The occurrence of microplastics in the beach sand of the Bohai Sea was investigated for the first time. The Bohai Sea is the largest Chinese inner sea and its coastal region is one of the most ...densely urbanized and industrialized zones of China. Samples from three costal sites (i.e., Bijianshan, Xingcheng and Dongdaihe) were collected, quantified and identified for microplastic analysis. Effects of sample depth and tourism activity were investigated. Surface samples (2 cm) contained higher microplastic concentrations than deep samples (20 cm). Samples from the bathing beach exhibited higher microplastic concentrations than the non-bathing beach, suggesting the direct contribution of microplastics from tourism activity. Of eight types of microplastics that were found, PEVA (polyethylene vinyl acetate), LDPE (light density polyethylene) and PS (polystyrene) were the largest in abundances. Moreover, the non-plastic items from samples were analyzed and results revealed that the majority abundance of the observed non-plastics were viscose cellulose fibers. Further studies are required to evaluate the environmental hazards of microplastics, especially as they may “act as a contaminant transporter” to the Bohai Sea ecosystem.
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•Microplastics in bathing beaches and non-bathing beaches of Bohai Sea were quantified and characterized.•The abundance of microplastics was in the range of 102.9–163.3 pieces/kg sand.•Eight chemical types of microplastics were identified.•Effects of sampling depth and tourism activity on microplastic concentration were studied.•Viscose fibers were found to be the dominant non-plastic fibers.
The abundance and chemical composition of microplastics in the beach sand of the Bohai Sea seashore were investigated.
Mariculture activities including enclosure, raft and cage cultures employ a variety of plastic gear such as fishing nets, buoyant material and net cages. The plastic gear poses a potential source of ...microplastics to the coastal environment, but relevant data on the impacts of mariculture are still limited. To this end, a semi-enclosed narrow bay (i.e., Xiangshan Bay, China) with a long-term mariculture history was investigated to assess how mariculture activities affect microplastics in seawater and sediment. The results indicated that mariculture-derived microplastics accounted for approximately 55.7% and 36.8% of the microplastics in seawater and sediment, respectively. The average microplastic abundances of seawater and sediment were 8.9 ± 4.7 (mean ± SD, n = 18) items/m3 seawater and 1739 ± 2153 (n = 18) items/kg sediment, respectively. The types of mariculture-derived microplastics included polyethylene (PE) foam, PE nets, PE film, polypropylene (PP) rope, polystyrene (PS) foam and rubber. PE foam had the highest proportion (38.6%) in the seawater samples. High usage rates and the porous structure of PE foam led to the high abundance. The average microplastic sizes of seawater and sediment are 1.54 ± 1.53 mm and 1.33 ± 1.69 mm, respectively. The spatial variations in the abundance and size of microplastics implied that the mariculture-derived microplastics in Xiangshan Bay were transported along the Bay to the open sea. The results of this study indicate that mariculture activity can be a significant source of microplastics. Further research is required to investigate how the high microplastic abundance in mariculture zone affects marine organisms, especially cultured seafood.
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•The surface seawater of Xiangshan Bay had 8.9 ± 4.7 (n = 18) microplastics per m3 seawater.•The sediments of Xiangshan Bay had 1739 ± 2153 (n = 18) microplastics per kg sediment.•Approximately 55.7% and 36.8% of the seawater and sediment microplastics were from mariculture, respectively.•The porous structure of PE foam led to high fragmentation.•Mariculture-derived microplastics in Xiangshan Bay were transported to the open sea.
Results of this work imply that the long-term intensive mariculture activities have caused a significant microplastic issue for Xiangshan Bay, China.
•The quantity and composition of microplastics are investigated at 5 sediment sites in China for the first time.•The number of microplastics was at the range of 251–436 items/50g ...sediment.•Polyesters, polyethylene terephthalate, high density polyesters and polystyrene were identified using u-FTIR.
