Surface Water Ecosystems Research Articles

Assessment of sulfamethoxazole adsorption capacity on Pirangi clay from the State of Sergipe, Brazil, modified by heating and addition of organic cation

Abstract Sulfamethoxazole (SMX) is a widely-used antibiotic in human and veterinary medicine for treating diseases and infections and is often detected in the surface water ecosystem. Thus, this study evaluated the capacity of removing SMX from aqueous systems using Pirangi clay (PIR) from the state of Sergipe (Brazil). Pirangi clay samples were treated at 100, 400 and 600 °C and modified with hexadecyltrimethylammonium (HDTMA) cationic surfactant. The modification process used was based on the layered organization of the mineral clay, allowing the intercalation of cationic surfactant, giving a hydrophobic character to the clay. The Pirangi clay treated at 100 °C and modified with HDTMA (org-PIR-100) showed adsorption capacity of 27.3 mg.g-1 with 90% removal of the SMX in 100 min and pH 6, following the pseudo-second-order model and Langmuir isotherm. Different characterization methods were employed to characterize the clays, such as XRF, FTIR, XRD, thermogravimetric analyzes (TG/DTG) and BET method, confirming that the surfactant molecules were incorporated on the clay surface and that org-PIR-100 showed potential for use in water treatment plant filters.

Phosphorus Removal from Textile Industrial Wastewater using Aerated High Calcium Steel Slag Filter System

Phosphorus in wastewater accelerates eutrophication in water body. Textile wastewater is one of contributors to the phosphorus loading into water body which promotes the growth of algae, reducing the oxygen content and detrimental to surface water ecosystem. Myriad existing treatments for phosphorus removal have been developed but it requires a high cost treatment and maintenance. Rock filter system emerged as one of the alternative method for phosphorus removal from wastewater with steel slag as the filter media. However, application of the system in treating industrial wastewater is still unclear especially in big scale application and requires extensive study. This study is done to provide solution of phosphorus loading from textile wastewater using steel slag as filter material and to investigate the removal capacity of steel slag with high calcium and low ferum content. The steel slag was analyzed using XRF for its composition and to ensure the steel slag has high Ca content. Then, the aerated steel slag filter system was set-up on the site of textile industry for a month and analyzed according to parameter of pH, alkalinity, COD, DO, temperature and TSS. The result from this study showed that the aerated high calcium low ferum steel slag filter has a high efficiency of phosphorus removal rates varied from 35% to 67% in treating textile wastewater. It was found that aerated steel slag system was efficient in phosphorus removal by using industrial wastewater.

Dissolved Inorganic Geogenic Phosphorus Load to a Groundwater-Fed Lake: Implications of Terrestrial Phosphorus Cycling by Groundwater

The general perception has long been that lake eutrophication is driven by anthropogenic sources of phosphorus (P) and that P is immobile in the subsurface and in aquifers. Combined investigation of the current water and P budgets of a 70 ha lake (Nørresø, Fyn, Denmark) in a clayey till-dominated landscape and of the lake’s Holocene trophic history demonstrates a potential significance of geogenic (natural) groundwater-borne P. Nørresø receives water from nine streams, a groundwater-fed spring located on a small island, and precipitation. The lake loses water by evaporation and via a single outlet. Monthly measurements of stream, spring, and outlet discharge, and of tracers in the form of temperature, δ18O and δ2H of water, and water chemistry were conducted. The tracers indicated that the lake receives groundwater from an underlying regional confined glaciofluvial sand aquifer via the spring and one of the streams. In addition, the lake receives a direct groundwater input (estimated as the water balance residual) via the lake bed, as supported by the artesian conditions of underlying strata observed in piezometers installed along the lake shore and in wells tapping the regional confined aquifer. The groundwater in the regional confined aquifer was anoxic, ferrous, and contained 4–5 µmol/L dissolved inorganic orthophosphate (DIP). Altogether, the data indicated that groundwater contributes from 64% of the water-borne external DIP loading to the lake, and up to 90% if the DIP concentration of the spring, as representative for the average DIP of the regional confined aquifer, is assigned to the estimated groundwater input. In support, paleolimnological data retrieved from sediment cores indicated that Nørresø was never P-poor, even before the introduction of agriculture at 6000 years before present. Accordingly, groundwater-borne geogenic phosphorus can have an important influence on the trophic state of recipient surface water ecosystems, and groundwater-borne P can be a potentially important component of the terrestrial P cycle.

