Arsenic contamination of groundwater and its health impact on residents in a village in West Bengal, India

An in-depth study was carried out in Rajapur, an arsenic-affected village in West Bengal, India, to determine the degree of groundwater contamination with arsenic and the impact of this contamination on residents. The flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) method was used to measure arsenic concentrations in water and biological samples. Dermatologists recorded the dermatological features of arsenicosis. Out of a total of 336 hand-pumped tube-wells in Rajapur, 91% (307/336) contained arsenic at concentrations > 10 mg/l, and 63% (213/336) contained arsenic at > 50 mg/l. The type of arsenic in groundwater, the variation in concentrations of arsenic as the depth of tube-wells changed, and the iron concentration in the wells were also measured. Altogether 825 of 3500 residents were examined for skin lesions; of these, 149 had lesions caused by exposure to arsenic. Of the 420 biological samples collected and analysed, 92.6% (389) contained arsenic at concentrations that were above normal. Thus many villagers might be subclinically affected. Although five arsenic-filtering devices had been installed in Rajapur, it appears that villagers are still exposed to raised concentrations of arsenic in their drinking-water. Detailed village-level studies of arsenic-affected areas in West Bengal are required in order to understand the magnitude of contamination and its effects on people. Villagers are ill-informed about the dangers of drinking arsenic-contaminated water. The contamination could be brought under control by increasing community awareness of the dangers and implementing proper watershed management techniques that involve local people

Groundwater arsenic contamination in Ganga-Meghna-Brahmaputra plain, its health effects and an approach for mitigation

The authors’ survey of the Ganga–Meghna–Brahmaputra (GMB) plain (area 569,749 km2; population >500 million) over the past 20 years and analysis of more than 220,000 hand tube-well water samples revealed groundwater arsenic contamination in the floodplains of the Ganga–Brahmaputra river (Uttar Pradesh, Bihar, Jharkhand, West Bengal, and Assam) in India and the Padma–Meghna–Brahmaputra river in Bangladesh. On average, 50 % of the water samples contain arsenic above the World Health Organization guideline value of 10 μg/L in India and Bangladesh. More than 100 million people in the GMB plain are potentially at risk. The authors’ medical team screened around 155,000 people from the affected villages and registered 16,000 patients with different types of arsenical skin lesions. Arsenic neuropathy and adverse pregnancy outcomes have been recorded. Infants and children drinking arsenic-contaminated water are believed to be at high risk. About 45,000 biological samples analyzed from arsenic-affected villages of the GMB plain revealed an elevated level of arsenic present in patients as well as non-patients, indicating that many are sub-clinically affected. In West Bengal and Bangladesh, there are huge surface water in rivers, wetlands, and flooded river basins. In the arsenic-affected GMB plain, the crisis is not over water scarcity but about managing the available water resources.

Measurement of the angle between jet axes in Pb−-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}} = 5.02 TeV

International audienceThis letter presents the first measurement of the angle between different jet axes (denoted as ${\Delta}R$) in Pb$-$Pb collisions. The measurement is carried out in the 0$-$10% most-central events at $\sqrt{s_{\rm NN}} = 5.02$ TeV. Jets are assembled by clustering charged particles at midrapidity using the anti-$k_{\rm T}$ algorithm with resolution parameters $R=0.2$ and $0.4$ and transverse momenta in the intervals $40 < p_{\rm T}^{\rm ch jet} < 140$ GeV/$c$ and $80 < p_{\rm T}^{\rm ch jet} < 140$ GeV/$c$, respectively. Measurements at these low transverse momenta enhance the sensitivity to quark$-$gluon plasma (QGP) effects. A comparison to models implementing various mechanisms of jet energy loss in the QGP shows that the observed narrowing of the Pb$-$Pb distribution relative to pp can be explained if quark-initiated jets are more likely to emerge from the medium than gluon-initiated jets. These new measurements discard intra-jet $p_{\rm T}$ broadening as described in a model calculation with the BDMPS formalism as the main mechanism of energy loss in the QGP. The data are sensitive to the angular scale at which the QGP can resolve two independent splittings, favoring mechanisms that incorporate incoherent energy loss

First measurement of the ∣t∣|t|-dependence of incoherent J/ψ\psi photonuclear production

International audienceThe first measurement of the cross section for incoherent photonuclear production of J/$\psi$ vector meson as a function of the Mandelstam $|t|$ variable is presented. The measurement was carried out with the ALICE detector at midrapidity, $|y|<0.8$, using ultra-peripheral collisions of Pb nuclei at a centre-of-mass energy per nucleon pair $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV. This rapidity interval corresponds to a Bjorken-$x$ range $(0.3$$-$$1.4)\times 10^{-3}$. Cross sections are reported in five $|t|$ intervals in the range $0.04<|t|<1$~GeV$^2$ and compared to the predictions of different models. Models that ignore quantum fluctuations of the gluon density in the colliding hadron predict a $|t|$-dependence of the cross section much steeper than in data. The inclusion of such fluctuations in the same models provides a better description of the data

