Combined Remediation Effects of Sewage Sludge and Phosphate Fertilizer on Pb-Polluted Soil from a Pb-Acid Battery Plant.

Pb soil pollution poses a serious health risk to both the environment and humans. Immobilization is the most common strategy for remediation of heavy metal polluted soil. In this study, municipal sewage sludge was used as an amendment for rehabilitation of Pb-contaminated soils, for agricultural use, near a lead-acid battery factory. The passivation effect was further improved by the addition of phosphate fertilizer. It was found that the leachable Pb content in soils was decreased from 49.6 mg kg-1 to 16.1-36.6 mg kg-1 after remediation of sludge for 45 d at applied dosage of municipal sewage sludge of 4-16 wt%, and further decreased to 14.3-34.3 mg kg-1 upon extension of the remediation period to 180 d. The addition of phosphate fertilizer greatly enhanced the Pb immobilization, with leachable Pb content decreased to 2.0-23.6 mg kg-1 with increasing dosage of phosphate fertilizer in range of 0.8-16 wt% after 180 d remediation. Plant assays showed that the bioavailability of Pb was significantly reduced by the soil remediation, with the content of absorbed Pb in mung bean roots decreased by as much as 87.0%. The decrease in mobility and biotoxicity of the soil Pb is mainly attributed to the speciation transformation of carbonate, Fe-Mn oxides and organic matter bound Pb to residue Pb under the synergism of reduction effect of sludge and acid dissolution and precipitation effect of phosphate fertilizer. This study suggests a new method for remediation of Pb-contaminated soil and utilization of municipal sewage sludge resources.

Pb contaminated soil from a lead-acid battery plant immobilized by municipal sludge and raw clay.

Soil heavy metal pollution poses a serious threat to the eco-environment. Municipal sludge-based passivators and clay minerals have been widely applied to immobilize heavy metal contamination in soils. However, little is known about the immobilization effect and mechanisms of raw municipal sludge and clay in reducing the mobility and bioavailability of heavy metals in soils. Here, municipal sludge, raw clay and mixtures of thereof were used to remediate Pb-contaminated soil from a Pb-acid battery factory. The remediation performance was evaluated through acid leaching, sequential extraction, and plant assay. Results showed that the leachable Pb content in the soil decreased from 5.0 mg kg-1 to 4.8, 4.8 and 4.4 mg kg-1 after 30 d of remediation with MS and RC added at equal weights to give total dosage of 20, 40 wt% and 60 wt %, respectively. The leachable Pb further decreased to 1.7, 2.0 and 1.7 mg kg-1 after 180 d of remediation. Speciation analysis of the soil Pb indicated that the exchangeable and Fe-Mn oxide-bound Pb were transformed into residual Pb in the early stage of remediation, and the carbonate-bound Pb and organic matter-bound Pb were transformed into residual Pb in the later stage of remediation. As a result, Pb accumulation in mung beans decreased by 78.5%, 81.1% and 83.4% after 180 days of remediation. These results indicate that the leaching toxicity and phytotoxicity of Pb in remediated soils were significantly reduced, presenting a better and low-cost method for soil remediation.

Associations of hedonic and eudaimonic orientations with subjective experience and objective functioning in academic settings: The mediating roles of academic behavioral engagement and procrastination.

The question of how the pursuit of happiness affects an individual's actual well-being has received much scholarly attention in recent years. However, few studies have investigated the associations of happiness orientation with people's subjective experience and objective functioning simultaneously. The current research examines the possibility that hedonic and eudaimonic orientations have different relationships with college students' affective well-being and academic achievement, while taking into consideration the behavioral mechanism that underlies the process. We conducted online surveys to collect data including hedonic and eudaimonic orientations at the beginning of the semester and academic behavioral engagement, procrastination, and affective well-being at the end of the semester with a final sample of 566 Chinese undergraduate students. Their official grade point average for the semester was extracted from the university records system. The results confirmed that overall hedonic orientation was negatively associated with affective well-being and academic achievement, whereas eudaimonic orientation was positively associated with these outcomes. The study further found that both academic behavioral engagement and procrastination played mediating roles in the associations of happiness orientation with positive affect and academic achievement. However, only procrastination mediated the relationship between happiness orientation and negative affect. Theoretical and practical implications were discussed.

