Trend and concentrations of legacy lead (Pb) in highway runoff

Marsh archive reveals human population history and future implications for estuarine health in Long Island Sound

Coastal marshes are efficient ecosystems providing a multitude of benefits for invertebrates, birds, fish and humans alike. Yet despite these benefits, wetlands are threatened by anthropogenic inputs such as human wastewater which contain high levels of nitrogen (N). Increased nitrogen loads cause eutrophication and hypoxia in estuaries leading to further degradation of these valuable ecosystems that are already stressed by sea level rise and climate change. Policies to protect wetlands via wastewater treatments are reactive rather than proactive and a growing body of research shows that characteristics associated with population health and economic activity can be identified in wastewater. Analysis of a 2-m salt marsh sediment core reveals δN15 signatures indicative of human population rise and connects human impact to ecosystem health. Using key X-ray fluorescence (XRF), pollen, sediment and nitrogen signatures along the core, a robust chronology was produced dating back to 1700. This result was coupled with population data to observe the relationship between δN15 levels and population over three centuries. There is a statistically significant positive correlation between δN15 and population. Other external factors such as federal government policies (regulating clean water) show a clear reduction in this association but the use of synthetic nitrogen fertilizer masks the strength of this relationship. Further research to refine the relationship between population and δN15 could be beneficial in predicting nitrogen loads as human population grows, which in turn would create a proactive system to protect our coastal ecosystems.

Characteristics of dissolved organic matter in urban road runoff under different traffic densities in Beijing, China

The characteristics of dissolved organic matter (DOM) in road runoff under different traffic densities were compared using resin fractionation, molecular weight distribution analysis, three-dimensional excitation-emission matrix fluorescence spectroscopy, and UV-visible spectroscopy. Heavy traffic density strongly increased the concentration of DOM in road runoff, resulting in higher dissolved organic carbon. The distribution of molecular weights in DOM was not influenced by the traffic. DOM was dominated by colloidal organic matter with molecular weight in the 1 kDa to 0.45 μm size range. Hydrophobic fractions accounted for a large proportion than hydrophilic fractions in DOM, and hydrophobic acids increased with higher traffic density. Traffic density did not alter the fluorescent substances in DOM, including fulvic-like UV fluorescent substances and protein-like substances. However, more tryptophan-like protein substances were found in DOM from road runoff with heavy traffic. Moreover, the aromatization degree of DOM was not affected by heavy traffic, while the degree of humification decreased.

Environmental impacts and risks of bridges and tunnels across lakes: An overview

Bridges and tunnels are built across lakes, especially in China, to improve road connectivity for transportation. However, their environmental impacts and risks have not received adequate attention. In this study, the magnitude of bridges and tunnels across 142 lakes in China were investigated. The investigation revealed that 37 bridges and 10 tunnels (a total length of 56.82 km) were built across 26 lakes during 2000-2020. From 2011 to 2020, the construction rate of bridges and tunnels across lakes in China was ∼6 times higher than the average value worldwide. Their environmental impacts and risks on lakes were summarised by analyzing previous publications screened from the Web of Science platform. The environmental impacts and risks during the bridge/tunnel construction period generally include decrease in water exchange, habitat destruction, biological reduction, increase in suspended solids, and water quality pollution. Tunnel construction may also affect the ecological conditions of groundwater due to its disturbances in the underground area. During the bridge/tunnel operation period, environmental impacts and risks were mainly induced by rainfall events and water pollution accidents. The impacts and risks were highly related to the construction location, bridge/tunnel properties, moving vehicles, fixing activities, and atmospheric deposition. Owing to the existing weaknesses in management practices, a framework, aiming to reduce the environmental impacts and risks caused by bridges and tunnels across lakes, was proposed. The framework identified the critical issues and their corresponding management strategies during the bridge/tunnel construction and operation periods and enabled the generation of the best management strategy for each specific period.