Multiplicity-dependent production of Σ(1385)±\Sigma(1385)^{\pm} and Ξ(1530)0\Xi(1530)^{0} in pp collisions at s=13\sqrt{s}=13 TeV

International audienceThe production yields of the $\Sigma(1385)^{\pm}$ and $\Xi(1530)^{0}$ resonances are measured in pp collisions at $\sqrt{s}=13$ TeV with ALICE. The measurements are performed as a function of the charged particle multiplicity $\langle \mathrm{d}N_\mathrm{ch}/\mathrm{d}\eta \rangle$, which is related to the energy density produced in the collision. The results include transverse momentum ($p_{\rm T}$) distributions, $p_{\rm T}$-integrated yields, mean transverse momenta of $\Sigma(1385)^{\pm}$ and $\Xi(1530)^{0}$, as well as ratios of the $p_{\rm T}$-integrated resonance yields relative to yields of other hadron species. The $\Sigma(1385)^{\pm}/\pi^{\pm}$ and $\Xi(1530)^{0}/\pi^{\pm}$ yield ratios are consistent with the trend of the enhancement of strangeness production from low to high multiplicity pp collisions, which was previously observed for strange and multi-strange baryons. The yield ratio between the measured resonances and the long-lived baryons with the same strangeness content exhibits a hint of a mild increasing trend at low multiplicity, despite too large uncertainties to exclude the flat behaviour. The results are compared to predictions from models such as EPOS-LHC and PYTHIA 8 with Rope shoving. The latter provides the best description of the multiplicity dependence of the $\Sigma(1385)^{\pm}$ and $\Xi(1530)^{0}$ production in pp collisions at $\sqrt{s}=13$ TeV

Charged-particle production as a function of the relative transverse activity classifier in pp, p−-Pb, and Pb−-Pb collisions at the LHC

International audienceMeasurements of charged-particle production in pp, p$-$Pb, and Pb$-$Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum ($p_{\mathrm{T}}^{\rm trig}$) in the range $8<p_{\mathrm{T}}^{\rm trig}<15$ GeV$/c$. The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial- and final-state radiation. The relative transverse activity classifier, $R_{\mathrm{T}}=N_{\mathrm{ch}}^{\mathrm{T}}/\langle N_{\mathrm{ch}}^{\mathrm{T}}\rangle$, is used to group events according to their UE activity, where $N_{\mathrm{ch}}^{\mathrm{T}}$ is the charged-particle multiplicity per event in the transverse region and $\langle N_{\mathrm{ch}}^{\mathrm{T}}\rangle$ is the mean value over the whole analysed sample. The energy dependence of the $R_{\mathrm{T}}$ distributions in pp collisions at $\sqrt{s}=2.76$, 5.02, 7, and 13 TeV is reported, exploring the Koba-Nielsen-Olesen (KNO) scaling properties of the multiplicity distributions. The first measurements of charged-particle $p_{\rm T}$ spectra as a function of $R_{\mathrm{T}}$ in the three azimuthal regions in pp, p$-$Pb, and Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV are also reported. Data are compared with predictions obtained from the event generators PYTHIA 8 and EPOS LHC. This set of measurements is expected to contribute to the understanding of the origin of collective-like effects in small collision systems (pp and p$-$Pb)

Charm production and fragmentation fractions at midrapidity in pp collisions at s=13\sqrt{s} = 13 TeV

International audienceMeasurements of the production cross sections of prompt ${\rm D^0}$, ${\rm D^+}$, ${\rm D^{\ast +}}$, ${\rm D_s^+}$, ${\rm \Lambda_{c}^{+}}$, and ${\rm \Xi_{c}^{+}}$ charm hadrons at midrapidity in proton$-$proton collisions at $\sqrt{s}=13$ TeV with the ALICE detector are presented. The D-meson cross sections as a function of transverse momentum ($p_{\rm T}$) are provided with improved precision and granularity. The ratios of $p_{\rm T}$-differential meson production cross sections based on this publication and on measurements at different rapidity and collision energy provide a constraint on gluon parton distribution functions at low values of Bjorken-$x$ ($10^{-5}-10^{-4}$). The measurements of ${\rm \Lambda_{c}^{+}}$ (${\rm \Xi_{c}^{+}}$) baryon production extend the measured $p_{\rm T}$ intervals down to $p_{\rm T}=0(3)$~GeV$/c$. These measurements are used to determine the charm-quark fragmentation fractions and the ${\rm c\overline{c}}$ production cross section at midrapidity ($|y|<0.5$) based on the sum of the cross sections of the weakly-decaying ground-state charm hadrons ${\rm D^0}$, ${\rm D^+}$, ${\rm D_s^+}$, ${\rm \Lambda_{c}^{+}}$, ${\rm \Xi_{c}^{0}}$ and, for the first time, ${\rm \Xi_{c}^{+}}$, and of the strongly-decaying J/$psi$ mesons. The first measurements of ${\rm \Xi_{c}^{+}}$ and ${\rm \Sigma_{c}^{0,++}}$ fragmentation fractions at midrapidity are also reported. A significantly larger fraction of charm quarks hadronising to baryons is found compared to e$^+$e$^-$ and ep collisions. The ${\rm c\overline{c}}$ production cross section at midrapidity is found to be at the upper bound of state-of-the-art perturbative QCD calculations

