The herbicides 2,4-diclorophenoxiacetic and 4-chloro-2-methylphenoxyacetic acids (2,4-D and MCPA) are widely used in agricultural practices worldwide. Not only are these practices responsible of surface waters contamination, but also agrochemical industries through the discharge of their liquid effluents. In this investigation, the ability of a 2,4-D degrading Delftia sp. strain to degrade the related compound MCPA and a mixture of both herbicides was assessed in batch reactors. The strain was also employed to remove and detoxify both herbicides from a synthetic effluent in a continuous reactor. Batch experiments were conducted in a 2-L aerobic microfermentor, at 28 °C. Continuous experiments were carried out in an aerobic downflow fixed-bed reactor. Bacterial growth was evaluated by the plate count method. Degradation of the compounds was evaluated by UV spectrophotometry, gas chromatography (GC), and chemical oxygen demand (COD). Toxicity was assessed before and after the continuous process by using Lactuca sativa seeds as test organisms. Delftia sp. was able to degrade 100 mg L⁻¹ of MCPA in 52 h. When the biodegradation assay was carried out with a mixture of 100 mg L⁻¹ of each herbicide, the process was accomplished in 56 h. In the continuous reactor, the strain showed high efficiency in the simultaneous removal of 100 mg L⁻¹ of each herbicide. Removals of 99.7, 99.5, and 95.0% were achieved for 2,4-D, MCPA, and COD, respectively. Samples from the influent of the continuous reactor showed high toxicity levels for Lactuca sativa seeds, while toxicity was not detected after the continuous process.

The mobility and distribution of metals in the environment is related not only to their concentration but also to their availability in the environment. Most chromium (Cr) exists in oxidation states ranging from 0 to VI in soils but the most stable and common forms are Cr(0), Cr(III), and Cr(VI) species. Chromium can have positive and negative effects on health, according to the dose, exposure time, and its oxidation state. The last is highly soluble; mobile; and toxic to humans, animals, and plants. On the contrary, Cr(III) has relatively low toxicity and mobility and it is one of the micronutrients needed by humans. In addition, Cr(III) can be absorbed on the surface of clay minerals in precipitates or complexes. Thus, the approaches converting Cr(VI) to Cr(III) in soils and waters have received considerable attention. The Cr(III) compounds are sparingly soluble in water and may be found in water bodies as soluble Cr(III) complexes, while the Cr(VI) compounds are readily soluble in water. Chromium is absorbed by plants through carriers of essential ions such as sulfate. Chromium uptake, accumulation, and translocation, depend on its speciation. Chromium shortage can cause cardiac problems, metabolic dysfunctions, and diabetes. Symptoms of Cr toxicity in plants comprise decrease of germination, reduction of growth, inhibition of enzymatic activities, impairment of photosynthesis and oxidative imbalances. This review provides an overview of the chemical characteristics of Cr, its behavior in the environment, the relationships with plants and aspects of the use of fertilizers.

Sediments deposited on road surfaces are contaminated with pollutants; the load of pollution increases from coarse to fine particles. When it rains, different fractions of the road-deposited sediments are washed off depending on the rain intensity, the slope of the catchment, and other site-specific factors. This road runoff is often treated using settling processes implemented in different types of manufactured treatment devices. These devices can be tested with well-defined artificial test materials to determine the removal efficiencies of particulate matter in a reproducible manner. However, the suitability of the currently deployed artificial test materials to represent the settling behavior of real runoff particle collectives is largely unknown. In this study, a laboratory method to measure and compare the settling behavior of artificial and real particle collectives with a reproducible particle size composition was developed. The particle collectives were obtained from different road surfaces, fractionated into sieve classes, and then recomposed into a defined particle size distribution that represented the road runoff. The settling velocity was analyzed in a modified settling column setup under constant conditions. The resulting data form a cumulative curve of the settling velocities for both artificial and real particle collectives. The main result from this work is that the tested artificial material and the recomposed real particle collectives have comparable settling behaviors despite different losses on ignition and densities.