Evaluation of Stream and Wetland Restoration Using UAS-Based Thermal Infrared Mapping

Large-scale wetland restoration often focuses on repairing the hydrologic connections degraded by anthropogenic modifications. Of these hydrologic connections, groundwater discharge is an important target, as these surface water ecosystem control points are important for thermal stability, among other ecosystem services. However, evaluating the effectiveness of the restoration activities on establishing groundwater discharge connection is often difficult over large areas and inaccessible terrain. Unoccupied aircraft systems (UAS) are now routinely used for collecting aerial imagery and creating digital surface models (DSM). Lightweight thermal infrared (TIR) sensors provide another payload option for generation of sub-meter-resolution aerial TIR orthophotos. This technology allows for the rapid and safe survey of groundwater discharge areas. Aerial TIR water-surface data were collected in March 2019 at Tidmarsh Farms, a former commercial cranberry peatland located in coastal Massachusetts, USA (41°54′17″ N 70°34′17″ W), where stream and wetland restoration actions were completed in 2016. Here, we present a 0.4 km2 georeferenced, temperature-calibrated TIR orthophoto of the area. The image represents a mosaic of nearly 900 TIR images captured by UAS in a single morning with a total flight time of 36 min and is supported by a DSM derived from UAS-visible imagery. The survey was conducted in winter to maximize temperature contrast between relatively warm groundwater and colder ambient surface environment; lower-density groundwater rises above cool surface waters and thus can be imaged by a UAS. The resulting TIR orthomosaic shows fine detail of seepage distribution and downstream influence along the several restored channel forms, which was an objective of the ecological restoration design. The restored stream channel has increased connectivity to peatland groundwater discharge, reducing the ecosystem thermal stressors. Such aerial techniques can be used to guide ecological restoration design and assess post-restoration outcomes, especially in settings where ecosystem structure and function is governed by groundwater and surface water interaction.

Analysis of Selected Endocrine Disrupters Fraction Including Bisphenols Extracted from Daily Products, Food Packaging and Treated Wastewater Using Optimized Solid-Phase Extraction and Temperature-Dependent Inclusion Chromatography.

The aim of this research is to demonstrate the concept and ability for the fast and preliminary screening of complex food and environmental samples for the presence of endocrine disrupters fractions, consisting of low-molecular mass micropollutants, particularly various bisphenols (A, B, C, E, F, S, Z, AF, AP, BP and FL). The developed analytical protocol for this research requires two main steps: (i) optimized solid phase extraction (SPE) for selective isolation, purification and pre-concentration of target fraction, and (ii) selective temperature-dependent inclusion chromatography for samples analysis via a HPLC-UV-VisDAD system using isocratic elution and internal standard quantification approach. The chromatographic experiment revealed that both β-CD and its hydroxypropyl derivative strongly interact with selected bisphenols. This is in contrast to the steroids and PAHs molecules investigated previously, where a strong interaction with β-cyclodextrin was observed. Integrated areas derived from acquired chromatographic profiles for each individual sample were used as the simple classification variable enabling samples comparison. We demonstrated that the proposed analytical protocol allows for fast estimation of EDC fractions in various daily use products, food and environmental samples. The materials of interest were selected due to the presence in surface water ecosystems of their residues, and finally, in raw wastewater including rice bags, plastic bags, cloths, sanitary towels, fish baits and various plastic foils from food products. Treated sewage water released directly to the environment from a municipal treatment plant (Jamno, Koszalin) was also investigated. It has been demonstrated that a whole range of low-molecular mass compounds, which may be detected using UV-Vis detector, can easily be emitted from various in daily use products. The presence of micropollutants in treated wastewater, water ecosystems and plastic waste utilization via technological wastewater treatment processes must be addressed, especially in terms of microplastic-based pollutants acting as endocrine disrupters. It is hoped that the proposed simple analytical protocol will be useful for fast sample classification or selection prior to advanced targeted analysis involving the more accurate quantification of specific analytes using e.g., mass spectrometry detectors.

