Safe Drinking Water Standards Research Articles

Impacts of Flash Flood on Ground Water Quality: Case Study of Central River Region, The Gambia

Floods rank as one of the most common natural calamities, impacting the lives of millions across the globe. With ongoing population growth and expanding water and land usage, the potential for contamination and human disturbances to negatively impact water bodies continues to rise globally. This paper aims to comprehensively analyze the repercussions of floods on the groundwater quality of a region called CRR in the Gambia, during the July 2022 flood event. The focus lies on exploring the change in water quality parameters of twelve water samples from wells and boreholes through laboratory analysis of eight parameters such as pH, turbidity, temperature, electrical conductivity, total dissolved solids, nitrate, iron, sulfate, and microbial proliferation. The laboratory analysis results of the physiochemical parameters such as turbidity, and iron exceeded the safe drinking water standards set by the World Health Organization (WHO) in about 60% of the sites and fecal coliform presence in 75 % of the samples. The other parameters varied differently across all sites. However, most of the values are observed to be more prominent at the open well than borehole. The Water Quality Index (WAWQI) score also shows that 1 site has excellent water quality, 25%, has good quality and 25% has fair quality. The rest of the sites which make up 42% of the samples, are all of poor quality and unsuitable for drinking purposes. The results provide a crucial groundwork for subsequent studies targeting the water quality in this area.

Speciation, mobility, and risks of heavy metals in sediment and water of a freshwater Lake in Fujian Province, China

ABSTRACT This study investigated the level of dissolved heavy metals in the water of Longhu Lake and focused on the speciation, mobility, and risks of heavy metals (Cr, Mn, Ni, Cu, Zn, As, Cd, and Pb) in sediment. The levels of heavy metals in the water were found to be below the thresholds set by the Chinese safe drinking water standard. The highest average percentages of Cr, Ni, Zn, and As were bound with residual fractions, while Pb and Cu were bound with reducible fractions. Additionally, the highest percentage of Cd and Mn was bound to the acid-soluble fraction in the sediment. These findings suggest that Cd, Mn, Pb, and Cu likely originated from anthropogenic sources in the lake. There was a strong correlation between total organic carbon (TOC) and metal fractions in the sediment, indicating that TOC may play a role in transporting heavy metal fractions. Risk assessment code values for Cd and Mn indicated higher risks and mobility, while Ni, Cu, and Zn showed medium risks and mobility for aquatic biota. To mitigate heavy metal contamination, it is recommended to improve monitoring and regulation of urban runoff and inlet areas.

Evaluation of hydrogeochemical processes and saltwater intrusion in the coastal aquifers in the southern part of Puri District, Odisha, India.

Groundwater is widely regarded as being among the freshwater natural resources with the lowest levels of contamination. Nevertheless, the saltwater intrusion has resulted in the contamination of groundwater in coastal regions with lower elevation. The rationale of the present work is to investigate the chemistry of groundwater, to identify the various facies of groundwater, to identify the processes that influence groundwater chemistry and saltwater intrusion, and to evaluate the groundwater's aptness for use in drinking and farming. In order to gain an understanding of the groundwater quality as well as the salinization process that occurs in coastal aquifers as a result of hydrogeochemical processes, a total of 108 groundwater samples (54 each in pre- and post-monsoon) were taken and analyzed for several physiochemical parameters in the southern part of the Puri district in the Indian state of Odisha. The data has undergone analysis and examination to identify the factors (such as hydrological facies, potential solute source in water, and salinization process) that contribute to groundwater salinity. The result showed the chemistry controlling processes of rock-water interaction as per Gibbs diagram. The majority of shallow aquifers exhibit the Na-Cl type of facies as per the Piper plot. A total of 37% pre-monsoon and 33% post-monsoon samples having Na+/Cl- ratio below the threshold of 0.86 indicating the influence of saltwater intrusion. In both seasons, it was observed that 74% of the samples exhibited a Na+ concentration that exceeded the permissible limit set by the World Health Organization (WHO) for drinking purposes. The findings indicate that most groundwater failed to pass safe drinking water and irrigation standards due to saltwater intrusion. Consequently, the monitoring of coastal aquifer quality has become imperative in order to ensure the sustainability of aquifers and the development of groundwater resources. This is because coastal aquifers are highly vulnerable to saltwater intrusion, primarily as a result of the extensive extraction of groundwater for diverse purposes.

