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This study comprehensively analyzes the environmental risk of heavy metals (HMs) in the dewatering process of dredged sediment. First, the toxicity leaching capacity, total content, and chemical speciation of the HMs (As, Cd, Co, Cr, Cu, Hg, Mo, Pb, Sb, Sr, Tl, Zn) in dewatered sediment were determined using toxicity characteristic leaching procedure and modified Community Bureau of Reference sequential extraction procedure. The ecotoxicity and environmental risk of the HMs were then evaluated based on sediment quality guidelines, geo-accumulation index, enrichment factor, potential ecological risk, and risk assessment code. The results showed that flocculants reduced the ecological risk of Hg and Mo in sediment, and promoted the transformation of Mo, Sb, and Tl from the biologically active fraction to the more stable fraction. The transformation percentages of Mo, Sb, and Ti were 45.15%, 50.59% and 76.44%, respectively, after chitosan (CTS) treatment, and 64.55%, 31.75% and 99.90%, respectively, after cationic polyacrylamide (CPAM) treatment. CTS reduced the potential risks of bioavailable As, Cr, Cu, Mo, Sb, and Hg by (at most) 46.28%, 45.92%, 43.01%, 100.00%, 44.45%, and 39.69%, respectively, whereas CPAM decreased the ecotoxicity of bioavailable Cd, Co, and Zn by (at most) 27.49%, 16.10%, and 20.89%, respectively. According to the result of principal component analysis, the main factors affecting the environmental risk of HMs in sediment dewatering were nitrogenous organic compounds (mainly protein substances), fulvic acid substances, and minerals. The most essential factor was nitrogenous organic compounds, which accounted for 89.52% of the total variance. Chemical speciation was apparently more suitable for environmental risk assessment of sediment dewatering than total content. This study provides an important basis for controlling the environmental risk of HMs caused by sediment dewatering. [Display omitted] • Flocculant greatly reduced the ecological risk of Hg and Mo in sediment. • Chemical speciation of HMs in sediment was changed by flocculant. • Nitrogenous substance was the major factor affecting dewatering ecological risk. • Chemical speciation was more suitable for HMs risk assessment than total content. [ABSTRACT FROM AUTHOR]

Social experiences, especially during early development, have profound effects on the brain and behaviour in later life. We examined whether the provision of alloparental care by older siblings affects anxiety, sociability and parental behaviour at adulthood in both them and the younger siblings for which they care. Using mandarin voles, Microtus mandarinus, we kept the older litter in the parents'' cage at weaning where they provided alloparental care to younger siblings of the next litter. We found that mandarin voles that had cared for younger siblings displayed significantly more locomotor activity in a novel environment and engaged in more social investigation of unfamiliar same-sex individuals. Females of this group also provided more parental care compared to control voles. Individuals cared for by older siblings demonstrated lower levels of anxiety and aggression, and higher levels of parental investment at adulthood, compared to control animals. These results suggest that providing alloparental care increases locomotor activity, social investigation and maternal care in adulthood, and that receiving alloparental care reduces levels of anxiety and aggression and increases biparental care in adulthood. Giving and receiving alloparental care has clear benefits in this species and suggests that alloparental care may increase the inclusive fitness of both givers and receivers. [Copyright &y& Elsevier]

Juveniles of cooperative breeding species usually remain in the natal area and provide care to younger siblings, a behavior considered one form of alloparenting in the natural condition. Previous studies have demonstrated the effects of providing or receiving alloparental care on adult behaviors, including anxiety-like behavior, social interaction, and parental behavior, but little is known about the influences on species-typical bonding behaviors, such as pair-bond formation. In this study, we explored this concept using socially monogamous mandarin voles (Lasiopodomys mandarinus). As the oxytocin (OT) and dopamine systems are involved in alloparental and pair-bonding behaviors, we also examined the levels of central OT and tyrosine hydroxylase (TH), as well as OT receptor (OTR) and dopamine D1-type and D2-type receptors (D1R and D2R) mRNA expression in the nucleus accumbens (NAcc) and amygdala to investigate the underlying mechanisms. Our results show that mandarin voles providing alloparental care to younger siblings displayed facilitation of partner preference formation, lower levels of OT expression in the paraventricular nucleus of the hypothalamus (PVN) and lateral hypothalamus (LH), and increased OTR and D2R mRNA expression in the NAcc compared to controls. Individuals receiving alloparental care also demonstrated facilitation of partner preference formation in adult voles. Additionally, alloparental care enhanced OT expression in the PVN, anterior medial preoptic nucleus (MPOAa), medial amygdala (MeA), and TH expression in the ventral tegmental area (VTA) and zona incerta (ZI). Furthermore, males displayed decreased D1R mRNA expression in the NAcc, whereas females showed slightly increased D2R expression in the amygdala. These results demonstrate that providing or received alloparental care can promote partner preference formation in monogamous species and that these changes are associated with altered OT and dopamine levels and their receptors in specific brain regions. • Providing alloparental care promoted partner preference in monogamous species. • Providing alloparental care decreased OT expression in the PVN and LH. • Providing alloparental care increased OTR and D2R mRNA expression in the NAcc. • Receiving alloparental care increased OT expression in the PVN, MPOAa and MeA. • Receiving alloparental care increased TH expression in the VTA and ZI. [ABSTRACT FROM AUTHOR]