Freshwater spring indicator taxa of benthic invertebrates

Groundwater and subsurface water have important roles in river ecosystems: e.g., stabilizing flow regime and water temperature, supplying nutrients, and increasing biodiversity. However, detection of springs and quantitative estimation of groundwater contribution to the surface water ecosystems are not easy in the field. Although some indirect measurements combing simulations and models have been widely used to estimate the groundwater flow, they require certain assumptions, thus it is rather difficult to estimate the discharge of groundwater on a local scale. Direct field-scale measurement of groundwater flow is also difficult particularly for researches of ecology and environmental science.In this study, we present biological indicators of benthic invertebrates to evaluate the contribution of groundwater to surface water bodies. Because the benthic invertebrates show distribution patterns reflecting habitat scale environmental conditions in a sensitive manner, they are expected to serve as a biological indicator of groundwater spring sites. We collected data of benthic invertebrates from literature in a global scale and additional field research in Japan. By analyzing their taxonomic features and biological habits, we identified spring indicator taxa of benthic invertebrates based on the degree of dependency to groundwater environment.A total of 1,448 aquatic invertebrate species representing 58 orders were found from 249 research sites. The spring indicators were identified as spring dependent species including groundwater species (Stygobites and Stygophiles), cave species (Troglobites and Troglophile), and stenothermal species. Considering the geographical distribution patterns of the spring indicator taxa, stenothermal species were classified into "cold stenothermal species" which evolutionarily originate in more boreal regions and "warm stenothermal species" derived from more tropical regions. Ecological interpretation of these stenothermal species was discussed in relation to climatic zones and altitude of the basin concerned. Based on the variations of spring contribution into river ecosystems suggested by the spring indicator species, we proposed an application procedure of the spring indicators for environmental assessment and nature conservation works in river management.

The role of freshwater copepods in the environmental risk assessment of caffeine and propranolol mixtures in the surface water bodies of Spain

In this study we aimed at assessing: (i) the environmental risk posed by mixtures of caffeine and propranolol to the freshwater ecosystems of Spain; (ii) the sensitivity of freshwater copepod species to the two compounds; (iii) if the toxicity of caffeine and propranolol to freshwater copepods contributes to the environmental risk posed by the two compounds in the freshwater bodies of Spain. The environmental risk was computed as the ratio of MECs (i.e. the measured environmental concentrations) to PNECs (i.e. the respective predicted no-effect concentrations). The effects of caffeine and propranolol on the freshwater cyclopoid Diacyclops crassicaudis crassicaudis were tested both individually and in binary mixtures. Propranolol posed an environmental risk in some but not in all the surface water ecosystems of Spain investigated in this study, while caffeine posed an environmental risk to all the investigated freshwater bodies, both as single compound and in the mixture with propranolol. Propranolol was the most toxic compound to D. crassicaudis crassicaudis, while caffeine was non-toxic to this species. The CA model predicted the toxicity of the propranolol and caffeine mixture for this species. D. crassicaudis crassicaudis was much less sensitive than several other aquatic species to both compounds. The sensitivity of D. crassicaudis crassicaudis does not increase the environmental risk posed by the two compounds in the freshwater bodies of Spain, however, further testing is recommended since the effect of toxicants on freshwater copepods can be more pronounced under multiple stressors and temperature increasing due to climate change.