Spatial Distribution of Arsenic in the Aksu River Basin, Xinjiang, China: The Cumulative Frequency Curve and Geostatistical Analysis

The quality of drinking water is crucial for human health and the sustainable development of societies. The Aksu River Basin, a typical inland river system, has areas where groundwater arsenic levels exceed safe drinking water standards (i.e., arsenic concentrations greater than 10 μg/L). Identifying the causes of high arsenic levels in the basin’s groundwater requires further study. Analyzing the hydrogeochemical composition of the Aksu River basin helps us to understand the spatial distribution of groundwater environments and locate areas with dangerously high arsenic levels. In this research, we collected 196 groundwater samples from along the river. Out of these, 38 samples had arsenic levels above 10 μg/L, which represents 19.4% of the total samples collected. By examining the slope changes in the cumulative frequency curves of major ion ratios and employing geostatistics (specifically, the Kriging interpolation), and taking into account the environmental characteristics of the entire basin, we divided the study area into five sub-regions (Zone I through Zone V). The geostatistical analysis showed a significant spatial variability in groundwater arsenic levels, with a clear spatial correlation. Our findings demonstrate that arsenic concentrations in the Aksu River basin’s groundwater vary widely, with Zones II and III—mainly located in the northeastern part of the basin and in Awat County—being hotspots for high-arsenic water. Factors such as a weak reducing environment, intense evaporation, strong cation exchange, and the low-permeability recharge of surface water contribute to the accumulation of arsenic in the basin’s groundwater. The results of this study are vital for assessing the risk of arsenic contamination in groundwater in similar basins and for identifying critical areas for further investigation and research.

Challenges and Possible Solutions for Riverbank Filtration: Case Studies of Three Sites in Egypt

In response to Egypt’s escalating water scarcity and pollution, Riverbank Filtration (RBF) technology is emerging as an effective solution to enhance water quality and simplify drinking water provision. This study evaluates RBF at three sites in Upper Egypt by assessing hydrogeological conditions and water quality based on 36 parameters from 2022 to 2023. Findings indicate that RBF efficiently treats infiltrated river water, with all sites meeting turbidity and microbiological standards (Total Bacterial Count and Coliforms), achieving removal rates of approximately 90% and 99%, respectively. Despite these successes, challenges persist in reducing manganese to safe levels, with concentrations at Alsaayda site reaching 0.51 mg/L, over the drinking water safe limit of 0.4 mg/L. To address this, further post-treatment strategies are proposed to remove the excess manganese. A practical application of an Oxidizer at the Bani Murr groundwater treatment plant has demonstrated the effective removal of iron and manganese, bringing their levels down to safe drinking water standards. This case exemplifies a successful solution for iron and manganese removal. This research highlights RBF’s potential in water treatment in developing countries, while emphasizing the need for supplementary measures to manage specific contaminants.

Potential of rice straw derived activated biochar to remove arsenic and manganese from groundwater: A cleaner approach in the Indo-Gangetic Plain

Heavy metal pollution in groundwater has become a public health concern due to its non-degradable and poisonous nature. Several research studies were conducted using various adsorbents to extract heavy metals from water. However, the removal of As and Mn using rice straw-derived activated biochar in a binary metal system was found to be limited. This study examined a comparative analysis of As and Mn adsorption by CO2-activated biochar derived from rice straw in a single and binary metal approach. Findings showed that the maximal sorption capacity of As and Mn in single metal systems was 18.26 and 12.18 mg g−1 and 8.51 and 5.42 mg g−1 in binary metal systems. PSO kinetic model (R2> 0.99) and Langmuir isotherm model (R2> 0.95) show good agreement with experimental data. The highest removal efficiency of As (99.53%) and Mn (96.23%) was achieved in naturally contaminated water (Sahibganj, India). Health risk assessment indicates chances of cancer (CR> 1 × 10−4 and HQ>1) in humans due to the high concentration of As (192 μg L−1). Water treated with 0.1 g activated biochar had lower CR and HQ values, and metal concentration was below the WHO safe drinking water standard.

