Population’s exponential growth along with drought has increased water resources limitation, especially in arid and semi-arid area. Therefore, the use of non-conventional water is an important tool for water resource management. If unconventional water has no negative impact on soil properties and water, it can be used for irrigation coupled with desertification projects. So, this paper tries to present the effect of irrigation with municipal wastewater, salt water, brackish water, and combination of salty water and wastewater on some soil properties including nitrogen, phosphorus, and potassium in Qom plain. Soil samples were taken from agricultural land treated by wastewater, saline water, brackish water, combination of salty water, and wastewater and range land as control in five treatments from depths of 0-30 and 60-90 centimeter. The results showed that wastewater has increased the amount of N, P, and K to other treatments and control area. The concentration of potassium in surface layer of area treated by combination of salty water and wastewater with amount of 459.39 ppm has the most significant difference to control and other treatments. Also, the maximum amount of nitrogen was observed in sub layer of saline and brackish water treatment with amount of 0.08 percent.

Salt marsh estuaries serve as sources and sinks for nutrients and elements to and from estuarine water, which enhances and alleviates watershed fluxes to the coastal ocean. We assessed sources and sinks of mercury in the intertidal Plum Island Sound estuary in Massachusetts, the largest salt marsh estuary of New England, using 25-km spatial water sampling transects. Across all seasons, dissolved (FHg) and total (THg) mercury concentrations in estuarine water were highest and strongly enhanced in upper marshes (1.31 ± 0.20 ng L⁻¹ and 6.56 ± 3.70 ng L⁻¹, respectively), compared to riverine Hg concentrations (0.86 ± 0.17 ng L⁻¹ and 0.88 ± 0.34 ng L⁻¹, respectively). Mercury concentrations declined from upper to lower marshes and were lowest in ocean water (0.38 ± 0.10 ng L⁻¹ and 0.56 ± 0.25 ng L⁻¹, respectively). Conservative mixing models using river and ocean water as endmembers indicated that internal estuarine Hg sources strongly enhanced estuarine water Hg concentrations. For FHg, internal estuarine Hg contributions were estimated at 26 g yr⁻¹ which enhanced Hg loads from riverine sources to the ocean by 44%. For THg, internal sources amounted to 251 g yr⁻¹ and exceeded riverine sources six-fold. Proposed sources for internal estuarine mercury contributions include atmospheric deposition to the large estuarine surface area and sediment re-mobilization, although sediment Hg concentrations were low (average 23 ± 2 μg kg⁻¹) typical of uncontaminated sediments. Soil mercury concentrations under vegetation, however, were ten times higher (average 200 ± 225 μg kg⁻¹) than in intertidal sediments suggesting that high soil Hg accumulation might drive lateral export of Hg to the ocean. Spatial transects of methylated Hg (MeHg) showed no concentration enhancements in estuarine water and no indication of internal MeHg sources or formation. Initial mass balance considerations suggest that atmospheric deposition may either be in similar magnitude, or possibly exceed lateral tidal export which would be consistent with strong Hg accumulation observed in salt marsh soils sequestering Hg from current and past atmospheric deposition.

Freshwater cyanobacteria produce highly toxic secondary metabolites, which can be transported downstream by rivers and waterways into the sea. Estuarine and coastal aquaculture sites exposed to toxic cyanobacteria raise concerns that shellfish may accumulate and transfer cyanotoxins in the food web. This study aims to describe the competitive pattern of uptake and depuration of a wide range of microcystins (MC-LR, MC-LF, MC-LW, MC-LY, [Asp3]-MC-LR/[Dha7]-MC-LR, MC-HilR) and nodularins (NOD cyclic and linear) within the common blue mussel Mytilus edulis exposed to a combined culture of Microcystis aeruginosa and Nodularia spumigena into the coastal environment.Different distribution profiles of MCs/NODs in the experimental system were observed. The majority of MCs/NODs were present intracellularly which is representative of healthy cyanobacterial cultures, with MC-LR and NOD the most abundant analogues. Higher removal rate was observed for NOD (≈96%) compared to MCs (≈50%) from the water phase. Accumulation of toxins in M. edulis was fast, reaching up to 3.4 μg/g shellfish tissue four days after the end of the 3-days exposure period, with NOD (1.72 μg/g) and MC-LR (0.74 μg/g) as the dominant toxins, followed by MC-LF (0.35 μg/g) and MC-LW (0.31 μg/g). Following the end of the exposure period depuration was incomplete after 27 days (0.49 μg/g of MCs/NODs). MCs/NODs were also present in faecal material and extrapallial fluid after 24 h of exposure with MCs the main contributors to the total cyanotoxin load in faecal material and NOD in the extrapallial fluid. Maximum concentration of MCs/NODs accumulated in a typical portion of mussels (20 mussels, ≈4 g each) was beyond greater the acute, seasonal and lifetime tolerable daily intake. Even after 27 days of depuration, consuming mussels harvested during even short term harmful algae blooms in close proximity to shellfish beds might carry a high health risk, highlighting the need for testing.

