Removal of Pb and MDF from contaminated soils by EDTA- and SDS-enhanced washing

Heavy metal- and organic-contaminated sites are ubiquitous, but few studies have been conducted to address such an issue. EDTA- and SDS-enhanced washing was studied for remediation of Pb- and/or marine diesel fuel (MDF)-contaminated soils. The feasibility of recovery and reuse of EDTA and SDS, as well as the physicochemical interactions among the chemical agents, contaminants and soils were extensively investigated using batch experiments. The optimal washing sequence was then determined. The experimental results showed that EDTA could be recovered and reused for four cycles without significant loss of its chelating capacity, while the extraction capability of SDS was noticeably reduced after each reuse cycle. The free phase of marine diesel fuel (MDF) in soils physically isolated the sorbed Pb on soils and thus reducing its extraction by EDTA. The presence of SDS alone or together with low concentration of EDTA was found to enhance Pb removal probably via electrostatic interaction and dissolution of soil organic matter. However, it hindered Pb extraction by high concentration of EDTA, because of the potential formation of complexes between some strongly-bound Pb and SDS, that are more resistant to desorption. Therefore, EDTA washing followed by SDS achieved the highest Pb removal efficiency. On the other hand, MDF removal by SDS was significantly hindered by coexisting Pb in soils, probably because the formation of Pb-dodecyl sulfate (DS) complex would decrease the effective amount of SDS available for forming micelles in solution and enhance MDF sorption. EDTA alone or together with SDS could enhance MDF removal, but the residual MDF after EDTA-washing became more resistant to SDS removal. Consequently, SDS washing followed by EDTA is considered as the optimal washing sequence for MDF removal.     

Coastal Management of Failaka Island, Kuwait

Failaka Island is one of the most important islands belonging to the State of Kuwait. With the Iraqi invasion of Kuwait on 2 August 1990, most of the activies on Failaka Island were destroyed. After the liberation of Kuwait, the Kuwaiti government decided to reconstruct the island for touristic and recreational purposes. Thus, a coastal development plan was needed. The presented study is an attempt to address the coastal zone management of the island. Based on the overall geomorphological features of the island, the coast was classified into four coastal zones. The wave and tidal conditions were identified around the island. The major items controlling the coastal development were specified. Accordingly, a detailed coastal zone management map for future development was developed. The overall goal was to provide decision-makers with guidelines for the future development of the island.     

Effect of spatial variability of storm on the optimal placement of best management practices (BMPs)

It is significant to design best management practices (BMPs) and determine the proper BMPs placement for the purpose that can not only satisfy the water quantity and water quality standard, but also lower the total cost of BMPs. The spatial rainfall variability can have much effect on its relative runoff and non-point source pollution (NPSP). Meantime, the optimal design and placement of BMPs would be different as well. The objective of this study was to discuss the relationship between the spatial variability of rainfall and the optimal BMPs placements. Three synthetic rainfall storms with varied spatial distributions, including uniform rainfall, downstream rainfall and upstream rainfall, were designed. WinVAST model was applied to predict runoff and NPSP. Additionally, detention pond and swale were selected for being structural BMPs. Scatter search was applied to find the optimal BMPs placement. The results show that mostly the total cost of BMPs is higher in downstream rainfall than in upstream rainfall or uniform rainfall. Moreover, the cost of detention pond is much higher than swale. Thus, even though detention pond has larger efficiency for lowering peak flow and pollutant exports, it is not always the determined set in each subbasin.     

Droplet digital PCR is a cost-effective method for analyzing long cell-free DNA in maternal plasma: Application in preeclampsia

Objective

Long cell-free DNA (cfDNA) can be found in the plasma of pregnant women and cancer patients. We investigated if droplet digital PCR (ddPCR) can analyze such molecules for diagnostic purposes using preeclampsia as a model.

Method

Plasma samples from ten preeclamptic and sixteen normal pregnancies were analyzed. Two ddPCR assays targeting a single-copy gene, VCP, and one ddPCR assay targeting LINE-1 repetitive regions were used to measure the percentages of long cfDNA >533, 1001, and 170 bp, respectively. The LINE-1 assay was developed as guided by in silico PCR analyses to better differentiate preeclamptic and normal pregnancies.

Results

Preeclamptic patients had a significantly lower median percentage of long cfDNA than healthy pregnant controls, as determined by the LINE-1 170 bp assay (28.9% vs. 35.1%, p < 0.0001) and the VCP 533 bp assay (6.6% vs. 8.7%, p = 0.014). The LINE-1 assay provided a better differentiation than the VCP 533 bp assay (area under ROC curves, 0.94 vs. 0.79).