Aquatic Fungi: A Disregarded Trophic Level in Ecological Risk Assessment of Organic Fungicides

Freshwater fungi are a diverse group of organisms and fulfil important functions in the food web dynamics of surface water ecosystems. Ascomycetic and basidiomycetic hyphomycetes play key roles in leaf litter breakdown in rivers and creeks, while parasitic chytrids are an important food source for small invertebrates in lakes. Field studies indicate that fungal communities are affected by fungicides at environmentally relevant concentrations. However, despite their ecological importance, freshwater fungi are currently not specifically addressed in the EU regulatory frameworks with respect to the protection of surface waters. Specifically, the prospective risk assessment of fungicides does not evaluate adverse effects on non-target aquatic fungi. This paper aims to describe important functions of freshwater fungi, provides an overview of adverse effect levels of fungicides on this organism group, and proposes to integrate the fungal community of freshwater ecosystems as an additional trophic level in the current fungicide risk assessment frameworks. Results of a literature review on the effects of fungicides on aquatic fungi revealed that information on the toxicity of fungicides to non-target aquatic fungi is limited. This is, in part, due to the lack of standardised bioassays using aquatic fungi as test species. Although there is an encouraging number of bioassays focusing on the degradation of dead organic material by hyphomycetes, studies on fungicide effects on other important ecological functions, like the control of algal blooms in lentic surface waters by parasitic chytrid fungi, or on mutualistic fungi living in the guts of aquatic arthropods are largely missing. Thus, the further development and standardisation of different fungi bioassays is recommended.

Dye Removal from Water and Wastewater Using Various Physical, Chemical, and Biological Processes.

Synthetic dyes or colorants are key chemicals for various industries producing textiles, food, cosmetics, pharmaceutics, printer inks, leather, and plastics. Nowadays, the textile industry is the major consumer of dyes. The mass of synthetic colorants used by this industry is estimated at the level of 1 ÷ 3 × 105 tons, in comparison with the total annual consumption of around 7 × 105 tons worldwide. Synthetic dyes are relatively easy to detect but difficult to eliminate from wastewater and surface water ecosystems because of their aromatic chemical structure. It should be highlighted that the relatively high stability of synthetic dyes leads to health and ecological concerns due to their toxic, mutagenic, and carcinogenic nature. Currently, removal of such chemicals from wastewater involves various techniques, including flocculation/coagulation, precipitation, photocatalytic degradation, biological oxidation, ion exchange, adsorption, and membrane filtration. In this review, a number of classical and modern technologies for synthetic dye removal from industry-originated wastewater were summarized and discussed. There is an increasing interest in the application of waste organic materials (e.g., compounds extracted from orange bagasse, fungus biosorbent, or green algal biomasses) as effective, low-cost, and ecologically friendly sorbents. Moreover, a number of dye removal processes are based on newly discovered carbon nanomaterials (carbon nanotubes and graphene as well as their derivatives).

The Potential Impacts of Anthropogenic and Climate Changes Factors on Surface Water Ecosystem Deterioration at Kenyir Lake, Malaysia

Water ecosystem deterioration can be affected by various factors of either natural environment or physical changes in the river basin.. Data observation were made during dry season (April 2017) and wet season (December 2017). 21 sampling stations were selected along Kenyir Lake Basin. Overall, the water quality status as stated in NWQS is categorized as Class I on dry season and Class II on wet season. The major pollutants in Kenyir Lake are Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Dissolve Oxygen and pH which are contributed largely by untreated or partially treated sewage from tourism development and construction activities around the basin. The sedimentation problem level in the Kenyir Lake Basin is not in critically stage but the flow rate of water and land use activities (development around basin) will be contributed to the increasing levels of sedimentation. The good site management such as the implementation of proper site practice measures to control and treat run-off prior to discharge will ensure that the construction works will not affect the quality and quantity of the receiving waters or have significant impact upon the receiving waters.

Do composition and diversity of bacterial communities and abiotic conditions of spring water reflect characteristics of groundwater ecosystems exposed to different agricultural activities?