This study aimed to evaluate and qualify field-based potential risks of seven neonicotinoid and phenylpyrazole (fipronil) insecticides on aquatic invertebrates, including estuary-resident marine crustaceans. One hundred and ninety-three estuarine water samples, with salinity ranging from 0.5 to 32.7, were collected from four estuarine sites in the Seto Inland Sea of Japan, in 2015–2018 and the insecticide levels were measured. Five neonicotinoid and fipronil insecticides were successfully identified, and their occurrence varied temporally. Marine crustaceans were simultaneously harvested every month from one of the estuarine water sampling sites in 2015–2017. Three predominant crustacean species, kuruma prawn (Penaeus japonicus), sand shrimp (Crangon uritai), and mysid (Neomysis awatschensis), were captured and their seasonal presence was species independent. A 96-h laboratory toxicity study with the insecticides using kuruma prawn, sand shrimp, and a surrogate mysid species (Americamysis bahia) indicated that fipronil exerted the highest toxicity to the three crustaceans. Using both toxicity data and insecticide occurrence in estuarine water (salinity ≥10, n = 169), the potential risks on the three marine crustaceans were quantified by calculating the proportion of mixture toxicity effects (Pₘᵢₓ). The Pₘᵢₓ of seven neonicotinoids on the crustaceans was less than 0.8%, which is likely to be too low to indicate adverse effects caused by the insecticides. However, short temporal detection of fipronil (exclusively in June and July) significantly affected the Pₘᵢₓ, which presented the maximal Pₘᵢₓ values of 21%, 3.4%, and 72% for kuruma prawn, sand shrimp, and mysid, respectively, indicating a significant effect on the organisms. As for estuarine water (salinity <10), some water samples contained imidacloprid and fipronil exceeding the freshwater benchmarks for aquatic invertebrates. The present study provides novel insights into the seasonally varying risks of insecticides to estuarine crustaceans and highlights the importance of considering whether ecological risk periods coincide with crustacean presence.

Estuaries are considered hot spots for the production and emissions of nitrous oxide (N2O) and easily occur suspended particles (SPS), however, current understanding about the role of SPS in the N2O emissions from the oxic estuarine waters of lacustrine ecosystems is still limited. In this study, field investigations were performed in the estuaries of hypereutrophic Taihu Lake, and laboratory simulations were simultaneously conducted to ascertain the characteristics of N2O emissions with different SPS concentrations. The results showed that the N2O emission fluxes ranged from 9.75 to 118.38 μg m−2 h−1, indicating a high spatial heterogeneity for the N2O emissions from the estuaries of Taihu Lake. Although the dissolved oxygen (DO) concentrations were up to 7.85 mg L−1 in the estuarine waters, from where the N2O emissions fluxes were approximately three times that of the lake regions. Multiple regression model selected the total nitrogen (TN), SPS, and DO concentrations as the crucial factors influencing the N2O emission fluxes. Particularly for SPS, the simulation results showed that the N2O concentrations increased gradually with the increase in the SPS concentrations of an oxic water column containing 4 mg L−1 of NO3−-N, indicating that a high SPS concentration can accelerate the N2O emissions. It was related to the change of denitrifying bacteria population in the SPS, as evidenced by its significantly positive correlation with N2O emissions (p < 0.01). Our findings will draw attentions to the role of SPS playing in the N2O productions and emissions in eutrophic lakes, and its effect on nitrogen cycle should be considered in the future study.

We measured the temporal and spatial trajectory of oiling from the April, 2010, Deepwater Horizon oil spill in water from Louisiana's continental shelf, the estuarine waters of Barataria Bay, and in coastal marsh sediments. The concentrations of 28 target alkanes and 43 target polycyclic aromatic hydrocarbons were determined in water samples collected on 10 offshore cruises, in 19 water samples collected monthly one km offshore at 13 inshore stations in 2010 and 2013, and in 16–60 surficial marsh sediment samples collected on each of 26 trips. The concentration of total aromatics in offshore waters peaked in late summer, 2010, at 100 times above the May, 2010 values, which were already slightly contaminated. There were no differences in surface or bottom water samples. The concentration of total aromatics declined at a rate of 73% y−1 to 1/1000th of the May 2010 values by summer 2016. The concentrations inside the estuary were proportional to those one km offshore, but were 10–30% lower. The oil concentrations in sediments were initially different at 1 and 10 m distance into the marsh, but became equal after 2 years. Thus, the distinction between oiled and unoiled sites became blurred, if not non-existent then, and oiling had spread over an area wider than was visible initially. The concentrations of oil in sediments were 100–1000 times above the May 2010 values, and dropped to 10 times higher after 8 years, thereafter, demonstrating a long-term contamination by oil or oil residues that will remain for decades. The chemical signature of the oil residues offshore compared to in the marsh reflects the more aerobic offshore conditions and water-soluble tendencies of the dissolved components, whereas the anaerobic marsh sediments will retain the heavier molecular components for a long time, and have a consequential effect on the ecosystems.