Impacts of Highway Runoff on Metal Contamination Including Rare Earth Elements in a Small Urban Watershed: Case Study of Bordeaux Metropole (SW France)

High temporal resolution sampling of runoff (15 samples/4 h) and river water (24 samples/24 h) was performed during a major rainstorm (41 mm/4 h) in the Bordeaux Metropole, after a dry and high vehicle-density period. Runoff was sampled at the outlet of one collector draining Northern Bordeaux Highway (NBH; 80,000-93,000 vehicles/day) and river water in the downstream Jalle River. The studied metals, including priority and emergent (Rare Earth Elements [REEs]) contaminants, showed major temporal and spatial variations in the dissolved and particulate concentrations. Hierarchical cluster analyses distinguished metal groups, reflecting different: (i) sources (i.e., automotive traffic: Zn-Cu-Ce and wastewater treatment plant: Cd-Ag-Gd) and/or (ii) processes (i.e., groundwater dilution by rainwater and sorption processes). The contribution of the particulate fraction to total metal fluxes was predominant in the NBH collector (except for Sr and Mo) and highly variable in the Jalle River, where the highest particulate metal loads were due to the export of road dusts exported by the NBH collector. Metal fluxes from the NBH collector represented highly variable fractions of daily fluxes into the Gironde Estuary at the outlet of the Jalle River, depending on elements and partitioning. The resulting relative contributions ranged from: 5% (Sr) to 40% (Cu) for dissolved phases and 30% (As) to 88% (Cu) for particulate phases. The first 40 min of the event accounted for 65% of the suspended particulate matter flux (and associated particulate metals) exported by the NBH collector, whereas the respective water flux contribution was 35%. This finding clearly demonstrates the importance of monitoring the first minutes of rainy events when establishing mass balances in urban systems.

Application of Nanomaterials in Isothermal Nucleic Acid Amplification

Because of high sensitivity and specificity, isothermal nucleic acid amplification are widely applied in many fields. To facilitate and improve their performance, various nanomaterials, like nanoparticles, nanowires, nanosheets, nanotubes, and nanoporous films are introduced in isothermal nucleic acid amplification. However, the specific application, roles, and prospect of nanomaterials in isothermal nucleic acid amplification have not been comprehensively reviewed. Here, the application of different nanomaterials (0D, 1D, 2D, and 3D) in isothermal nucleic acid amplification is comprehensively discussed and recent progress in the field is summarized. The nanomaterials are mainly used for reaction enhancer, signal generation/amplification, or surface loading carriers. In addition, 3D nanomaterials can be also functioned as isolated chambers for digital nucleic acid amplification and the tools for DNA sequencing of amplified products. Challenges and future recommendations are also proposed to be better used for recent covid-19 detection, point-of-care diagnostic, food safety, and other fields.

Investigation into the utility of flying foxes as bioindicators for environmental metal pollution reveals evidence of diminished lead but significant cadmium exposure

Due to their large range across diverse habitats, flying-foxes are potential bioindicator species for environmental metal exposure. To test this hypothesis, blood spots, urine, fur, liver and kidney samples were collected from grey-headed flying-foxes (Pteropus poliocephalus) and black flying-foxes (P. alecto) from the Sydney basin, Australia. Concentrations of arsenic, cadmium, copper, lead, mercury and zinc and 11 other trace metals were determined using inductively coupled plasma mass spectrometry. As predicted, kidney and fur lead concentrations were lower compared to concentrations found in flying-foxes in the early 1990's, due to reduced environmental lead emissions. Tissue cadmium concentrations in flying-foxes were higher compared to previous studies of flying-foxes and other bat species, suggesting that flying-foxes were exposed to unrecognized cadmium sources. Identification of these sources should be a focus of future research. Urine concentrations of arsenic, cadmium, mercury, and lead were proportional to kidney concentrations. Given that urine can be collected from flying-foxes without handling, this demonstrates that many flying-foxes can be assessed for metal exposure with relative ease. The analysis of blood spots was not viable because of variable metal concentrations in the filter paper used. Fur concentrations of metals correlated poorly with tissue concentrations at the low levels of metals found in this study, but fur could still be a useful sample if flying-foxes are exposed to high levels of metals. Lastly, heat inactivation had minimal impact on metal concentrations in kidney and liver samples and should be considered as a tool to protect personnel working with biohazardous samples.

