The experiment was performed to evaluate effect of heavy metals on total phytoplankton load (TPL) using water of Turag River adjacent to Ashulia locating on the north-eastern side of Dhaka city, Bangladesh. Total phytoplankton load comprises of Euglena sp., Borodinella sp., Pediastrum biradiatum, Pinnularia sp., Fragillaria sp., Fragillaria crotonensis, Gloeocapsa sp., Navicula sp., Cynedra sp., Crucigenia sp., Chlorella sp., Spirogyra sp., Phacus acuminatus, Phacus circulatus., Nitzschia sp. and Nitzschia clausii. Phytoplankton load showed the abundances Bascillariophyceae (43.75%) > Chlorophyceae (37.50%) > Euglenophyceae (18.75%). The average maximum growth rate (log transformed) of TPL in control culture was -0.25μg/l and treated cultures using 1ppm, 3ppm, 5ppm, 7ppm concentration of heavy metals (Zn and Cu) were 0.03 μg/l, 0.03 μg/l, -0.11 μg/l and -0.26 μg/l, respectively. In treated culture using 1ppm concentration of heavy metals (Zn and Cu) the growth rate of phytoplankton load increased significantly whereas the growth rate decreased at higher concentrations (3ppm, 5ppm and 7ppm) of heavy metals. The implication of this finding can be used to monitor health of riverine ecosystems and management of river pollution.

International audience | The aim of this study is to assess the annual balance of the fluxes of Cd, Cu, Ni, Pb and Zn within different cropping systems, in an experimental site located near Versailles, France. Four fluxes through the cultivated horizon were considered to assess the annual heavy metal balance in these systems: 1) atmospheric depositions, 2) fertilisers as inputs, 3) crops and 4) leaching water as outputs. The water mass flow was estimated with a model (CERES) while the other parameters were actually measured through field sampling. Some large uncertainties are related to analytical detection limits, specially for Pb which presents very low concentrations in nitrogen fertilisers, in crops and in soil solution. Cd was also close to the detection limits in atmospheric deposition and in soil water, and Zn could not be analysed in soil solution. Nevertheless, the following trends clearly appeared: firstly, atmospheric deposition is the major input way of Cu, Ni, Pb and Zn in the soil, whatever the cropping system, whereas Cd is introduced mainly by fertilisers. Secondly, the uptake of heavy metal by wheat is generally larger than by a pea culture, except for Ni. Finally, the global pattern shows an accumulation of Cd, Ni and Pb in the cultivated horizon while Cu decreased. The annual balances, during the cropping year 2001–2002, represented about 0.33, −0.024, 0.014 and 0.014% of the actual stocks in the cultivated horizon, of Cd, Cu, Ni, and Pb, respectively.

International audience | The aim of this study is to assess the annual balance of the fluxes of Cd, Cu, Ni, Pb and Zn within different cropping systems, in an experimental site located near Versailles, France. Four fluxes through the cultivated horizon were considered to assess the annual heavy metal balance in these systems: 1) atmospheric depositions, 2) fertilisers as inputs, 3) crops and 4) leaching water as outputs. The water mass flow was estimated with a model (CERES) while the other parameters were actually measured through field sampling. Some large uncertainties are related to analytical detection limits, specially for Pb which presents very low concentrations in nitrogen fertilisers, in crops and in soil solution. Cd was also close to the detection limits in atmospheric deposition and in soil water, and Zn could not be analysed in soil solution. Nevertheless, the following trends clearly appeared: firstly, atmospheric deposition is the major input way of Cu, Ni, Pb and Zn in the soil, whatever the cropping system, whereas Cd is introduced mainly by fertilisers. Secondly, the uptake of heavy metal by wheat is generally larger than by a pea culture, except for Ni. Finally, the global pattern shows an accumulation of Cd, Ni and Pb in the cultivated horizon while Cu decreased. The annual balances, during the cropping year 2001–2002, represented about 0.33, −0.024, 0.014 and 0.014% of the actual stocks in the cultivated horizon, of Cd, Cu, Ni, and Pb, respectively.

