Surface Water Loads Research Articles

High-resolution mapping and multivariate technique (factor analysis) to support hydrogeochemical analysis and identification of surface water contamination

The study presented a high-resolution regional mapping of a significant Brazilian watershed, which is heavily influenced by mining, agriculture, and domestic/industrial effluents. Upper São Francisco Basin encompasses the largest karst area in the country and includes three important Brazilian biomes: Cerrado, Atlantic Forest, and Caatinga. Surface water (1418 samples) was collected during the dry season and was analyzed for physical-chemical parameters, cations, anions, and some metals. The spatial distribution and abundance of variables were assessed, and the processes controlling the sources of dissolved loads in surface waters were discussed. The results indicate that rock weathering is the primary factor controlling water chemistry, with a strong influence of carbonate and silicate minerals. Anthropogenic activities, particularly agriculture, play a key role in the chemical composition of the microbasins. Soil erosion and leaching processes also contribute significantly to the region, driven by land use practices and mineral extraction, which intensify erosion processes. The northern sector of the Upper São Francisco Basin, characterized by an arid climate and Caatinga vegetation, experiences low precipitation and high evapotranspiration rates. The VG stands out due to the presence of the karst zone and for the mixture of natural to anthropogenic sources.

Removal of sulfur and nitrogen pollutants in a sediment microbial fuel cell coupled with Vallisneria natans: Efficiency, microbial community structure, and functional genes

The rapid development of the economy has led to an increase in the sulfur and nitrogen load in surface water, which has the potential to cause river eutrophication and the emission of malodorous gases. A lab-scale sediment microbial fuel cell coupled with Vallisneria natans (P-SMFC) was designed for surface water remediation. The enhancement of pollutant removal performance of P-SMFC was evaluated in contrast to the SMFC system without plants (SMFC), the open-circuit control system with plants (C–P), and the open-circuit control system without plants (C–S), while illustrating the mechanisms of the sulfur and nitrogen transformation process. The results demonstrated that the effluent and sediment of P-SMFC had lower concentrations of sulfide compared to other systems. Furthermore, P-SMFC exhibited higher removal efficiency for COD (73.1 ± 8.7%), NH4+-N (80.5 ± 19.8%), and NO3−-N (88.5 ± 11.8%) compared to other systems. The closed-circuit conditions and growth of Vallisneria natans create a favorable ecological niche for functional microorganisms involved in power generation, sulfur oxidation, and nitrogen transformation. Additionally, metagenomic analysis revealed that multifunctional bacteria possessing both denitrification and sulfur oxidation genes, such as Thiobacillus, Dechloromonas, and Bacillus, may play simultaneous roles in metabolizing sulfur and nitrogen, thus serving as integral factors in maintaining the performance of P-SMFC. In summary, these findings provide a theoretical reference for the concurrent enhancement of sulfur and nitrogen pollutants removal in P-SMFC and will facilitate its practical application in the remediation of contaminated surface water.

Trace Metal Based Eco-Biological and Health Risk Status of Surface Water and Sediments of Noyyal River Basin, Tamil Nadu, India

ABSTRACT Pollution in the Noyyal river is a well-known and documented issue and recently, heavy metal contamination has become a serious issue requiring immediate attention. So, to understand the severity of heavy metal contamination in the surface water and sediments of the Noyyal river, a comprehensive study was conducted. About 27 surface water samples and 25 sediment samples were collected at different sites along the Noyyal river. The concentrations of heavy metals were determined using inductively coupled plasma mass spectrometry (ICP-MS). The Noyyal river’s surface water showed significant variations with nickel (Ni), copper (Cu), and zinc (Zn) concentrations exceeding acceptable limits for irrigation and aquatic life. Lead (Pb) concentrations were within acceptable limits for irrigation but potentially harmful to aquatic organisms. Noyyal river sediments also contained varying concentrations of chromium (Cr), copper (Cu), nickel (Ni), zinc (Zn), and gallium (Ga). Various assessment indices were employed to assess the eco-biological and human health risks associated with heavy metal contamination. The results highlighted alarming ecological and biological risks due to the accumulation of trace metals. Sediments exhibited high ecological risk (ERI values ranging from 43.81 to 371.43), while surface water samples intended for irrigation and aquatic purposes displayed extreme risks (ERI values exceeding 1200) to agricultural crops and aquatic organisms. The probability of toxicity to aquatic organisms, particularly benthic communities, was over 76% according to the biological risk assessment. The study also identified potential non-carcinogenic risks associated with metals like chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn) in the sediments. Moreover, elevated levels of Cr, Ni, and Cu in both sediments and surface water were likely to pose significant carcinogenic risks to exposed adults. Additionally, the heavy metal toxicity load in both surface water and sediments exceeded permissible limits, highlighting the urgent need for efficient removal strategies.