Microbial biochemical pathways of arsenic biotransformation and their application for bioremediation.

Arsenic is a ubiquitous toxic metalloid, the concentration of which is beyond WHO safe drinking water standards in many areas of the world, owing to many natural and anthropogenic activities. Long-term exposure to arsenic proves lethal for plants, humans, animals, and even microbial communities in the environment. Various sustainable strategies have been developed to mitigate the harmful effects of arsenic which include several chemical and physical methods, however, bioremediation has proved to be an eco-friendly and inexpensive technique with promising results. Many microbes and plant species are known for arsenic biotransformation and detoxification. Arsenic bioremediation involves different pathways such as uptake, accumulation, reduction, oxidation, methylation, and demethylation. Each of these pathways has a certain set of genes and proteins to carry out the mechanism of arsenic biotransformation. Based on these mechanisms, various studies have been conducted for arsenic detoxification and removal. Genes specific for these pathways have also been cloned in several microorganisms to enhance arsenic bioremediation. This review discusses different biochemical pathways and the associated genes which play important roles in arsenic redox reactions, resistance, methylation/demethylation, and accumulation. Based on these mechanisms, new methods can be developed for effective arsenic bioremediation.

UIO-66/Ag/TiO2 Nanocomposites as Highly Active SERS Substrates for Quantitative Detection of Hexavalent Chromium

Sensitive determination of Cr(VI) is of great importance as this is one of the most toxic heavy metal ions in the environment. In this work, a metal–organic framework (MOF) material, UIO-66 (University of Oslo, UIO), was introduced for the first time to develop a composite substrate, UIO-66/Ag/TiO2, for the sensitive SERS detection of Cr(VI) in water. The composition, morphology, crystal structure and optical property of the UIO-66/Ag/TiO2 were characterized by SEM, XRD, EDX, UV-Vis and Raman spectroscopy. The control experiment revealed the introduction of UIO-66 and TiO2 can improve the adsorption to Cr ions and thus greatly enhance the SERS signal of Cr(VI) on this composite substrate. The SERS signal can also be tuned by changing the dosage of TiO2. Under optimized conditions, UIO-66/Ag/TiO2 was used to detect Cr(VI) in water with different concentrations, which showed high sensitivity and good stability. The SERS signals showed a linear increase as the concentration of Cr(VI) increases from 5 × 10−9 M to 5 × 10−6 M. The detection limit was 5 nM, which was lower than the safe drinking water standard of the US Environmental Protection Agency (1 μM). Detection of Cr(VI) in the range of 1 × 10−7 M to 5 × 10−6 M in real lake water was also achieved. These results demonstrate the great potential of UIO-66/Ag/TiO2 composites as SERS substrates for the trace determination of Cr(VI) in the environmental field.

Evaluation and strategy for improving the quality of desalinated water.

Seawater desalination is practiced in many coastal countries, which is accepted as clean water by the general populations. The untreated seawater reported high concentrations of bromide (50,000 - 80,000µg/L) and iodide (21 - 60µg/L) ions, which are reduced to non-detectable levels during thermal desalination while the concentrations of bromide and iodide ions were reduced to 250-600µg/L and < 4-16µg/L, respectively during reverse osmosis processes. During the treatment and/or disinfection, many brominated and iodinated disinfection byproducts (Br-DBPs and I-DBPs) are formed in desalinated water, some of which are genotoxic and cytotoxic to the mammalian cells and possible/probable human carcinogens. In this paper, DBPs' formation in desalinated and blended water from source to tap, toxicity to the mammalian cells, their risks to humans and the strategies to control DBPs were investigated. The lifetime excess cancer risks from groundwater, and desalinated and blended water sourced DBPs were 4.15 × 10-6 (4.72 × 10-7 - 1.30 × 10-5), 1.75 × 10-5 (2.58 × 10-6 - 5.25 × 10-5) and 2.59 × 10-5 (4.02 × 10-6 - 8.35 × 10-5) respectively, indicating higher risks from desalinated and blended water (2.56 and 4.51 times respectively) than groundwater systems. Few emerging DBPs in desalinated/blended water showed higher cyto- and genotoxicity in the mammalian cells. The findings were compared with safe drinking water standards and strategies to produce cleaner desalinated water were demonstrated.