Dielectron production in central Pb−-Pb collisions at sNN\sqrt{s_\mathrm{NN}} = 5.02 TeV

International audienceThe first measurement of the e$^+$e$^-$ pair production at midrapidity and low invariant mass in central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV at the LHC is presented. The yield of e$^+$e$^-$ pairs is compared with a cocktail of expected hadronic decay contributions in the invariant mass ($m_{\rm ee}$) and pair transverse momentum ($p_{\rm T,ee}$) ranges $m_{\rm ee} < 3.5$ GeV$/c^2$ and $p_{\rm T,ee} < 8$ GeV$/c$. For $0.18 < m_{\rm ee} < 0.5$ GeV$/c^2$ the ratio of data to the cocktail of hadronic contributions without $\rho$ mesons amounts to $1.42 \pm 0.12 \ ({\rm stat.}) \pm 0.17 \ ({\rm syst.}) \pm 0.12 \ ({\rm cocktail})$ and $1.44 \pm 0.12 \ ({\rm stat.}) \pm 0.17 \ ({\rm syst.}) ^{+0.17}_{-0.21} \ ({\rm cocktail})$, including or not including medium effects in the estimation of the heavy-flavor background, respectively. It is consistent with predictions from two different models for an additional contribution of thermal e$^+$e$^-$ pairs from the hadronic and partonic phases. In the intermediate-mass range ($1.2 < m_{\rm ee} < 2.6$ GeV$/c^2$), the pair transverse impact parameter of the e$^+$e$^-$ pairs (DCA$_{\rm ee}$) is used for the first time in Pb$-$Pb collisions to separate displaced dielectrons from heavy-flavor hadron decays from a possible (thermal) contribution produced at the interaction point. The data are consistent with a suppression of e$^+$e$^-$ pairs from ${\rm c\overline{c}}$ and an additional prompt component. Finally, the first direct-photon measurement in the 10% most central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is reported via the study of virtual direct photons in the transverse momentum range $1 < p_{\rm T} < 5$ GeV$/c$. A model including prompt photons, as well as photons from the pre-equilibrium and fluid-dynamic phases, can reproduce the result, while being at the upper edge of the data uncertainties

Dielectron production in central Pb−-Pb collisions at sNN\sqrt{s_\mathrm{NN}} = 5.02 TeV

International audienceThe first measurement of the e$^+$e$^-$ pair production at midrapidity and low invariant mass in central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV at the LHC is presented. The yield of e$^+$e$^-$ pairs is compared with a cocktail of expected hadronic decay contributions in the invariant mass ($m_{\rm ee}$) and pair transverse momentum ($p_{\rm T,ee}$) ranges $m_{\rm ee} < 3.5$ GeV$/c^2$ and $p_{\rm T,ee} < 8$ GeV$/c$. For $0.18 < m_{\rm ee} < 0.5$ GeV$/c^2$ the ratio of data to the cocktail of hadronic contributions without $\rho$ mesons amounts to $1.42 \pm 0.12 \ ({\rm stat.}) \pm 0.17 \ ({\rm syst.}) \pm 0.12 \ ({\rm cocktail})$ and $1.44 \pm 0.12 \ ({\rm stat.}) \pm 0.17 \ ({\rm syst.}) ^{+0.17}_{-0.21} \ ({\rm cocktail})$, including or not including medium effects in the estimation of the heavy-flavor background, respectively. It is consistent with predictions from two different models for an additional contribution of thermal e$^+$e$^-$ pairs from the hadronic and partonic phases. In the intermediate-mass range ($1.2 < m_{\rm ee} < 2.6$ GeV$/c^2$), the pair transverse impact parameter of the e$^+$e$^-$ pairs (DCA$_{\rm ee}$) is used for the first time in Pb$-$Pb collisions to separate displaced dielectrons from heavy-flavor hadron decays from a possible (thermal) contribution produced at the interaction point. The data are consistent with a suppression of e$^+$e$^-$ pairs from ${\rm c\overline{c}}$ and an additional prompt component. Finally, the first direct-photon measurement in the 10% most central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is reported via the study of virtual direct photons in the transverse momentum range $1 < p_{\rm T} < 5$ GeV$/c$. A model including prompt photons, as well as photons from the pre-equilibrium and fluid-dynamic phases, can reproduce the result, while being at the upper edge of the data uncertainties