Modern agricultural practices have undeniably increased global food production. On the other hand, agricultural practices not only lead to a degradation of natural ecosystems but also affect the functioning of ecosystems and the related services they provide. Even though impacts of anthropogenic activities vary across ecosystems, freshwater ecosystems are among those affected to a higher degree. In comparison to surface water ecosystems, groundwater ecosystems are less affected by anthropogenic pollutants, as the overlaying soil retains organic and inorganic substances. However, it has become evident that the excessive use of fertilizers has led to the eutrophication of many aquifers. Bacterial communities, which significantly contribute to the cycling of matter due to their metabolic capacities, are prone to environmental perturbations, and structural variation of bacterial communities may consequently affect the functioning of groundwater ecosystems. Our present paper intends to evaluate the impact of anthropogenic activities on environmental conditions as well as on the structural properties of bacterial communities in groundwater. We repeatedly sampled emerging groundwater at five spring sites belonging to different catchments and determined the concentration of abiotic variables as well as the diversity and composition of bacterial communities on a local scale. We hypothesized that anthropogenic activities influence the concentration of abiotic variables, especially of nitrate, as well as the composition and diversity of bacterial communities in groundwater. Our results show that underground spring catchment areas only slightly differ regarding the concentration of abiotic variables as well as the structure of bacterial communities. Furthermore, abiotic variables, presumably influenced by anthropogenic activities, do not correlate with the diversity and composition of bacterial communities. Although supported only by circumstantial evidence, we suggest that upwelling groundwater from the deeper aquifer affects the diversity and composition of bacterial communities, and we argue that bacterial communities act as useful indicators for environmental changes.

Explicit consideration of preferential groundwater discharges as surface water ecosystem control points

Explicit consideration of preferential groundwater discharges as surface water ecosystem control points

Persistence of the antibiotic sulfamethoxazole in river water alone or in the co-presence of ciprofloxacin

Sulfamethoxazole and ciprofloxacin are among the most prescribed antibiotics and are frequently detected in surface water ecosystems. The aim of this study was to assess the role of a riverine natural microbial community in sulfamethoxazole (SMX) degradation in presence and absence of ciprofloxacin (CIP). River samples were collected from a stretch of the Tiber River highly impacted by human pressure. An experimental set up was performed varying some abiotic (dark/UV-light) and biotic (presence/absence of microorganisms) conditions that can affect antibiotic degradation.The residual concentrations of SMX and CIP were measured (HPLC-MS or HPLC-UV/FLD) and the effects on the natural microbial community were assessed in terms of microbial number (N. live cells/mL) and structure (Fluorescence In Situ Hybridization - FISH). Finally, the occurrence of the antibiotic resistance sul1 gene was also verified using quantitative PCR (qPCR).In 28 days, in the presence of both UV-light and microorganisms SMX disappeared (<LOD). SMX decreased partially in the dark (24%) and a slightly higher depletion was found in sterile river water and UV-light (30%). However, only in the presence of the microbial populations and in dark conditions, SMX disappeared subsequently at days 60. In the co-presence of CIP and light, SMX was more persistent (50%) than when alone. The depletion of CIP was not negatively influenced by SMX occurrence. The antibiotics did not negatively affect the microbial numbers. The FISH analysis showed that some bacterial populations were initially inhibited by the presence of the antibiotics, but at the end of the experiment, a general increase in most groups was observed together with an increase in the copy numbers of the sul1 gene. Therefore, the antibiotics at the dose of 500 μg/L did not have biocide effects on the natural microbial community and, instead, promoted some resistant natural bacterial populations able to degrade them.

Miniaturized Temperature-Controlled Planar Chromatography (Micro-TLC) as a Versatile Technique for Fast Screening of Micropollutants and Biomarkers Derived from Surface Water Ecosystems and During Technological Processes of Wastewater Treatment.