Until recently, there have been only few published reports concerning the use of mangrove macroalgae as biomonitors to assess the estuarine metal contamination. Therefore, the present study was an effort to investigate the biomonitoring of metal contamination using mangrove macroalgae in the tropical Miri estuary of Sarawak, Malaysia. The metal concentrations (Cu, Fe, Mn, and Zn) were determined in the surface sediments, estuarine water, and six dominant macroalgae species that epiphytically grow on mangrove pneumatophores. The results showed that the scheme of metal occurrences in estuarine surface water and sediments was Fe > Mn > Zn > Cu and Fe > Zn > Mn > Cu, respectively. Among the studied metals in algal tissues, irrespective of macroalgal species, the concentration of Fe was found to be the highest. Significant positive correlations were found between Cu and Zn in all macroalgal species (except Caloglossa ogasawaraensis and Dictyota sp.), indicating the common origin of those elements. Concentrations of each of the studied metal in algal tissues varied among macroalgal species, probably because of the differences of structure, age, and growth of thallus among macroalgal species. To our knowledge, this is the first comprehensive report describing the biomonitoring of metal contamination using macroalgae from Malaysian mangrove systems.

Manure application on frozen soil, which is a common practice in the upper Midwest of USA, results in degraded soil and water quality. During snowmelt or precipitation events, water runoff carries nutrients into nearby streams and impairs the water quality. There is a need, therefore, to identify improved management of manure application in the soils. This study was conducted to assess water quality impacts associated following manure application during winter months when soil is completely covered with snow. The study site included three watersheds, named south (SW), east (CW), and north (NW) managed with a corn (Zea mays L.)-soybean (Glycine max L.) rotation located in South Dakota. The SW and NW were used as treatment, and CW as the control watershed. The treatments included manure application on the upper half of the SW and lower half of the NW, and CW received no manure application. This study showed that manure improved soil properties including infiltration rate and organic matter. Nitrogen and phosphorus losses in the surface runoff were higher from NW compared to that of SW. The CW had similar nutrient losses compared to the NW with slight differences. It can be concluded that maintaining a setback distance can help in improving the environmental quality as well as managing the agricultural wastes during the winter months.

Tetrachlorobisphenol A (TCBPA) is a widely used flame retardant and a potential endocrine disruptor. We estimated the role of the microbial community in degradation of TCBPA in river sediment from the vicinity of an E-waste processing facility. The effects of different anaerobic conditions on degradation efficiency of TCBPA were investigated, and differences in bacterial communities among these conditions were analyzed by 16S ribosomal RNA (rRNA) gene sequencing. The most effective dechlorination of TCBPA occurred under methanogenic conditions followed by electron donor-enhanced conditions and sulfate-reducing conditions with initial sulfate concentrations of 1, 10, and 20 mM. The extent of TCBPA removal under these conditions mentioned above was 65, 44, 43, 23, and 23%, respectively. 16S rRNA gene sequence analysis indicated that five dominant genera in the phylum Chloroflexi and another five species of Bacteroidetes, Chlorobi, and Firmicutes in these five systems were largely involved in TCBPA dechlorination. The initial sample had a total relative abundance of autochtonous potential dechlorinating bacteria of 12%. After 160 days, these values increased to 29–43% under above conditions. Addition of TCBPA decreased bacterial diversity. Efficiency of TCBPA degradation depends on the abundance and metabolism of dechlorinating bacterial guilds. The effectiveness of dechlorinating microbes in degradation of TCBPA was reduced by high sulfate concentrations.

