Wastewater Inputs Research Articles

Nutrients and chlorophyll-a concentration in Socah Estuary receiving shrimp pond waste, Bangkalan Regency

This study investigates the nutrient content, water quality, and its relationship with chlorophyll-a in the Socah Estuary, Bangkalan Regency. The research was conducted in four stations. Determination of nitrate and nitrite in samples was performed by the colorimetric method. Meanwhile, phenate and Nessler reagent spectrophotometric methods were used to determine the ammonia and ammonium content in samples, respectively. The phosphate and chlorophyll-a were determined using ascorbic acid and spectrophotometry, respectively. The Spearman rank correlation was used to measure the degree of relationship between nutrients and chlorophyll- a content. Based on the results of Spearman rank correlation, the nitrate showed the strongest correlation (rho = 0.76) compared to other nutrients. Moreover, the increased chlorophyll-a level in the water will be closely related to the increased nitrate level. According to the value of Secchi depth, nutrients, and chlorophyll-a concentration, eutrophic is a trophic state in Socah Estuary. This condition is caused by the input of shrimp pond wastewater which triggers nutrient enrichment, decreasing the water quality and increasing the phytoplankton biomass in Socah Estuary.

Vertical and horizontal distribution model of lead (Pb) in Padelegan Waters, Pademawu District, Pamekasan Regency

Seawater quality is importantly used in salt production, but it could be contaminated due to input of anthropogenic wastewater. This study aims to understand the quality of the water and the content of Pb in seawater, which will be used as raw material for salt production. Descriptive research methods and purposive sampling methods were used for the research method and the determination of the sampling respectively. Sampling of seawater was carried out water sampler, followed by analysis of heavy metal Pb based on APHA 1998 using Atomic Absorption Spectrophotometry (AAS). The concentration of Pb on the surface ranged from 0.6332 to 1.0815 mg/L, in the water column from 0.5842 to 1.0516 mg/L, and in the bottom waters from 0.5571 to 0.9375 mg/L, according to the findings. The horizontal distribution of the Pb showed an increasing trend towards the sea with concentrations ranging from 0.6332 to 1.0815 mg/L. Meanwhile, the concentrations of Pb in surface waters increased vertically, ranging from 0.5571 to 1.0815 mg/L. The horizontal distribution is higher towards open sea, while vertical distribution is higher towards the water surface. Seawater in vicinity of study area is still probably used although caution must be observed regarding to the Pb content.

The Raphidiopsis (= Cylindrospermopsis) raciborskii pangenome updated: Two new metagenome-assembled genomes from the South American clade

Two Raphidiopsis (=Cylindrospermopsis) raciborskii metagenome-assembled genomes (MAGs) were recovered from two freshwater metagenomic datasets sampled in 2011 and 2012 in Pampulha Lake, a hypereutrophic, artificial, shallow reservoir, located in the city of Belo Horizonte (MG), Brazil. Since the late 1970s, the lake has undergone increasing eutrophication pressure, due to wastewater input, leading to the occurrence of frequent cyanobacterial blooms. The major difference observed between PAMP2011 and PAMP2012 MAGs was the lack of the saxitoxin gene cluster in PAMP2012, which also presented a smaller genome, while PAMP2011 presented the complete sxt cluster and all essential proteins and clusters. The pangenome analysis was performed with all Raphidiopsis/Cylindrospermopsis genomes available at NCBI to date, with the addition of PAMP2011 and PAMP2012 MAGs (All33 subset), but also without the South American strains (noSA subset), and only among the South American strains (SA10 and SA8 subsets). We observed a substantial increase in the core genome size for the ‘noSA’ subset, in comparison to ‘All33’ subset, and since the core genome reflects the closeness among the pangenome members, the results strongly suggest that the conservation level of the essential gene repertoire seems to be affected by the geographic origin of the strains being analyzed, supporting the existence of a distinct SA clade. The Raphidiopsis pangenome comprised a total of 7943 orthologous protein clusters, and the two new MAGs increased the pangenome size by 11%. The pangenome based phylogenetic relationships among the 33 analyzed genomes showed that the SA genomes clustered together with 99% bootstrap support, reinforcing the metabolic particularity of the Raphidiopsis South American clade, related to its saxitoxin producing unique ability, while also indicating a different evolutionary history due to its geographic isolation.