Determination of (Bio)-available mercury in soils: A review

Despite the mercury (Hg) control measures adopted by the international community, Hg still poses a significant risk to ecosystem and human health. This is primarily due to the ability of atmospheric Hg to travel intercontinentally and contaminating terrestrial and aquatic environments far from its natural and anthropogenic point sources. The issue of Hg pollution is further complicated by its unique physicochemical characteristics, most noticeably its multiple chemical forms that vary in their toxicity and environmental mobility. This meant that most of the risk evaluation protocols developed for other metal(loid)s are not suitable for Hg. Soil is a major reservoir of Hg and a key player in its global cycle. To fully assess the risks of soil Hg it is essential to estimate its bioavailability and/or availability which are closely linked to its toxicity. However, the accurate determination of the (bio)-available pools of Hg in soils is problematic, because the terms 'bioavailable' and 'available' are ill-defined. In particular, the term 'bioavailable pool', representing the fraction of Hg that is accessible to living organisms, has been consistently misused by interchanging with other intrinsically different terms e.g. mobile, labile, reactive and soluble pools. A wide array of physical, chemical, biological and isotopic exchange methods were developed to estimate the (bio)-available pools of Hg in soil in an attempt to offer a plausible assessment of its risks. Unfortunately, many of these methods do not mirror the (bio)-available pools of soil Hg and suffer from technical drawbacks. In this review, we discuss advantages and disadvantages of methods that are currently applied to quantify the (bio)-availability of Hg in soils. We recommended the most feasible methods and give suggestions how to improve the determination of (bio)-available Hg in soils.

Anthropogenic-induced acceleration of elemental burial rates in blue carbon repositories of the Arabian Gulf

Along the past century, the Arabian Gulf has experienced a continuous and fast coastal development leading to increase the human pressures on the marine environment. The present study attempts to describe the historical changes of trace elements in the sediments of vegetated coastal habitats in the western Arabian Gulf. ²¹⁰Pb-dated sediment cores collected from seagrass, mangrove and saltmarsh habitats were analyzed to evaluate historical variations in concentrations and burial rates of 20 trace elements (Al, As, Ba, Ca, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, S, Sr, V and Zn). The highest correlations (Spearman correlation coefficients ≥0.51) were found between crustal elements (Al, Fe, Co, Cr, K, Na, Mg, Mn, Ni, V, and P), suggesting a common crustal source in the Gulf. The increased concentrations of these crustal elements in modern marine sediments of the Arabian Gulf seem to be linked to increased mineral dust deposition in the area. Over the last century, both elemental concentrations and burial rates increased by factors of 1-9 and 1-15, respectively, with a remarkably fast increase occurring in the past six decades (~1960 - early 2000). This is most likely due to an increase in anthropogenic pressures along the Gulf coast. Our study demonstrates that sediments in vegetated coastal habitats provide long-term archives of trace elements concentrations and burial rates reflecting human activities in the Arabian Gulf.

The removal of lead, copper, zinc and cadmium from aqueous solution by biochar and amended biochars

The exponential growth in the use of motor vehicles is a key contributor to freshwater degradation. Current remediation techniques require prohibitively expensive contaminant treatment and extraction. Biochar represents an inexpensive option to ameliorate contaminants from motorway runoff. Biochar from Norway spruce (Picea abies (L.) Karst.) was produced under fast pyrolysis-gasification (450-500 °C for 90 s) and amended with wood ash and basaltic rock dust to evaluate sorption of Pb, Cu, Zn and Cd. The column study, designed to mimic field conditions, confirmed that unamended biochar can bind contaminants for short periods, but that the addition of amendments, particularly wood ash, significantly improves contaminant removal. Wood ash-amended biochar removed 98-100% of all contaminants during the study, driven by pH (r = 0.73-0.74; p < 0.01 dependent on metal species) and phosphorus levels causing precipitation (r = 0.47-0.59; p < 0.01, dependent on metal species). The contaminants' progression through the biochar subsections in the column indicated that increasing the thickness of the biochar layer increased contaminant residence time and removal.

