Enhanced release of phosphorus (P) from soils with snowmelt flooding poses a threat of eutrophication to waterbodies in cold climatic regions. Reductions in P losses with various soil amendments has been reported, however effectiveness of MgSO₄ has not been studied under snowmelt flooding. This study examined (a) the P release enhancement with flooding in relation to initial soil P status and (b) the effectiveness of MgSO₄ at two rates in reducing P release to floodwater under simulated snowmelt flooding. Intact soil monoliths were collected from eight agricultural fields from Southern Manitoba, Canada. Unamended and MgSO₄ surface-amended monoliths (2.5 and 5.0 Mg ha⁻¹) in triplicates were pre-incubated for 7 days, then flooded and incubated (4 °C) for 56 days. Pore water and floodwater samples collected at 7-day intervals were analyzed for dissolved reactive P (DRP), pH, Ca, Mg, Fe and Mn. Redox potential (Eh) was measured on each day of sampling. Representative soil samples collected from each field were analyzed for Olsen and Mehlich 3-P. Simulated snowmelt flooding enhanced the mobility of soil P with approximately 1.2–1.6 -fold increase in pore water DRP concentration from 0 to 21 days after flooding. Mehlich-3 P content showed a strong relationship with the pore water DRP concentrations suggesting its potential as a predictor of P loss risk during prolonged flooding. Surface application of MgSO₄ reduced the P release to pore water and floodwater. The 2.5 Mg ha⁻¹ rate was more effective than the higher rate with a 21–75% reduction in average pore water DRP, across soils. Soil monoliths amended with MgSO₄ maintained a higher Eh, and had greater pore water Ca and Mg concentrations, which may have reduced redox-induced P release and favored re-precipitation of P with Ca and Mg, thus decreasing DRP concentrations in pore water and floodwater.

Nowadays, the accumulation of toxic heavy metals in soil and water streams is considered a serious environmental problem that causes various harmful effects on plants and animals. Phytoremediation is an effective, green, and economical bioremediation approach by which the harmful heavy metals in the contaminated ecosystem can be detoxified and accumulated in the plant. Hyperaccumulators exude molecules called transporters that carry and translocate the heavy metals present in the soil to different plant parts. The hyperaccumulator plant genes can confine higher concentrations of toxic heavy metals in their tissues. The efficiency of phytoremediation relies on various parameters such as soil properties (pH and soil type), organic matters in soil, heavy metal type, nature of rhizosphere, characteristics of rhizosphere microflora, etc. The present review comprehensively discusses the toxicity effect of heavy metals on the environment and different phytoremediation mechanisms for the transport and accumulation of heavy metals from polluted soil. This review gave comprehensive insights into plants tolerance for the higher heavy metal concentration their responses for heavy metal accumulation and the different mechanisms involved for heavy metal tolerance. The current status and the characteristic features that need to be improved in the phytoremediation process are also reviewed in detail.

The in situ use of carbon amendments such as activated carbon (AC) and biochar to minimize the bioavailability of organic contaminants is gaining in popularity. In the first in situ experiment conducted at a Canadian PCB-contaminated Brownfield site, GAC and two types of biochar were statistically equal at reducing PCB uptake into plants. PCB concentrations in Cucurbita pepo root tissue were reduced by 74%, 72% and 64%, with the addition of 2.8% GAC, Burt's biochar and BlueLeaf biochar, respectively. A complementary greenhouse study which included a bioaccumulation study of Eisenia fetida (earthworm), found mechanically mixing carbon amendments with PCB-contaminated soil (i.e. 24 h at 30 rpm) resulted in shoot, root and worm PCB concentrations 66%, 59% and 39% lower than in the manually mixed treatments (i.e. with a spade and bucket). Therefore, studies which mechanically mix carbon amendments with contaminated soil may over-estimate the short-term potential to reduce PCB bioavailability.