With the increasing usage of titanium dioxide nanoparticles (NPs), their release into the environment makes it important to understand their transport, fate and behaviour in natural waters. In this study, aggregation and deposition of TiO2 NPs were studied during a 3-h period by using a dynamic light scattering instrument and a UV–vis spectrophotometer, respectively. TiO2 NPs were spiked in 34 lake and 5 brackish water samples at an initial concentration of 10 mg L−1. Depending on the physicochemical properties of the natural waters, TiO2 NPs exhibited different colloidal stability. In brackish waters with high salinity, TiO2 NPs were prone to aggregate and settled rapidly. Whereas under conditions of humic and humus-poor lake waters, TiO2 NPs were suspended in water column for a longer time without remarkable change in particle size and concentration. Deposition likely occurred in nutrient-rich lakes which had high amount of nitrogen and phosphorus accompanied by high values of conductivity, alkalinity, pH and turbidity. Linear regression analysis revealed the statistically significant relationships (p ≤ 0.008) between the TiO2 NPs stability and these water properties. Our study makes a better understanding of the water properties that control the aggregation and deposition of TiO2 NPs in complex natural waters.

In the context of the European Water Framework Directive, controlled flooding of lowlands is considered as a potential water management strategy to minimise the risk of flooding of inhabited areas. However, due to historical pollution and overbank sedimentation, metal levels are elevated in most wetlands, which can cause adverse effects on the ecosystem's dynamics. Additionally, salinity affects the bioavailability of metals present or imported into these systems. The effect of different flooding regimes and salinity exposure scenarios (fresh- and brackish water conditions) on Cu and Zn accumulation in the oligochaete Tubifex tubifex (Müller, 1774) was examined. Metal mobility was closely linked to redox potential, which is directly related to the prevalent hydrological regime. Flooded, and thus more reduced, conditions minimized the availability of metals, while oxidation of the substrates during a drier period was associated with a rapid increase of metal availability and accumulation in the oligochaetes.

With the phase-out of legacy halogenated flame retardants (HFRs), such as decabromodiphenyl ether (BDE-209), emerging ones, such as decabromodiphenyl ethane (DBDPE), are being widely produced. We conducted field campaigns to assess the trophic transfer of legacy and emerging HFRs in estuarine and coastal food webs of Laizhou Bay, which are located near the largest HFR manufacturing base in China. Seawater, sediment, plankton, invertebrates, and fish were collected from both sites. BDE-209 was the predominant compound in the estuary, whereas DBDPE was the main contributor to HFRs in the bay, followed by BDE-209. Invertebrates, especially bivalves and sea cucumbers, showed higher levels of BDE-209 and DBDPE than fish. The HFR levels in the organisms of the two coastal zones were comparable to each other, although their concentrations in the estuarine water were one order of magnitude higher than those in the bay. The HFR profiles in benthic organisms were similar to those in the sediments, indicating that the bioaccumulation of HFRs in coastal food webs depended on the habitat. The ΣHFR concentrations followed the order filter-feeding > carnivorous for invertebrates, and demersal non-migratory fish showed higher HFR levels than oceanodromous fish. The trophic magnification factors estimated for BDE-209, dechlorane plus, and DBDPE were lower than 1, suggesting biodilution potential in both food webs, whereas several PBDE congeners exhibited biomagnification capacity. Feeding habits, habitats, hydrophobicity, bioavailability, and metabolism may be the main factors impacting the bioaccumulation of HFRs in organisms in estuarine–coastal ecosystems of northern China.

Dechlorane Plus (DP), which has severe effects on marine ecosystems, has been proposed for listing under the Stockholm Convention as a persistent organic pollutant (POPs). This study was the first comprehensive investigation of the concentration and fate of DP in the Bohai Sea (BS) based on determination of river estuary water, river estuary sediment, surface seawater, bottom seawater, and sea sediments samples. The highest water DP levels were found in river estuary in Tianjin in North China due to the huge usage of DP in recent years, and spatial distribution analysis indicates it was mainly affected by regional high urbanization and emission of E-waste. The spatial distribution of DP in the BS was mainly affected by a combination of coastal hydrodynamics and land anthropogenic activities. On the basis of multi-box mass balance, simulations of DP in seawater showed an increase from 2014 to 2025, before leveling off at 184 pg L ⁻¹ by a constant DP input to the BS. Riverine discharge almost contributed to the total input (∼99%) and dominated the DP levels in the BS. Degradation of DP accounted for 55.3% and 78.1% of total DP output in seawater and sediment, respectively, indicating that degradation mainly affected decline of DP in the environment.