An integrated approach using chemical ecological risk assessment and multi-integrated biomarker indexes approach to assess pollution: A case study of Ruditapes philippinarum in four bays on the Shandong Peninsula in China.

Considering the ecological risks of polycyclic aromatic hydrocarbons (PAHs) to the marine environment, it is urgent to find scientific and effective monitoring methods. In this study, an integrated approach combining chemical ecological risk assessment and multi-integrated biomarker indexes approach was used to assess the marine environment. Samples included seawater, sediments, and clam Ruditapes philippinarum were collected from four bays on the Shandong Peninsula, China in the four seasons of 2019. The concentrations, composition, potential sources, and ecological risk of PAHs were investigated in seawater and sediments. Risk quotient (RQ) and sediment quality guidelines (SQGs) were calculated to assess the ecological risks of PAHs in seawater and sediment, respectively. And then, clam Ruditapes philippinarum's multi-level biological response, including its ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), superoxide dismutase (SOD), lipid peroxidation (LPO), and acetylcholinesterase (AChE) were investigated in-depth, by which multi-integrated biomarker indexes approach were calculated to evaluate marine environmental quality. Taken together, the results showed that the concentration of PAHs was in good agreement with the response of biomarkers, and the usefulness of the combined use of chemical ecological risk assessment and integrated biomarker indexes to assess PAHs pollution was verified.

Integration of chemical and biological methods: A case study of polycyclic aromatic hydrocarbons pollution monitoring in Shandong Peninsula, China.

Polycyclic aromatic hydrocarbons (PAHs), as persistent toxic substances (PTS), have been widely monitored in coastal environment, including seawater and sediment. However, scientific monitoring methods, like ecological risk assessment and integrated biomarker response, still need massive researches to verify their availabilities. This study was performed in March, May, August and October of 2018 at eight sites, Yellow River estuary (S1), Guangli Port (S2), Xiaying (S3), Laizhou (S4), Inner Bay (S5), Outer Bay (S6), Hongdao (S7) and Hongshiya (S8) of Shandong Peninsula, China. The contents of 16 priority PAHs in local seawater and sediment were determined, by which ecological risk assessment risk quotient (RQ) for seawater and sediment quality guidelines (SQGs) were calculated to characterize the PAHs pollution. Meanwhile, multiple biomarkers in the digestive gland of clam Ruditapes philippinarum were measured to represent different biological endpoints, including ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST), sulfotransferase (SULT), superoxide dismutase (SOD) and lipid peroxidation (LPO), by which integrated biomarker response (IBR) was calculated to provide a comprehensive assessment of environmental quality. Taken together, these results revealed the heaviest pollution at S2 as both PAHs concentrations and biomarkers responses reflected, and supported the integrated biomarker response as a useful tool for marine environmental monitoring, through its integration with SQGs.

Underwater wireless optical communication using an arrayed transmitter/receiver and optical superimposition-based PAM-4 signal.

In this work, we propose an underwater wireless optical communication (UWOC) system using an arrayed transmitter/receiver and optical superimposition-based pulse amplitude modulation with 4 levels (PAM-4). At the transmitter side, we design a spatial summing scheme using a light emitting diode (LED) array, which is divided into two groups in a uniformly interleaved manner. With on-off keying (OOK) modulation for each group, optical superimposition-based PAM-4 can be realized. It has enhanced tolerance to the modulation nonlinearities of LEDs. We numerically investigate the feasibility of the proposed spatial summing scheme in various underwater channels via Monte Carlo simulation. With the increase of divergence angle of LEDs and link distance, the optical power distribution tends to be more uniform at the reception plane. It can significantly relax the requirement on the link alignment. Furthermore, we conduct a proof-of-concept experiment employing two blue LEDs. A multi-pixel photon counter (MPPC), containing an array of single-photon avalanche diodes (SPADs), is used as the detector. It has a much higher sensitivity and can further relax the requirement for pointing. Over a 2-m tap water channel, data rates of 6.144 Mb/s, 8.192 Mb/s, and 12.288 Mb/s were achieved by using the PAM-4 signal generated by optical superimposition, within a 2.5-MHz system bandwidth. With 0.570-mg/L Mg(OH)2, the measured optical power is just 12.890 µW after a 2-m underwater channel. The corresponding bit error rate (BER) of the 12.288-Mbs PAM-4 signal is 2.9 × 10-3, which is still below the forward error correction (FEC) limit of 3.8 × 10-3. It implies that the UWOC system based on the high-sensitivity MPPC with array structure has superior power efficiency and robustness.