Microplastics in sediments from the Beibu Gulf and the coastline of China Sea were investigated to evaluate the occurrence and abundance of microplastics in China for the first time. Microplastics (<5mm) were taken from sediments by a flotation method. The number of microplastics was counted by a fluorescence microscope, an instrument that is rarely used in the detection of microplastics in sediments. This instrument led to results that were satisfactory. Compared with other sampled areas, microplastics were found in massive concentrations in China. Four types of microplastics, HDPE, PET, PE and PS, were identified. The results will provide useful background information for further investigations.
To investigate the occurrence and distribution of microplastics in the southeastern coastal region of the United States, we quantified the amount of microplastics in sand samples from multiple ...coastal sites and developed a predictive model to understand the drift of plastics via ocean currents. Sand samples from eighteen National Park Service (NPS) beaches in the Southeastern Region were collected and microplastics were isolated from each sample. Microplastic counts were compared among sites and local geography was used to make inferences about sources and modes of distribution. Samples were analyzed to identify the composition of particles using Fourier transform infrared spectroscopy (FTIR). To predict the spatiotemporal distribution and movements of particles via coastal currents, a Regional Ocean Modeling System (ROMS) was applied. Microplastics were detected in each of the sampled sites although abundance among sites was highly variable. Approximately half of the samples were dominated by thread-like and fibrous materials as opposed to beads and particles. Results of FTIR suggested that 24% consisted of polyethylene terephthalate (PET), while about 68% of the fibers tested were composed of man-made cellulosic materials such as rayon. Based on published studies examining sources of microplastics, the shape of the particles found here (mostly fibers) and the presence of PET, we infer the source of microplastics in coastal areas is mainly from urban areas, such as wastewater discharge, rather than breakdown of larger marine debris drifting in the ocean. Local geographic features, e.g., the nearness of sites to large rivers and urbanized areas, explain variance in amount of microplastics among sites. Additionally, the distribution of simulated particles is explained by ocean current patterns; computer simulations were correlated with field observations, reinforcing the idea that ocean currents can be a good predictor of the fate and distribution of microplastics at the sites sampled here.
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•Microplastics were detected from sand samples in each of the sampled Southeastern NPS units, United States.•Microplastic abundances among sites were highly variable.•Polyethylene terephthalate (PET) was dominant in the composition of microplastics.•About 68% of the fibers tested were composed of man-made cellulosic materials such as rayon.•A Regional Ocean Modeling System model was successfully applied to predict the spatiotemporal distribution of particles.
The necessity to eliminate nickel (Ni) from wastewater stems from its environmental and health hazards. To enhance the Ni adsorption capacity, this research applied a copper sulfate-ammonia complex ...(tetraamminecopper (II) sulfate monohydrate, Cu(NH
)
SO
·H
O) as a modifying agent for a Phragmites australis-based activated carbon preparation. The physiochemical properties of powdered activated carbon (PAC) and a modified form (Cu(NH
)
-PAC) were examined by measuring their surface areas, analyzing their elemental composition, and using Boehm's titration method. Batch experiments were conducted to investigate the impact of various factors, such as Ni(II) concentration, contact time, pH, and ionic strength, on its substance adsorption capabilities. Additionally, the adsorption mechanisms of Ni(II) onto activated carbon were elucidated via Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The findings indicated that modified activated carbon (Cu(NH
)
-PAC) exhibited a lower surface area and total volume than the original activated carbon (PAC). The modification of PAC enhanced its surface's relative oxygen and nitrogen content, indicating the incorporation of functional groups containing these elements. Furthermore, the modified activated carbon, Cu(NH
)
-PAC, exhibited superior adsorption capacity relative to unmodified PAC. Both adsorbents' adsorption behaviors conformed to the Langmuir model and the pseudo-second-order kinetics model. The Ni(II) removal efficiency of PAC and Cu(NH
)
-PAC diminished progressively with rising ionic strength. Modified activated carbon Cu(NH
)
-PAC demonstrated notable pH buffering and adaptability. The adsorption mechanism for Ni(II) on activated carbon involves surface complexation, cation exchange, and electrostatic interaction. This research presents a cost-efficient preparation technique for preparing activated carbon with enhanced Ni(II) removal capabilities from wastewater and elucidates its underlying adsorption mechanisms.
