Using silkworm excrement to restore vegetation and soil ecology in heavily contaminated mining soils by multiple metal(loid)s: A recyclable sericulture measure

Arsenic accumulation and reproductive toxicity in freshwater snail (Pomacea canaliculata)

This study aimed to investigate the tissue-specific accumulation patterns of arsenic (As) and the potential toxicological effects of As on the oviposition of a globally distributed aquatic invertebrate, the apple snail (Pomacea canaliculata). An eight-compartment physiologically based pharmacokinetic (PBPK) model was utilized to simulate the distribution and depuration kinetics of arsenite and arsenate in the snails. Modeling and biotransformation suggested that intestine-stomach was the main uptake site for As and plays an important role in maintaining the balance of As species. Liver and kidney were the accumulation and biotransformation sites, while shell was the main storage site. Moreover, compared with arsenite, arsenate was more prone to accumulate in the organs (intestine-stomach, head-foot, kidney, gonad, shell, heart, and hemolymph). Excretion through excrement is likely the primary mechanism contributing to the low accumulation of As and the subsequent rapid decline in As concentrations observed in various organs during the depuration period. Furthermore, our findings revealed a stimulating effect of As on the oviposition of P. canaliculata. Specifically, a concentration of 500 μg L-1 of arsenite in water significantly increased the oviposition rate by 36.88 %. These findings suggest a behavioral response and changes in reproductive patterns under As exposure. The increased egg production observed in response to As exposure provides insights into the adaptive mechanisms of this species in contaminated habitats.

Influence of biochar derived from Cd polluted silkworm excrement on the phytoavailability of Cd in a paddy soil and its accumulation in mulberry

Developing sericulture industry is a promising model for the utilization of soils heavily contaminated with cadmium (Cd), but the management of polluted silkworm excrement (SE) becomes challenging. This study aimed to evaluate the effects of the SE biochar (SB) with Cd (SB-Cd) and without Cd (SB-Cd free) on the chemical properties of paddy soil, the mulberry leaf quality and the accumulation of Cd in mulberry. The soil incubation experiments showed that the two SBs all raised the acidic soil pH (20.24 %∼49.97 %) significantly (P < 0.05) with the increasing SB addition rates. The two SBs increased the soil cation exchange capacity (CEC) and played an essential role in reducing the phytoavailability of Cd. The pot experiment elucidated the two SBs all promoted the growth of mulberry, increased the crude protein content and the chlorophyll content, reduced the total sugar content in leaves. The Cd concentrations in root, stem, leaf were decreased with the increase of SB respectively, but no significant differences were found between the same additions of SB-Cd free and SB-Cd. The use of SB-Cd for remediation of the Cd polluted soils could be a reasonable method to address the Cd polluted SE.

Safe utilization and remediation potential of the mulberry-silkworm system in heavy metal-contaminated lands: A review

Mulberry cultivation and silkworm rearing hold a prominent position in the agricultural industries of many Asian countries, contributing to economic growth, sustainable development, and cultural heritage preservation. Applying the soil-mulberry-silkworm system (SMSS) to heavy metal (HM)-contaminated areas is significant economically, environmentally, and socially. The ultimate goal of this paper is to review the main research progress of SMSS under HM stress, examining factors affecting its safe utilization and remediation potential for HM-contaminated soils. HM tolerance of mulberry and silkworms relates to their growth stages. Based on the standards for HM contaminants in various mulberry and silkworm products and the bioconcentration factor of HMs at different parts of SMSS, we calculated maximum safe Cd and Pb levels for SMSS application on contaminated lands. Several remediation practices demonstrated mulberry's ability to grow on barren lands, absorb various HMs, while silkworm excreta can adsorb HMs and improve soil fertility. Considering multiple factors influencing HM tolerance and accumulation, we propose a decision model to guide SMSS application in polluted areas. Finally, we discussed the potential of using molecular breeding techniques to screen or develop varieties better suited for HM-contaminated regions. However, actual pollution scenarios are often complex, requiring consideration of multiple factors. More large-scale applications are crucial to enhance the theoretical foundation for applying SMSS in HM pollution risk areas.