Synthesis and characterization of metal oxide based ion exchanger from chicken egg shell biomass for the removal of arsenic from water

A new metal oxided-based high capacity biosorbent for As(III) was designed and synthesized from egg shell biomass and characterized using FTIR, FE-SEM, EDX, XRD, chemical analysis. For this, raw egg shell (RES) powder was first dissolved with HCl and mixed with ZrOCl2∗8H2O solution then precipitated to obtain hydrated double oxide precipitate (HDOP), which was employed for As(III) removal. As(III) biosorption onto HDOP is fast, depends on pH and As(III) concentration. Pseudo second order kinetics and Langmuir isotherm models successfully described the As(III) biosorption mechanism. HDOP provided exchangeable hydroxide/or chloride ligands for improved biosorption of As(III). Maximum biosorption capacity of HDOP for As(III) from Langmuir isotherm modelling was found to be 40 mg g−1 at optimum pH 10. Chloride and nitrate cause negligible interference whereas sulphate and phosphate significantly reduced As(III) biosorption capacity of HDOP. HDOP completely removed arsenic from contaminated ground water and the remaining concentration was reached below the safe drinking water standard (10 μg L−1) set by WHO. Moreover, HDOP exhibited effective regeneration and high stability with As(III) removal up to 8 cycles. Thus, HDOP synthesized from egg shell biomass can be used as a low cost, environmentally benign and high capacity biosorbent for the treatment of arsenic polluted water.

Thermochemical study of Cr(VI) sequestration onto chemically modified Areca catechu and its recovery by desorptive precipitation method

A new biosorbent for Cr(VI) sequestration was investigated from betel nut waste (BNW), Areca catechu, by H2SO4 charring. Aqueous insolubility and Cr(VI) uptake capacity of native BNW were potentially improved after H2SO4 modification due to cross-linking reaction of betel nut cellulose, thereby creating suitable complexation sites for Cr(VI) ion removal. Langmuir isotherm and pseudo second order (PSO) kinetic models described well with the experimental data. A trace amount of Cr(VI) was effectively removed below the safe drinking water standard (WHO, 0.05 mg/L) using charred BNW (CBNW). The negative value of ΔG° evaluated for all the temperatures suggested the spontaneous nature of Cr(VI) sequestration and positive value of ΔH° (42.43±0.13 kJ/mol) confirmed an endothermic reaction. Co-existing NO3−, Cl−, Na+ and Zn2+ ions showed negligible interferences, whereas SO42− and PO43− notably reduced Cr(VI) uptake capacity of CBNW. More than 98% of adsorbed Cr(VI) was desorbed using 1M NaOH solution. A light yellow precipitate of BaCrO4 was recovered from the desorbed solution after precipitation with BaCl2 solution. Therefore, the CBNW biosorbent investigated in this work is expected to be a promising material for Cr(VI) sequestration and its recovery from polluted water.

Multistrategy Preparation of Efficient and Stable Environment-Friendly Lead-Based Perovskite Solar Cells.

Perovskite solar cells (PSCs) have achieved huge success in power conversion efficiency (PCE) and stability. However, further improving the PCE of PSCs and stability is still a big challenge. Here, we attempt to improve the PCE and stability of PSCs using a functional additive named 3-mercaptopropyltriethoxysilane (SiSH) in the perovskite antisolvent. It is revealed that SiSH can release the stress in the film, reduce the defects, and inhibit lithium-ion migration and lead leakage. As a result, the target device achieves an efficiency enhancement from 20.80 to 22.42% as compared to the control device. Meanwhile, device stability is ameliorated after SiSH modification. Furthermore, new adsorbents are used to treat the leaked lead to make it comply with safe drinking water standards. This work provides an idea for developing multifunctional antisolvent additives and adsorbents for high PCE, long stability, and environment-friendly Pb-based PSCs.