Challenges in dealing with water pollution issues in the West Java island

Water is the most basic need for all living things on Earth. The abundance of water on Earth makes humans indifferent to the efficient use of water, including human activities, which are said to cause increasing pollutant loads in surface waters. The western part of Java, consisting of DKI Jakarta, West Java and Banten, has the highest population pressure in all parts of Indonesia. This has led to a decrease in the environment's carrying capacity, especially in the region's water resources. Agricultural and industrial activities and household activities cause decreasing water availability in quantity and reducing water quality. This has become a trigger for water scarcity both in quantity and quality. Based on the data, the western part of Java Island has rivers with critical status. In this study, researchers will analyze water availability, water pollution problems, and challenges in overcoming water pollution, especially in the western part of Java Island. This study used a qualitative method by conducting a literature review. In overcoming water pollution, serious efforts need to be made, including increasing community participation in the manufacture of household-scale WWTPs, limiting the use of pesticides in agricultural activities, and improving water quality by improving land cover in the upstream area and increasing water absorption in urban areas.

Characterization of Sub-Catchment Stream and Shallow Groundwater Nutrients and Suspended Sediment in a Mixed Land Use, Agro-Forested Watershed

Excess nutrients and suspended sediment exports from agricultural watersheds are significant sources of global water quality degradation. An improved understanding of surface water and groundwater pollutant loads is needed to advance practices and policies. A study was conducted in an agricultural-forested catchment of the mid-Atlantic region of the United States. Stream water (SW) and shallow groundwater (SGW) samples were collected monthly between January 2020 and December 2021 from eight sub-catchment study sites. Samples were analyzed for nitrate (NO3-N), nitrite (NO2-N), total ammonia (NH3-N), total nitrogen (TN-N), orthophosphate (PO43-P), and total phosphate (TP-P) concentrations using spectrophotometric methods. Total suspended solids concentrations (mg/L) were quantified gravimetrically and volumetrically to estimate mean particle diameter (MZ, µm), particle surface area (CS, m2/mL), sample skewness (Ski), and particle size distributions (sand/silt/clay%). Results showed significant (p < 0.05) differences in nutrient concentrations and suspended sediment characteristics between SW and SGW between study sites. Differences were attributed to source water type and sub-watershed location. Principal components analysis indicated seasonal effects on water quality in summer months and connected land use with TSS, TN-N, and TP-P concentrations. Study results emphasize the importance of SGW water quality metrics for non-point source loading predictions to inform management decisions in agro-forested watersheds.

Study on the management efficiency of lanthanum/iron co-modified attapulgite on sediment phosphorus load

Attapulgite co-modified by lanthanum-iron (MT-LHMT) was used to study its effectiveness and mechanism in controlling phosphorus release from sediments. MT-LHMT has high adsorption capacity for phosphate and the maximum adsorption capacity of MT-LHMT to phosphate can reach 75.79 mg/g. The mechanism mainly involved electrostatic action, surface precipitation and ligand exchange between MT-LHMT bonded hydroxyl and phosphate to form La–O–P and Fe–O–P inner-sphere complexes. MT-LHMT has excellent adsorption performance in the pH range of 3–8. In addition to HCO3−, CO32− and HA− had a negative effect on the phosphorus removal of MT-LHMT, while NO3−, Cl−, SO42−, K+, Ca2+ and Mg2+ had a positive or no effect on phosphorus removal. MT-LHMT significantly reduced the risk of phosphorus release from overlying water in different dose effects and covering methods, as well as the unstable inactivation of flowing phosphorus, sediment dissolved reactive phosphorus (DRP) and available phosphorus with medium diffusion gradient in thin film in the sediment-water interface (Labile-PDGT). The MT-LHMT capping wrapped with fabric can reduce the risk of nitrogen release from sediment to overlying water more than only MT-LHMT capping. The results of this study showed that the MT-LHMT capping wrapped with fabric has high potential and can be used as an active capping material to manage the nitrogen and phosphorus load in surface water.

