This study explored the spatial pattern of heavy metals in Beijing agricultural soils using Moran’s I statistic of spatial autocorrelation. The global Moran’s I result showed that the spatial dependence of Cr, Ni, Zn, and Hg changed with different spatial weight matrixes, and they had significant and positive global spatial correlations based on distance weight. The spatial dependence of the four metals was scale-dependent on distance, but these scale effects existed within a threshold distance of 13 km, 32 km, 50 km, and 29 km, respectively for Cr, Ni, Zn, and Hg. The maximal spatial positive correlation range was 57 km, 70 km, 57 km, and 55 km for Cr, Ni, Zn, and Hg, respectively and these were not affected by sampling density. Local spatial autocorrelation analysis detected the locations of spatial clusters and spatial outliers and revealed that the pollution of these four metals occurred in significant High-high spatial clusters, Low-high, or even High-low spatial outliers. Thus, three major areas were identified and should be receiving more attention: the first was the northeast region of Beijing, where Cr, Zn, Ni, and Hg had significant increases. The second was the southeast region of Beijing where wastewater irrigation had strongly changed the content of metals, particularly of Cr and Zn, in soils. The third area was the urban fringe around city, where Hg showed a significant increase.

To achieve the full theoretical potential of high energy ZnS electrochemistry, the incomplete and sluggish conversion during battery discharging and high reactivation energy barrier during battery recharging associated with the sulfur cathodes must be overcome. Herein, the atomically dispersed Fe sites with FeN 4 coordination are experimentally and theoretically predicted as bidirectional electrocatalytic hotspots to simultaneously manipulate the complete sulfur conversion and minimize the energy barrier of ZnS decomposition. It is discovered that the Fe sites were favorable for strong sulfur and possible zinc polysulfide intermediate adsorption, and ensure nearly complete sulfur to ZnS conversion during discharge. For the following recharging process, the electrodeposited ZnS can be readily reversible charged back to S without a noticeable activation overpotential around FeN 4 moieties comparing to pure carbon matrixes. As expected, the freestanding iron embedded carbon fiber cloth supported sulfur cathode delivers a high specific capacity of 1143 mAh g −1 and a lower voltage hysteresis of 0.61 V. As elaborated by postmortem analysis, the degradation mechanism of ZnS cell is the accumulation of inactive ZnS crystals on the cathode side rather than the Zn metallic depletion. More encouragingly, a flexible solid-state ZnS battery with a high discharge capacity and stable reversibility is also demonstrated.

a b s t r a c tNine soybean cultivars widely cultivated in Northeast China were investigated in present study to assess their O 3 sensitivities on the basis of the response of photosynthesis and seed yield to ambient and future ozone (O 3 ) concentrations, and determine whether the effects of O 3 vary with the developmental stages (flowering and seed filling stages). Relative to charcoal-filtered air (CF), elevated O 3 concentration (E-O 3 , ambient air + 40 ppb) significantly reduced soybean yields by 40%, with a range of 32-46% among cultivars. E-O 3 also induced significant decreases in pigment contents, net photosynthetic rate and chlorophyll a fluorescence at both flowering and seed filling stages in most cultivars. Except net photosynthetic rate and stomatal conductance (g s ) at seed filling stage, all variables showed no significant interaction between O 3 and cultivar, suggesting that all tested cultivars had similar sensitivities to O 3 . The responses of seed N content to E-O 3 differed among cultivars. Ambient O 3 concentration (mean of daily concentration of 19 ppb) did not induce any change relative to CF. Significant positive relationship between endogenous g s in CF and yield loss among cultivars was found only at seed filling stage. Positive correlation between effects of E-O 3 on leaf N content and effects on light saturated photosynthetic rate (A sat ) indicated that g s and leaf N content at seed filling stage contributes to yield loss and decreased photosynthesis by E-O 3 , respectively. It can be inferred that E-O 3 had a larger negative effects on seed filling stage than flowering stage of soybean.