicts that the rate and predictability of fluctuations should favor distinct strategies, ranging from phenotypic plasticity to bet-hedging, which are likely to have important consequences for species distribution patterns and their responses to environmental change. To date, we have few empirical studies that test those predictions in natural systems, and little is known about how genetic, environmental, and developmental factors interact to define the "fluctuation niche" of species in temporally variable environments. In this study, we evaluated the effects of hydrological variability on fitness and functional trait variation in three closely related plant species in the genus Lasthenia that occupy different microhabitats within vernal pool landscapes. Using a controlled greenhouse experiment, we manipulated the mean and variability in hydrological conditions by growing plants at different depths with respect to a shared water table and manipulating the magnitude of stochastic fluctuations in the water table over time. We found that all species had similarly high relative fitness above the water table, but differed in their sensitivities to water table fluctuations. Specifically, the two species from vernal pools basins, where soil moisture is controlled by a perched water table, were negatively affected by the stochasticity treatments. In contrast, a species from the upland habitat surrounding vernal pools, where stochastic precipitation events control soil moisture variation, was insensitive to experimental fluctuations in the water table. We found strong signatures of genetic, environmental (plastic), and developmental variation in four traits that can influence plant hydrological responses. Three of these traits varied across plant development and among experimental treatments in directions that aligned with constitutive differences among species, suggesting that multiple sources of variation align to facilitate phenotypic matching with the hydrological environment in Lasthenia. We found little evidence for predicted patterns of phenotypic plasticity and bet-hedging in species and traits from predictable and stochastic environments, respectively. We propose that selection for developmental shifts in the hydrological traits of Lasthenia species has reduced or modified selection for plasticity at any given stage of development. Collectively, these results suggest that variation in species' sensitivities to hydrological stochasticity may explain why vernal pool Lasthenia species do not occur in upland habitat, and that all three species integrate genetic, environmental, and developmental information to manage the unique patterns of temporal hydrological variation in their respective microhabitats.


Assuntos
Asteraceae/fisiologia , Aptidão Genética/fisiologia , Traços de História de Vida , Dispersão Vegetal , Ciclo Hidrológico , Asteraceae/genética , Ecossistema , Estações do Ano
19.
Environ Pollut ; 251: 302-311, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31091494

RESUMO

Responses of streamflow and nutrient export to changing climate conditions should be investigated for effective water quality management and pollution control. Using downscaled climate projections and the Soil and Water Assessment Tool (SWAT), we projected future streamflow, sediment export, and riverine nutrient export in the St. Croix River Basin (SCRB) during 2020-2099. Results show substantial increases in riverine water, sediment, and nutrient load under future climate conditions, particularly under the high greenhouse gas emission scenario. Intensified water cycling and enhanced nutrient export will pose challenges to water quality management and affect multiple Best Management Practices (BMPs) efforts, which are aimed at reducing nutrient loads in SCRB. In addition to the physical impacts of climate change on terrestrial hydrology, our analyses demonstrate significant reductions in ET under elevated atmospheric CO2 concentrations. Changes in plant physiology induced by climate change may markedly affect water cycling and associated sediment and nutrient export. Results of this study highlight the importance of examining climate change impacts on water and nutrient delivery for effective watershed management.


Assuntos
Mudança Climática , Conservação dos Recursos Hídricos/tendências , Modelos Teóricos , Rios/química , Poluentes da Água/análise , Qualidade da Água/normas , Hidrodinâmica , Minnesota , Ciclo Hidrológico , Wisconsin
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