Effect of agricultural activities on surface water quality from páramo ecosystems.

Páramos are high mountain ecosystems strategic for water provision in South America. Currently, páramos are under threat due to agricultural intensification that impairs surface water sources. This research analyzed the effect of agriculture (spring onion—Allium fistulosum, potato—Solanum tuberosum, and livestock farming) on water quality in páramo ecosystems. A Hydrographic Unit upstream of the Jordan river catchment (Colombia) was selected and monitored in two different rainfall regimes, following the paired catchments and upstream-downstream approaches to compare water quality from natural and anthropic areas. Twenty-two parameters related to agricultural activities were analyzed (nutrients, salts, organic matter, sediments, and pathogens). The studied agricultural activities increased loads of surface water in quality in nitrates (0.02 to 2.56 mg N-NO3/L), potassium (0.13 to 1.24 mg K/L), and Escherichia coli (63 to 2718 FCU/100 mL), generating risks on the human health and promoting eutrophication. Total nitrogen and organic matter in the rainy season were higher than dry. BOD5, COD, turbidity, and E. coli were above international standards for direct human consumption. However, water could be used for irrigation, livestock watering, and aquatic life ambient freshwater. The results show that a small land-use change of almost 15% from natural páramo vegetation to agricultural uses in these ecosystems impairs water quality, limiting its uses, and the need to harmonize small-scale livelihoods in the páramo with the sustainability of ecosystem service provision.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-022-21709-6.

Potential of constructed wetlands to reduce nitrate pollution in agricultural catchments

Nitrate (NO3−) concentrations and loads are still above ecologically acceptable levels in many open waters, including coastal seas. Agricultural measures aimed at reducing the nitrogen (N) surplus in fields usually only have an effect in the long term. A short-term reduction of N pollution can be achieved through technical solutions such as surface-flow constructed wetlands (SFWs). We analyzed the effect of SFWs to reduce nitrate‑nitrogen (NO3−-N) loads in the tile-drained agricultural Warnow river basin (approx. 3000 km2) in northeastern Germany. The aim of the study was to transfer the results from individual SFWs to the scale of the river basin. For this purpose, an eco-hydrological model (Soil and Water Assessment Tool) was used to reproduce streamflow and NO3−-N loads on a monthly basis for the basin outlet and six subbasins. Measured water and compound fluxes depicted well with the model, so that we could conduct a scenario analysis. 97 locations for the establishment of SFWs in tile-drained areas throughout the river basin were identified and integrated into the model environment. The results indicate that the NO3−-N loads for the entire basin could be reduced from 902,200 kg yr−1 to 842,900 kg yr−1, which corresponds to a NO3−-N reduction of 6.6%. NO3−-N removal rates varied widely between the subbasins, ranging from 5 to 86 g m−2 yr−1, and were positively correlated with NO3−-N input loads. We conclude that SFWs, if installed area-wide, can help to significantly reduce NO3−-N loads in a river basin and can be an important component of a comprehensive management strategy to reduce N loads in surface waters to acceptable levels. The installation of SFWs should be prioritized in hot-spot areas where the greatest benefit can be expected.

Contribution of rain events to surface water loading in 3 watersheds in Canada’s Alberta Oil Sands region

Study regionIn the oil sands region of Canada, hydrology of rivers is strongly influenced by snowmelt and a shifting climate resulting in shortening of snow cover duration and increases in the frequency of rain events. Study focusTo evaluate the importance of rain events to these rivers, discharge and water quality sampling was conducted at river sites in this region. Two approaches were used to collect water quality samples: (1) event-based automated samplers that triggered repeated sampling in response to 10% increases in surface flow, and (2) an intensive program of routine sampling at daily, weekly or biweekly intervals from April 2013 to January 2014. New hydrological insights for the regionThe importance of rain events as contributors to loading of nutrients and priority pollutants differed temporally. During fall, when baseflow conditions prevailed, average daily loads differed when calculated using routine only versus routine + rain-event data. However, on an annual basis, the inclusion of rain-event sampling did not change pollutant loads. Thus, when assessing loads on an annual basis, rain event sampling may not provide enough benefit to warrant the additional logistical considerations for this remote region. However, when monitoring focuses on capturing fall conditions, efforts should be expanded to include rain event sampling in order to capture spikes in chemical concentration during this ecologically important time period. Predictions of a shorter snow season with more precipitation falling as rain rather than snow reinforce the need to adapt monitoring schemes to ensure that the timing and frequency of water chemistry sampling reflects changing climate and hydrological patterns.