Zn and Cu are two of the essential trace elements and it is important to understand the regulation of their distribution on cellular functions. Herein, we for the first time investigated the subcellular fate and behavior of Zn and Cu in zebrafish cells through bioimaging, and demonstrated the completely different behaviors of Zn and Cu. The distribution of Zn²⁺ was concentration-dependent, and Zn²⁺ at low concentration was predominantly located in the lysosomes (76.5%). A further increase of cellular Zn²⁺ resulted in a spillover and more diffusive distribution, with partitioning to mitochondria and other regions. In contrast, the subcellular distribution of Cu⁺ was time-dependent. Upon entering the cells, Cu²⁺ was reduced to Cu⁺, which was first concentrated in the mitochondria (71.4%) followed by transportation to lysosomes (58.6%), and finally removal from the cell. With such differential transportation, Cu²⁺ instead of Zn²⁺ had a negative effect on the mitochondrial membrane potential and glutathione. Correspondingly, the pH of lysosomes was more sensitive to Zn²⁺ exposure and decreased with increasing internalized Zn²⁺, whereas it increased upon Cu²⁺ exposure. The responses of cellular pH showed an opposite pattern from the lysosomal pH. Lysosome was the most critical organelle in response to incoming Zn²⁺ by increasing its number and size, whereas Cu²⁺ reduced the lysosome size. Our study showed that Zn²⁺ and Cu²⁺ had completely different cellular handlings and fates with important implications for understanding of their toxicity.

Microbial biofilms can rapidly colonize plastic debris in aquatic environments and subsequently, accumulate chemical pollutants from the surrounding water. Here, we studied the microbial colonization of different plastics, including polyethylene terephthalate (PET), polypropylene (PP), polyvinyl chloride (PVC), and polyethylene (PE) exposed in three freshwater systems (the Qinhuai River, the Niushoushan River, and Donghu Lake) for 44 days. We also assessed the biofilm mass and associated metals attached to plastics. The plastics debris characteristics, such as contact angle and surface roughness, greatly affected the increased biofilm biomass. All types of metal accumulation onto the plastic substrate abundances significantly higher than the concentrations of heavy metal in the water column, such as Ba (267.75 μg/g vs. 42.12 μg/L, Donhu Lake), Zn (254 μg/g vs. 0.023 μg/L the Qinhuai River), and Cr (93.75 μg/g vs. 0.039 μg/L, the Niushoushan River). Compared with other metals, the heavy metal Ba, Cr and Zn accumulated easily on the plastic debris (PET, PP, PVC, and PE) at all incubation sites. Aquatic environmental factors (total nitrogen, total phosphorus, and suspended solids concentrations) largely shaped metal accumulation onto plastic debris compared with plastic debris properties.

Soil aggregates are often considered the basic structural elements of soils. Aggregates of different size vary in their ability to retain or transfer heavy metals in the environment. Here, after incubation of a sieved (<2 mm) topsoil with copper, bulk soil was separated into four aggregate-size fractions and their adsorption characteristics for Cu were determined. By combining nano-scale secondary ion mass spectrometry and C-1s Near Edge X-ray Absorption Fine Structure Spectroscopy, we found that copper tends to bind onto organic matter in the <2 μm and 20–63 μm aggregates. Surprisingly, Cu correlated with carboxyl-C in the <2 μm aggregates but with alkyl-C in the 20–63 μm aggregates. This is the first attempt to visualize the spatial distribution of copper in aggregate size fractions. These direct observations can help improve the understanding of interactions between heavy metals and various soil components.

The effects of salinity on metal toxicity are complex: not only affecting metal bioaccumulation, but also altering the physiology and sensitivity of organisms. In this study, we used a toxicokinetic-toxicodynamic (TK-TD) model to separate and quantify the dual effects of salinity on copper (Cu) toxicity in a euryhaline clam Potamocorbula laevis. The toxicokinetics of Cu was determined using the stable isotope 65Cu as a tracer at concentrations (10–500 μg L−1) realistic to contaminated environments and at salinities ranging from 5 to 30. At low Cu concentrations (ca. 10 μg L−1), Cu bioaccumulation decreased monotonically with salinity, and the uptake rate constant (ku, 0.546 L g−1 h−1 to 0.213 L g−1 h−1) fitted well with an empirical equation, ku = 1/(1.35 + 0.116·Salinity), by treating salinity as a pseudo-competitor. The median lethal concentrations (LC50s) of Cu were 269, 224, and 192 μg L−1 at salinity 5, 15, and 30, respectively. At high Cu concentrations (ca. 500 μg L−1), elevating salinity were much less effective in decreasing Cu bioaccumulation; whereas Cu toxicity increased with salinity. The increased toxicity could be explained by the increases in Cu killing rates (kks), which were estimated to be 0.44–2.08 mg μg−1 h−1 and were presumably due to the osmotic stress caused by the deviation from the optimal salinity of the clams. The other toxicodynamic parameter, internal threshold concentration (CIT), ranged from 79 to 133 μg−1 g−1 and showed no clear trend with salinity.