Berdan Nehri Yüzey Sedimanlarında Ekolojik ve Sağlık Riski Değerlendirmesi (Mersin-Türkiye)

Berdan River (Tarsus-Mersin) is one of the major rivers flowing into the coastal region of Northeastern (NE) Mediterranean Sea. Determination of water and sediment quality is of great importance for the sustainable management of streams and rivers. In this study, it was aimed to determine heavy metal pollution status and health risk assessment of sediments in Berdan River caused by human activities. Study findings showed that while nickel and cadmium pollution were determined at all sampling points of the Berdan River Basin, there was a regional pollution of lead and zinc caused by anthropogenic pressures due to industrial and agricultural activities as well as domestic wastewater and atmospheric inputs into the Berdan River. Furthermore, the potential health risk assessment of sediments indicated significant health hazards for the children and adults living in the study area from the carcinogenic lead, chromium and nickel.

The distribution and characterisation of microplastics in air, surface water and sediment within a major river system

Rivers are key pathways for the transfer of microplastics (MP) to marine environments. However, there are considerable uncertainties about the amount of microplastics transported by rivers to the ocean; this results in inaccuracies in our understanding of microplastic quantity and transport by freshwater systems. Additionally, it has been suggested that rivers may represent long-term sinks, with microplastics accumulating in sediment due to their high density or other biological, chemical, and physical factors. The atmosphere is also an important pathway by which airborne microplastics may enter aquatic habitats. Here, we compare for first time microplastics type and concentration in these key environmental mediums (air, water and sediment) along a major river (Ganges), from sea to source to understand 1) the abundance, 2) the spatial distribution, and 3) characteristics. Mean microplastic abundance settling from the atmosphere was 41.12 MP m2 day−1; while concentrations in sediment were 57.00 MP kg−1 and in water were 0.05 MP L−1. Across all sites and environmental mediums, rayon (synthetically altered cellulose) was the dominant polymer (54–82 %), followed by acrylic (6–23 %) and polyester (9–17 %). Fibres were the dominant shape (95–99 %) and blue was the most common colour (48–79 %). Across water and sediment environmental mediums, the number of microplastics per sample increased from the source of the Ganges to the sea. Additionally, higher population densities correlated with increased microplastic abundance for air and water samples. We suggest that clothing is likely to be the prominent source of microplastics to the river system, influenced by atmospheric deposition, wastewater and direct input (e.g. handwashing of clothes in the Ganges), especially in high density population areas. However, we suggest that subsequent microplastic release to the marine environment is strongly influenced by polymer type and shape, with a large proportion of denser microplastics settling in sediment prior to the river discharging to the ocean.

High spatiotemporal resolution analysis on suspended sediment and microplastic transport of a lowland river

The suspended sediment (SS) and microplastic (MP) transport in rivers is quite a complex process, influenced by several spatially and temporally changing factors (e.g., hydrology, sediment availability, human impact). Researchers usually investigate these factors individually and based on limited repetition in space and time. Therefore, this study aims to compare the driving factors of SS and MP transport by applying dense temporal (72 measurements) and spatial monitoring (at 26 sites). This study was performed on the medium-sized Tisza River, Central Europe. The suspended sediment concentration (SSC) was measured by water sampling and estimated based on Sentinel-2 images, while MP concentration was measured by pumping of water (1 m3). The SSC of the Tisza varied between 12.6 and 322.5 g/m3, whereas the MP concentration ranged 0–129 item/m3. Most of the transported particles were fibers (81–98 %), thus, it was assumed that MPs originated from wastewater. The results reflect that the hydrological conditions basically influence the SS and MP concentrations, as a strong positive correlation was found (ρSSC–MP = 0.6) between them during a year; however, the correlation during floods (minor floods: ρ = 0.63; medium floods: ρ = 0.41) was higher than at low stages (ρ = 0.1). It was assumed that run-off and mobilization of channel materials both contribute to increased SS and MP transport during floods. In contrary, the importance of mobilization of channel materials and wastewater input increase during low stages. The repeated measurements revealed that slope and velocity conditions, proximity of sources, tributaries, and dams influence the longitudinal changes in SS and MP concentrations. However, the effects of tributaries and dams are ambiguous (especially for MP) and require further research. The longitudinal measurements were conducted at low stages; hence, moderate negative correlations (ρ2021 = −0.35; ρ2022 = −0.41) were found between the SS and MP concentrations. Therefore, additional monitoring during (overbank) floods and denser spatial sampling are required to precisely reveal the spatiotemporal changes of SS and MP concentrations in rivers.