Hierarchical 13X zeolite/reduced graphene oxide porous material for trace Pb (II) capturing from drinking water

The removal of lead in drinking water has attracted considerable attention of researchers in recent years, especially, the trace characteristic of lead is a challenge to water treatment. Herein, 13X zeolite/reduced graphene oxide composite material (13X-rGO) with hierarchically porous structure was successfully prepared using graphene oxide (GO) and 13X zeolite via a chemical reduction method and presented great performance for removing trace Pb(II) from drinking water. The influence of some important parameters including adsorbent dosage, contact time, initial lead concentration, coexisting competing ions, solution pH value, etc. on the removal of Pb(II) was systematically investigated. The composite material showed better adsorption properties compared with a single component and their physical mixture, confirming the synergistic effect of rGO and 13X zeolite on Pb(II) adsorption. The effluent lead concentration could be decreased to the level permitted by World Health Organization (WHO) (<10 ppb) within 30 s under calcium content of 20 ppm and initial lead concentration of 150 ppb. Simultaneously, the as-prepared 13X-rGO performed excellent adsorption capacity meeting WHO standard (6.07 mg/g), which was about 2.23 times that of single 13X zeolite (2.72 mg/g). In the presence of interfering ions, the lead concentration could still be reduced to safe drinking water standard. Moreover, the adsorbent could be effectively regenerated by saturated sodium chloride solution. Therefore, 13X-rGO can be introduced as a promising adsorption material for the purification of drinking water contaminated with trace lead owing to rapid adsorption, low cost and recycling potential. • 13X-rGO with hierarchically porous structure was prepared by a one-step green method. • 13X-rGO composite achieves the synergistic effect of rGO and 13X zeolite. • 13X-rGO exhibits rapid and selective adsorption ability for trace lead (II) in water. • 13X-rGO shows high adsorption capacity, low cost and recycling potential. • 13X-rGO shows significant potential for trace lead removal from drinking water.

Distribution, source and health risk assessment based on the Monte Carlo method of heavy metals in shallow groundwater in an area affected by mining activities, China

Mining activities exert a far-reaching impact on the quality of groundwater, and health problems caused by heavy metal pollution have attracted global attention. In this study, inductively coupled plasma-mass spectrometry (ICP-MS) was employed to determine the contents of 8 heavy metals (Cd, Cr, As, Fe, Mn, Cu, Zn, and Pb) in shallow groundwater samples retrieved from a mining area in northern Anhui. Multivariate statistical methods were adopted to analyze the distribution and source of pollution and to evaluate 5% and 95% health risks based on Monte Carlo simulation. Fe, As and Cr significantly exceeded the safe drinking water standards of the World Health Organization (WHO). The average concentrations of As and Cr were as high as 46.45 μg/L and 133.96 μg/L, respectively. The correlation analysis and principal component analysis (PCA) results revealed that heavy metals are affected by complex factors, the main factor being human activities. The total carcinogenic health risks of Cr and As in adults were 2.49 × 10−3 and 3.43 × 10−4, respectively, which exceeded the maximum acceptable risk value (1 ×10−4) recommended by the United States Environmental Protection Agency (USEPA), affecting human health. According to the USEPA classification of hazardous ingestion (HI), at HI < 1, the impact of non-carcinogenic heavy metals on human health is negligible. These results indicate that local residents should strengthen the monitoring of Cr and As pollution in shallow groundwater.

Acute toxicity of the insecticide cypermethrin to three common European mayfly and stonefly nymphs

Freshwaters are particularly vulnerable to pesticide contamination from adjacent agriculture and forestry. Cypermethrin is a commonly used pyrethroid insecticide, but information on its toxicity to non-target freshwater invertebrates is limited to a small number of taxa. We assessed cypermethrin toxicity to nymphs of the common European mayflies Baetis rhodani and Ecdyonurus venosus, and the stonefly Isoperla grammatica in 96 h static bioassays. The 96 h median lethal concentrations (LC50) we recorded for the three species were 0.08 μg/L, 0.15 μg/L, and 0.13 μg/L, respectively. The effective concentration (EC50), quantified as lack of escape response (implying inability to avoid drift, predation or abiotic stress), was usually 32 % of the LC50. All 96 h LC50 values were lower than the maximum concentrations detected in streams in UK and continental Europe. Alarmingly, the 96 h LC50 for B. rhodani was below the currently applied single-pesticide EU safe drinking water standard of 0.1 μg/L. Contrasts among species were most evident at 24 h LC50, when B. rhodani was approximately ten times more sensitive than the other two taxa. B. rhodani is a key algal grazer, ubiquitous in European streams, and its decline could exacerbate algal blooms. The order of taxa sensitivity to cypermethrin in our study contrasts with their sensitivity to organic pollution in the same region, which suggests a tolerance trade-off, and thus a compounding effect of simultaneous stressors. Mayflies and stoneflies are important prey for instream and riparian predators, and key components of most eutrophication indices globally, all of which could be compromised in presence of cypermethrin.