Hydrological drought characterization based on GNSS imaging of vertical crustal deformation across the contiguous United States

Continuous Global Navigation Satellite System (GNSS) measurements allow us to track subtle elastic crustal deformation in the response to hydrological mass variations and provide an additional tool to independently characterize hydrological extremes (e.g., droughts and floods). In this study, we develop a time-varying GNSS imaging strategy that depends on the principal component analysis of GNSS-sensed vertical crustal displacement (VCD) in 2006–2020 and the monthly images of hydrology-induced deformation are generated for drought characterization across the contiguous United States. The first 12 principal components are selected in our time-varying imaging system, which account for 85% of the data variance. Considering that surface water loads are inversely correlated with the induced elastic vertical motions, we reverse the signs of the GNSS-imaged time series in all grids in subsequent studies (referred to as negative VCD (NVCD)). The GNSS-NVCD data generally correlate well with the water estimates from the Gravity Recovery and Climate Experiment (GRACE) and North American Land Data Assimilation System (NLDAS). Using the GNSS-imaged gridded NVCD products, we produce a GNSS-based drought severity index (GNSS-DSI) based on the climatological methodology, which is implemented by standardizing the GNSS NVCD anomalies that deviate from climatological normal. In most regions, strong linear correlations are accessible for GNSS-DSI relative to GRACE-DSI and the self-calibrating Palmer Drought Severity Index (scPDSI). The new drought monitoring tool, which is based solely on GNSS-measured vertical positions, is used for hydrological drought characterization (onset, end, duration, magnitude, intensity, and recovery); it succeeds in identifying well-documented historical droughts from the US drought monitor (USDM). Our study presents a new drought characterization framework using solely GNSS-measured hydrological loading displacements from a dense GNSS network, which has great potential to strengthen operational drought monitoring and assessment.

Passive sampling and ecohydrologic modeling to investigate pesticide surface water loading in the Zollner Creek watershed, Oregon, USA

In the U.S. Pacific Northwest and California contaminants entering surface water may harm Endangered Species Act (ESA) listed salmonid species and consequently there is ongoing concern regarding agricultural practices and resulting pesticide surface water loading may adversely impact salmonid species, their food web, and habitat. Characterizing pesticide exposure in surface water at the watershed scale and beyond is challenging due to uncertainty regarding pesticide use practices and sparse monitoring data. We report here a 2-year continuous deployment of passive sampling devices (PSDs) for monitoring of pesticides in surface water at the outflow of the Zollner Creek watershed located within the Willamette Basin, Oregon, USA. This watershed is predominately agricultural and within the geographic range of two ESA listed Pacific salmonid species. Grab and passive sampling monitoring data were used to evaluate the performance of a probabilistic application of the Soil and Water Assessment Tool (SWAT), a physically based process model which integrates institutional and local knowledge and expertise to investigate the relationship between land use practices and pesticide surface water loading at the watershed scale. SWAT estimated pesticide surface water concentrations for the pesticides chlorpyrifos and trifluralin followed temporal trend in PSD monitoring results and the 5th to 95th percentile range of estimated pesticide concentrations based on the probabilistic assessment encompassed 65–76% of the observed PSD concentrations. Evaluation of model estimates for metolachlor in surface water was challenged by insufficient publicly available grab sample monitoring data. A process to estimate pesticide surface water concentrations on biologically relevant time scales and comparison to screening level aquatic life benchmarks is presented. Additionally, model estimates were used to characterize the variance in surface water concentrations in this small hydrologically responsive watershed to determine grab sampling frequency adequate for model evaluation.

Potassium and its isotope behaviour during chemical weathering in a tropical catchment affected by evaporite dissolution