Wastewater inputs reduce the CO2 uptake by coastal oceans

Every year a large quantity of wastewater is generated worldwide, but its influence on the carbon dioxide (CO2) uptake by coastal oceans is not well understood. Here, sea surface CO2 partial pressure (pCO2) and air-sea CO2 flux were examined in the Jiaozhou Bay (JZB), a temperate coastal bay strongly disturbed by wastewater inputs. Monthly surveys from April 2014 through March 2015 showed that surface pCO2 in the JZB substantially varied both temporally and spatially between 163 μatm and 1222 μatm, with an annual average of 573 μatm. During April–December, surface pCO2 was oversaturated with respect to the atmosphere, with high values exceeding 1000 μatm in the northeastern part of the bay, where seawater salinity was low mainly due to the inputs of wastewater with salinity close to zero. During January–March, surface pCO2 was undersaturated, with the lowest value of <200 μatm also mainly in the northeastern part because of low water temperature and strong biological production. Over an annual cycle, apparently sea surface temperature dominated the monthly variation of surface pCO2 in this shallow bay, while wastewater inputs and related biological production/respiration dominated its spatial variability. Overall, the JZB was a net CO2 source to the atmosphere, emitting 9.6 ± 10.8 mmol C m−2 d−1, unlike its adjacent western part of the Yellow Sea and most of the temperate coastal oceans which are a net CO2 sink. This was possibly associated with wastewater inputs that cause high sea surface pCO2 via direct inputs of CO2 and degradation of organic matter. Thus, from this viewpoint reducing wastewater discharge or lowering CO2 levels in discharged wastewater may be important paths to enhancing the CO2 uptake by coastal oceans in the future.

Residual circulations and wind conditions affect the transport and distribution of Pb

Hydrodynamic conditions affect the dispersion and transportation of pollutants. In this study, 102 surface water samples were collected and numerical simulations were conducted by coupling SWAT (Soil and Water Assessment Tool) and MIKE 21 models to investigate the effect of hydrodynamic conditions on the transport and distribution of Pb in Jiaozhou Bay, China. The tidal current velocity was lowest at flood tide and highest at ebb tide in summer, mainly due to the strong runoff caused by heavy rainfall in summer. The velocity of the residual current near the bay mouth was high, with an average value of 0.32 m/s. The residual currents had alternating clockwise and counter-clockwise circulations of different diameters in the bay mouth and the northern bay. The circulation diameter in the bay mouth area was large, and the circulation extended from the bay mouth to the Yellow Sea. Due to the small circulation diameters and opposite directions of the adjacent circulations in the northern bay, pollutants were easily trapped there. The dissolved Pb particles released from the northern bay mainly migrated to the shore, while the dissolved Pb particles released from the bay mouth tended to migrate to the Yellow Sea. The dominant wind directions and residual currents were the main driving forces affecting the trajectories of the particle tracking simulations. The dissolved Pb concentration in the water was high near shore and in the southwestern bay and under the combined effects of tidal residual current, wind force, and river and wastewater inputs. The low Pb concentration near the bay mouth was mainly influenced by the high residual current velocity. These results can provide improved insights into the mechanism of Pb transport and distribution in a semi-enclosed bay.

Comparative study of pristine and polluted estuaries in Souss Massa National Park (Morocco): Implications for conservation strategies

Estuaries are among the ecosystems most affected by human actions worldwide. Economic development in Morocco puts pressure on these aquatic systems, making them vulnerable. This study compares the state of benthic communities between a pristine estuary (Massa estuary) and a polluted one (Souss estuary). Both ecosystems belong to the Souss Massa National Park (SMNP), registered in the Ramsar list for its ecological importance as a Marine Protected Area (MPA). Twenty-one benthic species were identified in the pristine estuary, but only six species in the polluted one. Similar differences were detected for the species abundance and biomass. The total organic matter and the water-dissolved oxygen also revealed a notable negative effect of the sewage discharge. The results confirmed human disturbances on faunal communities related to direct wastewater inputs and indirect anthropogenic activities such as the urbanization and the litter generation. A combination of ending wastewater discharge and adding tertiary-level water treatment plants is recommended. The findings highlight the importance of MPAs in conservation strategies if coupled with continuous surveillance of pollution.