Isotope tracers for lead and strontium sources in the Tieguanyin tea garden soils and tea leaves

The concentrations of Pb & Sr in Tieguanyin tea leaves and soils from 15 tea gardens of Anxi, China, were determined and the sources of Pb & Sr in soil and leaf samples were analysed using isotope tracing technology. The results showed pH in soils had significant correlations to both acid-extractable Pb & Sr in soils and new leaves. The Pb concentration in leaves was significantly lower than that in soils, especially the acid-extractable Pb in soils. The low Bio-concentration Factor (BCF) indicated the bioavailable Pb in soils could not easily be transferred to leaves. The contribution rates of parent material were 61%-100% and 45%-100% for total Pb isotope and acid-extractable Pb isotope in soils, respectively, indicating a low impact of human activity. A sizeable influence of parent material for leaves was also observed, suggesting that Pb may be present in the dust-fall. Although Sr concentrations in leaves were not high, they exceeded that in soils. The high BCF also indicated that tea has a high capacity to accumulate Sr, with the coincidence that Sr⁸⁷/Sr⁸⁶ in the acid-extractable isotope in soils were similar to new leaves. A Pb-Sr joint tracer indicated that Sr in old and new leaves may be influenced by parent material and anthropogenic sources, respectively.

The pollution conveyed by urban runoff: A review of sources

Urban stormwater and snowmelt pollution contributes significantly to the deterioration of surface waters quality in many locations. Consequently, the sources of such pollution have been studied for the past 50 years, with the vehicular transportation sector and the atmospheric deposition identified early as the major pollution sources. In search for mitigation of this pollution, source controls, besides other measures, were recognised as effective pollution mitigation tools, whose successful implementation requires a good knowledge of pollution sources. Even though great research efforts have been exerted to document specific sources of urban runoff pollution, or specific groups of pollutants present in urban runoff, a comprehensive overview of all known contributing sources is still missing. This review contributes to closing this gap by compiling findings of previous research and critically synthesizing the current knowledge of various stormwater pollution sources. As the emphasis is placed on the sources, the related issues of implications for urban surface water quality and possible source controls for individual sources are touched upon just briefly, where required. The review showed that the atmospheric deposition, vehicular transportation-related activities and metallic building envelopes continue to be among the major pollution sources, which have been studied in a far greater detail than other sources. Furthermore, it was noted that because of the rapid advances in clean manufacturing and pollution control technologies, a large part of the body of data on stormwater quality available in the literature should be considered as historical data, which may no longer describe well the current conditions. Progressing historical data obsolescence, combined with continuing releases of new materials and chemicals, and, in some cases of new substances of potential concern, into the environment, suggests that the identification of important stormwater runoff/snowmelt pollution sources, and the associated pollutants, has been and will remain to be a work in progress.

Analysis of swale factors implicated in pollutant removal efficiency using a swale database

Swales are traditional basic open-drainage systems which are able to remove stormwater-borne pollutants. In spite of numerous case studies devoted to their performances, parameters influencing the reduction of pollutant concentrations by swales remain elusive. In order to better characterize them, a database was set up by collecting performance results and design characteristics from 59 swales reported in the literature. Investigations on correlations among pollutant efficiency ratios (ERs) indicated that total trace metals (copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb)), total suspended solids (TSS), total phosphorus (TP), and total Kjeldahl nitrogen (TKN) exhibited many cross-correlated ERs. High ERs were observed for pollutants including a particulate form such as TSS (median ERs = 56%) and total trace metals (median ERs ≥ 62%), suggesting that these pollutants are efficiently trapped by sedimentation in swale bed and/or filtered within swale soil. Medium to high ERs were found for dissolved trace metals (median ERs ≥ 44%), whereas ERs for nutrient species were lower (median ERs ≤ 30%). The inflow concentration was identified as a major factor correlated to ER for most pollutants. For some pollutants, there is also a trend to get higher ER when the geometrical design of the swale increases the hydraulic residence time. Overall, this database may help to better understand swale systems and to optimize their design for improving pollutant removal.