With the increase in the occurrence of heavy metal polluted rice in Asian countries, food safety of rice products is of utmost concern to consumers. The current study discusses the distribution of trace elements Cr, Cu, Zn, As, Se, Cd, Hg, and Pb in Asian rice-derived food products. Three types of food products, rice noodles, rice vinegar/wine, and rice snacks, were chosen for examination. Most toxic heavy metals and metalloid such as As, Cd, Hg, and Pb were found to be within the safe level of EPA. Since rice vinegar/wine is not the staple food for people, there is no noticeable safety concern. Rice noodles and snacks are consumed with noticeable Se content and they are possible for human Se source addition. With comparison with raw rice, rice-derived food products showed better quality in terms of toxic heavy metals and metalloids. This study is for the first time reporting a thorough understanding of safety concern of rice-derived food products. It provides baselines and understanding on current levels of trace elements and heavy metals in Asian-derived rice products as affected by food processes. It would also help consumers build up confidence on the food safety of Asian rice products.

Phthalic acid esters (PAEs) is a class of refractory organic compounds, widely used as additives or plasticizers in plastic industry. PAEs are ubiquitous endocrine-disrupting pollutants and can be degraded by microorganisms. The present study described the assimilation of four PAE mixture (dimethyl, diethyl, dipropyl, and dibutyl phthalate) by two bacillus species: Bacillus thuringiensis and Bacillus cereus, isolated from different agricultural soil and their consortium. Among which, the optimal degradation of 82–96% was achieved by B. thuringiensis. This is the first report on the metabolic breakdown of four basic PAE mixture. The optimum conditions for biodegradation were found to be pH 7, temperature 30 °C, inoculum size 10 mL, and concentration 400 mg/L. Moreover, the respective biodegradation followed the first-order kinetic model. Our results proffered supplementary confirmation of the wide spectrum of PAE utilization by B. thuringiensis and suggest the possibility of applying it for the remediation of PAE contamination waste.

A treatment system combining the coal-based carbon membrane with electrochemical oxidation process was designed for the enhanced microalgae removal from simulated ballast water. The effects of various parameters including microalgae species, microalgae density, electric field intensity, and electrical conductivity on the separation performance were carried out. Fouling test was further performed for assessing the antifouling ability of the treatment system. The results showed big microalgae species tended to form a thick fouling layer on the carbon membrane, resulting in low permeate flux. High microalgae density gave rise to serious membrane fouling, which decreases the permeate flux. The treatment system showed enhanced permeate flux and fouling resistance by coupling with electrochemical oxidation process. High conductivity favored the electrochemical reactions on the surface of the carbon membrane, which reduces the clogging of the microalgae to the carbon membrane. After cleaning, the treatment system still kept high permeate flux, implying its good regeneration ability.

Despite its isolation and scarce occupation, Antarctica is not exempt from the input of contaminants related to present and past human activities. Several deleterious compounds, such as the persistent organic pollutants (POPs) may reach Antarctic ecosystems, mostly via atmospheric long-range transport and further deposition. In this context, snow and its seasonal melting water represent a sink to these pollutants and also the last compartment before they reach marine primary producers. In order to assess the concentration of a selection of organic contaminants, a PDMS headspace extraction method was chosen due to its improvement in fieldwork sampling. Samples were collected in King George Island, during the austral summers from 2007 to 2010. PBDEs and PAHs remained under the method detection limits in all of the cases, restricting data interpretation to organochlorine compounds: average Σ HCHₛ ranged from 1.46 to 4.17, HCBs from 1.36 to 3.77, Σ Dᵣᵢₙₛ from <0.35 to 4.29, Σ Cₕₗₒᵣdₐₙₑₛ from 5.72 to 13.3, Σ DDTₛ from 4.32 to 24.4, and PCBs from 132 to 156 (always in pg kg⁻¹). Results were, in general, in agreement with previous literature. Nevertheless, due to the fact that samples were collected progressively later into the austral summer, one trend can be noticed: the sum of the concentrations in both matrixes seems to decrease, with a proportional increase in snow. Some exceptions can be remarked, hypothetically linked to the passage of South American frontal systems. Finally, results for these two compartments are compatible with the exposure expected for lower trophic-level organisms from such ecosystem.