A facile method to achieve dopamine polymerization in MOFs pore structure for efficient and selective removal of trace lead (II) ions from drinking water

Heavy metals are seriously hazardous contaminants and drinking water has been identified as an important route of human exposure to them. Herein, to efficiently and selectively remove trace heavy metal ions, a facile method was reported to achieve the slow polymerization of dopamine in the cages of MIL-100 (Fe) via ultrasonic treatment followed by the hydrolysis of the urea. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Brunner-Emmet-Teller (BET) and pore size distribution determination confirmed the formation of the polydopamine (PDA) and binding with the unsaturated Fe3+ site in MIL-100 (Fe) pores. The composite not only retained pore structure of MOFs but also contained abundant reactive functional groups. When initial lead concentration was 150 ppb and 20 ppm calcium coexisted at pH of 6.5 ± 0.25, the effluent lead concentration met the safe drinking water standard in several tens of seconds, and decreased to 1.13 ppb in 10 min. The adsorption rate reached 99.35%. The synthetic strategy effectively overcomes mass transfer resistance of trace heavy metal ions and provides a facile approach to prepare adsorption materials for efficient and selective removal of trace heavy metal ions from drinking water.

Tillage Effects on Drainage Fluxes and Nitrate Leaching through Unsaturated Zone under Irrigated Corn-Soybean Rotation

Abstract. High levels of nitrate-nitrogen (NO3-N) in the nation’s groundwater are a significant environmental concern. To date no studies have yet evaluated the effects of various tillage practices on percolated drainage and NO3-N fluxes below the rootzone of cropping systems in the northern Great Plains. A field study was conducted to examine and compare the effect of no-tillage (NT) and conventional tillage (CT) practices on seasonal drainage fluxes and NO3-N leaching losses below the rootzone in irrigated corn ( L.) and soybean ( L.) on a Lihen sandy loam soil. Sixteen passive capillary lysimeters, PCAPs (75 cm long polyvinyl chloride pipe with a collecting surface area of 0.1 m2) were placed 90 cm below the soil surface to quantify percolated drainage water below the rootzone of corn-soybean rotation under NT and CT practices. The study was designed as a randomized complete block with four replications. Drainage and NO3-N fluxes were not significantly affected by the tillage in 2014, 2015, 2016, and 2017 due to substantial spatial variations among lysimeters within each treatment. Average cumulative seasonal drainage depths across 4 years were 22.26 and 34.46 mm for corn and 24.95 and 28.16 mm for soybean under NT and CT, respectively. Averaged 4-yr cumulative NO3-N losses were 17.61 and 26.74 kg ha-1 for corn and 25.47 and 23.56 kg ha-1 for soybean under NT and CT, respectively. Flow-weighted NO3-N concentrations over 4 years were 57.9 and 65.7 mg L-1 for corn while those for soybean were 74.8 and 67.0 mg L-1 under NT and CT, respectively. Nitrate-nitrogen concentrations generally exceed the safe drinking water standard of 10 mg L-1. Reducing N inputs in well-drained soils and using site specific N and irrigation management practices are required to lower input expenses, reduce N leaching losses and sustain environmental quality. Keywords: Drainage, Fluxes, Leaching, Lysimeter, Nitrate-nitrogen, Rootzone, Tillage.