Human Health Risk Assessment of Toxic Elements in Farmland Topsoil with Source Identification in Jilin Province, China

The presence of toxic elements in agricultural soils from anthropogenic activities is a potential threat to human health through the food chain. In this study, the concentration of toxic elements in 122 agricultural topsoil composite samples were determined in order to study the current status, identify their sources and assess the level of pollution and human health risk. The results showed that the mean concentrations of Zn, Cu, Pb, Cd, Hg and As in the farmland topsoil were 21.72, 15.09, 36.08, 0.2451, 0.0378 and 4.957 mg·kg⁻¹, respectively. The spatial distribution showed that the soils were mainly contaminated by Cd, Pb and Hg in midwest Jilin but by Cu and As in the east. According to the pollution index (Pi), Nemerow integrated pollution index (PN) and Geo-Accumulation Index (I_geo), Cd and Pb were the main pollutants in the soils. The occurrence of these elements was caused by anthropogenic activities and they were concentrated in the Songyuan-Changchun-Siping economic belt. There is limited non-carcinogenic and carcinogenic health risk to humans. Principal component analyses suggest the Pb, Cd and Hg soil contamination was mainly derived from anthropogenic activities in the Midwest, but all examined toxic elements in the east were mainly due to geogenic anomalies and came from atmospheric deposition.

Long-term variation in concentrations and mass loads in a semi-arid watershed influenced by historic mercury mining and urban pollutant sources

Urban watersheds are significantly anthropogenically-altered landscapes. Most previous studies cover relatively short periods, without addressing concentrations, loads, and yields in relation to annual climate fluctuations, and datasets on Ag, Se, PBDEs, and PCDD/Fs are rare. Intensive storm-focused sampling and continuous turbidity monitoring were employed to quantify pollution at two locations in the Guadalupe River (California, USA). At a downstream location, we determined loads of suspended sediment (SS) for 14yrs., mercury (HgT), PCBs, and total organic carbon (TOC) (8yrs), total methylmercury (MeHgT) (6yrs), nutrients, and trace elements including Ag and Se (3yrs), DDTs, chlordanes, dieldrin, and PBDEs (2yrs), and PCDD/Fs (1yr). At an upstream location, we determined loads of SS for 4yrs. and HgT, MeHgT, PCBs and PCDD/Fs for 1yr. These data were compared to previous studies, climatically adjusted, and used to critically assess the use of small datasets for estimating annual average conditions. Concentrations and yields in the Guadalupe River appear to be atypical for total phosphorus, DDTs, dieldrin, HgT, MeHgT, Cr, Ni, and possibly Se due to local conditions. Other pollutants appear to be similar to other urban systems. On average, wet season flow varied by 6.5-fold and flow-weighted mean (FWM) concentrations varied 4.4-fold, with an average 7.1-fold difference between minimum and maximum annual loads. Loads for an average runoff year for each pollutant were usually less than the best estimate of long-term average. The arithmetic average of multiple years of load data or a FWM concentration combined with mean annual flow was also usually below the best estimate of long-term average load. Mean annual loads using sampled years were also less than the best estimate of long-term average by a mean of 2.2-fold. Climatic adjustment techniques are needed for computing estimates of long-term average annual loads.

A novel test method to determine the filter material service life of decentralized systems treating runoff from traffic areas

In recent years, there has been a significant increase in the development and application of technical decentralized filter systems for the treatment of runoff from traffic areas. However, there are still many uncertainties regarding the service life and the performance of filter materials that are employed in decentralized treatment systems. These filter media are designed to prevent the transport of pollutants into the environment. A novel pilot-scale test method was developed to determine - within a few days - the service lives and long-term removal efficiencies for dissolved heavy metals in stormwater treatment systems. The proposed method consists of several steps including preloading the filter media in a pilot-scale model with copper and zinc by a load of n-1 years of the estimated service life (n). Subsequently, three representative rain events are simulated to evaluate the long-term performance by dissolved copper and zinc during the last year of application. The presented results, which verified the applicability of this method, were obtained for three filter channel systems and six filter shaft systems. The performance of the evaluated systems varied largely for both tested heavy metals and during all three simulated rain events. A validation of the pilot-scale assessment method with field measurements was also performed for two systems. Findings of this study suggest that this novel method does provide a standardized and accurate estimation of service intervals of decentralized treatment systems employing various filter materials. The method also provides regulatory authorities, designers, and operators with an objective basis for performance assessment and supports stormwater managers to make decisions for the installation of such decentralized treatment systems.