It is well known that chloride ions could affect the oxidation kinetics and mechanism of contaminant based on SO
4
•−
in the wastewater. Here, the degradation of an organic acid, fumaric acid (FA), ...was investigated in the presence of chloride (0–300 mM) by the Fe(II)/peroxymonosulfate (Fe(II)/PMS) system. A negative impact of chloride was observed on the rates of FA degradation. The degree of inhibitory effect was higher in Fe(II)/PMS addition order. Some chlorinated byproducts were identified during the FA oxidation process in the presence of Cl
−
by the ultraperformance liquid chromatography and quadrupole-time of flight mass spectrometer (UPLC-QTOF-MS). With the increasing content of Cl
−
, an accumulation of adsorbable organic halogen (AOX), an increase in acute toxicity, and an inhibition of mineralization were observed. According to the results of kinetic modeling, the production and transformation of oxidative species were dependent on Cl
−
dosage and reaction time. SO
4
•−
was supposed to be the main radical for FA degradation with Cl
−
concentration below 5 mM, whereas Cl
2
•−
was primarily responsible for the depletion of FA at Cl
−
> 5 mM. A possible degradation pathway of FA was discussed. This study reveals the potential environmental risk of organic acid and is necessary to explore useful strategies for ameliorating the treatment of chloride-rich wastewater.
Trace copper ion (Cu(II)) in water and wastewater can trigger peroxymonosulfate (PMS) activation to oxidize organic compounds, but it only works under alkaline conditions. In this work, we found that ...the presence of chloride could significantly accelerate the oxidation of Acid Orange 7 (AO7) by the Cu(II)/PMS process at a wide pH range (4.0–9.0). The observed pseudo-first-order rate constant
k
for AO7 oxidation was linearly correlated with the increased Cl
−
concentration (0–300 mM). An increase in mineralization rate was observed in the presence of Cl
−
, while the overall mineralization was quite low. Decomposition of PMS facilitated when Cl
−
concentration or pH value increased. Based on the scavenger experiments and electron paramagnetic resonance (EPR) measurement, the mechanism of Cu(II)-catalyzed PMS oxidation process in the presence of Cl
−
was proposed as both the radical and non-radical pathway, and
1
O
2
was the reactive oxygen species in the Cu(II)/PMS system. Finally, a possible degradation pathway of AO7 was elucidated. The feasibility of in situ utilizing high salinity and trace cupric species to accelerate the degradation of organic pollutants by the Cu(II)/PMS process in water and wastewater was demonstrated. However, the identification of undesired chlorinated by-products reminds us of cautiousness in assessing the application of Cu(II)/PMS system under chloride-rich environment. The findings of this work provide a simple and efficient approach to apply PMS in the remediation of refractory organic contaminants in the presence of trace cupric species under a high salinity environment with a wide range of pH.
Lateglacial and Holocene summer sea-surface temperature (SST) variability in the northern North Atlantic was reconstructed based on diatom records from two sediment cores from the North Icelandic ...shelf. The temperature changes are discussed in relation to palaeoceanographic circulation patterns and past climatic changes. Modern diatom data from surface sediments from around Iceland and Southeast and West Greenland, with known modern environmental variables, were used as the basis for the quantitative reconstruction of summer SST. The results show that summer SSTs varied during both the Lateglacial and the Holocene, but the amplitude of SST variations during the Lateglacial was greater than that during the Holocene. No pronounced warm or cool events were recorded on the North Icelandic shelf during the GI-1e to GI-1a events (Bølling-Allerød) and the GS-1 event (Younger Dryas). The changes in SST were possibly caused by major changes in the ocean circulation pattern around Iceland, and by minor variations in the interaction between the cold and warm currents in the region. Comparison of the reconstructed summer SSTs with other marine records from the North Atlantic suggests an antiphase relationship between the oceanic climatic responses off North Iceland and in the eastern North Atlantic during the Lateglacial and the earliest part of the Holocene (the Preboreal).
