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[求助]
翻譯幾句話——土壤方面
1. 題目:Association of macroaggregates and metals in coastal waters(不清楚這里的Association of翻譯成什么合適)
2. The composition and structure of marine dissolved organic matter(DOM) are important features that can affect the rates and extent of its degradation (Kujawinski et al., 2004) and aggregation into colloids—aggregates and macrogels (Verdugo et al., 2004).(不清楚colloids—aggregates and macrogels翻譯成什么合適 )
3. Macroaggregates (macrogels) occurring episodically in the northern Adriatic, offer a rare opportunity to study interactions between marine organic macromolecules and metals and metalloids (Me). Macrogels are formed by agglomeration of dissolved heteropolysaccharides, mostly of phytoplankton origin. Filtration and centrifugation were used to discriminate between macrogel matrix and interstitial water colloids. The interstitial fraction was then used in an incubation experiment to follow the progress of microbial degradation of colloids. The colloids were ultrafiltered through membranes and each size class of colloids (N30 kDa, 10–30 kDa and 5–10 kDa) was analyzed for metal, metalloid, organic carbon (Corg) and total nitrogen (Ntot) content. Higher Me concentrations and lower Me/Corgratios in matrix, which are an indicator of Me bound to organic matter, suggest that Me in a matrix can also be bound onto Me containing particles. All the studied Me in macroaggregate colloidal fraction, except Se, proved to be bound to large macromolecules (N30 kDa), mainly glycoproteins and aminopolysaccharides. During the rapid degradation of all, except the 5–10 kDa fraction, the Me associated with theN30 kDa fraction were markedly preserved. Consequently, the Me/Corgratios increased due to the loss of Corgand relative increase of metal-binding sites. The observed differences between our Me/Corgratios and the Irving–Williams series can be explained by variable background concentrations of the studied Me in the northern Adriatic. Comparison between Me levels in macroaggregate colloids and dissolved marine colloids, considered to be macroaggregate precursors, revealed similar values. Distribution coefficients (Kd)between colloidal and truly dissolved Me were lower than Kdfor particulate matter, suggesting that organic colloids, including macroaggregates, exhibit rather weak Me binding capacity and that Me are not distributed homogenously in the various particle pools in the northern Adriatic coastal waters |
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