Potential sources and racial disparities in the residential distribution of soil arsenic and lead among pregnant women

Exposure to arsenic (As) or lead (Pb) has been associated with adverse health outcomes, and high-risk populations can be disproportionately exposed to these metals in soils. The objectives of this study were: to examine if predicted soil As and Pb concentrations at maternal residences of South Carolina (SC) low-income mothers differed based on maternal race (non-Hispanic black versus white), to examine whether differences in predicted residential soil As and Pb concentrations among black and white mothers differed by socioeconomic status (SES), and to examine whether such disparities persisted after controlling for anthropogenic sources of these metals, including direction from, and distance to industrial facilities. Kriged soil As and Pb concentrations were estimated at maternal residences in 11 locations in SC, and models with maternal race and individual and US Census block group level SES measures were examined. US Environmental Protection Agency Toxics Release Inventory (TRI) facility As and Pb releases categorized by distance and direction to block groups in which mothers resided were also identified, as were proxy measures for historic use of leaded gasoline (road density) and Pb-based paint (categories of median year home built by US Census block group). Consistent racial disparities were observed for predicted residential soil As and Pb concentrations, and the disparity was stronger for Pb than As (betas from adjusted models for black mothers were 0.12 and 2.2 for As and Pb, respectively, all p<0.006). Higher road density and older homes in block groups were more closely associated with higher predicted soil As and Pb concentrations than on-site releases of As and Pb categorized by facility location. These findings suggest that non-Hispanic black mothers in this study population had elevated residential As and Pb soil concentrations, after adjusting for SES, and that soil As and Pb concentrations were not associated with recent industrial releases.

Untreated runoff quality from roof and road surfaces in a low intensity rainfall climate

Sediment and heavy metals in stormwater runoff are key pollutants of urban waterways, and their presence in stormwater is driven by climatic factors such as rainfall intensity. This study describes the total suspended solids (TSS) and heavy metal concentrations found in runoff from four different urban surfaces within a residential/institutional catchment, in a climate where rainfall is typically of low intensity (<5.1mm·h(-1)). The results were compared to untreated runoff quality from a compilation of international studies. The road runoff had the highest TSS concentrations, while copper and galvanized roof runoff had the highest copper and zinc concentrations, respectively. Pollutant concentrations were found to be significantly different between surfaces; quantification and prediction of pollutant contributions from urban surfaces should thus take account of the different surface materials, instead of being aggregated into more generalized categories such as land use. The TSS and heavy metal concentrations were found to be at the low to medium end of ranges observed internationally, except for total copper and zinc concentrations generated by dissolution of copper and galvanized roofing material respectively; these concentrations were at least as high as those reported internationally. TSS wash-off from the roofs was seen to be a source-limited process, where all available TSS is washed off during the rain event despite the low intensity rainfall, whereas both road TSS and heavy metals wash-off from roof and road surfaces appeared to all be transport-limited and therefore some carryover of pollutants occurs between rain events. A first flush effect was seen from most surfaces for TSS, but not for heavy metals. This study demonstrates that in low intensity rainfall climates, quantification of untreated runoff quality from key individual surface types in a catchment are needed to enable development of targeted and appropriately sized stormwater treatment systems.