This work presents the systematic investigation of K contents and stable K isotopic compositions of surface waters, groundwater, wastewaters, suspended particles, bed sediments, and fertilizers in the Upper Mun Rive catchment, northeast Thailand. This area is of particular interest because its abundant potash deposits and intensive agricultural activities and urbanization, therefore this will improve our understanding whether the K isotope is robust enough to resist evaporite dissolution and anthropogenic disturbances on tracing silicate weathering in the highly weathered tropical region. The dissolved loads in surface waters and shallow groundwater display the large variation in δ41Kdiss values from −0.54‰ to +0.09‰ relative to suspended particles (−0.60‰ to −0.41‰), river bed sediments (−0.54‰ to −0.47‰), the upper continental crust (UCC, −0.44 ± 0.05‰), which agrees with the fact that 39K is preferentially retained in weathering products during silicate weathering. The wet and dry seasons difference ranging from −0.05‰ to +0.10‰ δ41K, which is slightly greater than our long-term analytical uncertainty of ±0.06‰. There is likely a limited K input from evaporites dissolution due to weak correlation between δ41Kdiss values and Cl concentrations or Cl/K ratios in the UMR and world rivers, while a major tributary Takhong River is clearly influenced by the contribution of domestic sewage with lower δ41K and higher δ15N values. Based on a mass balance of K budge, the dissolved K in the UMR is mostly (>90%) derived from silicate weathering in the unpolluted area, this is consistent with previous studies of large river basins, and the evaporite dissolution and other non-silicate sources may not strongly influence dissolved K and δ41Kdiss values in rivers, even in evaporite-rich catchment. Therefore, K isotopes cannot be used as lithological tracers in catchments, rather the K isotopic fractionation mainly occurs during silicate weathering, such as the formation of secondary minerals which favor light isotope. Hence, the mechanism of K isotopic fractionation linked to secondary minerals K uptake needs further consideration. Overall, these results clearly show that K isotopes could be an ideal indicator to constrain silicate weathering processes and anthropogenic inputs at catchment scale.

Biologically facilitated precipitation of metals in low-Fe waters at the sulphidic Mount Chalmers mine, Queensland, Australia

Biofilms enriched in copper and zinc have formed at the aqueous-air interface and in subaqueous environments at the abandoned Mount Chalmers volcanic-hosted massive sulphide mine in Queensland, Australia. Remedial activity on site has limited acid mine drainage and associated iron-rich discharges, and surface waters leave the site at pH ~ 7. Unlike in many other oxygenated metal-sulphide environments, (bio)precipitates at this site conspicuously lack iron and manganese. Hence, this site provides an opportunity to observe the interactions of microorganisms with other metals, unobscured by the usually dominant Fe and Mn processes. Small subunit rRNA gene sequencing analyses suggest that biofilms are dominated by neutrophilic species of moss, diatoms, fungi and rotifera, as well as minor cyanobacteria and photosynthesising microorganisms adapted to high metal loads (e.g., up to ~ 8 mg/L Zn and ~ 2 mg/L Cu) in surface waters. Microbial communities formed metal-bearing biofilms on a time-scale of months. Investigations of these biofilms using scanning electron microscopy with electron dispersive x-ray spectroscopy and synchrotron-based X-ray fluorescence microscopy indicate that biofilms are intimately associated with metals, especially Cu and Zn, with Cu concentrations of up to ~ 20 wt%. Microorganisms on site help to catalyse dissolution and precipitation processes, although abiotic precipitation and anthropogenic intervention (raised pH) are the main geochemical drivers of remediation. Our observations suggest that microorganisms catalysed metal accumulation processes by (1) providing a substrate to which metals can attenuate during wetting and drying cycles and (2) micro-fossilisation induced by microorganism-metal interactions. This site provides a unique view of the impacts of rehabilitation processes on the microbial community, and vice versa. However, small numbers of bacteria that can contribute to acid mine drainage remain in the biome, ready to proliferate should remediation activities wane. Processes identified at this site are also relevant for potentially economic, enhanced metal extraction from legacy mine sites.

Modeling Northern Hemispheric Ice Sheet Dynamics, Sea Level Change, and Solid Earth Deformation Through the Last Glacial Cycle

AbstractRetreat or advance of an ice sheet perturbs the Earth's solid surface, rotational vector, and the gravitational field, which in turn feeds back onto the evolution of the ice sheet over a range of timescales. Throughout the last glacial cycle, ice sheets over the Northern Hemisphere have gone through multiple growth and retreat phases, but the dynamics during these phases are not well understood. In this study, we apply a coupled ice sheet‐glacial isostatic adjustment model to simulate the Northern Hemisphere Ice Sheets over the last glacial cycle. We focus on understanding the influence of solid Earth deformation and gravitational field perturbations associated with surface (ice and water) loading changes on the dynamics of terrestrial and marine‐based ice sheets during different phases of the glacial cycle. Our results show that solid Earth deformation enhances glaciation during growth phases and melting during retreat phases in terrestrial regions through ice‐elevation feedback, and gravitational field perturbations have a stabilizing influence on marine‐based ice sheets in regions such as Hudson Bay in North America and Barents and Kara Seas in Eurasia during retreat phases through sea‐level feedback. Our results also indicate that solid Earth deformation influences the relative sensitivity of the North American and Eurasian ice sheets to climate and thus the timing and magnitude of their fluctuations throughout the last glacial cycle.