•Reconstructed summer SSTs off North Iceland during the Lateglacial and Holocene.•The amplitude of the Lateglacial SSTs was greater than that during the Holocene.•An antiphase relationship between the SSTs from the western&eastern North Atlantic.
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•Hydrophobic contaminants in coking wastewater were removed selectively.•Biodegradability of coking wastewater increased by selective adsorption.•High TOC removal achieved for coking ...wastewater after selective adsorption.•Non-π functional group is critical for selective removal of hydrophobic compound.
As a typical industrial wastewater, coking wastewater is characterized as high organic load, complicated composition and strong biological inhibition. Based on the analysis between organic composition and toxicity contribution of coking wastewater, a selective removal for targeting hydrophobic contaminants was conducted by organic modified acid-vermiculites (Chlorotrimethylsilane modification, CTMS-V; and Chlorotriethysilane modification, CTES-V), powdered activated carbon (PAC) and XAD-16 polymer adsorbent. Binary solution containing hydrophilic (phenol) and hydrophobic (diethyl phthalate, DEP) compounds was employed to evaluate the performance of selective adsorption then coking wastewater was further tested. Results of binary adsorption indicated that the average adsorption percentages of DEP for PAC, XAD-16, CTMS-V and CTES-V were 32.6±11.1%, 50.8±17.4%, 68.7±22.6%, 75.5±27.4% (mean±standard deviation, n=5) at varying phenol:DEP ratios (10–100, mol:mol). Coking wastewater treated by PAC, XAD-16 CTMS-V and CTES-V had a decrease of chemical oxygen demand (COD) at 24.6±3.0%, 11.3±1.5%, 4.4±0.08% and 6.8±1.1%. For biochemical oxygen demand (BOD5), PAC and XAD-16 gave a decrease of 47.5±5.6% and 7.8±1.4%, whereas CTMS-V and CTES-V gave an increase of 36.7±4.1% and 57.2±4.6%, respectively. The resulting BOD5:COD were 0.21±0.03, 0.31±0.04, 0.42±0.05 and 0.50±0.05 after treatment by PAC, XAD-16, CTMS-V and CTES-V, respectively. Post incubation of treated coking wastewater showed that the residual TOC after ten-day incubation were 73.1±1.5%, 77.9±3.5%, 73.2±3.7% and 59.2±3.0% for PAC, XAD-16 CTMS-V and CTES-V, respectively. The non-π functional surface (i.e., –CH3 and –CH2CH3) of modified acid-vermiculites played a critical role for capturing hydrophobic compounds from the solution with high concentration of hydrophilic competitive compounds.
This paper reports on the development of organovermiculite-based adsorbent for removing Congo Red (CR), a model anionic dye, from aqueous solution. The organovermiculite was prepared using hexadecyl ...trimethylammonium bromide (HDTMAB) with variations in cation exchange capacity (CEC) and was then characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results from the adsorption experiments showed that with the organic modification of 50, 100, and 200% CEC, the adsorption capacity of vermiculite towards CR was greatly improved from 2.6 to 74.07, 175.44 and 192.31
mg/g, respectively, at 298
K. The adsorption isotherm experiment was conducted at different temperatures (298, 308 and 318
K), and it was found that the uptake of CR increased with increasing temperature. Langmuir and Freundlich isotherm models were applied and the Langmuir model was found to fit the equilibrium data better. The adsorption kinetics was found to follow the pseudo-second-order model. In addition, various thermodynamic parameters such as changes in enthalpy, entropy, and the Gibbs free energy were calculated, showing adsorption to be an endothermic yet spontaneous process. The results indicated that the organovermiculite may be an effective adsorbent for the removal of anionic dyes from wastewater.