Critical review of heavy metal pollution of traffic area runoff: Occurrence, influencing factors, and partitioning

A dataset of 294 monitored sites from six continents (Africa, Asia, Australia, Europe, North and South America) was compiled and evaluated to characterize the occurrence and fate of heavy metals in eight traffic area categories (parking lots, bridges, and three types each of both roads and highways). In addition, site-specific (fixed and climatic) and method-specific (related to sample collection, preparation, and analysis) factors that influence the results of the studies are summarized. These factors should be considered in site descriptions, conducting monitoring programs, and implementing a database for further research. Historical trends for Pb show a sharp decrease during recent decades, and the median total Pb concentrations of the 21st century for North America and Europe are approximately 15 μg/L. No historical trend is detected for Zn. Zn concentrations are very variable in traffic area runoff compared with other heavy metals because of its presence in galvanized structures and crumbs of car tire rubber. Heavy metal runoff concentrations of parking lots differ widely according to their use (e.g., employee, supermarket, rest areas for trucks). Bridge deck runoff can contain high Zn concentrations from safety fences and galvanizing elements. Roads with more than 5000 vehicles per day are often more polluted than highways because of other site-specific factors such as traffic signals. Four relevant heavy metals (Zn, Cu, Ni, and Cd) can occur in the dissolved phase. Knowledge of metal partitioning is important to optimize stormwater treatment strategies and prevent toxic effects to organisms in receiving waters.

Mobilization and distribution of lead originating from roof dust and wet deposition in a roof runoff system

In this research, the mobilization and distribution of lead originating in roof dust and wet deposition were investigated within a roof dust-rooftop-runoff system. The results indicated that lead from roof dust and wet deposition showed different transport dynamics in runoff system and that this process was significantly influenced by the rainfall intensity. Lead present in the roof dust could be easily washed off into the runoff, and nearly 60 % of the total lead content was present in particulate form. Most of the lead from the roof dust was transported during the late period of rainfall; however, the lead concentration was higher for several minutes at the rainfall beginning. Even though some of the lead from wet deposition, simulated with a standard isotope substance, was adsorbed onto adhered roof dust and/or retained on rooftop in runoff system, most of it (50-82 %) remained as dissolved lead in the runoff for rainfall events of varying intensity. Regarding the distribution of lead in the runoff system, the results indicated that it could be carried in the runoff in dissolved and particulate form, be adsorbed to adhered roof dust, or remain on the rooftop because of adsorption to the roof material. Lead from the different sources showed different distribution patterns that were also related to the rainfall intensity. Higher rainfall intensity resulted in a higher proportion of lead in the runoff and a lower proportion of lead remaining on the rooftop.

Source apportionment of trace contaminants in urban sewer catchments

Sampling and analysis of Water Framework Directive priority chemicals were undertaken in nine urban catchments across the UK. Over 9000 samples were collected from a number of different catchment sources including tap water, domestic waste water, surface water runoff, trade discharges, town centre and light industrial estate wastewaters. Determinands included trace metals, polyaromatic hydrocarbons (PAHs), persistent organic pollutants and a number of common pharmaceuticals. Loads of the chemicals from each catchment entering the local wastewater treatment works (WwTW) were estimated and were shown to be relatively consistent between different catchments, after taking population into account. A Monte Carlo mixing model was used to combine the concentrations and flows from the different catchment sources and to predict concentrations and loads entering the WwTW. Based on the model output, the significance of the different sources could be evaluated. The study highlighted the importance of domestic wastewater as a source of contaminants, including metals and trace organic substances (such as ethylenediaminetetraacetic acid (EDTA), bisphenol A, nonylphenol and tributyl tin (TBT)). Concentrations in trade discharges were important in some locations in the case of nonylphenol, EDTA, TBT, as well as for some metals such as copper, zinc and nickel. Contributions to the total load from town centre and light industrial estate sources were generally less than 10% of the total.

N-doped carbon dots synthesized by rapid microwave irradiation as highly fluorescent probes for Pb2+ detection

New NCDs were obtained and exhibit highly sensitive response to Pb²⁺ which could be applied to real sample detection.