Conclusion

ddPCR is a cost-effective approach for unlocking diagnostic information carried by long cfDNA in plasma and may have applications for the detection of preeclampsia. Further longitudinal studies with larger cohorts are required to assess the clinical utility of this test.     

Assessment of heavy metal cations in sediments of Shing Mun River, Hong Kong

The extent of heavy metal cation contamination in the Shing Mun River has been assessed. Sediment samples were taken at eight strategic locations along the river system. The highest concentrations of copper (Cu, 1.66 mg/g), lead (Pb, 0.354 mg/g), zinc (Zn, 2.2 mg/g) and chromium (Cr, 0.047 mg/g) were found in the Fo Tan Nullah, a major tributary of the Shing Mun River. The highest concentrations of aluminum (114 mg/g) and cadmium (Cd, 0.047 mg/g) were found in the Shing Mun Main River Channel. These contaminated sediments, accumulated over the years on the river bed, could act as secondary sources of pollution to the overlying water column in the river.     

Use of environmental DNA in assessment of fish functional and phylogenetic diversity

Assessing the impact of global changes and protection effectiveness is a key step in monitoring marine fishes. Most traditional census methods are demanding or destructive. Nondisturbing and nonlethal approaches based on video and environmental DNA are alternatives to underwater visual census or fishing. However, their ability to detect multiple biodiversity factors beyond traditional taxonomic diversity is still unknown. For bony fishes and elasmobranchs, we compared the performance of eDNA metabarcoding and long-term remote video to assess species’ phylogenetic and functional diversity. We used 10 eDNA samples from 30 L of water each and 25 hr of underwater videos over 4 days on Malpelo Island (pacific coast of Colombia), a remote marine protected area. Metabarcoding of eDNA detected 66% more molecular operational taxonomic units (MOTUs) than species on video. We found 66 and 43 functional entities with a single eDNA marker and videos, respectively, and higher functional richness for eDNA than videos. Despite gaps in genetic reference databases, eDNA also detected a higher fish phylogenetic diversity than videos; accumulation curves showed how 1 eDNA transect detected as much phylogenetic diversity as 25 hr of video. Environmental DNA metabarcoding can be used to affordably, efficiently, and accurately census biodiversity factors in marine systems. Although taxonomic assignments are still limited by species coverage in genetic reference databases, use of MOTUs highlights the potential of eDNA metabarcoding once reference databases have expanded.     

Diversity and complexity in the acoustic behaviour of Dacyllus flavicaudus (Pomacentridae)

Synchronous underwater audio–video recordings and a passive acoustic detector were used to study the behaviour of Dascyllus flavicaudus. These damselfish produced sounds during six different behaviours and showed three different colour patterns while doing so. These sounds can be grouped into three classes: sounds associated with (1) fighting; (2) mating/visiting and (3) chasing and signal jumps. Moreover, the evolution of the different kinds of sound is discussed: the first calls could be a single pulse originating in teeth snapping. Modifications in the rhythm and number of pulses allowed the fish to build new messages. Daily recordings showed that sound production rates were higher at sunrise and sunset than during the day and that no sound was produced during the night. However, the kinds of call were different: sunrise sounds seemed mainly associated with mating/visiting, whereas the sounds associated with chasing and to signal jumps were mainly found at sunset.     

沉积物毒性鉴别评估技术在一个有着多重污染物输入地点的应用

沉积物毒性鉴别评估用于确定造成沉积物整体毒性测试中观察到有害效果的原因。然而在多污染物的情况下,将总体毒性划分为为不同个体污染物单独造成的毒性的方法存在很多问题。利用一个有着多重输入与相关污染物的站点数据,我们为毒性鉴别评估提出一种通过追踪毒性单位（TUs）来确定是否囊括全部毒性的方法。首先确定出沉积物整体的毒性水平,然后将毒性来源划分至几种污染物大类,例如氨类,金属,非极性有机物等。本文中毒性很大程度上来源于非极性有机物,所以在萃取沉积物之后,将萃取物重新加回稀释水中以检测毒性的复原。每一部分污染物的毒性占比由溶剂梯度测量,并进行毒性检测。目标占比由气相色谱-质谱分析得到,从而鉴定出与特定成分相关的毒性。之后对这些成分相关的毒性单位进行测定以确定可能的原因组合和是否已囊括全部毒性。数据表明毒性既与已有化合物相关,又与新兴污染物相关,而两种污染物对于总体毒性的具体贡献则随实验地点改变。
精选自Howard C. Bailey, Catherine A. Curran, Peter Arth, Bonnie P. Lo, Rich Gossett. Application of Sediment Toxicity Identification Evaluation Techniques to a Site with Multiple-Contaminants. Environmental Toxicology and Chemistry: Volume 35, Issue 10, pages 2456–2465, October 2016. DOI: 10.1002/etc.3488
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3488/full