When Do Hedonic and Eudaimonic Orientations Lead to Happiness? Moderating Effects of Orientation Priority.

The effects of hedonic and eudaimonic orientations on individual well-being have received much scholarly attention. However, the empirical findings from previous research are not consistent, raising the question of when the pursuit of hedonia and eudaimonia lead to actual improvements in individual well-being. We argue that the relationship between orientations to happiness and well-being outcomes are moderated by orientation priorities, which reflect the relative level of importance individuals place on eudaimonic motives compared to hedonic motives. A total of 312 Chinese undergraduate students completed surveys assessing hedonic and eudaimonic orientations, orientation priorities, and well-being outcomes, including psychological well-being, positive affect, and negative affect. The results revealed that a eudaimonic orientation was positively related to psychological well-being, a hedonic orientation was positively related to positive affect, and both relationships were moderated by orientation priorities. For individuals who prioritized eudaimonia over hedonia, both orientations improved well-being. For individuals who prioritized hedonia over eudaimonia, the benefits related to well-being from both orientations decreased or disappeared. These findings suggest that orientation priorities are of equal importance in regard to hedonic and eudaimonic orientations.

Distinct Associations of Hedonic and Eudaimonic Motives with Well-Being: Mediating Role of Self-Control.

The pursuit of hedonia and eudaimonia are two ways to fulfill the goal of a "good life". While some studies report that both hedonic and eudaimonic motives improve well-being, others suggest that hedonic motives are counterproductive, raising the question of whether and why eudaimonic motives are more positively associated with well-being. We aimed to identify the distinct associations of hedonic and eudaimonic motives with well-being and investigate whether they are partly mediated by self-control. A total of 2882 college freshmen (1835 females, 1047 males, mean age 18.16 years) completed measures assessing hedonic and eudaimonic motives, self-control, life satisfaction, positive and negative affect, and eudaimonic well-being. Eudaimonic motives were associated with higher life satisfaction, more positive affect, less negative affect, and better eudaimonic well-being. In contrast, hedonic motives were positively associated with life satisfaction, while also being correlated with a greater degree of negative affect and impaired eudaimonic well-being. Self-control mediated the relationships between hedonic and eudaimonic motives and well-being. Eudaimonic and hedonic motives were positively and negatively related to self-control, respectively. Further, high self-control was associated with greater life satisfaction, positive affect, and eudaimonic well-being and lower negative affect. Thus, eudaimonic motives can lead to a better life than hedonic motives because the former enhance self-control, while the latter lower it.

The source of punishment matters: Third-party punishment restrains observers from selfish behaviors better than does second-party punishment by shaping norm perceptions.

Punishment aims to deter individuals' selfish behaviors, but it can occasionally backfire. Some scholars have proposed promoting prosocial behaviors using punishment that communicates positive social norms because it provides additional motivation. However, it is unclear which factors affect the norm expressive function of punishment. This study proposes that third-party punishment communicates more positive normative information, and thus, promotes more prosocial behavior in observers than does second-party punishment. Using dictator games, we investigated the effects of second-party punishment compared to third-party punishment of another's unfair sharing on observers' norm perceptions and subsequent sharing decision-making. Two experiments consistently found that third-party punishment was more effective than second-party punishment at inducing observers' beliefs that unfair distribution was unusual (descriptive norm) and unacceptable (injunctive norm). The altered descriptive but not injunctive norm perception further guided individuals' own sharing behaviors. Taken together, these results suggest that third-party punishment might be better than second-party punishment at decreasing selfish behaviors by shaping individuals' norm perceptions, especially descriptive norm perception, regarding the relevant behaviors.