Shifts in precipitation and agricultural intensity increase phosphorus concentrations and loads in an agricultural watershed

Fertilizers and manure applied to cropland to increase yields are often lost via surface erosion, soil leaching, and runoff, increasing nutrient loads in surface and sub-surface waters, degrading water quality, and worsening the ‘dead zone’ in the Gulf of Mexico. We leverage spatial and temporal variation in agricultural practices and precipitation events to examine how these factors affect stream total phosphorus (TP) concentrations and loads in the Sugar River (Wisconsin), recently listed as impaired. To perform our analysis, we first collected water quality data from 1995 to 2017 from 40 sites along the Sugar River and its tributaries. Starting in 2004, three dairy farms expanded to become concentrated animal feeding operations (CAFOs) in this watershed. We then estimated how time of year, stream position, discharge volume, and proximity to the newly expanded CAFOs affected TP concentrations and loads. Total P concentrations, which ranged from 0.02 to 1.4 mg/L and often exceeded the EPA surface water standard of 0.1 mg/L, increased with increases in stream discharge and proximity to dairy operations, peaking in early spring to mid-summer coincident with extreme precipitation events. Our empirical analysis also shows that TP concentrations downstream from the newly permitted CAFOs increased by 19% relative to upstream concentrations. When examining total daily phosphorus loads (concentration × discharge) from this 780 km2 watershed, we found that loads ranged from 5.88 to 4801 kg. Compared to upstream TP loads, those downstream from the CAFOs increased by 91% after the expansions – over four times that of concentration increases – implying that the rate of downstream phosphorus transfer has increased due to CAFO expansion. Our results argue for standards that focus on loads rather than concentrations and monitoring that includes peak events. As agriculture intensifies and extreme rainfall events become more frequent, it becomes increasingly important to limit soil and TP runoff from manure and fertilizer. Siting CAFOs carefully, limiting their size, and improving farming practices in proximity to CAFOs in spring and early summer could considerably reduce nutrient loads.

Marked spatio-temporal point patterns, periodicity analysis and earthquakes: an analytical extension including hypocenter depth

The longitude, latitude and depth of the hypocenter in 3-D space and the date and time of rupture makes an earthquake a “point” in a spatio-temporal point pattern, observed over a region and months, years or decades. The magnitude of earthquakes marks the point pattern, as would hypocenter depth do if only the longitude and latitude of epicenters were used for location in 2-D space. Stochastic declustering, based on a space–time ETAS model (ETAS: epidemic-type aftershock sequence), is a procedure that can be applied in the preliminary stage of an earthquake catalog data analysis. Stochastic declustering procedures have underlying assumptions, such as the time independence of the background intensity function whether the spatial framework is 2-D or 3-D, and a separate treatment of hypocenter depth from longitude and latitude when the spatial framework is 3-D. Cyclical processes in the Earth, including tides and seasonal surface water loads, can introduce periodic behavior in earthquake occurrence and related variables. The effects of ETAS-based 2-D and 3-D declustering on the outcome of periodicity analyses performed from the resulting earthquake data catalogs are studied. The research objectives and statistical challenges include the detection of periodicities for hypocenter depth in addition to monthly earthquake number, and the risk of missing observations for hypocenter depth when the monthly earthquake number after declustering is zero. A version of the method of multi-frequential periodogram analysis (MFPA) that allows for missing observations in the input temporal series is presented in detail, and applied to hypocenter depth (monthly mean and median) for central and northern California from January 2006 to December 2014. The results obtained for the 2-D and 3-D declustered catalogs are compared with those for the original catalog for this region. A semiannual periodicity in hypocenter depth is detected for the original and 2-D declustered catalogs, and fitted with the goal of relating it to periodicities found in the time series of monthly earthquake numbers. Using these results for central and northern California earthquakes, some of the assumptions on the intensity function of the spatio-temporal point process in stochastic declustering are discussed and future research perspectives are proposed.