There is increasing interest in the development of simple analytical systems enabling the fast screening of target components in complex samples. A number of newly invented protocols are based on quasi separation techniques involving microfluidic paper-based analytical devices and/or micro total analysis systems. Under such conditions, the quantification of target components can be performed mainly due to selective detection. The main goal of this paper is to demonstrate that miniaturized planar chromatography has the capability to work as an efficient separation and quantification tool for the analysis of multiple targets within complex environmental samples isolated and concentrated using an optimized SPE method. In particular, we analyzed various samples collected from surface water ecosystems (lakes, rivers, and the Baltic Sea of Middle Pomerania in the northern part of Poland) in different seasons, as well as samples collected during key wastewater technological processes (originating from the "Jamno" wastewater treatment plant in Koszalin, Poland). We documented that the multiple detection of chromatographic spots on RP-18W microplates-under visible light, fluorescence, and fluorescence quenching conditions, and using the visualization reagent phosphomolybdic acid-enables fast and robust sample classification. The presented data reveal that the proposed micro-TLC system is useful, inexpensive, and can be considered as a complementary method for the fast control of treated sewage water discharged by a municipal wastewater treatment plant, particularly for the detection of low-molecular mass micropollutants with polarity ranging from estetrol to progesterone, as well as chlorophyll-related dyes. Due to the low consumption of mobile phases composed of water-alcohol binary mixtures (less than 1 mL/run for the simultaneous separation of up to nine samples), this method can be considered an environmentally friendly and green chemistry analytical tool. The described analytical protocol can be complementary to those involving classical column chromatography (HPLC) or various planar microfluidic devices.

Миграционные процессы тяжелых металлов и нефтепродуктов в системе «почвенный покров – поверхностные воды» на урбанизированной территории

The seasonal dynamics of the content of heavy metals and petroleum products in the soil and aqueous ecosystems within urbanized territory of Ulyanovsk has been examined. With the application of statistical methods of analysis the influence of physicochemical factors on migratory processes of heavy metals (Zn, Cu, Ni, Cd, Pb) has been investigated in the soil cover – surface water ecosystem.

Multi-Functional Dike-Pond SYSTEM Adaptive to Water Level Change: Application of Pond-Based Ecological Wisdom in Ecological Restoration of the Hydro-Fluctuation Belt of the Three Gorges Reservoir

There are many ponds with different sizes and shapes in nature, providing a variety of ecological services. In the era of traditional farming, people created pond systems with ecological wisdom, such as Beitang ponds, multi-pond system, mulberry-based dike fish pond, etc., which perform ecological functions including water storage, stormwater regulation, pollution purification, micro-climate adjustment, and habitat provision. Due to global climate change and human interference, problems such as the surface water shortage, water pollution and water ecosystem destruction are becoming more and more serious. To deal with the changing environment, restore ecology, and construct landscape effectively, we not only could be inspired by the natural pond system, but also need to learn from the traditional cultural heritage, such as the ecological wisdom of the various pond systems. The multi-functional dike pond system plays an important role in dealing with the environmental changes and optimizing the ecological services. On the basis of clarifying the composition, structure and function of ponds in nature, this article explores the ecological wisdom of the pond systems in traditional villages, taking the design and practices of the Three Gorges Reservoir as an example to discuss the application of the multi-functional dike pond in the ecological restoration and landscape optimization of the hydro-fluctuation belt with seasonal water level fluctuation.

Exploring micropollutant biotransformation in three freshwater phytoplankton species.

Phytoplankton constitute an important component of surface water ecosystems; however little is known about their contribution to biotransformation of organic micropollutants. To elucidate biotransformation processes, batch experiments with two cyanobacterial species (Microcystis aeruginosa and Synechococcus sp.) and one green algal species (Chlamydomonas reinhardtii) were conducted. Twenty-four micropollutants were studied, including 15 fungicides and 9 pharmaceuticals. Online solid phase extraction (SPE) coupled with liquid chromatography (LC)-high resolution tandem mass spectrometry (HRMS/MS) was used together with suspect and nontarget screening to identify transformation products (TPs). 14 TPs were identified for 9 micropollutants, formed by cytochrome P450-mediated oxidation, conjugation and methylation reactions. The observed transformation pathways included reactions likely mediated by promiscuous enzymes, such as glutamate conjugation to mefenamic acid and pterin conjugation of sulfamethoxazole. For 15 compounds, including all azole fungicides tested, no TPs were identified. Environmentally relevant concentrations of chemical stressors had no influence on the transformation types and rates.