New insights into the distribution, potential source and risk of microplastics in Qinghai-Tibet Plateau

Microplastics (MPs) as emerging contaminants have become a major global concern, however, the distribution and origin of MPs in Qinghai-Tibet Plateau (QTP) and their impacts on ecosystem are poorly known. Hence, we systematically evaluated the profile of MPs on the representative metropolitan locations of Lhasa and Huangshui Rivers and the scenic sites of Namco and Qinghai Lake. The average abundance of MPs in the water samples was 7020 items/m3, which was 34 and 52 times higher than those for the sediment (206.7 items/m3) and soil samples (134.7 items/m3), respectively. Huangshui River had the highest levels, followed by Qinghai Lake, Lhasa River and Namco. Human activities rather than altitude and salinity impacted the distribution of MPs in those areas. Besides the consumption of plastic products by locals and tourists, laundry wastewater and exogenous tributary inputs, the unique prayer flag culture also contributed to the MPs emission in QTP. Notably, the stability and fragment of MPs were crucial for their fate. Multiple assessment models were employed to evaluate the risk of MPs. PERI model took MP concentration, background value and toxicity into account, comprehensively describing the risk differences of each site. The large PVC proportion in Qinghai Lake posed the highest risk. Furthermore, concerns should be raised about PVC, PE and PET in Lhasa and Huangshui Rivers, and PC in Namco Lake. Risk quotient suggested that aged MPs in sediments slowly released biotoxic DEHP and should be cleaned up promptly. The findings offer baseline data of MPs in QTP and ecological risks, providing important support for the prioritization of future control measures.

Impacts of anthropogenic discharge on distribution, mass budget, and long-term risk of total mercury in coastal region: A case study of the Jiaozhou Bay, China

Mercury (Hg) as a toxic pollutant in marine systems have been paid more attention. The Jiaozhou Bay (JZB) is located at the western coast of the Yellow Sea surrounded by Qingdao city, a developed city in China. >10 rivers and several sewage treatment plants carry lots of Hg input it, increasing the environmental risks JZB facing. However, there is still a lack of knowledge on its cycling in the JZB, limiting sound understanding of Hg fate in coastal regions. To address these needs, four cruises were conducted in different seasons, to investigate distribution, influencing factors, and mass budget of total Hg (THg) in the JZB. Higher THg concentrations were determined in seawater (22.8 ± 13.9 ng L−1) and sediment (148 ± 107 ng g−1), indicating serious Hg pollution in the JZB. Temperature, salinity in water and enrich factor (EF) in sediment were identified to be possible environmental factors influencing THg distribution in the JZB. Mass budget of THg showed that anthropogenic discharge (river, wastewater input, and atmospheric deposition) was dominant source of THg in the JZB. The results of statistical analyses and mass budget of THg also indicated that anthropogenic discharge plays important roles in long-term risk of THg in the JZB. These results suggested that anthropogenic discharge comprehensively affects distribution, mass budget, and long-term risk of THg in coastal systems. The outcomes highlighted that regular investigations of Hg cycling should be conducted to assess Hg pollution in coastal ecosystems. Our study also shed new light on control of long-term risk posed by Hg in marine systems according to investigations of Hg cycling and link between Hg contamination and other pollutant (e.g., nutrient).

Using in situ measurements of optical brighteners for rapid reconnaissance of wastewater inputs to water resources

Untreated wastewater entering the environment through leaking infrastructure and sewer overflows threatens both human and aquatic health. Water managers therefore need low cost, in situ methods to detect sewage contamination in real time to promptly employ mitigation strategies. However, wastewater has traditionally been identified in waterbodies using chemical and microbial tracers and indicators that can be non-unique to wastewater and often require complex and expensive analyses. Optical brighteners (synthetic brightening compounds present in laundry detergents and paper products) are emerging as ideal tracers of wastewater because of their quick and inexpensive field detection using handheld fluorometers. To test the efficacy of optical brighteners as standalone, in situ wastewater tracers, field readings of their fluorescence were compared with traditional wastewater analytes (e.g., B, F−, microbial indicators) at multiple points in time and space for a suburban watershed (Fishpot Creek, Saint Louis, Missouri, United States). We also used chemical tracers in three mixing models of endmembers to assess the wastewater fraction across the watershed. Compared to other analytes, optical brightener fluorescence measurements had the strongest correlation with wastewater infrastructure density (r = 0.71, p < 0.05), indicating their utility as tracers. All our endmember mixing models employing optical brightener readings predicted positive and significant correlations between the untreated wastewater fraction in streamflow and sewer pipe density at each site (r ≥ 0.77, p < 0.05). While using optical brightener readings for wastewater detection has some limitations (e.g., minor photodegradation), we found them to be more robust tracers than other analytes. Thus, optical brightener fluorescence measurements are an ideal initial screening tool for identifying wastewater contributions to the environment.