Sources and concentrations of nutrients in surface runoff from waterfront homes with different landscape practices

Development along Florida's coastal waterways has led to significant degradation in water quality over time. Numerous sources have contributed to increased nutrient loads in surface waters. Nitrogen (N) and phosphorus (P) pollution from urban fertilizer use has been addressed at the state, county, and municipality level yet the success of these efforts is rarely evaluated. This study aimed to validate these efforts by assessing the source and concentration of nutrients from surface water associated with waterfront homes with or without Florida Friendly Landscaping™, a nonstructural best management practice. The objectives were: to compare nutrient concentrations in runoff from differing landscape designs; compare the NO3− isotopic signature to that of known N sources; and evaluate the impact of a fertilizer ordinance blackout that is in effect during the wet season. Results from the study indicate no statistical reduction in the nutrient concentration of lawn runoff from either landscape design or the implementation of a fertilizer blackout ordinance. Results show that the sources of N in home landscapes are highly variable and cannot be solely attributed to fertilizer sources and highlight the influence of atmospheric depositions and soil nutrient pools which contribute 53–65% of the nitrate in lawn runoff. Nutrient management strategies need to address multiple sources of urban nutrients and mitigation efforts will not be immediate.

Optimization and application of hollow fiber liquid-phase microextraction and microwave-assisted extraction for the analysis of non-steroidal anti-inflammatory drugs in aqueous and plant samples.

Human consumption of non-steroidal anti-inflammatory drugs (NSAIDs) is increasing, which poses a great risk of pollution by these pharmaceuticals on the aquatic environment. Therefore, this study reports the optimization of microwave-assisted extraction using water as a green solvent and hollow fiber liquid-phase microextraction (HF-LPME) methods followed by high-performance liquid chromatography-high resolution mass spectrometry analysis of NSAIDs in wastewater and aquatic plant, Eichhornia crassipes. The optimized MAE resulted in efficient transfer of selected NSAIDs from plant samples into the aqueous phase yielding the recoveries ranging from 91 to115%. A multivariate approach based on half fractional factorial and central composite design was used during the optimization of HF-LPME. Under the optimized conditions, the maximum enrichment factors for naproxen, fenoprofen, diclofenac, and ibuprofen were 49, 126, 93 and 156, respectively. The overall analytical method recoveries ranged from 86 to 116% while the limits of quantitation for wastewater and plant samples ranged from 0.09 to 0.59μgL-1 and from 0.11 to 0.59μgkg-1, respectively. The precision of the proposed analytical method which was measured in terms of RSD values did not exceed 5%. Naproxen was the most abundant compound in both wastewater and the Eichhornia crassipes plant samples with concentrations of up to 3.30μgL-1 and 10.97μgkg-1, respectively. The detection of NSAIDs in Eichhornia crassipes means this plant has the ability to bioaccumulate pharmaceutical load in surface water.

Quantifying Groundwater to Sediment and Surface Water Loads for Mercury and Lead in Tidal Wetlands: Case Study

AbstractPortions of the marsh sediments at the LCP Chemicals Georgia Site (Site) were dredged and removed in 1999. However, sediment samples obtained four years later showed 0.54 mg/kg average merc...

Monitoring and assessment of pollution load in surface water of River Ganga around Kanpur, India: A study for suitability of this water for different uses

Abstract A study was conducted during April 2016–March 2017 to evaluate the surface water quality of River Ganga at selected Ghats (stairway in India leading down to a landing on the water) of Kanpur by analyzing the water samples for physico-chemical properties with emphasis on heavy metals. The metals detected were: Cr, Cd, Pb, As, Se, Mn, Fe, Co, Ni, Cu, Zn, and Mo whose concentrations ranged between 27.85-37, ND-2.92, 21.85-166.62, 39.49-129.49, 3.02-23.96, 18.20-335.69 ± 9, 836-8074, 0.53-3.40, 12.41-238.70, 23.62-256.36, 54.18-213, 19.2-454.54 μ gl − 1, respectively. Of all the metals found at the study site, the concentration of Cr, Fe Cu, As and Pb in all the samples were higher than the limit prescribed by Bureau of Indian Standard (BIS) and World Health Organization (WHO) and Food and Agricultural Organization (FAO) for drinking water, water for aquatic life and that for irrigation. The results of pollution indices, show that the river water is not suitable for drinking, aquatic life even not for irrigation uses except at Bithoor and Sarsaiyaghat where it was slightly to moderately affected and can be use for irrigation purpose only after proper treatment.