A novel chemical sensor with multiple all-solid-state electrodes and its application in freshwater environmental monitoring.

Freshwater quality detection is important for pollution control. Three important components of water quality are pH, ammonia and dissolved H2S and there is an urgent need for a high-precision sensor for simultaneous and continuous measurement. In this study, all-solid-state electrodes of Eh, pH, NH4 + and S2- were manufactured and mounted to a wireless chemical sensor with multiple parameters. Calibration indicated that the pH electrode had a Nernst response with slope of 53.174 mV; the NH4 + electrode had a detection limit of 10-5 mol/L (Nernst response slope of 53.56 mV between 10-1 to 10-4 mol/L). Ag/Ag2S has a detection limit of 10-7 mol/L (Nernst response slope of 28.439 mV). The sensor was cylindrical and small with low power consumption and low storage demand to achieve continuous in-situ monitoring for long periods. The sensor was tested for 10 days in streams at Trawsgoed Dairy farm in Aberystwyth, UK. At the intensively farmed Trawsgoed, the concentration of NH4 + in the stream rose sharply after the application of slurry to adjacent fields. Further, the stream was overhung with extensive vegetation and exhibited changes in pH, which correlated with photosynthetic activity. Measurements of S2- were stable throughout the week. Our data demonstrate the applicability of our multiple electrode sensor.

N2O emission in temperate seagrass meadows: Fluxes, pathway and molecular mechanism.

Seagrass meadows act as filters for nitrogen in coastal areas, but whether they are a source or sink for N2O has been still controversy. Additionally, the production pathways of N2O as well as the microbial driving mechanism in seagrass meadows are seldom reported. In this study, the air-sea fluxes, sediment release potential, and production pathway of N2O in a temperate Zostera marina and Z. japonica mixed meadow were investigated by using gas chromatography and 15N isotopic tracing methods. The qPCR and metagenome sequencing were used to compare the difference in functional gene abundance and expression between seagrass vegetated and non-grass sediments. The results showed that the N2O air-sea fluxes in the meadow ranged from -1.97 to -1.77 nmol m⁻2 h⁻1, which was slightly lower in the seagrass region than in the adjacent bare region. Seagrass sediment N2O release potential dramatically increased after warming and nitrogen enrichment treatments. Heterotrophic nitrification was firstly investigated in seagrass meadows, and the process (26.80%-62.41%) and denitrification (37.55%-72.83%) contributed significantly to N2O production in the meadow, affected deeply by sediment organic content, while the contribution of autotrophic nitrification can be neglected. Compared with the bare sediments, the ammonia monooxygenase genes amoA, amoB and amoC, and nitrite oxidoreductase genes nxrA and nxrB, as well as nitrite reductase gene nirS and nitric oxide reductase gene norB were down-regulated, while the nitrous oxide reductase gene nosZ was up-regulated in the seagrass sediments, explaining less N2O emission in seagrass regions from the perspective of molecular. The nosZII-bearing bacteria like Bacteroidia, Polyangia, Anaerolineae, and Verrucomicrobiae could play important roles in N2O reduction in the seagrass meadow. The result is of great significance for highlighting the ability of seagrass meadows to mitigate climate changes.

Typhoon-induced stormwater drives nutrient dynamics and triggers phytoplankton blooms in Laizhou Bay, China.

In this study, we investigated the hydrological and ecological impacts of heavy rainfall caused by the storm Rumbia and Typhoon Lekima on Laizhou Bay (LZB) through land‒sea synchronous field surveys, online remote sensors, and simulated enclosure experiments. Within two weeks of Rumbia, approximately 9% and 16% of the annual riverine total nitrogen (TN) and total phosphorus (TP) fluxes, respectively, were transported to the LZB and the proportions were 17% and 35%, respectively, for Lekima. The land use on the watersheds increased the rates of land-derived nutrient loading and altered their biogeochemical forms. Consequently, the average concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) in the LZB increased by 2.6 and 1.0 times post-Rumbia and by 3.5 and 1.3 times post-Lekima, respectively. Relatively lower salinity and temperature, sudden increases in DIN, and strengthened coastal currents stimulated the growth of highly adaptable and small diatoms, resulting in the first diatom blooms. Subsequently, a bloom of Noctiluca scintillans formed.