Investigating bio-remediation capabilities of a constructed wetland through spatial successional study of the sediment microbiome

Constructed wetlands (CWs) are engineered environments designed to utilise natural processes to treat urban or industrial wastewater, with the core driver of the bioremediation process provided by the microorganisms present within. This study isolated 32 bacterial strains from sediment across the Sardar Bherry CW to find candidates with remediation properties and to understand how the physiochemical gradient from wastewater input influences the functional properties of the bacteria present. Bacterial isolates recovered closer to the wastewater effluence were more likely to be pathogenic, with increased haemolytic activity, causing high rates of fish mortality. In contrast, isolates recovered further from the wastewater source were observed to be non-pathogenic and have increased inhibitory effect against pathogenic strains. Extracellular proteins extracted from non-pathogenic isolates also appeared to be effective at inhibiting the growth of pathogenic bacteria, including multidrug resistant strains. Non-pathogenic isolates recovered across all sampling sites displayed the ability to reduce high levels of ammonia in solution during laboratory testing. Antibiogram assays of the recovered isolates showed a relatively high rate of multidrug resistant or marginally resistant bacteria across all sampling sites, highlighting a potential limitation within the CW bioremediation process in mitigating antibiotic resistant strains. This isolate based study provided an avenue to understand the influence of spatial succession from wastewater effluence on bacterial characteristics, as well as obtain candidates that can be further investigated for optimisation in bioremediation efforts. The cultured isolates can supplement future environmental sequencing studies by providing wet lab specimens to compare (meta)genomic information discovered within the CW ecosystem.

Acesulfame allows the tracing of multiple sources of wastewater and riverbank filtration

Aquifers providing drinking water are increasingly threatened by emerging contaminants due to wastewater inputs from multiple sources. These inputs have to be identified, differentiated, and characterized to allow an accurate risk assessment and thus ensure the safety of drinking water through appropriate management. We hypothesize, that in climates with seasonal temperature variations, the sweetener acesulfame potassium (ACE) provides new pathways to study wastewater inputs to aquifers. Specifically, this study investigates the temperature-driven seasonal oscillation of ACE to assess multiple sources of wastewater inputs at a riverbank filtration site. ACE concentrations in the river water varied from 0.2 to 1 μg L−1 in the cold season (T < 10 °C) to 0–0.1 μg L−1 in the warm season (T > 10 °C), due to temperature-dependent biodegradation during wastewater treatment. This oscillating signal could be traced throughout the aquifer over distances up to 3250 m from two different infiltration sources. A transient numerical model of groundwater flow and ACE transport was calibrated over hydraulic heads and ACE concentrations, allowing the accurate calculation of mixing ratios, travel times, and flow-path directions for each of the two infiltration sources. The calculated travel time from the distant infiltration source was of 67 days, while that from the near source was of 20 days. The difference in travel times leads to different potential degradation of contaminants flowing into the aquifer from the river, thus demonstrating the importance of individually assessing the locations of riverbank infiltration. The calibrated ACE transport model allowed calculating transient mixing ratios, which confirmed the impact of river stage and groundwater levels on the mixing ratio of the original groundwater and the bank filtrate. Therefore, continuous monitoring of ACE concentrations can help to optimize the management of the water works with the aim to avoid collection of water with very short travel times, which has important regulative aspects. Our findings demonstrate the suitability of ACE as a transient tracer for identifying multiple sources of wastewater, including riverbank filtration sites affected by wastewater treatment plant effluents. ACE seasonal oscillation tracking thus provides a new tool to be used in climates with pronounced seasonal temperature variations to assess the origins of contamination in aquifers, with time and cost advantages over multi-tracer approaches.