Remote Sensing and GIS for Surface Water Resources in Rawa Biru – Torasi Merauke Papua

The research describe about surface water ecosystem study in Merauke Papua by using multisource and multistage remote sensing data which was splitted into two parts based on the study areas. First, it is for micro scale spatial analysis focusing on the Rawa Biru – Torasi watershed, while the second is for macro scale spatial analysis for Transfly ecoregionin the floodplain areas of Merauke. Multispectral approach was adopted for Landsat image analysis, followed by field survey on the selected areas. Auxilary data used are maps, secondary documents in order to improve understanding of the areas. Interview and discussion with related institutions (Wasur National Sanctuary, Potable Water Services, Internal Affairs Government, Forestry Service) accordingly were carried out. The research result showed that remote sensing imagery are usefull for surface water resources study. Physical condition of the Rawa Biru – Torasi watershed, vegetation analysis by using multitemporal data, wetland type, hydrological process in the floodplain were presented. Rawa Biru watershed as a resource for drinking water supply environmentaly decreased considerably due to the species invasion, with successively dominated by hydrophilla, tebu rawa, rumput pisau, dan Mellaleuca and sedimentation took place in the main body of swamp. Upper part of the watershed is actually included in the Papua New Guinea, in long water resources development scheme, it need administratively belong to one recharge areas for the watershed.

Distribution of pesticides in dust particles in urban environments

In regions with a mild climate, pesticides are often used around homes for pest control. Recent monitoring studies have linked pesticide use in residential areas to aquatic toxicity in urban surface water ecosystems, and suggested dust particles on paved surfaces as an important source of pesticides. To test the hypothesis that dust on hard surfaces is a significant source of pesticides, we evaluated spatial and temporal patterns of current-use insecticides in Southern California, and further explored their distribution as a function of particle sizes. Pyrethroid insecticides were detected in dust from the driveway, curb gutter and street at 53.5–94.8%, with median concentrations of 1–46 ng g−1. Pyrethroid residues were uniformly distributed in areas adjacent to a house, suggesting significant redistribution. The total levels of pyrethroids in dust significantly (p < 0.01) decreased from October to February, suggesting rainfalls as a major mechanism to move pesticide residues offsite. Fipronil as well as its degradation products, were detected at 50.6–75.5%, and spatial and temporal patterns of fipronil residues suggested rapid transformations of fipronil to its biologically active intermediates. Moreover, pyrethroids were found to be enriched in fine particles that have a higher mobility in runoff than coarse particles. Results from this study highlight the widespread occurrence of pesticides in outdoor dust around homes and the potential contribution to downstream surface water contamination via rain-induced runoff.

The consequences of increased groundwater abstraction for groundwater dependent closed-basin lakes in glacial terrain

According to the European Union Water Framework Directive groundwater and surface-water resources have to be managed in an integrated way. The utilisation of groundwater resources must not harm surface-water ecosystems that are directly dependent on groundwater. The study evaluates the effects of increased groundwater abstraction (a) on a regional scale to groundwater and lake levels in a lake district, and (b) on a local scale to the seepage patterns in one example lake. After a 51 % increase in the pumping rates from an unconfined aquifer the water levels of three closed-basin lakes near the intake fell 0.3–0.7 m in 1 year, but did not change in the two lakes further from the intake. Groundwater levels in the aquifer dropped up to 0.8 m near the intake, but did not change further from the wells. Seepage measurements at the bottom of one lake showed that before the increased abstraction outseepage occurred in its northern side, after the increased abstraction the outseepage area had widened towards its western side. The results confirm that the groundwater level drop and the consequent lake-level drop were caused by the increased abstraction rate. The outcomes of the rare opportunity to analyse lake/groundwater interactions both before and after increased human intervention provide a cautionary example of what may happen to and in groundwater-dependent lakes if the groundwater/surface-water interactions are not fully clarified before the intervention in potentially similar cases around the world.