Ambient fine particulate matter (PM2.5) pollution has been implicated in the development of hypertensive disorders of pregnancy. However, evidence on the effects of PM2.5-derived chemical constituents on gestational blood pressure (BP) is limited, and the potential mechanisms underlying the association remain unclear. In this study, we repeated three consecutive 72-h personal air sampling and BP measurements in 215 pregnant women for 590 visits during pregnancy. Individual PM2.5 exposure level was assessed by gravimetric method and 28 PM2.5 chemical constituents were analyzed by ED-XRF method. Plasma biomarkers of endothelial function and inflammation were measured using multiplexed immunoassays. Robust multiple linear regression models were used to estimate the associations among personal PM2.5 exposure and chemical constituents, BP changes (compared with pre-pregnancy BP) and plasma biomarkers. Mediation analyses were performed to evaluate underlying potential pathways. Result showed that exposure to PM2.5 was significantly associated with increases in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) in the early second trimester. Meanwhile, elevated concentration of lead (Pb) constituent in PM2.5 was significant associated with increases in DBP and MAP after adjusting for PM2.5 total mass. PM2.5 and Pb constituent also presented positive associations with plasma biomarkers of endothelial function (ET-1, E-selectin, ICAM-1) and inflammation (IL-1β, IL-6, TNFα) significantly. After multiple adjustment, elevated ET-1 and IL-6 were significantly correlated with increased gestational BP, and respectively mediated 1.24%–25.06% and 7.01%–10.69% of the increased BP due to PM2.5 and Pb constituent exposure. In conclusion, our results suggested that personal exposure to PM2.5 and Pb constituent were significantly associated with increased BP during pregnancy, and the early second trimester might be the sensitive window of PM2.5 exposure. The endothelial dysfunction and elevated inflammation partially mediated the effect of PM2.5 and Pb constituent on BP during pregnancy.

Colloids are ubiquitous in soils, and it has been reported that colloids can act as carriers to increase the mobility of poorly soluble contaminants in subsurface environments. Addition of sulfur (S) fertilizer greatly influences on heavy metal behavior in paddy soil, while the influence of S fertilizer on Cu migration and transformation in colloids of soil pore water has not yet been studied. The influence of S fertilizer (S⁰ and Na₂SO₄) applied in paddy soils on Cu migration and transformation in colloids of soil pore water from the rice rhizosphere region was explored in this study. The speciation of Cu in colloids of soil pore water from the rice rhizosphere region was explored by advanced synchrotron-based X-ray absorption near-edge spectroscopy (XANES) techniques. The morphology of colloids was characterized by field emission scanning electron microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDX). At a depth of 20 cm, the concentration of Cu in colloids of the rhizosphere soil pore water in the control was 2.4- and 6.5- fold higher than that in treatments of S⁰ and Na₂SO₄, respectively. The colloids in soil pore water were all positively charged, ranging from 2.4 to 7.8 mV, and the size of colloids was 440–740 nm. The proportion of Fe in colloids in the rhizosphere region decreased with S fertilizer application, while the proportions of C and O increased. Sulfur fertilizer application, increased the proportion of Cu-Cysteine, while the proportion of Cu₂S decreased in soil colloids. In conclusion, application of sulfur fertilizer in paddy soil decreased the Cu concentration in soil pore water and colloids of the rhizosphere region, thereby decreasing the vertical migration of Cu in soil pore water.

The current study aims to understand the speciation and fate of Cu complexes in hydrothermally altered sediments from the Central Indian Ocean Basin and assess the probable impacts of deep-sea mining on speciation of Cu complexes and assess the Cu flux from this sediment to the water column in this area. This study suggests that most of the Cu was strongly associated with different binding sites in Fe-oxide phases of the hydrothermally altered sediments with stabilities higher than that of Cu-EDTA complexes. The speciation of Cu indicates that hydrothermally influenced deep-sea sediments from Central Indian Ocean Basin may not significantly contribute to the global Cu flux. However, increasing lability of Cu-sediment complexes with increasing depth of sediment may increase bioavailability and Cu flux to the global ocean during deep-sea mining.