Seasonal biodegradation of the artificial sweetener acesulfame enhances its use as a transient wastewater tracer

The persistence of the artificial sweetener acesulfame potassium (ACE) during wastewater treatment and subsequently in the aquatic environment has made it a widely used tracer of wastewater inputs to both surface water and groundwater. However, the recently observed biodegradation of ACE during wastewater treatment has questioned the validity of this application. In this study, we assessed the use of ACE not only as a marker of wastewater, but also as a transient wastewater tracer that allows both the calculation of mixing ratios and travel times through the aquifer as well as the calibration of transient groundwater flow and mass transport models. Our analysis was based on data obtained in a nearly 8-year river water and groundwater sampling campaign along a confirmed wastewater-receiving riverbank filtration site located close to a drinking water supply system. We provide evidence that temperature controls ACE concentration and thus its seasonal oscillation. River water data showed that ACE loads decreased from 1.5–4 mg·s−1 in the cold season (December to June; T<10 °C) to 0–0.5 mg·s−1 in the warm season (July to November; T>10 °C). This seasonal variability of >600% was detectable in the aquifer and preserved >3 km, with ACE concentrations oscillating between <LOQ in the warm season up to 1 μg·L−1 in the cold season. The large seasonal variation in ACE concentrations during wastewater treatment, compared to the other sweeteners (sucralose, cyclamate, and saccharin) and chloride enables its use as a transient tracer of wastewater inflows and riverbank filtration. In addition, the arrival time of the ACE concentration peak can be used to estimate groundwater flow velocity and mixing ratios, thereby demonstrating its potential in the calibration of groundwater numerical models.

Surface Water Monitoring Systems—The Importance of Integrating Information Sources for Sustainable Watershed Management

The complex interactions from anthropogenic activities, climate change, sedimentation and the input of wastewater has significantly affected the aquatic environment and entire ecosystem. Over the years, the researchers have investigated water monitoring approaches in terms of traditional monitoring or even integrated systems to handle such an environmental assessment and predictions based on warning systems. However, research into the selection and optimisation of water monitoring systems by the combination of parallel approach in terms of sampling techniques, process analysis and results is limited. The research objectives of the present study are to evaluate the existing water monitoring systems based on the latest approach and then provide insights into factors affecting sensor implementation at sampling locations. Here we summarize the advancement and trends of various water monitoring systems as well as the suitability of sensor placement in the area by reviewing more than 300 papers published between 2011 and 2022. The research highlights the urgency of an integrative approach with regard to water monitoring systems including water quality model and water quantity model. A framework is proposed to incorporate all water monitoring approaches, sampling techniques, and predictive models to provide comprehensive information about environmental assessment. It was observed that the urgency of model-based approaches as verification and fusion of data assemble has the ability to improve the performances of the systems. Furthermore, integrated systems with the inclusion of a separate modeling approach through integrated - semi-mechanistic models, data science and artificial intelligence are recommended in the future. Overall, this study provides guidelines for achieving standardized water management by implementing integrated water monitoring systems.

Analysis of the Contribution of TSS, pH, Fe, and Mn Parameters to the Pollution Load Capacity of Coal Mines in the Oal River, South Sumatra

The Oal River receives coal wastewater input at several companies. Coal mining in the vicinity of the location adds to the burden of water pollution in the Oal River due to waste water disposal activities. The increase in the concentration of coal waste and the pollution load that enters the Oal River water body will have an impact on the reducing capacity of the pollution load. This study aim to provide information on the condition of the pollution load carrying capacity of the Oal River. Determination of the carrying capacity of water pollution loads at water sources using the mass balance method. The characteristic of the Oal River water with the parameters TSS, pH, Fe and Mn have not yet passed the quality standards for river water and wastewater, both according to PP No. 22 of 2021 and South Sumatra Governor Regulation No. 8 of 2012. The Oal River still has the capacity to accommodate TSS and pH parameters.