Assessment of ecological and human health risks of heavy metal contamination in agriculture soils disturbed by pipeline construction

The construction of large-scale infrastructures such as nature gas/oil pipelines involves extensive disturbance to regional ecosystems. Few studies have documented the soil degradation and heavy metal contamination caused by pipeline construction. In this study, chromium (Cr), cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) levels were evaluated using Index of Geo-accumulation (I_geo) and Potential Ecological Risk Index (RI) values, and human health risk assessments were used to elucidate the level and spatial variation of heavy metal pollution risks. The results showed that the impact zone of pipeline installation on soil heavy metal contamination was restricted to pipeline right-of-way (RoW), which had higher I_geo of Cd, Cu, Ni and Pb than that of 20 m and 50 m. RI showed a declining tendency in different zones as follows: trench > working zone > piling area > 20 m > 50 m. Pipeline RoW resulted in higher human health risks than that of 20 m and 50 m, and children were more susceptible to non-carcinogenic hazard risk. Cluster analysis showed that Cu, Ni, Pb and Cd had similar sources, drawing attention to the anthropogenic activity. The findings in this study should help better understand the type, degree, scope and sources of heavy metal pollution from pipeline construction to reduce pollutant emissions, and are helpful in providing a scientific basis for future risk management.

Global assessment of oceanic lead pollution using sperm whales (Physeter macrocephalus) as an indicator species

Lead (Pb) is an oceanic pollutant of global concern. Anthropogenic activities are increasing oceanic levels, but to an unknown extent. The sperm whale (Physeter macrocephalus) has a global distribution and high trophic level. The aim of this study was to establish a global baseline of oceanic Pb concentrations using free-ranging sperm whales as an indicator species. Skin biopsies (n=337) were collected during the voyage of the Odyssey (2000-2005) from 17 regions considering gender and age. Pb was detectable in 315 samples with a global mean of 1.6 ug/gww ranging from 0.1 to 129.6 ug/gww. Papua New Guinea, Bahamas and Australia had the highest regional mean with 6.1, 3.4, and 3.1 ug/gww, respectively. Pb concentrations were not significantly different between sex and age in males. This is the first global toxicological dataset for Pb in a marine mammal and confirms Pb is widely distributed with hotspots in some regions.

Environmental factors and unhealthy lifestyle influence oxidative stress in humans--an overview

Oxygen is the most essential molecule for life; since it is a strong oxidizing agent, it can aggravate the damage within the cell by a series of oxidative events including the generation of free radicals. Antioxidative agents are the only defense mechanism to neutralize these free radicals. Free radicals are not only generated internally in our body system but also trough external sources like environmental pollution, toxic metals, cigarette smoke, pesticides, etc., which add damage to our body system. Inhaling these toxic chemicals in the environment has become unavoidable in modern civilization. Antioxidants of plant origin with free radical scavenging properties could have great importance as therapeutic agents in several diseases caused by environmental pollution. This review summarizes the generation of reactive oxygen species and damage to cells by exposure to external factors, unhealthy lifestyle, and role of herbal plants in scavenging these reactive oxygen species.

Review of highway runoff characteristics: comparative analysis and universal implications

This review interprets highway runoff characterization studies performed on different continents. The results are synthesized to discuss the historical trends, first flush effects of pollutants, pollutant form as dissolved vs. particulate, and to identify surrogate water quality parameters. The information presented in this review showed that: (1) variability has been observed in all quality parameters from each continent and among continents; (2) with a few exceptions the variability seems to be within the expected range; (3) inconsistent monitoring data as well as inconsistent quality assurance and quality control measures were reported among studies, which may be partially responsible for variability of water quality results; (4) compared with historic data, the concentration of total Pb decreased exponentially, which can mostly be credited to leaded gasoline phase-out regulation; (5) first flush effects of pollutants based on concentration have been reported consistently (however, mass first flush effects for pollutants have been reported inconsistently compared with concentration first flush effect); (6) most metal pollutants and phosphorus are present in both the particulate and dissolved forms; and (7) strong correlations were observed between TSS, TDS, TOC and iron (Fe) and 13 other constituents and water quality parameters (turbidity, O&G, TPH, DOC, TKN, EC, Cl, Cd, Cr, Cu, Ni, Pb, Zn).