Enhanced real-time cyanobacterial fluorescence monitoring through chlorophyll-a interference compensation corrections

In situ fluorometers can be used as a real-time cyanobacteria detection tool to maintain safe drinking and recreational water standards. However, previous studies into fluorometers have established issues arising mainly from measurement inaccuracies due to green algae interference. Therefore, this study focusses on developing correction factors from a systematic study on the impact of green algae as an interference source. This study brings a novel technique where the chlorophyll-a (Chl-a) and phycocyanin measurements are used to correct the fluorometer output for interference bias; four fluorometers were tested against three key cyanobacterial species and the relationship between phycocyanin output, green algae and cyanobacteria concentrations were investigated. Good correlation (R2 > 0.9, p-value < 0.05) was found between the fluorometer phycocyanin output and increasing green algae concentration. The optimal correction method was selected for each of the fluorometer and cyanobacteria species pairs by validating against data from the investigation of green algae as an interference source. The correction factors determined in this study reduced the measurement error for almost all the fluorometers and species tested by 21%–99% depending on the species and fluorometer, compared to previous published correction factors in which the measurement error was reduced by approximately 11%–81%. Field validation of the correction factors showed reduction in fluorometer measurement error at sites in which cyanobacterial blooms were dominated by a single species.

Origin and distribution of nitrate in water well of settlement areas in Yogyakarta, Indonesia.

Pollution of nitrate in water wells in Yogyakarta City was reported to increase for two decades. This study aimed to describe nitrate contamination in the water wells of colorectal cancer (CRC) and inflammatory bowel disease (IBD) patients, previously described elsewhere. Nitrate and chloride content of 150 water samples from the wells of patients with CRC and IBD who were residing in Yogyakarta, Sleman, or Bantul districts were examined. Description of nitrate contamination was presented in the form of box plot charts and map. Kruskal-Wallis analysis was used to measure the difference of nitrate concentration in three areas of study. Comparisons of nitrate and chloride concentrations were used to determine the source of nitrate contamination in water well. Fisher's exact test was used to describe the relationship of well distance with the septic tank to nitrate concentration in water well. The wells in Yogyakarta City had the highest median nitrate content compared to Sleman and Bantul (P = 0.001) with the median of 56.6, 13.1, and 7.7 for Yogyakarta, Sleman, and Bantul, respectively, and most tested samples exceed WHO safe drinking water standards. The spread of nitrate contamination has occurred in areas adjacent to Yogyakarta City compared to the previous report. The ratio of nitrate to chloride (1-8:1) suggested that the source of nitrate contamination in water wells in the study area came from feces due to inadequate on-site sanitation. The mapping showed nitrate contamination in water wells in Yogyakarta City, Sleman, and Bantul districts had spread according to urban development.

The road less traveled: Assessing the impacts of farmer and stakeholder participation in groundwater nitrate pollution research

After decades of effort and investment to promote the use of agricultural best management practices (BMPs) to address nutrient losses from farms, the level of adoption of most BMPs remains relatively low. One increasingly common response has been to involve stakeholders more directly in research on local water quality challenges, with twin goals of improving the science and engaging local residents in the diagnosis of problems and development of effective responses. This paper uses qualitative and quantitative data to assess the impacts of a multiyear nitrate (NO3−) leaching study in a central Montana watershed that used a highly participatory research and outreach approach. For decades, the Judith River watershed has experienced groundwater NO3− levels that exceed safe drinking water standards, and many local residents install expensive water treatment devices, purchase drinking water from private vendors, or drink contaminated water. The project is notable for engaging local farmers, community leaders, and agency staff in the design, implementation, and interpretation of research to identify the sources of NO3− and to understand the effectiveness of alternative management practices in reducing NO3− leaching into groundwater. Two advisory groups regularly met with the science team to develop research questions, structure field research activities, select management practices, discuss interpretation of data, and design outreach efforts. Evidence of project impacts was gathered through interviews with our local collaborators and from a comparison of pre- and postproject surveys of the broader farm operator population in the watershed. The qualitative results suggest that the people most involved in the project became much more engaged with and concerned about how to address the local NO3− problem. The project9s research findings were also more compelling to stakeholders because farmers had been involved in designing and interpreting the data, and the research had been conducted under real-world farming conditions. Survey results collected in the final year of the project showed that farmers in the watershed were familiar with and had very positive impressions about the project, and their levels of awareness and concern about NO3− issues rose over the course of the project. However, widespread changes in farmer behaviors had not been detected three years into the project, and the impact of the project on long-term NO3− contamination trends in the region is still uncertain.