Occurrence, characteristics, and removal of microplastics in wastewater treatment plants located on the Moroccan Atlantic: The case of Agadir metropolis

Wastewater treatment plants (WWTPs) are some of the main sources of microplastics (MPs) in the environment. However, studies on the occurrence and removal efficiency of MPs in WWTPs are still scarce, especially in African countries. Thus, the aim of this work was to study the abundance of MPs in the influent and effluent of two WWTPs (Aourir and M'zar) from the Agadir metropolis (Moroccan Atlantic). The two WWTPs receive different wastewater inputs (domestic and industrial). In addition, the impacts of seasonality on the fate and removal efficiency were investigated. The results showed that the MPs abundance in the wastewater decreased from 188 MPs/L in the influent to 50 MPs/L in the effluent for Aourir WWTP (domestic inputs); while the abundance was greater in the M'zar WWTP (urban and industrial inputs) recording a mean value of 519 MPs/L and 86 MPs/L in the influent and effluent, respectively. MPs collected in the Aourir WWTP ranged from 290 to 3200 μm, while MPs from the M'zar WWTP, ranged from 330 to 4200 μm. Overall, the size range of 100–500 μm was the most abundant for both WWTPs. Fibers were the highest MPs morphotype found, followed by fragments. MP colors were mainly red, black, blue, and transparent for both treatment plants. Additionally, FTIR spectroscopy showed the presence of eight different polymers, mainly polyethylene (PE), polypropylene (PP), and polystyrene (PS). Seasonal variation analysis showed that MPs abundance in summer was significantly higher compared to other seasons. However, the comparison of the removal efficiency (RE) between the different seasons indicated that the winter season (74 %) recorded the highest RE for Aourir WWTP. Conversely, spring (87 %) recorded the highest RE for M'zar WWTP. SEM/EDX micrographs showed different degrees of weathering and chemical elements adhering to the surface of the MPs. The findings of the current study will serve as a baseline for future considerations about management strategies, wastewater reuse, as well as the understanding of the occurrence of microplastic pollution along the marine ecosystems of Morocco.

Analytical strategies to measure gadolinium as a wastewater marker in surface and groundwater systems

The increasing use of gadolinium (Gd)-based contrast agents in magnetic resonance imaging and the recalcitrant behavior of Gd during municipal wastewater treatment have led to increased concentrations of the tracer in aquatic environments. These anthropogenic Gd emissions to wastewater and, subsequently, to surface and groundwater systems can be exploited to calculate groundwater travel times and mixing ratios, identify wastewater inputs, and calibrate groundwater models. However, analytical complexity, costs, and the time needed to directly measure anthropogenic inputs hinder the practical use of Gd. While direct measurements with inductively coupled plasma-mass spectrometry (ICP-MS) are highly efficient and feasible, only total Gd can be detected with this approach. In unknown hydrogeological systems, the differentiation between total, anthropogenic, and geogenic Gd by interpolating rare earth element patterns requires complex sample pre-treatment and pre-concentration. Direct measurements of Gd can be obtained using anion-exchange chromatography coupled to ICP-MS but the limit of quantification will be higher. Here we provide guidelines for selecting the optimal method for the analysis of Gd as a wastewater tracer in surface-groundwater systems.•The cost-effectiveness of existing analytical strategies to measure Gd when used as a wastewater tracer in surface-groundwater systems is addressed•A novel analytical strategy for direct determination of total Gd is presented

In situ remediation mechanism of internal nitrogen and phosphorus regeneration and release in shallow eutrophic lakes by combining multiple remediation techniques

Large anthropogenic inputs of N and P alter the nutrient cycle and exacerbate global eutrophication problems in aquatic ecosystems. This study in Lake Datong, China, investigates the remediation mechanism of multiple remediation technique combinations (dredging, adsorbent amendment, and planting aquatic vegetation) on sediment N and P loads based on two high-resolution sampling techniques (HR-Peeper and DGT) and P sequential extraction procedures. The results showed that high temperature and low dissolved oxygen considerably enhanced pore water dissolved reactive P (DRP) and NH4+ concentrations attributable to abundant Fe-P and organic matter content in the sediment. Fe reduction is critical for regulating pore water DRP release and promoting N removal. Overall, for Lake Datong, combining multiple remediation techniques is more effective in controlling sediment P loads (pore water DRP, P fluxes, forms of P, and labile P), from a long-term perspective, than a single remediation. Lanthanum-modified bentonite (LMB) inactivation treatment can transfer mobile P in the surface sediment into more refractory forms over time, thereby reducing the risk of sediment labile P release. However, it is difficult to effectively remediate internal P loads owing to inappropriate dredging depths and low biomass of aquatic vegetation. Future lake restoration practices should optimize the selection of different remediation technique combinations based on internal N and P pollution characteristics, while reducing external wastewater input. These results are important for understanding the remediation mechanisms of internal N and P and provide suggestions for sediment management of shallow eutrophic lakes.