Investigating the levels, spatial distribution, and trophic transfer patterns of short-chain chlorinated paraffins in the Southern Bohai Sea, China.

The marine environment of the southern Bohai Sea is severely polluted by short-chain chlorinated paraffins (SCCPs). To improve understanding of how SCCPs occur and of how they migrate, are transformed, and transferred in this area, we collected seawater, sediment, and organism samples, and determined the SCCP contents using a new approach based on high-resolution mass spectrometry. The ΣSCCP concentrations in the seawater, sediment, and organism samples ranged from 57.5 to 1150.4 ng/L, 167.7-1105.9 ng/g (dry weight), and 11.4-583.0 ng/g (wet weight), respectively. Simulation of the spatial distribution of SCCPs using Kriging interpolation showed that SCCPs were markedly influenced by land-based pollution. Substantial quantities of SCCPs were transported to the marine environment via surface runoff from rivers that passed through areas of major SCCP production. Once discharged from such rivers into the Bohai Sea, these SCCPs were further dispersed under the influence of ocean currents. Furthermore, the logarithmic bioaccumulation factor that varied from 2.12 to 3.20 and the trophic magnification factor that reached 5.60 (r2 = 0.750, p < 0.01) suggest that organisms have the ability to accumulate and biomagnify SCCPs through the food chain, which could potentially present risks to both marine ecosystems and human health.

Carbon sequestration from refractory dissolved organic carbon produced by biodegradation of Saccharina japonica.

Using macroalgae cultures to sequester carbon has been proposed in recent years. Yet the key mechanism of carbon sequestration-how carbon in degrading biomass is converted into refractory dissolved organic carbon (RDOC) remains poorly understood. The process of producting RDOC via biomass degradation of Saccharina japonica, the most productive algae in China, was thus studied in the laboratory. Most of the carbon in the kelp biomass was converted to dissolved inorganic carbon (DIC) by bacterial respiration. Only 7.8% of the carbon in the kelp biomass was converted into labile DOC, semi-labile or semi-refractory DOC, and refractory DOC in turn. The enrichment of DIC resulted in hypoxic conditions in the water. For the hypoxia in the experiment, the sulfur-degrading bacteria Campylobacteria and Bacteroidia became the dominant bacterial classes, which were the key drivers for the transformation of labile DOC to semi-labile or semi-refractory DOC. Then, semi-labile or semi-refractory DOC was converted to RDOC, driven by the sulfite-reducing bacteria Clostridia and Kapabacteria. Finally, 0.3% of the carbon content in kelp was transformed into RDOC. The resulting RDOC, which was rich in sulfur and nitrogen elements, increased the molecular diversity and average molecular weight in the water. An important finding was that the production of RDOC may be accompanied by the environmental risk of hypoxia.

Automatic kernel counting on maize ear using RGB images.

BACKGROUND: The number of kernels per ear is one of the major agronomic yield indicators for maize. Manual assessment of kernel traits can be time consuming and laborious. Moreover, manually acquired data can be influenced by subjective bias of the observer. Existing methods for counting of kernel number are often unstable and costly. Machine vision technology allows objective extraction of features from image sensor data, offering high-throughput and low-cost advantages. RESULTS: Here, we propose an automatic kernel recognition method which has been applied to count the kernel number based on digital colour photos of the maize ears. Images were acquired under both LED diffuse (indoors) and natural light (outdoor) conditions. Field trials were carried out at two sites in China using 8 maize varieties. This method comprises five steps: (1) a Gaussian Pyramid for image compression to improve the processing efficiency, (2) separating the maize fruit from the background by Mean Shift Filtering algorithm, (3) a Colour Deconvolution (CD) algorithm to enhance the kernel edges, (4) segmentation of kernel zones using a local adaptive threshold, (5) an improved Find-Local-Maxima to recognize the local grayscale peaks and determine the maize kernel number within the image. The results showed good agreement (> 93%) in terms of accuracy and precision between ground truth (manual counting) and the image-based counting. CONCLUSIONS: The proposed algorithm has robust and superior performance in maize ear kernel counting under various illumination conditions. In addition, the approach is highly-efficient and low-cost. The performance of this method makes it applicable and satisfactory for real-world breeding programs.